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.

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)

El desafio en la dosificación de colistin: actualización de las recomendaciones disponibles / The challenge in colistin dosing: updating available recommendations

Resumen Las polimixinas están disponibles desde la década de los 60; sin embargo, debido a sus efectos adversos su uso ha sido reservado para el tratamiento de infecciones provocadas por bacterias multi-resistentes. El aumento en la experiencia clínica adquirida en los últimos años y la literatura médica publicada han planteado dudas respecto de la información entregada del producto, poniendo en manifiesto la necesidad de actualizar las recomendaciones posológicas, su farmacocinética y la información farmacocinética/farmacodinámica. Además, las diferencias en cuanto a concentración y dosis entre los distintos productos del colistín pueden dar lugar a errores de indicación/administración y suponer un riesgo para los pacientes. El año 2013, la Agencia Europea de Medicamento (EMA) encargó al Comité de Productos Medicinales para uso Humano (CHPM) la revisión de los datos disponibles y que formulara recomendaciones actualizadas del uso de colistín. Dicho procedimiento arrojó un primer informe en 2014. Esta revisión destaca los aspectos críticos de seguridad y eficacia, revisa los recientes avances farmacocinéticos y de estabilidad, las formas farmacéuticas disponibles en Chile, proporcionando los esquemas actualmente recomendados por agencias sanitarias y expertos en el tema para distintos escenarios clínicos.

Polymyxins have been available since the 1960s, however, because of their adverse effects, their use has been reserved for the treatment of infections caused by multiresistant bacteria. The increase in the clinical experience acquired in recent years and the published medical literature have raised doubts about the information provided by the product, indicating the need to update dosage recommendations, pharmacokinetics and pharmacokinetic/pharmacodynamic information (PK/PD). In addition, differences in concentration and dose between the different products of colistin may lead to errors of indication/administration and pose a risk to patients. In 2013, the European Medicines Agency (EMA) commissioned the Committee for Medicinal Products for Human Use (CHPM) to review available data and to make updated recommendations on the use of colistin. This procedure yielded a first report in 2014. This review highlights critical safety and efficacy aspects, reviews the recent pharmacokinetic and stability advances, the available pharmaceutical forms in Chile, providing the schemes currently recommended by health care agencies and experts in the field.

Evaluación de la susceptibilidad directa desde hemocultivos positivos utilizando el sistema Vitek 2: comparación de dos protocolos rápidos / Evaluation of antimicrobial susceptibility testing directly from positive blood cultures using the Vitek 2 system: comparison of two rapid protocols

Antimicrobial susceptibility testing using Vitek® 2 (bioMérieux) cards inoculated directly from positive blood cultures was compared with the standard method for gramnegative rods. Two different protocols for the inoculum preparation were evaluated. Protocol 2 was faster and easier to perform. Rapid susceptibility testing was accurate and reduced time to results in 24 h.

Se comparó el ensayo de susceptibilidad a los antimicrobianos utilizando las tarjetas Vitek® 2 (bioMérieux) inoculadas directamente de hemocultivos positivos con el método estándar para bacilos gramnegativos. Se evaluaron dos protocolos diferentes para la preparación del inóculo. El segundo protocolo fue más rápido y fácil de realizar. Las pruebas de susceptibilidad rápida fueron precisas y redujeron el tiempo de los resultados en 24 h.

Factores asociados a nefrotoxicidad por polimixina B en un hospital universitario de Neiva, Colombia. 2011-2015 / Risk factors for acute kidney injury in patients treated with polymyxin B experience from 139 cases at a tertiary university hospital in Colombia

Background: The rise of infections caused by multidrug-resistant Gram negative bacilli (MDR-GNB), added to paucity of newer therapy, have led to increase polymyxin B use, despite adverse renal toxicity profile. Aim: To determine the incidence and risk factors associated to acute kidney injury (AKI) and polymyxin B use, in patients with infections caused by MDR-GNB. Methods: A retrospective cohort, with a nested case-control study of adults who received polymyxin B for more than 48 hours at a tertiary university hospital in Colombia (2011-2015) was performed. AKI was defined by AKIN criteria. Results: Of 139 patients included in our study, 102 were male with median age of 49 years (IQR:28-64). Sixty-one patients (44%) developed AKI. Independent risk factors for development of AKI included: total polymyxin B daily dose (OR = 2.19, 95% CI, 1.04-4.64); length of stay at ICU (OR = 1.03, 95% CI, 1.00-1.06); nosocomial infection (OR = 6.43, 95% CI, 2.12, -19.47); and vasopressor use (OR = 5.38, 95% CI, 2.40-12.07). Mortality was higher among AKI-patients (58.6%) compared with non-AKI patients (25.6%) (p = 0.001). Conclusion: In this study, the rate of AKI associated to polymyxin B use was greater than reported in studies from last decade, and associated with increased mortality. AKI associated to polymyxin B use is likely multifactorial and aggravated by the critically ill state of patients suffering nosocomial infections caused by mdr-gnb.

