Identificación y sensibilidad antibiótica directas desde el hemocultivo positivo para bacilos gram negativos. Rendimiento comparativo de los sistemas Vitek 2C y Phoenix / Direct identification and susceptibility testing from positive blood cultures. A head-to-head performance comparison between Vitek 2C and Phoenix systems / Identificação e sensibilidade antibiótica diretas a partir da hemocultura positiva para bacilos gram negativos. Desempenho comparativo dos sistemas Vitek 2C e Phoenix

Resumen El objetivo de este estudio fue comparar los resultados de las pruebas de identificación y sensibilidad antimicrobiana obtenidos por los sistemas Vitek 2C (bioMérieux, Francia) y Phoenix (Becton Dickinson, EE.UU.) directamente a partir de hemocultivos positivos. Se realizó un estudio observacional prospectivo en el Hospital Naval Pedro Mallo de Buenos Aires, Argentina, que incluyó 70 bacteriemias monomicrobianas por gram negativos. Se obtuvo una identificación correcta por Vitek® 2C y por Phoenix del 100% y 97% respectivamente [p: no significativa (NS)]. La concordancia categórica para todos los antimicrobianos fue 97,1% y 98,1% (p: NS) con Vitek 2C y con Phoenix respectivamente. El tiempo medio para obtener un resultado fue de 10,19 h y 13,8 h (p: NS), respectivamente. Vitek 2C y Phoenix son herramientas importantes, rápidas y confiables para la identificación y las pruebas de sensibilidad realizadas directamente a partir de hemocultivos positivos.

Abstract The aim of this study was to compare the results of identification and antimicrobial susceptibility tests obtained by the Vitek 2C (bioMérieux, France) and Phoenix (Becton Dickinson, USA) systems directly from positive blood cultures. A prospective observational study was performed at the Pedro Mallo Navy Hospital in Buenos Aires, Argentina, which included 70 monomicrobial bacteremias by gram negative rods. Correct identification by Vitek® 2C and Phoenix was 100% and 97%, respectively [p: not significant (NS)]. Categorical agreement for all antimicrobials was 97.1% and 98.1% (p: NS) with Vitek 2C and Phoenix, respectively. The mean time to result was 10.19 h and 13.8 h (p: NS), respectively. Vitek 2C and Phoenix are important, rapid and reliable tools for identification and susceptibility testing when performed directly from positive blood cultures.

Resumo O objetivo deste estudo foi comparar os resultados dos testes de identificação e de suscetibilidade antimicrobiana obtidos pelos sistemas Vitek 2C (bioMérieux, França) e Phoenix (Becton Dickinson, EUA) diretamente a partir de culturas de sangue positivas. Foi realizado um estudo observacional prospectivo no Hospital Naval Pedro Mallo em Buenos Aires, Argentina, incluindo 70 bacteriemias monomicrobianas devido a gram negativos. A identificação correcta por Vitek® 2C e Phoenix obtida foi de 100% e 97% respectivamente [p: não significativo (NS)]. O acordo categórico para todos os antimicrobianos foi de 97,1% e 98,1% (p: NS) com Vitek 2C e Phoenix respectivamente. O tempo médio para obter o resultado foi de 10,19 h e 13,8 h (p: NS), respectivamente. Vitek 2C e Phoenix são ferramentas importantes, rápidas e fiáveis para a identificação e testes de sensibilidade realizados diretamente a partir de hemoculturas positivas.

Impacto de un programa de vigilancia activa y medidas de control de infecciones sobre la incidencia de bacilos gram negativos resistentes a carbapenems en una unidad de cuidados intensivos

Resumen Las infecciones hospitalarias causadas por bacilos gram negativos resistentes a carbapenems (BGNCR) están asociadas al aumento de morbimortalidad y gasto sanitario. La identificación mediante cultivos de vigilancia y las medidas de control de infecciones permiten reducir su diseminación. El objetivo del estudio fue evaluar el impacto de un programa de vigilancia integrado a protocolos de control de infecciones sobre la incidencia de BGNCR y conocer su epidemiología molecular en una unidad de cuidados intensivos. Se realizaron auditorías seguidas de un programa de cultivo de vigilancia activa y caracterización molecular de BGNCR, antes y después de la implementación de programas de prevención y control de infecciones. El screening microbiológico se realizó en medios cromogénicos; la caracterización molecular de p-lactamasas (blaKPC, bla0XA-48-like, blaVIM, blaiMP, blaNDM, blaSHV y blaCTx-M) por PCR y la tipificación molecular por PFGE y MLST para Klebsiella pneumoniae. El protocolo desarrollado permitió reducir la colonización global de 16,92% al 9,67%. La diseminación de K. pneumoniae fue a expensas de diversos clones portadores de KPC-2 asociada a BLEE SHV-2 y CTX-M-15, y distribuidos en varios secuenciotipos (ST17, ST13, ST2256, ST353); no se observó persistencia de un clon particular y ningún aislamiento presentó factores de virulencia asociados a hipervi-rulencia. Los aislamientos de Acinetobacter baumannii fueron mayoritariamente productores de IMP-1. El análisis PFGE individualizó 3 clusters, asumiendo que la diseminación fue clonal.

Abstract Hospital-acquired infections caused by carbapenem-resistant Gram-negative bacteria (CRGNB) have been increasingly reported worldwide and are associated with high rates of mortality especially in intensive care units(ICUs). Early identification through rectal surveillance cultures and implementation of infection control measures(ICM) including contact precautions, staff education on cleaning and hand hygiene may reduce the spread of these microorganisms. The aim of this work was to assess the impact of enhanced ICM on CRGNB colonization and to describe the molecular epidemiology of these bacteria in a polyvalent ICU in a tertiary level hospital. A prospective study including audits and active surveillance culture program, with molecular characterization, was conducted before and after the implementation of prevention programs and infection control measures. Microbiological screening was performed in chromogenic media; PCR targeting p-lactamases genes (ó/qkpc, óíQndm, blaviM and blaoxA-48, blasHv and ó/qctx-m), molecular typing by PFGE; and MLST in K. pneumoniae were performed. CRGNB colonization was reduced from 16.92% to 9.67% upon implementing the infection control measures. In K. pneumoniae the most frequent carbapenemase type was KPC-2 associated with SHV-2 and CTX-M-15, and was disseminated in various STs (ST17, ST13, ST2256, ST353); there was no persistence of particular clones and virulence factors showed no association with hypervirulence. IMP-1 carbapenemase predominated in A. baumannii and the PFGE analysis individualized 3 clusters, assuming that the dissemination in the ICU was clonal. The early detection of patients colo-nized with CRBGN by using epidemiological surveillance cultures and the implementation of prophylactic measures are key to reducing the incidence of these microorganisms.

