Salmonella spp. in the fish production chain: a review / Salmonella spp. na cadeia produtiva do peixe: uma revisão

ABSTRACT: Salmonella spp is a pathogen responsible for severe foodborne infections, can be introduced into the fish production chain through inadequate handling or hygiene or contact with contaminated water, and is not a biological contaminant originally reported in fish. Fish microbiological safety is a concern for consumers, industries and regulatory agencies worldwide, since fish, an important food category in the international trade and often exported to several countries, can act as a vehicle for Salmonella transmission throughout the production chain. In addition, concerns regarding the misuse of antibiotics in aquaculture are also an issue, as a result of the increased isolation of resistant and multiresistant Salmonella serovars. In this review, we examined aspects associated with the microbiological risks of the presence of Salmonella spp. in fish and their implication in the aquaculture production chain. In addition, incidence and antimicrobial resistance data are presented, as well as strategies for Salmonella prevention and control in fish.

RESUMO: Salmonella spp. é um patógeno responsável por uma grave infecção alimentar que pode ser introduzida na cadeia do pescado, por meio da manipulação e higiene inadequada ou por contato do peixe com águas contaminadas. Essa bactéria não é contaminante natural no pescado. Por isso, a segurança microbiológica do pescado é uma preocupação dos consumidores, indústrias e das agências reguladoras em todo mundo, uma vez que o pescado é importante produto para comércio internacional de alimentos, sendo frequentemente exportados para vários países podendo ser veículador da transmissão de Salmonella em toda a cadeia produtiva. Outro aspecto preocupante é quanto ao uso inadequado de antibióticos na aquicultura, o que vem resultando no aumento do isolamento de sorovares de Salmonella resistentes e multidroga resistentes. Nesta revisão, são examinados aspectos associados ao risco microbiológico da presença de Salmonella spp. no pescado e sua implicação na cadeia produtiva da aquicultura. Dados sobre a incidência e resistência antimicrobiana e estratégias de prevenção e controle de Salmonella no pescado no Brasil e no mundo são apresentados e discutidos.

Detection and characterization of multidrug-resistant enterobacteria bearing aminoglycoside-modifying gene in a university hospital at Rio de Janeiro, Brazil, along three decades / Detección y caracterización de enterobacterias resistentes a múltiples fármacos, portadoras del gen modificador de aminoglucósidos en un hospital universitario de Río de Janeiro, Brasil, durante tres décadas

Introduction: Multidrug-resistant Enterobacteriaceae, particularly those resistant to gentamicin, have become one of the most important causes of nosocomial infections. Objective: We sought to investigate the presence of genes conferring resistance to aminoglycosides, specially to gentamicin, in Klebsiella pneumoniae and Escherichia coli multidrug-resistant strains isolated from different clinical materials among patients hospitalized in a university hospital in Rio de Janeiro, Brazil. Materials and methods: Ten colonization strains and 20 infection strains were evaluated during three decades (1980 to 2010) using selective media containing 8 µg/ml of gentamicin. Thirty strains were tested for antimicrobial susceptibility. Twenty two strains were subjected to plasmid DNA extraction and 12 to hybridization assays using as probe a 1.9 kb plasmid DNA fragment from one of the K. pneumoniae strains isolated from faecal samples. This fragment was sequenced and assigned to the GQ422439 GenBank record. PCR was also performed using oligonucleotides designed for aminoglycoside-modifying enzymes. Results: An accC2 acetylase, besides transposons and insertion sequences, were evidenced. Twenty-four (80%) of the isolates were positive for the aacC2 gene in agreement with antibiotic susceptibility testing profiles, indicating the persistent presence of this gene throughout the three decades. We detected high molecular weight plasmids in 54,5% of the strains. Of the tested strains, 91% showed positive signal in the hybridization assays. Conclusion: A gene codifying for one specific aminoglycoside-modifying enzyme was detected all throughout the three decades. Our data back the adoption of preventive measures, such as a more conscious use of antimicrobial agents in hospital environments, which can contribute to control the dissemination of microorganisms harboring resistance gene plasmids.