Introducción: El surgimiento de infecciones graves causadas por bacilos gramnegativos multi-resistentes (BGN-MR), sumado a la carencia de nuevas opciones terapéuticas efectivas, ha llevado a retomar el uso de polimixina B, a pesar de su perfil de nefrotoxicidad. Objetivo: Determinar la incidencia y factores relacionados con el desarrollo de nefrotoxicidad asociada al uso de polimixina B, en pacientes adultos con infecciones causadas por BGN-MR. Materiales y Métodos: Estudio observacional, analítico, tipo cohorte histórica, con un análisis de casos y controles anidado, realizado en un hospital universitario de tercer nivel de Colombia entre 2011 y 2015, en pacientes que recibieron polimixina B intravenosa por más de 48 h. Resultados: De 139 pacientes incluidos en el estudio, 61 (44%) desarrollaron falla renal aguda por criterios AKIN. Los factores de riesgo independientes para nefrotoxicidad fueron: dosis diaria de polimixina B (OR 2,19; IC 95% 1,04-4,64), días de estancia en UCI (OR 1,03; IC 95% 1,00-1,06), presencia de infección nosocomial (OR 6,43; IC 95% 2,12-19,47) y requerimiento de fármacos vasopresores (OR 5,38; IC 95%: 2,40-12,07). Conclusión: La tasa de nefrotoxicidad observada en pacientes que recibieron polimixina B es considerable; su origen probablemente multifactorial y agravada por estado crítico de pacientes con infecciones nosocomiales por BGN-MR.

Bacilos gramnegativos no fermentadores en agua embotellada: susceptibilidad antimicrobiana y formación de biopelículas / Non fermenting Gram negative bacilli in bottled water: antimicrobial susceptibility and biofilms formation

El agua puede ser un vehículo para agentes patógenos y oportunistas portadores de multiresistencia y con capacidad de formar biopelículas (CFB). Se evaluó la presencia de indicadores microbiológicos y bacilos gramnegativos no fermentadores (BGNNF) en agua potable envasada y se estudió la susceptibilidad antimicrobiana y la CFB de los mismos. Se seleccionaron al azar 50 muestras de 250 mL obtenidos de envases de agua potable (20 L), provenientes de igual número de hogares. A cada muestra le fue realizado recuento de heterótrofos aerobios (vertido en placa), coliformes totales y termotolerantes (filtración por membrana), CFB (microplaca) y susceptibilidad antimicrobiana (Kirby-Bauer). El 92% y el 84% de las muestras presentaron coliformes totales y termotolerantes respectivamente, valores por encima de lo establecido en la Gaceta Oficial Venezolana N.° 36.395, mientras que el 86% presentó heterótrofos aerobios con cuentas >100 UFC/mL. El mayor porcentaje de BGNNF aislados pertenecía al complejo Acinetobacter baumannii/calcoaceticus (29,3%), seguido de Pseudomonas aeruginosa (17,4%), con moderada capacidad de formar biopelículas. No hubo asociación significativa entre la resistencia antimicrobiana y la CFB (p>0,05). Un porcentaje elevado de las muestras, no se ajustó a los parámetros microbiológicos establecidos en Gaceta, por lo que no se garantiza la inocuidad de las mismas.

Water can be a vehicle for multiresistant carrier pathogenic and opportunist agents with biofilm forming capacity (BFC). The presence of microbiological indicators and non fermenting Gram negative bacilli (NFGNB) was evaluated in bottled drinking water, as well as their antimicrobial susceptibility and BFC. Fifty 250 mL drinking water samples were randomly selected from 20 L drinking water bottles from the same number of homes. Each sample was tested for aerobic heterothrophics (discharged in a plate) counts, total and thermo tolerant coliforms (membrane filtration), BFC (microplate) and antimicrobial susceptibility (Kirby-Bauer). The results showed that 92% and 84% of the samples carried total and thermo tolerant coliforms respectively, values above those established in the Venezuelan Official Gazette N.o 36,395, while 86% presented aerobic heterothrophics with counts >100 CFU/mL. The highest percentage of isolated NFGNBs belonged to the Acinetobacter baumannii/calcoaceticus complex (29.3%), followed by Pseudomonas aeruginosa (17.4%) which has a moderate biofilm formation capacity. There was no significant association between antimicrobial resistance and the BFC (p>0.05). A high percentage of the samples were not adjusted to the biological parameters established in the Official Government Gazette; therefore, it is not possible to guarantee their safety.

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.