Presencia de Bacilos Gram-negativos y Candida albicans en provisionales de polimetilmetacrilato (PMM)en pacientes de Clínica Integrada de la Universidad Autónoma de Asunción / Presence of Gram-negative bacilli and Candida albicans in provisional polymethylmethacrylate in patients of the Integrated Clinic of the Autonomous University of Asunción

Las resinas a base de polimetilmetacrilato (PMM) son una solución para la reposición de estructuras dentarias. Este material ha sido muy utilizado debido a su buena estética, pero las rugosidades, grietas y defectos de este material son propicios para la proliferación de microrganismos que podrían constituir un riesgo para la salud de los pacientes. Estudio observacional descriptivo de corte transversal, donde se tomaron muestras de provisorios de PMM de 20 pacientes de la cátedra de Clínica Integrada de Odontología de la Universidad Autónoma de Asunción. Los datos sobre el crecimiento de los microorganismos fueron anotados en planillas Excel para análisis estadísticos. De los 20 pacientes que participaron en esta investigación, 50% fueron de sexo femenino y 50% masculino, el promedio de edad fue de 32,35 años (DE±11,94). Se analizaron un total de 7 pónticos (6 pónticos de 3 piezas y 1 de 6 piezas) y 19 coronas unitarias, el tiempo de permanencia en boca fue de entre 4 a 20 semanas con una media de 8,6 semanas. El 65% de las muestras dio positivo al cultivo microbiológico. En algunas muestras se aislaron más de un género de microorganismos. Se aislaron 5 especies de bacterias Gram-negativas, la más frecuente fue K. pneumoniae con un 40%. Se aisló C. albicans en un 10% de las muestras. En el proceso de elección de los materiales para rehabilitación es fundamental considerar la situación global de cada paciente, pues exponerlos a un material con grandes capacidades retentivas de microrganismos conlleva un peligro

Polymethylmethacrylate (PMM) based resins are a solution for the replacement of dental structures. This material has been widely used due to its good aesthetics, but the roughness, cracks and defects of this material are propitious for the proliferation of microorganisms that could constitute a risk to the health of patients. This was a descriptive cross-sectional observational study, where samples of PMM provisionals were taken from 20 patients of the Department of Integrated Dental Clinic of the Autonomous University of Asunción. Data on the growth of microorganisms were recorded in Excel spreadsheets for statistical analysis. Of the 20 patients who participated in this research, 50% was female and 50% male, and the average age was 32.35 years (SD±11.94). Seven pontics (6 pontics of 3 pieces and 1 of 6 pieces) and 19 unit crowns were analyzed, the time spent in the mouth was between 4 to 20 weeks with an average of 8.6 weeks. Sixty-five percent of the samples tested positive in the microbiological culture. In some samples, more than one genus of microorganisms was isolated. Five species of Gram-negative bacteria were isolated, the most frequent was Klebsiella pneumoniae with 40%. Candida albicans was isolated in 10% of the samples. In the process of choosing materials for rehabilitation, it is essential to consider the overall situation of each patient, since exposing them to a material with high retention capacities of microorganisms carries a danger

Primer reporte de bacterias y dinoflagelados marinos luminiscentes del Parque Nacional Isla del Coco, Costa Rica

Introducción: La bioluminiscencia es la capacidad de ciertos organismos para transformar la energía química en energía lumínica mediante varios procesos bioquímicos. Objetivo: El aislamiento e identificación por primera vez de bacterias luminiscentes en agua marina superficial y la identificación de dinoflagelados luminiscentes marinos del Parque Nacional Isla del Coco, Costa Rica. Metodología: Se colectaron muestras de agua marina obtenida por buceo a 20 m y a nivel superficial de 13 sitios en la Isla del Coco, Costa Rica. Por otra parte, se analizaron muestras de fitoplancton colectadas desde la superficie hasta los 30 m de profundudad en los alrededores de 8 sitios de la Isla del Coco, y se determinaron varias especies luminiscentes pertenecientes a los géneros Ornithocercus y Ceratocorys. Resultados: Se logró obtener 7 aislados bacterianos luminiscentes, se identificaron y caracterizaron bioquímicamente mediante una plataforma automatizada (Vitek) con altos niveles de confianza, se ubicaron taxonómicamente dentro del género Vibrio,2 especies: V. alginolyticus y V. parahaemolyticus, además, algunos aislados presentaron resistencia al antibiótico ampicilina y 100% capacidad hemolítica. Esta investigación muestra evidencia de la presencia de especies microscópicas marinas en Isla del Coco, Costa Rica, capaces de presentar el fenómeno de la luminiscencia, por lo que profundizar en su estudio sería relevante en cuanto a la importancia de estos microorganismos en la producción de metabolitos secundarios y como indicadores de floraciones algales nocivas, por lo que se hace necesario realizar más investigación científica para determinar su potencial biotecnológico. Conclusiones: De la misma forma, los resultados obtenidos en esta investigación sugieren expandir las localidades de colecta y aislamientos de microorganismos luminiscentes, acompañado de una caracterización bioquímica y molecular, con el fin de explorar la diversidad microbiana asociada a eventos de luminiscencia y determinar los ambientes en el que estas especies se desarrollan.

Introduction: Bioluminescence is the ability of certain organisms to transform chemical energy into light energy through various biochemical processes. Objective: Isolation and identification for the first time of luminescent bacteria of superficial marine water, and the identification of marine luminescent dinoflagellates of Isla del Coco National Park, Costa Rica. Methods: Samples of seawater obtained by diving at 20 m and at a surface level of 13 sites were collected. On the other hand, phytoplankton samples collected from the surface up to 30 m deep were analyzed in the surroundings of 8 sites of Cocos Island, and several luminescent species belonging to the genera Ornithocercus and Ceratocorys were determined. Results: Seven luminescent bacterial isolates were obtained, they were identified and characterized biochemically by means of an automated platform (Vitek) with high levels of confidence, they were taxonomically located within the genus Vibrio, 2 species: V. alginolyticus and V. parahaemolyticus, in addition, some isolates presented resistance to the antibiotic ampicillin and 100% hemolytic capacity. This research shows evidence of the presence of marine microscopic species in Cocos Island, Costa Rica, capable of presenting the phenomenon of luminescence, so that further study would be relevant in terms of the importance of these microorganisms in the production of metabolites secondary and as indicators of harmful algal blooms, so it is necessary to conduct more scientific research to determine their biotechnological potential. Conclusions: In the same way, the results obtained in this investigation suggest expanding the collection and isolation of luminescent microorganisms, accompanied by a biochemical and molecular characterization, in order to explore the microbial diversity associated with luminescence events and determine the environments in which that these species develop.

Colonization and risk of infection by multidrug-resistant bacteria in hemodialysis patients: a topic of concern / Colonización e infección por bacterias multirresistentes en pacientes en hemodiálisis: un tema de preocupación

Antimicrobial resistance worsens the prognosis in patients with chronic diseases. Patients on hemodialysis have infection rates that exceed those reported in other types of patients. Colonization has been suggested as a risk factor for the development of infections. However, the majority of the studies that have evaluated this association have methodological limitations that have called into question the validity of the results; such as the lack of use of molecular methods to confirm that the colonizing species are the same as that which causes infection, the measurement of exposure only at the beginning of the study, the absence of follow-up, the evaluation of bacteremia as the only important outcome and the focus only on Staphylococcus aureus, without including other resistant bacteria of clinical importance such as multidrug-resistant Gram-negative bacteria. This lead to the need to use molecular epidemiology methods for refine the association between colonization and infection in endemic countries like Colombia, where the high rates of antimicrobial resistance demand accurate prevention strategies in susceptible patients.