Introducción. Las enterobacterias resistentes a la gentamicina se asocian frecuentemente a infecciones hospitalarias. Objetivo. Verificar la presencia de los genes que confieren resistencia a los aminoglucósidos, específicamente a la gentamicina, en cepas de Klebsiella pneumoniae y Escherichia coli multirresistentes, obtenidas de pacientes internados en un hospital universitario de Río de Janeiro. Materiales y métodos. Se recolectaron y evaluaron 10 cepas de colonización y 20 de infección entre 1980 y 2010, utilizando medios selectivos enriquecidos con gentamicina (8 µg/ml). Se obtuvieron 30 cepas en las que se determinó la resistencia a los antibióticos por medios fenotípicos. Veintidós muestras se sometieron a extracción de ADN plasmídico y se hicieron ensayos de hibridización en 12 de ellas, usando como sonda un fragmento de ADN plasmídico de 1,9 kb obtenido de una cepa de K. pneumoniae aislada de muestra fecal. Este fragmento fue secuenciado y correspondió al registro GQ422439 del GenBank. Se verificó la presencia de genes de enzimas modificadoras de aminoglucósidos mediante reacción en cadena de la polimerasa. Resultados. En las cepas analizadas se evidenció la presencia de la acetilasa accC2, además de transposones y secuencias de inserción. Veinticuatro aislamientos (80 %) fueron positivos para el gen aacC2 en concordancia con los perfiles de sensibilidad a los antibióticos, lo que indicó su persistencia a lo largo de las tres décadas. Se detectaron plásmidos de alto peso molecular en 54,5 % de las cepas. El 91 % de las cepas analizadas mostró signos positivos en las pruebas de hibridación. Conclusión. Se detectó la persistencia de un gen codificador de una enzima modificadora de aminoglucósidos a lo largo de las tres décadas. Los resultados indican que las medidas de prevención, tales como un uso más responsable de los agentes antimicrobianos en el ambiente hospitalario, pueden contribuir al control de la diseminación de microorganismos que albergan plásmidos de genes de resistencia.

Pantoea dispersa: an unusual cause of neonatal sepsis

Neonatal septicemia is the most important cause of neonatal mortality. A wide variety of bacteria both aerobic and anaerobic can cause neonatal sepsis. Genus Pantoea is a member of Enterobacteriaceae family that inhabits plants, soil and water and rarely causes human infections, however, Pantoea dispersa has not been reported as a causative organism for neonatal sepsis. We hereby report two neonates with early onset sepsis caused by Pantoea dispersa. Early detection and appropriate antibiotic therapy can improve overall outcome of this rare infection in neonates.

Multirresistência microbiana e opções terapêuticas disponíveis / Microbial multi-resistance and available therapeutic options

JUSTIFICATIVA E OBJETIVOS: Devido ao uso irracional de antimicrobianos e a administração empírica, vários problemas de resistência microbiana surgiram como um novo desafio para a terapêutica, causando elevados índices de mortalidade. Dentre os grupos de micro-organismos relacionados a infecções resistentes destacam-se: Staphylococcus aureus resistente à meticilina e Staphylococcus aureus resistente à vancomicina, Enterococcus sp resistentes a diferentes classes de antimicrobianos, Streptococcus pneumoniae resistente à penicilina, Klebsiella pneumoniae carbapenemase, Pseudomonas aeruginosa e Acinetobacter baumanii resistentes aos carbapenêmicos e ainda as enterobactérias produtoras beta-lactamases de espectro ampliado (ESBL). O objetivo deste estudo foi rever na literatura científica a abordagem do surgimento de micro-organismos multirresistentes e as opções terapêuticas disponíveis no Brasil. CONTEÚDO: Novos antimicrobianos são lançados no mercado com o intuito de alcançar tratamento efetivo para infecções causadas por micro-organismos resistentes. Para abordar os mecanismos de resistência mais comuns, das novas opções terapêuticas disponíveis no Brasil e das novas diretrizes de uso desses fármacos. CONCLUSÃO: Enquanto o uso dos medicamentos antimicrobianos continuarem sendo de modo irresponsável e não for cumpridaa legislação para seu uso, os novos fármacos serão eficazes apenas temporariamente, fazendo constante o problema da multirresistência microbiana.

BACKGROUND AND OBJECTIVES: Due to antibiotics irrational use and the empiric administration, many microbial resistance problems become a new therapeutic challenge, causing elevated mortality rates. Among the microorganisms groups related with resistant infections are: methicillin-resistant and vancomycin-resistant Staphylococcus aureus, multi-resistant Enterococcussp, penicillin-resistant Streptococcus pneumoniae, Klebsiella pneumoniae carbapenemase, carbapenem-resistant Pseudomonas aeruginosa and Acinetobacter baumanii and extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL). The aim of this work was carry out a review of scientific literature in order to discuss the emergence of multidrug-resistant microorganism sand the therapeutic options available in Brazil. CONTENTS: New antimicrobials are launched in order to achieve effective treatment for resistant microorganisms infections. To discuss the most common resistance mechanisms, new therapeutic options available in Brazil and new guidelines for the use of these drugs. CONCLUSION: While the use of antimicrobial drugs to keep so irresponsible and the law for its use not met, the new drugs will be effective only temporarily, keeping constant the microbial multi-resistance problem.