Microorganismos inusuales en placa subgingival de pacientes con periodontitis crónica / Unusual microorganisms in subgingival plaque of patients with chronic periodontitis

Fundamento: en ambientes subgingivales de pacientes con periodontitis crónica se han encontrado microorganismos inusuales que incluyen bacilos entéricos gramnegativos y levaduras. En estos pacientes la terapia mecánica o antimicrobiana puede ser ineficiente para tratar o controlar la enfermedad periodontal. La característica que comparten los microorganismos inusuales es la de ser patógenos oportunistas, ya que aprovechan las condiciones de inmunodepresión para originar o agravar una enfermedad. Objetivo: presentar la prevalencia de microorganismos inusuales en placa subgingival de pacientes con periodontitis crónica en una población colombiana. Método: se evaluaron 76 pacientes sistémicamente sanos que asistieron a las clínicas odontológicas de la Facultad de Odontología de la Universidad de Antioquia. Las muestras subgingivales se procesaron mediante cultivo. Resultados: se observaron bacilos entéricos gramnegativos en 20 (26.31 %) pacientes y levaduras en 10 (13.2 %). Conclusiones: estos hallazgos tienen implicaciones terapéuticas importantes que deben tenerse en cuenta para el manejo de los pacientes con enfermedades periodontales.

Background: subgingival environment of patients with chronic periodontitis have been found unusual microorganisms including Gram-negative enteric bacilli and yeasts. Mechanical or antimicrobial therapy in these patients may be inefficient to treat or to control periodontal disease. The common feature unusual microorganisms share is to be opportunistic pathogens, taking advantage of immunosuppression conditions to cause or aggravate the disease. Objective: to present the prevalence of unusual microorganisms in subgingival plaque of patients with chronic periodontitis in a Colombian population. Method: 76 systemically healthy patients who were presented in the dental clinic at the Dental School of Antioquia University were evaluated. Subgingival samples were processed by cultivation. Results: enteric Gram-negative bacilli in 20 patients and yeasts in 10 were observed. Conclusions: these findings have important therapeutic implications that must be taken into account for patients management with periodontal diseases.

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.

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.

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.

Colistín en infecciones nosocomiales por bacilos gramnegativos pan-resistentes / Intravenous colistin in the treatment of infections due to pan-resistant Gram negative bacilli

La emergencia de bacilos gramnegativos pan-resistentes ha obligado a la reutilización progresiva de colistín. Objetivo: Describir la experiencia clínica con este compuesto. Metodología: Se efectuó un análisis retrospectivo de todos los tratamientos con colistín endovenoso administrados por más de 48 horas, analizando datos clínicos, microbiológicos, la respuesta terapéutica y evolución hasta el egreso. Resultados: Se aplicaron 24 tratamientos entre junio de 2005 y septiembre de 2006. Colistín endovenoso fue utilizado en eventos de neumonía asociada a VM (n = 10; 41,7 por ciento), colecciones o abscesos (12,5 por ciento), bacteriemias, neumonía no asociada a VM e infección urinaria (4,2 por ciento cada una, respectivamente). El tratamiento fue iniciado en promedio a 3,2 (± 2,85) días desde el diagnóstico de infección. Todos los pacientes tenían infecciones por Pseudomonas aeruginosa o Acinetobacter baumannii. Se evaluó la susceptibilidad por E-test en once aislados (CIM90 3,6 µg/mL, rango 0,38 a 4 µg/mL). Una cepa (9 por ciento) presentó resistencia. Se observó una respuesta favorable en 50 por cientoo de los casos (n = 12) con recaída en cinco de estos casos (41,7 por ciento). El único factor asociado a fracaso fue la presencia de neumonía (p = 0,04). Se observó erradicación en ocho casos (33,3 por ciento) y persistencia en once (45,8 por ciento). En cinco casos el resultado microbiológico no fue evaluable. Sobrevivió a la hospitalización 45,5 por ciento de los pacientes (n = 10). No se observó nefrotoxicidad. Conclusiones: Colistín endovenoso es un compuesto seguro para el tratamiento de infecciones por bacilos gramnegativos pan-resistentes. Sin embargo, su eficacia terapéutica es limitada, especialmente, entre aquellos pacientes tratados por neumonía.