La resistencia antimicrobiana empeora el pronóstico en pacientes con enfermedades crónicas. Los pacientes en hemodiálisis son un grupo particularmente afectado con porcentajes de infección bacteriana que exceden las reportadas en otro tipo de pacientes. La colonización ha sido sugerida como un factor de riesgo para el desarrollo de infecciones. Sin embargo, los estudios que han evaluado esta asociación presentan limitaciones metodológicas que han cuestionado la validez de los resultados; como la falta de utilización de métodos moleculares que confirmen que la especie que coloniza es la misma que causa infección, la medición de la exposición solo al inicio del estudio, la ausencia de seguimiento y la evaluación de bacteriemia como el único desenlace de importancia. Así mismo, la mayoría de los estudios se han enfocado solo en Staphylococcus aureus sin incluir otras bacterias resistentes de importancia clínica como son los bacilos Gram negativos multirresistentes. Lo anterior lleva a la necesidad de utilizar métodos de epidemiología molecular que permitan refinar el análisis de la asociación entre colonización e infección, más aún en países endémicos como Colombia, en el que los altos porcentajes de resistencia demandan estrategias de prevención más certeras en pacientes susceptibles.

Endocarditis infecciosa por bacilos gram negativos no HACEK. Experiencia en un centro de alta complejidad de la República Argentina (1998-2016) / Infective endocarditis due to non-HACEK gram-negative bacilli in a Level III cardiovascular center in Argentina (1998-2016)

Los bacilos gram negativos (BGN) que no pertenecen al grupo HACEK son una causa infrecuente de endocarditis infecciosa. Los aspectos epidemiológicos, diagnósticos y pronósticos de esta entidad son poco conocidos y la experiencia aún es limitada. Nuestros objetivos fueron analizar las características clínicas y microbiológicas de las endocarditis infecciosas (EI) por BGN no HACEK diagnosticadas en un centro de alta complejidad de Argentina en el período 1998-2016 y conocer su evolución hospitalaria, a fin de compararlas con las EI debidas a otros microorganismos.

Non-HACEK Gram-negative bacilli are a rare cause of infective endocarditis. Epidemiological, diagnostic and prognostic aspects of this entity are little known, and there is limited experience. The aim of this study was to analyze the clinical, microbiological and in-hospital outcomes of non-HACEK Gram negative bacilli endocarditis and to compare them with those due to other microorganisms.

Avaliação da multirresistência a antibióticos e produção de ESBL e carbapenemases em bacilos gram-negativos de efluente hospitalar e urbano / Evaluation of antibiotic multi-resistance and production of ESBL and carbapenemases in gram-negative bacilli of hospital and urban effluent

A multirresistência aos antibióticos observada em bacilos gram-negativos é um grave problema de saúde pública devido a alta morbidade e mortalidade apresentada, especialmente em instituições assistenciais de saúde. Como consequência do intenso uso de antibióticos, a multirresistência a esses fármacos é principalmente mediada por enzimas hidrolisantes, onde destaca-se as enzimas ?-lactamases, principal mecanismo de resistência aos ?-lactâmicos verificado em bacilos gram-negativos. Os esgotos de origem hospitalar e de estações de tratamento de esgoto (ETE) são considerados como reservatórios de bactérias multirresistentes pela presença de antibióticos que as selecionam e por favorecem a transmissão de determinantes de resistência. Nesse sentido, o presente estudo objetivou avaliar a multirresistência a antibióticos e a produção de enzimas ?-lactamases em bacilos gram-negativos isolados de efluente hospitalar e da estação de tratamento de esgoto, na cidade de Ribeirão Preto, SP. No hospital terciário, amostras de esgotos foram coletadas dos ambulatórios, das enfermarias e da junção do esgoto hospitalar. Na ETE, amostras foram coletadas na caixa de entrada do esgoto bruto e após ao tratamento. Dez microlitros foram semeados em ágar MacConkey, SalmonellaShigella, Cetrimide e TCBS e a identificação dos bacilos gram-negativos foi realizada pelo kit Bactray®. O teste de susceptibilidade aos antibióticos foi realizado pelo método de discodifusão em ágar. A detecção fenotípica de bacilos produtores de ESBL foi realizada pelos testes de sinergia de disco-duplo e disco combinado com ácido clavulânico, e para detecção de isolados produtores de carbapenemases foi utilizado os testes de disco combinado com ácido fenilborônico e EDTA e o teste Blue Carba. A PCR foi utilizada para amplificação dos genes codificadores de ESBL e carbapenemases. No total, 45 bacilos gram-negativos foram isolados, sendo as espécies Klebsiella pneumoniae e Pseudomonas aeruginosa as de maiores prevalências. Ampla resistência foi verificada aos antibióticos ?-lactâmicos, sendo a resistência ao aztreonam, a cefepime e a cefotaxima mais expressiva nos isolados do esgoto hospitalar, com diferenças estatisticamente significante (p<0,05). O fenótipo multidroga resistente foi atribuído a 33,3%, nos isolados exclusivamente do esgoto hospitalar, com diferença estatisticamente significante (p = 0,0025) em relação aos isolados do esgoto da ETE. Genes de ?-lactamases foram encontrados em 35,6% das bactérias, sendo o blaKPC e blaTEM os de maiores ocorrências, ambos em 17,8% dos isolados, e os genes blaSHV e blaCTX-M em 13,3% e 8,9%. Somente em um isolado de Enterobacter cloacae no esgoto tratado da ETE foi identificado o gene blaSHV, os demais isolados portadores dos genes de ?-lactamases foram encontrados no esgoto hospitalar. Os dados obtidos neste estudo são importantes levando em consideração que no Brasil o esgoto hospitalar pode ser lançado in natura na rede coletora municipal, no entanto, acredita-se que tal permissão favorece a disseminação da multirresistência bacteriana, posto que, os resultados demonstram alta frequência de bactérias portadoras de genes de resistência a antibióticos no esgoto hospitalar estudado. Assim, a implementação do tratamento de efluentes hospitalares, especialmente os de hospitais terciários, e adicionalmente ao tratamento da ETE evitaria a propagação dessas bactérias no ambiente e de impactar negativamente os recursos hídricos