Capacidad de los laboratorios nacionales de referencia en Latinoamérica para detectar mecanismos de resistencia emergentes / Capability of national reference laboratories in Latin America to detect emerging resistance mechanisms

Objetivo. Evaluar la capacidad de 17 laboratorios nacionales de referencia que participan en el Programa Latinoamericano de Control de Calidad en Bacteriología y Resistencia a los Antimicrobianos (LA-EQAS) para detectar mecanismos de resistencia emergentes, a saber: resistencia de enterobacterias a carbapenemes por presencia de Klebsiella pneumoniae carbapenemasa (KPC); resistencia de enterobacterias a carbapenemes por presencia de metalobetalactamasas (MBL) tipo IMP, y resistencia intermedia a vancomicina de aislamientos de Staphylococcus aureus (VISA). Métodos. Se enviaron los siguientes tres aislamientos a los 17 laboratorios participantes del LA-EQAS: Klebsiella pneumoniae OPS-161 productor de KPC, Enterobacter cloacae OPS-166 productor de IMP y S. aureus OPS-165 con resistencia intermedia a vancomicina. Se evaluó la interpretación de las pruebas de sensibilidad y detección del mecanismo de resistencia y el tamaño de los halos de inhibición (método de difusión por discos) o valor de la concentración inhibitoria mínima (CIM). Resultados. La concordancia en la detección de los mecanismos de resistencia fue de 76,4%, 73,3% y 66,7% con respecto a la cepas K. pneumoniae OPS-161, E. cloacae OPS-166 y S. aureus OPS-165, respectivamente. La concordancia entre las zonas de inhibición obtenidas por los laboratorios participantes y los rangos establecidos por el laboratorio coordinador fue aceptable en los tres aislamientos, ya que alcanzó 90,8%, 92,8% y 88,9%, respectivamente, para cada cepa. Conclusiones. La concordancia global en la detección de los mecanismos de resistencia KPC, MBL y VISA fue de 72,1%. Consideramos que los laboratorios nacionales de referencia de América Latina son capaces de reconocer estos mecanismos de resistencia emergentes y se espera que en el futuro la concordancia alcance su nivel máximo.

Objective. To evaluate the capability of 17 national reference laboratories participating in the Latin American Quality Control Program in Bacteriology and Antibiotic Resistance (LA-EQAS) to detect emerging resistance mechanisms— namely: resistance of enterobacteria to carbapenems due to the presence of Klebsiella pneumoniae carbapenemase (KPC) and metallo-beta-lactamase (MBL) type IMP, and intermediate resistance of Staphylococcus aureus isolates to vancomycin (vancomycinintermediate resistant S. aureus—VISA). Methods. The following three isolates were sent to the 17 participating LA-EQAS laboratories: KPC-producing Klebsiella pneumoniae PAHO-161, IMP-producing Enterobacter cloacae PAHO-166, and S. aureus PAHO-165 with intermediate resistance to vancomycin. Performance of each of the following operations was evaluated: interpretation of sensitivity tests, detection of the resistance mechanism, and assessment of either inhibition halo size (disk diffusion method) or minimum inhibitory concentration (MIC). Results. Concordance in the detection of resistance mechanisms was 76.4%, 73.3%, and 66.7% for the K. pneumoniae PAHO-161, E. cloacae PAHO-166, and S. aureus PAHO- 165 strains, respectively. Concordance between the inhibition areas observed by the participating laboratories and the ranges established by the coordinating laboratory was acceptable for all three isolates, at 90.8%, 92.8%, and 88.9%, respectively. Conclusions. Overall concordance in on the detection of KPC, MBL, and VISA resistance mechanisms was 72.1%. We consider the national reference laboratories in Latin America capable of recognizing these emerging resistance mechanisms and expect that maximum levels of concordance will be reached in the future.

Prevalence and risk factors for colonisation with extended spectrum β-lactamase producing enterobacteriacae vis-à-vis usage of antimicrobials.

Purpose: A point prevalence study was carried out in a teaching hospital in Assam to determine the prevalence, sensitivity profile and risk factors for acquisition of extended spectrum β-lactamase (ESBL) producing enterobacteriacae vis-ΰ-vis amount and pattern of antibiotic use. Materials and Methods: ESBL was detected by double disc synergy method. Defined daily dose and bed-days were calculated. Result: Colonisation rate of ESBL producing enterobacteriacae ranged from 14% (n=73) in medicine to the highest 41% (n=29) in orthopaedic with an intermediate 23% (n=80) in surgery. Presence of ESBL was found to be strongly associated with resistance to specific classes of antimicrobials. Exposure to cefotaxime and gentamicin, and surgery were risk factors for acquiring ESBL producing enterobacteriacae. Non-ESBL producing community isolates were found to be considerably more sensitive to different antibiotics with no resistance detected to trimethoprim, co-trimoxazole, ciprofloxacin and aminoglycosides. Conclusion: The study confirms the role of certain 'high risk' antimicrobials in acquisition of ESBL producing Enterobacteriaceae and shows that periodic cohort studies could be an effective strategy in surveillance of antimicrobial resistance in hospitals of resource poor countries to inform antibiotic policy and treatment guidelines.