Emergence of panresistant gram negative bacilli has lead to the progressive reintroduction of intravenous colistin. Aim: To describe the clinical experience observed with this compound. Methodology: A retrospective analysis was performed for all treatments lasting ≥ 48 hours. Medical records were analyzed to obtain clinical parameters and microbiological data, evaluate clinical response and evolution until discharge. Main results: 24 treatments lasting ≥ 48 hours were applied between June 2005 and September 2006. Intravenous colistin was indicated to treat cases of ventilator-associated (VA) pneumonia (n = 10; 41.7 percent), abscess or collections (12.5 percent), bloodstream infections, non-VA pneumonia or urinary tract infections (4.2 percent each one, respectively). Treatment was initiated on average at 3.2 days (± 2.85) from diagnosis of infection. All courses were microbiologically-guided, and involved P. aeruginosa or A. baumannii isolates. Susceptibility was evaluated by E-test in 11 isolates (MIC90 3.6 µg/mL, range 0.38 to 4 µg/mL). One isolate was resistant to colistin (9 percent). A favorable response was observed in 12 treatments (50 percent) with a relapse in 5 cases (41.7 percent). Being treated for pneumonia was the only factor associated to failure, (p = 0.04) Eradication was documented in 8 cases (33.3 percent) and persistence in 11 (45.8 percent). In 5 cases a microbiological follow-up was not available. Survival at time of discharge was 45.5 percent. (n = 10) None of the treatment courses was associated with nefrotoxicity. Conclusions: Intravenous colistin is a safe compound useful to treat various nosocomial infections due to pan-resistant gram negative bacilli. Nonetheless, its clinical efficacy is limited, especially among patients treated for nosocomial pneumonia.

Integrones y su relación con el fenotipo de resistencia en bacilos gramnegativos aislados en el Hospital Torres Galdames de Iquique, Chile / Integrons and their relationship with resistance phenotype in Gram negative bacilli isolated in the Hospital Torres Galdames, Iquique, Chile

La resistencia antimicrobiana es codificada por algunos elementos genéticos que generan un flujo horizontal, particularmente, en ambientes que están sometidos a una fuerte presión selectiva, como ocurre en el ambiente hospitalario. En tal sentido, los bacilos gramnegativos, en el último tiempo, han cobrado importancia como agentes de infección nosocomial. Objetivo. Investigar la presencia de integrones en aislados clínicos de bacilos gramnegativos y su relación con el fenotipo de resistencia, Material y Métodos. Se analizaron 88 aislados clínicos de distintos servicios del Hospital Torres Galdames, durante el período: junio a diciembre de 2004. Fueron identificadas de acuerdo con su perfil bioquímico y se determinó la susceptibilidad a antimicrobianos mediante el método de difusión en agar. La presencia de integrones se detectó mediante RPC. Se realizó un análisis de cluster para estudiar la relación entre el fenotipo de resistencia y la presencia de integrones. Las cepas fueron genotipificadas mediante ERIC-PCR. Resultados. Dieciocho por ciento de las cepas aisladas correspondió a Proteus mirabilis, 17 por ciento a Escherichia coli y 32 por ciento a bacilos gramnegativos no fermentadores. La mayoría de los aislados presentó una elevada resistencia a los antimicrobianos evaluados: ampicilina 83 por ciento, cefalotina 82 por ciento, ceftriaxona 82 por ciento, ciprofloxacina 81 por ciento, gentamicina 81 por ciento y cotrimoxazol 82 por ciento. De las 88 cepas, 75 por ciento presentó integrones, siendo más común la clase 2. Los resultados del análisis de cluster no revelaron una clara relación entre la presencia de éstos y el perfil de resistencia para los antimicrobianos ensayados. Con la información disponible no fue posible relacionar la presencia de integrones con un determinado patrón de resistencia. Los patrones de bandas obtenidos con la técnica de ERIC-PCR revelaron una gran variedad genética entre las cepas analizadas, definiendo...

The antimicrobial resistance is coded in genetic elements which generate a horizontal flow of information, particularly in conditions that are under strong selective pressure like the nosocomial environment. In that sense, in the last decades, gram negative bacilli have become important agents of nosocomial infection. In order to investigate the presence of integrons among clinical isolates of gram negative bacilli and their relationship with their resistance profile, we studied 88 strains isolated from clinical specimens of different wards of the Hospital Torres Galdames, during the June-December period, 2004. They were identified according to biochemical tests. The antimicrobial susceptibility was evaluated by agar diffusion method. The integron presence was investigated by polymerase chain reaction (PCR). A cluster analysis was carried out to study the relationship between the presence of integrons and the resistance profile. The genotyping of the isolates was carried out by ERIC-PCR technique. Results: Of the isolated strains, 18 percent corresponded to Proteus mirabilis, 17 percent to Escherichia coli, and 32 percent to Non Fermentative Gram Negative bacilli. Most isolates presented high resistance to the antibiotics studied: 83 percent to ampicillin, 85 percent to cephalotin, 82 percent to ceftriaxone, 82 percent to ciprofloxacin, 81 percent to gentamycin and 82 percent to cotrimoxazole. Seventy-five percent of the 88 strains presented integrons. Class 2 integrons were found to be the most common. The results of the cluster analysis did not show a clear relationship among the presence of the integrons and the resistance profile. With the available information it is not possible to relate the integron presence with a certain resistance pattern. The patterns of bands obtained with the technique ERIC-PCR revealed a great genetic variety among the analyzed isolations, defining diverse genotypes, distributed in the different services...

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.