Antibiotic multi-resistance observed in Gram-negative bacilli is a serious public health problem due to high morbidity and mortality, especially in health care institutions. As a consequence of the intense use of antibiotics, multi-resistance to these drugs is mainly mediated by hydrolyzing enzymes, in which ?-lactamases, the main ?-lactam resistance mechanism observed in Gramnegative bacilli, are prominent. Hospital sewage and wastewater treatment plants (WWTP) are considered reservoirs of multiresistant bacteria by the presence of antibiotics that select these bacteria and favor the transmission of resistance determinants. In this sense, the present study aimed to evaluate the antibiotics multi-resistance and the production of ?-lactamase enzymes in Gram-negative bacilli isolated from hospital effluent and the wastewater treatment plants in Ribeirão Preto city, SP. In the tertiary hospital, sewage samples from the outpatient clinics, rooms patients and the hospital sewage junction were collected. In the WWTP, raw and treated sewage were collected. Ten microliters were seeded on MacConkey, Salmonella-Shigella, Cetrimide and TCBS agar and the identification of Gram-negative bacilli was performed by the Bactray® kit. Antibiotic susceptibility test was performed by agar-diffusion method. Phenotypic detection of ESBL-producing bacilli was performed by double-disc and discsynergy tests combined with clavulanic acid, and for the detection of carbapenemase-producing isolates the combined disk tests with phenylboronic acid and EDTA and Blue Carba test were used. PCR amplification of ESBL and carbapenemases-encoding genes was used. In total, 45 Gram-negative bacilli were isolated, and Klebsiella pneumoniae and Pseudomonas aeruginosa being the most prevalent. Extensive resistance was verified to ?-lactam antibiotics and resistance to aztreonam, cefepime and cefotaxime was more pronounced in hospital sewage isolates, with statistically significant differences (p<0.05). Multidrug-resistant phenotype was attributed to 33.3% in isolates exclusively from hospital sewage, with a statistically significant difference (p = 0.0025) in relation to the sewage isolates from the WWTP. ?-lactamase genes were found in 35.6% of the bacteria, with blaKPC and blaTEM having the highest occurrences, both in 17.8% of the isolates, and the blaSHV and blaCTX-M genes in 13.3% and 8, 9%. Only in an isolate of Enterobacter cloacae in the treated sewage from WWTP was the blaSHV gene identified, the other isolates carrying the ?-lactamases genes were found in hospital sewage. The data obtained in this study are important considering that in Brazil the hospital sewage can be released in nature in municipal collection network, however, it is believed that such permission favors the dissemination of bacterial multi-resistance, since, the results show high frequency of bacteria carrying antibiotic resistance genes in the hospital sewer studied. Thus, the implementation of treatment of hospital effluents, especially those in tertiary hospitals, and in addition to the treatment of WWTP would prevent the spread of these bacteria in the environment and negatively impact water resources

Bacterial resistance in bats from the Phyllostomidae family and its relationship with unique health / Resistência bacteriana em morcegos da família Phyllostomidae e sua relação com a saúde única

The Phyllostomidae family is important among the bats found in Brazil, with several species and diverse eating habits, and is the only one to have frugivorous representatives. These bats can be found in urban and in wild life environments in search for the best reproductive and feeding conditions. The versatility of environments can be associated with the incidence and/or distribution of some diseases through pathogenic agents. The present paper has the purpose to identify the oral and perianal microbiota and to detect the bacterial resistance of frugivorous bats captured near communities inhabited by humans in the northwestern region of the state of Paraná. A total of 68 bats were captured, belonging to four species of the Phyllostomidae family, namely Artibeus lituratus, Artibeus planirostris, Carollia perspicillata and Sturnira lillium, originated from forest fragments in the micro region of Umuarama, state of Paraná. A total of 64 isolates from oral bacteria and 39 from perianal region were submitted to identification. They were later submitted to a susceptibility test to 22 human and veterinary antimicrobials. The most prevalent bacteria were Escherichia coli 33.3% in the oral region, and 35.90% in the perianal region, Enterobacter aerogenes 12.7% and 5.13%, Enterobacter agglomerans 7.9% and 10.25%, and Serratia liquefaciens 9.5% and 5.13% in the oral and perianal region respectively. All bat species studied had resistant strains, with a few of them presenting multi-resistance to antimicrobials. The species with the highest multi-resistance index to antimicrobials was Carollia perspicillata, with three strains of the oral region resistant to 15 antimicrobials; it also presented two strains in the perianal region, which were resistant to 13 and 10 antimicrobials respectively. Based on the results found, it is possible to conclude that the oral and perianal microbiota of bats is composed of several enterobacterial species resistant to one or several antimicrobials used in human and veterinarian medicine. This is an issue and a future warning for unique health, since high percentages of resistance were found against antimicrobials broadly used, such as ampicillin, amoxicillin and amoxicillin+clavulonate.(AU)

A família Phyllostomidae se destaca entre as famílias de morcegos encontrados no Brasil, com diversificadas espécies e hábitos alimentares, sendo a única a apresentar representantes frugívoros, podendo ser encontrada tanto em meio urbano, como de vida livre, em busca de melhores condições reprodutivas e alimentares. Essa versatilidade de ambientes pode estar associada à incidência e/ou distribuição de determinadas doenças por agentes patogênicos. O presente trabalho objetivou identificar a microbiota oral e perianal e detectar a resistência bacteriana em morcegos frugívoros capturados próximos às comunidades habitadas pelo homem na região noroeste do estado do Paraná. Foram capturados 68 morcegos, de quatro espécies da família Phyllostomidae, são eles Artibeus lituratus, Artibeus planirostris, Carollia perspicillata e Sturnira lillium, oriundos de fragmentos de Mata da microrregião de Umuarama, estado do Paraná. Um total de 64 isolados de bactérias da região oral e 39 da região perianal foram submetidos, identificação e posteriormente teste de susceptibilidade a 22 antimicrobianos de uso humano e veterinário. As bactérias mais prevalentes foram Escherichia coli 33,3% na região da boca e 35,90% na região perianal, Enterobacter aerogenes 12,7% e 5,13%, Enterobacter agglomerans 7,9% e 10,25% e Serratia liquefaciens 9,5% e 5,13% na região da boca e perianal, respectivamente. Todas as espécies de morcegos estudadas apresentaram cepas que foram resistentes, e algumas multirresistência aos antimicrobianos. A espécie que apresentou maior índice de multirresistência aos antimicrobianos foi Carollia perspicillata, com três cepas na região oral resistente a 15 antimicrobianos, e duas na perianal, com resistência a 13 e 10 antimicrobianos respectivamente. Baseados nos resultados encontrados, é possível concluir que a microbiota oral e perianal de morcegos, é composta por diversas espécies de enterobactérias, resistentes a um, ou vários antimicrobianos utilizados na medicina humana e veterinária, tornando-se um problema, e um alerta futuro para a saúde única, uma vez que foram encontrados elevados percentuais de resistência contra antimicrobianos utilizados em larga escala tais como ampicilina, amoxicilina e amoxicilina+clavulonato.(AU)

Bacteriemias por bacilos Gram negativos multirresistentes en neutropénicos febriles con enfermedades hematológicas / Bacteremia due to multiresistant Gram-negative bacilli in febrile neutropenic patients with hematological diseases

Las infecciones por bacilos Gram negativos multiresistentes (BGN-MR) son frecuentes en nuestro hospital. Presentan limitadas opciones terapéuticas e importante impacto en la morbimortalidad y costos. Objetivo: analizar los factoes de riesgo y evolución de las bacteriemias por BGN-MR en pacientes neutropénicos febriles con patologías hematológicas. Materiales y métodos: estudio prospectivo, descriptivo y observacional de los factores de riesgo para BGN-MR en la población descripta. Se realizó análisis univariado y multivariado de variables clínicas, epidemiológicas, microbiológicas y evolutivas. Resultados: El 27 % de los episodios de neutropenia y fiebre cursaron con bacteriemias por BGN, 42 % de ellos fueron producidos por BGN-MR. En el análisis univariado, dichas bacteriemias se asociaron al uso previo de antibióticos; a las bacteriemias de brecha y neutropenias mayores a 7 días. En el análisis multivariado la bacteriemia de brecha mantuvo su significancia estadística (P<0,001; OR: 5,17; IC 95 % 2,1-12,7). Acinetobacter spp fue el BGN-MR más frecuentemente aislado incluso en los pacientes fallecidos. No se detectó el foco en el 45,9 % de los episodios. Los tratamientos inadecuados fueron significativamente más frecuentes en los pacientes con BGN-MR y la mortalidad tanto global como atribuible también se asoció significativamente al tratamiento inadecuado de las bacteriemias por BGN-MR (P<0,04;RR: 2,46;IC 95 % 1,03-5,9 y P< 0,014; RR: 3,02; IC 95 % 1,22-0,45 respectivamente). Conclusiones: Las bacteriemias por BGN-MR son frecuentes en la población estudiada en especial los que han recibido ATB previo y en las que surgen intratratamiento ATB. Recibieron con mayor frecuencia tratamiento empírico inadecuado, lo que se asoció a mayor mortalidad...

Bacterial infections by multiresistant Gram-negative bacilli (BGN-MR) are an increasing problem in our hospital with a major impact on morbidity, mortality and costs. Objective: to analize risk factors and outcome in bacteremia due to multiresistant Gram-negative bacilli in febrile neutropenic patients with hematologic diseases. Material and Methods: We conducted a prospective, descriptive and observational study to describe the risk factors and outcome of BGN-MR bacteremia in these patients. Results: Twenty seven percent of neutropenia and fever episodes had Gram-negative bacilli bacteremia and 42 % of them were caused by BGN-MR. Previous use of antibioteics, breakthrough bacteremia and prolonged neutropenia (<7 days) were significant in univariate analysis. In multivariate analysis only breakthrough bacteremia was significant (P< 0.001; OR 5,17;IC 95 % 2.1-12.7). Acinetobactersppp was the most common BGN-MR isolated in blood-stream infections and in patients who died. The source of infections was unknown in 45,9 % of the episodes. Inadequate empirical therapy was most common in BGN-MR bacteremia and it was associated with increased overall and attributable mortality (P<0.04; RR: 2.46; IC 95 % 1.03-5.9 y P<0.014; RR: 3.02; IC 95 % 1.22-7.45). Conclusions: BGN-MR was frequent in neutropenic patients with hematological diseases specially in those exposed to antibiotics and in breakthroug bacteremia. Inappropiate antimicrobial therapy was common and is associated with adverse outcome...

Presence and antimicrobial profile of Gram-negative facultative anaerobe rods in patients with chronic periodontitis and gingivitis

La periodontitis crónica es una enfermedad infecciosa multifactorial hacen parte de la microflora subgingival. En los últimos años se han realizado estudios para valorar la presencia de bacilos Gramnegativos anaerobios facultativos (enterobacterias) y suimportancia en el desarrollo y rogresión de la periodontitis crónica. El objetivo de este estudio fue determinar la presencia de enterobacterias en pacientes con periodontitis crónica y gingivitis y conocer la susceptibilidad antimicrobiana de los aislamientosclínicos. Se realizó un estudio observacional y descriptivo en elque se incluyeron 64 pacientes con periodontitis crónica y 22 pacientes con gingivitis. Las muestras tomadas en el surco gingival con conos de papel se depositaron en caldo tioglicolato, seincubaron durante 4 horas a 37 oC y se resembraron finalmente en Agar MacConkey. En la identificación de las bacterias se utilizó el sistema API-20E (Biomerieux, France) y la susceptibilidadantimicrobiana se realizó por el método de difusión en disco. En los dos grupos se identificaron 29 especies enterobacterianas, 7 en el grupo con gingivitis y 22 en el grupo con periodontitis crónica. En el grupo de periodontitis crónica las especies masfrecuentes fueron: K. oxytoca n=5, S. liquefaciens n=4 y K.pneumoniaey E. coli con n=3. En el grupo con gingivitis, Erwiniasp tuvo la mayor frecuencia (n=2). Los aislamientos clínicos presentaron níveles muy bajos de sensibilidad a los B-lactamicosampicilina y amoxicilina/ ac.clavulanico, 17.2 y 27.6 por ciento, y la mayor sensibilidad a ciprofloxacina. En conclusión, la alta frecuencia de enterobacterias en pacientes con periodontitis debe conducir a la prevención y a desarrollar terapias mecánicas y antimicrobianas en las cuales se tengan en cuenta, como parte del tratamiento periodontal, los perfiles antimicrobianos reportados.

Prevalência de bacilos Gram-negativos não fermentadores de pacientes internados em Porto Alegre-RS / Prevalence of non-fermenting Gram-negative bacilli among inpatients from Porto Alegre-RS

INTRODUÇÃO: Os bacilos Gram-negativos não fermentadores (BGNNF) são frequentemente associados às infecções hospitalares. Além da alta incidência, esses microrganismos possuem resistência a diversos antimicrobianos. OBJETIVO: Analisar a prevalência e o perfil de resistência de BGNNF. MÉTODOS: Foram analisados 14.971 laudos de pacientes em um hospital privado de Porto Alegre-RS, no período de maio de 2006 a março de 2008, sem distinção de sexo e idade. RESULTADOS E CONCLUSÃO: Foram isoladas 326 amostras de BGNNF. As espécies mais prevalentes foram: Pseudomonas aeruginosa (65,03 por cento), Acinetobacter baumannii (16,56 por cento) e Stenotrophomonas maltophilia (9,5 por cento). Outras espécies apresentaram índices inferiores a 5 por cento. Os microrganismos foram isolados de diversos sítios infecciosos. Os materiais biológicos que apresentaram maior positividade para esses microrganismos foram o aspirado traqueal (38,34 por cento), o escarro (18,71 por cento) e a urina (15,95 por cento). A resistência bacteriana mostrou-se mais expressiva a tetraciclinas (89,57 por cento) e sulfametoxazol/trimetoprima (79,75 por cento). Os antimicrobianos mais ativos foram polimixina B, com 100 por cento de sensibilidade, e piperaciclina/tazobactam, com 75,2 por cento de sensibilidade.

INTRODUCTION: The non-fermenting Gram-negative bacilli (NFGNB) have been widely associated with nosocomial infections. Not only are these microorganisms highly prevalent but they are also highly resistant to NFGNB. OBJECTIVE: To assess the prevalence and resistance profile of non-fermenting Gram-negative bacilli. METHODS: 14.971 patient reports from a private hospital in Porto Alegre, Rio Grande do Sul, from May/2006 to March/2008 were analyzed. RESULTS AND CONCLUSION: Three hundred twenty-six samples of non-fermenting Gram-negative bacilli were isolated. The most prevalent species were Pseudomonas aeruginosa (65.03 percent), Acinetobacter baumannii (16.56 percent), and Stenotrophomonas maltophilia (9.5 percent). Other species showed rates lower than 5 percent. The microorganisms were isolated from several infectious sites and the biological materials that showed higher positivity were the following: tracheal aspirate (38.34 percent), spittle (18.71 percent) and urine (15.95 percent). Bacterial resistance was higher with tetracyclines (89.57 percent) and sulfamethoxazole/trimethoprim (79.75 percent). The most active antimicrobials were polymyxin B and piperacillin/tazobactam with 100 percent and 75.2 percent sensibility, respectively.

Criterios de ensayo, interpretación e informe de las pruebas de sensibilidad a los antibióticos en los bacilos gram negativos no fermentadores de importancia clínica: recomendaciones de la Subcomisión de Antimicrobianos de la Sociedad Argentina de Bacteriología, Micología y Parasitología Clínicas, Asociación Argentina de Microbiología / Antimicrobial susceptibility testing in clinically relevant non-fermenting gram-negative bacilli: recommendations from the Antimicrobial Agents Subcommittee of the Sociedad Argentina de Bacteriología, Micología y Parasitología Clínicas, Asociación Argentina de Microbiología

En este documento se dan a conocer una serie de recomendaciones para el ensayo, la lectura, la interpretación y el informe de las pruebas de sensibilidad a los antimicrobianos para los bacilos gram negativos no fermentadores (BGNNF) que se aíslan en humanos. Se adoptaron como base las recomendaciones internacionales, las de la Subcomisión de Antimicrobianos de la Sociedad Argentina de Bacteriología, Micología y Parasitología Clínicas y las de un grupo de expertos invitados. Se incluye, además, la nomenclatura actualizada de los BGNNF y la descripción de algunas de sus características individuales, de sus resistencias naturales o habituales a los antimicrobianos de uso clínico y de los mecanismos responsables de tales resistencias. También se indican los agentes antimicrobianos que se deberían ensayar frente a las distintas especies, con la especificación de cuáles deberían ser informados, y su ubicación estratégica en las placas de cultivo para poder detectar los mecanismos de resistencia más frecuentes y relevantes. Por último, se detallan los métodos de detección y de confirmación fenotípica de la presencia de b-lactamasas emergentes en Argentina, como las carbapenemasas clases A y B.

This document contains the recommendations for antimicrobial susceptibility testing of the clinically relevant non-fermenting gram-negative bacilli (NFGNB), adopted after conforming those from international committees to the experience of the Antimicrobial Agents Subcommittee members and invited experts. This document includes an update on NFGNB classification and description, as well as some specific descriptions regarding natural or frequent antimicrobial resistance and a brief account of associated resistance mechanisms. These recommendations not only suggest the antimicrobial drugs to be evaluated in each case, but also provide an optimization of the disk diffusion layout and a selection of results to be reported. Finally, this document also includes a summary of the different methodological approaches that may be used for detection and confirmation of emerging b-lactamases, such as class A and B carbapenemases.

Pesquisa de Acinetobacter sp e Pseudomonas aeruginosa produtores de metalo-β-lactamase em hospital de emergência de Porto Alegre, Estado do Rio Grande do Sul, Brasil / Investigation of metallo-β-lactamase-producing Acinetobacter sp and Pseudomonas aeruginosa at an emergency hospital in Porto Alegre, State of Rio Grande do Sul, Brazil

INTRODUÇÃO: O aparecimento de Pseudomonas aeruginosa e Acinetobacter sp produtores de metalo-β-lactamases (MBLs) é um desafio para os hospitais. MÉTODOS: Verificou-se a produção de MBL em cepas clínicas de Pseudomonas aeruginosa e Acinetobacter sp de um hospital de emergência de Porto Alegre pelo método de aproximação de disco e E-test MBL. Os genes bla foram pesquisados pela PCR. RESULTADOS: Duas cepas de Pseudomonas aeruginosa e oito Acinetobacter sp demonstraram fenótipo de MBLs. A amplificação do gene blaSPM-1 confirmou a enzima em P. aeruginosa.. CONCLUSÕES: Deve-se ter cautela ao avaliar testes fenotípicos utilizados na detecção rotineira de metalo-enzima.

INTRODUCTION: The appearance of metallo-β-lactamase (MBL)-producing Pseudomonas aeruginosa and Acinetobacter sp. is a challenge for hospitals. METHODS: The production of MBL in clinical isolates of Pseudomonas aeruginosa and Acinetobacter sp. From an emergency hospital in Porto Alegre was investigated using the disk approximation test and MBL E-test. The bla genes were determined using PCR. RESULTS: Two strains of Pseudomonas aeruginosa and eight of Acinetobacter sp were shown to be MBL phenotypes. Amplification of the blaSPM-1 gene confirmed the presence of the enzyme in P. aeruginosa. CONCLUSIONS: Caution is needed in evaluating phenotype tests used for routine detection of metallo-β-lactamases.

Achados bacterianos encontrados na secreção da otite média cronica: estudo comparativo entre o colesteatoma (OMCC) e a otite média cronica simples (OMCS) / Bacterial findings found in the chronic otitis media secretion: comparative study between cholesteatoma (OMCC) and simple chronic otitis media (SCOM)

Introdução: Foi feita uma comparação na frequencia com que os patogenos infectantes foram detectados na supuração causada pelo colesteatoma e pela otite crônica simples no período de 2006 a 2008. Objetivo: Fazer um estudo comparativo entre os achados bacterianos encontrados na secreção da otite crônica simples e a colesteatomatosa. Método: Foram estudados a bacterioscopia de 83 pacientes (125 orelhas) portadores de otite média crônica, sendo 43 (52 orelhas) com colesteatoma e 40 (73 orelhas) com otite crônica simples, com predominância de idade dos 16 aos 20 anos. A duração da otorreia variou entre 2 meses e 10 anos. Para a colheita do material utilizamos um equipamento bastante pratico com caldo de tioglicolato dentro e fora enviados ao laboratório por um período máximo de até 18 horas. Resultados: O S. aureus foi mais frequente na otite crônica simples, enquanto que os anaeróbios foram mais frequentes no colesteatoma. A P. aeruginosa foi mais frequente na otite crônica simples e o Corynebacterium sp. apresentou maior frequencia no colesteatoma. o S. epidermidis apareceu com frequencias iguais em ambas as doenças otológicas. Conclusão: Não encontramos mudanças notáveis na bacteriologia dessas duas doenças. Na otite crônica simples os achados mais frequentes foram S. aureus, Pseudomonas sp. e fungos. No colesteatoma os achados mais frequentes foram os Anaeróbios e o Corynibacterium sp. A frequencia de aparecimento para S. epidermidis, Klebisiela sp. e Streptococcus sp. foi igual em nosso estudo.

Introduction: This study carried out a comparison in the frequency with which the infecting pathogens were detected in the suppuration caused by cholesteatoma and simple chronic otitis media in the period from 2006 to 2008. Objective: To carry out a comparative study between the bacterial findings found in the simple and cholesteatomatous chronic otitis media secretion. Method: We studied the bacterioscopy of 83 patients (125 ears) with chronic otitis media, 43 (52 ears) with cholesteatoma and 40 (73 ears) with simple chronic otitis, and age prevalence from 16 to 20 years. The duration of otorrhea ranged between 2 months and 10 years. For collection of the material we used very practical instrument with tioglicolate broth inside and outside sent to the laboratory for a maximum period of until 18 hours. Results: The S. aureus was more frequent in the simple chronic otitis, and the anaerobic were more frequent in the cholesteatoma. The P. aeruginosa was more frequent in the simple chronic otitis and the Corynebacterium sp. presented a higher frequency in cholesteatoma. The S. epidermidis appeared with the same frequencies in both otologic diseases. Conclusion: We did not find any critical changes in the bacteriology of either disease. In the simple chronic otitis, the most frequent findings were S. aureus, Pseudomonas sp. and fungi. In the cholesteatoma, the most frequent findings were the Anaerobios and Corynibacterium sp. The frequency of S. epidermidis, Klebisiela sp. and Streptococcus sp. was the same in our study.

Uma revisão sobre metalo β lactamases: [revisão] / A review on metallo β lactamases: [revision]

A emergência e disseminação da resistência aos antimicrobianos são problemas de grande importância mundial, particularmente entre patógenos nosocomiais de importância clínica como os bacilos Gram negativos não fermentadores e membros da família Enterobacteriaceae. O principal mecanismo de resistência desses patógenos é a produção de β-lactamases, que são enzimas que hidrolisam o anel β-lactâmico impedindo assim a ação dos antimicrobianos β-lactâmicos. As β-lactamases foram dividas em quatro classes de acordo com a sua estrutura primária e podem também ser classificadas dentro de dois grupos com base no seu mecanismo catalítico, isto é, serina-β-lactamases (Classes A, C e D) e metalo-β-lactamases (Classe B). As metalo-β-lactamases (MβL) utilizam íons divalentes, comumente zinco, como co-fator para sua atividade catalítica e são atualmente uma das classes que mais merece destaque, devido à sua capacidade de hidrolisar todos os antimicrobianos β-lactâmicos, incluindo os carbapenens. Estes antimicrobianos são utilizados no tratamento de infecções causadas por bactérias Gram-negativas multirresistentes e conseguem se manter estáveis frente às serina-β-lactamases. A detecção de microrganismos produtores de MβL tem por finalidade auxiliar a Comissão de Controle de Infecção Hospitalar (CCIH) na prevenção da disseminação desse mecanismo de resistência no ambiente hospitalar e impedir que ele chegue até a comunidade, bem como enfatizar o uso racional dos antimicrobianos disponíveis para uso clínico, pois, atualmente,há poucos investimentos da indústria farmacêutica na pesquisa de novos agentes antimicrobianos.

The emergence and dissemination of antimicrobial resistance are problems of great importance worldwide, particularly between nosocomial pathogens of clinical importance such as nonfermentative Gram-negative bacilli and members of the family Enterobacteriaceae. The main mechanism of resistance these pathogens is the production of β-lactamases, which are enzymes that hydrolyzing the ring β-lactam hindering the action of antimicrobial β-lactam. The β- lactamases were classified into four classes of according its primary structure and may also be classified in two groups based on their catalytic mechanism, that is, serine-β-lactamases (Classes A, C and D) e metallo-β-lactamases (Class B). The metallo-β-lactamases (MβL) using ions divalentes, commonly zinc, as co-factor for its catalytic activity and currently represent one the most important class of enzymes, due of their ability to hydrolyze all antimicrobial β-lactam, including carbapenens, which are used in the treatment of Gram-negative bacteria multidrug-resistant and to remain stable before the serine-β-lactamases. The detection of samples producing of MβL helps infection control practioners to prevent the dissemination of this mechanism of resistance in the nosocomial environment and to prevent it come to the community, and emphasize the rational use of antimicrobial currently available for clinical use, since there are few investments in the pharmaceutical industry in search of new antimicrobial agents.

Epidemiología y factores de riesgo de mortalidad de las bacteriemias intrahospitalarias por bacilos gramnegativos / Nosocomial bloodstream infections caused by gram-negative bacilli: epidemiology and risk factors for mortality

Nosocomial bacteremia is a major cause of hospital infection, associated with high rate of morbidity and mortality, prolonged hospital stay and higher costs. However, few prospective studies analyse the prognostic factors associated with mortality of gramnegative rods bloodstream infections in hospital wards outside of intensive care units. A prospective/descriptive study was conducted from March to December 2006. All patients with nosocomial-acquired bloodstream infection due to gramnegative rods were included. Epidemiology and clinical features were analysed as potential prognostic factors for mortality. During the study period, 84 cases were detected, being A. baumannii, Burkholderia sp and E. coli the most frequent isolates, with a mortality of 48 percent>. Bacteremia derived from a high-mortality associated septic focus (RR 4.9, IC95 percent> 1.3 - 18.8) and admissionto intensive care unit (RR 4.78, IC95 percent> 1.7- 13.1) were independent variables associated with mortality. Inappropriate empirical antibiotic treatment was not associated with greater risk of mortality. Nosocomial gramnegative bloodstream infections in our series were mainly due to non-fermentative bacilli and were associated with high mortality rates when their origin was a high risk septic focus or the patient was admitted to intensive care unit.

La bacteriemia nosocomial es una causa importante de infección intrahospitalaria, asociada a alta morbi-mortalidad, pero pocos estudios examinan en forma prospectiva las bacteriemias por bacilos grammne-gativos (BGN) más allá de las áreas de cuidados intensivos. Se realizó un estudio descriptivo, prospectivo desde marzo a diciembre del 2006, reclutando todos los pacientes con bacteriemia por BGN de origen intra-hospitalario. Se analiza la epidemiología y características clínicas como potenciales factores pronósticos de mortalidad. En el período de estudio se detectaron 84 casos (los más frecuentes A. baumannii, Burkholderia sp. y E. coli), con una mortalidad de 48 por ciento. La bacteriemia derivada de un foco infecciosos asociada a alta mortalidad (RR 4.9, IC95 por ciento 1,3-18,8) y la internación en UCI (RR 4,78, IC95 por ciento 1,7-13,1) fueron variables independientes predictoras de mortalidad. El tratamiento antimicrobiano empírico inadecuado no se asoció a mayor mortalidad. La bacteriemia nosocomial por BGN en nuestra serie se debió principalmente a bacilos no fermentadores y ésta se asoció con alta mortalidad cuando el origen fue un foco de alto riesgo o el paciente se encontraba internado en la UCI.

Actividad "in vitro" de diferentes antibacterianos sobre bacilos gram-negativos no fermentadores, excluidos Pseudomonas aeruginosa y Acinetobacter spp / ‘In vitro' activity of different antimicrobial agents on gram-negative nonfermentative bacilli, excluding Pseudomonas aeruginosa and Acinetobacter spp

Los bacilos gram-negativos no fermentadores se encuentran ampliamente distribuidos en el medio ambiente. Además de causar dificultades en la identificación, a menudo presentan una marcada multirresistencia a los antimicrobianos incluyendo aquellos activos frente a Pseudomonas aeruginosa. El objetivo de este trabajo fue evaluar la actividad "in vitro" de diferentes antimicrobianos sobre 177 aislamientos de bacilos gram-negativos no fermentadores (excluidos Pseudomonas aeruginosa y Acinetobacter spp.) provenientes de especimenes clínicos. Las concentraciones inhibitorias mínimas (CIM) se determinaron por el método de dilución en agar Mueller Hinton frente a los siguientes antibacterianos: ampicilina, piperacilina, piperacilina-tazobactama, sulbactama, cefoperazona, cefoperazona-sulbactama, ceftazidima, cefepima, aztreonam, imipenem, meropenem, colistina, gentamicina, amicacina, trimetoprima-sulfametoxazol (TMS), cloranfenicol, eritromicina, rifampicina, norfloxacina, ciprofloxacina y minociclina. Sobre siete aislamientos: Sphingobacterium multivorum (2), Sphingobacterium spiritivorum (1), Empedobacter brevis (1), Weeksella virosa (1), Bergeyella zoohelcum (1) y Oligella urethralis (1) se ensayó la sensibilidad a amoxicilina-ácido clavulánico y ampicilina-sulbactama y no se determinó la actividad de cefoperazona ni de sulbactama. La multirresistencia fue comúnmente observada en los aislamientos de Stenotrophomonas maltophilia, Burkholderia cepacia, Chryseobacterium spp., Myroides spp., Achromobacter xylosoxidans y Ochrobactrum anthropi. En cambio, Pseudomonas stutzeri, Shewanella putrefaciens-algae, Sphingomonas paucimobilis, Pseudomonas oryzihabitans, Bergeyella zoohelcum, Weeksella virosa y Oligella urethralis, fueron ampliamente sensibles a los antibacterianos ensayados. Debido a la gran variabilidad observada en la sensibilidad a los antimicrobianos en las distintas especies, se hace imprescindible realizar la prueba de sensibilidad a los antibacterianos a fin de abordar la elección correcta del mismo. Debido a la marcada multirresistencia de algunas especies, surge la necesidad del desarrollo de nuevos agentes antimicrobianos que posean actividad sobre este grupo de bacterias, así como tambien la búsqueda de combinaciones sinérgicas.

Gram-negative nonfermentative bacilli (NFB) are widely spread in the environment. Besides of difficulties for identification, they often have a marked multiresistance to antimicrobial agents, including those active against Pseudomonas aeruginosa. The objective of this study was to evaluate the ‘in vitro' activity of different antimicrobial agents on 177 gram-negative nonfermentative bacilli isolates (excluding Pseudomonas aeruginosa and Acinetobacter spp.) isolated from clinical specimens. Minimum inhibitory concentrations (MIC) were determined according to the Mueller Hinton agar dilution method against the following antibacterial agents: ampicillin, piperacillin, piperacillin-tazobactam, sulbactam, cefoperazone, cefoperazone-sulbactam, ceftazidime, cefepime, aztreonam, imipenem, meropenem, colistin, gentamicin, amikacin, trimethoprim-sulfamethoxazole, chloramphenicol, erythromycin, rifampin, norfloxacin, ciprofloxacin and minocycline. Seven isolates: Sphingobacterium multivorum (2 ), Sphingobacterium spiritivorum (1), Empedobacter brevis (1), Weeksella virosa (1), Bergeyella zoohelcum (1) and Oligella urethralis (1), were tested for amoxicillin-clavulanic acid and ampicillin-sulbactam susceptibility, and susceptibility to cefoperazone or sulbactam was not determined. Multiresistance was generally found in Stenotrophomonas maltophilia, Burkholderia cepacia, Chryseobacterium spp., Myroides spp., Achromobacter xylosoxidans, and Ochrobactrum anthropi isolates. On the other hand, Pseudomonas stutzeri, Shewanella putrefaciens-algae, Sphingomonas paucimobilis, and Pseudomonas oryzihabitans, Bergeyella zoohelcum, Weeksella virosa and Oligella urethralis were widely susceptible to the antibacterial agents tested. As a result of the wide variation in antimicrobial susceptibility shown by different species, a test on susceptibility to different antibacterial agents is essential in order to select an adequate therapy. The marked multiresistance evidenced by some species, prompts the need to develop new antimicrobial agents active against this group of bacteria and to search for synergistic combinations.

Sensibilidad a colistín: evaluación de los puntos de corte disponibles en el antibiograma por difusión / Susceptibility to colistin: evaluation of breakpoints available in disk diffusion test

Las infeccionesproducidas por microorganismos multirresistentes son uno de los mayores problemas en los centros asistenciales. Frecuentemente, sólo las polimixinas muestran actividad “in vitro” frente a aislamientos de bacilos gram-negativos resistentes a los carbapenemes. Sin embargo, el National Committee for Clinical Laboratory Standards (NCCLS) no incluye, actualmente, recomendaciones para la realización de las pruebas de sensibilidad para este grupo de antibióticos. Se determinóla actividad de colistín y la correlación entre las pruebas de difusión y dilución de este antibiótico frente a 186 aislamientos contemporáneos en el Hospital de Clínicas “José de San Martín”, siguiendo las recomendaciones generales del NCCLS. Se evaluaron dos puntos de corte: NCCLS 1981 (resistente £ 8 mm y sensible > 11mm) y R. Jones 2001 (resistente £ 11mm y sensible > 14mm). Utilizando el punto de corte del NCCLS 1981 se cometieron los siguientes errores: 0,5% “minor”; 2,2% “major” y 4,4% “very major”, mientras que con el propuesto por R. Jones 2001: 18,9% “minor”; 3,8% “major” y 0,5% “very major”. En conclusión, dado que el punto de corte utilizado por R. Jones 2001 disminuye el error “very major” pero aumenta el “minor” se recomienda la utilización de la concentración inhibitoria mínima (CIM) para confirmar la sensibilidad a colistín cuando sea usada en el tratamiento de infecciones, sin embargo no se detectó resistencia a colistín con halos de inhibición > a 16 mm.

Infections produced by multidrug resistant organisms are one of the greatest problems in health centers. Often, only polymyxines show good activity “in vitro” against the carbapenem resistant gram-negative strains; but the National Committee for Clinical Laboratory Standards (NCCLS) documents do not currently provide interpretative criteria for testing the polymyxines.The antimicrobial activity ofcolistin,and the correlation betweenthe agar dilution test and disk diffusion test were evaluated against 186 gram-negative strains isolated at the Hospital de Clínicas “José de San Martín” of Buenos Aires city. All susceptibility tests were performed according to the NCCLS recommendations. Were evaluated two breakpoints, NCCLS 1981 (£ 8mm and >11mm), and R. Jones 2001 (£ 11 mm and > 14 mm). Discrepancies on interpretative category were found (0.5% minor; 2.2% major and 4.4% very major) with NCCLS 1981, and (18.9% minor; 3.8% majorand 0.5% very major) with R. Jones 2001 criteria. Conclusions. In spite of the fact that the breakpoint used by R. Jones 2001decreases the very major error but increases the minor error, according to our results we recommend the use of MIC methods to assist the therapeutic application of colistin; however resistance to colistin was not detected with zone diameters > 16mm.