Resistência a β-lactâmicos em Acinetobacter spp isolados de efluente hospitalar no sul do Brasil Resistance to β-lactams among Acinetobacter spp isolated from hospital sewage in southern Brazil

Acinetobacter spp é um importante patógeno causador de infecções nosocomiais que acomete pacientes imunocomprometidos e capaz de adquirir resistência a antimicrobianos com facilidade. Os esgotos hospitalares são importantes disseminadores de genes de resistência a antimicrobianos para a microbiota ambiental. Neste contexto, 30 cepas de Acinetobacter spp provenientes de efluente de um hospital em Porto Alegre, RS, foram analisados quanto ao perfil de susceptibilidade a &#946;-lactamases, quinolonas e aminoglicosídeos através de antibiograma e testes de triagem para metalo beta-lactamases e &#946;-lactamases de espectro estendido. O perfil encontrado revela cepas multi-resistentes e que mecanismos de resistência como a produção de &#946;-lactamases de espectro estendido e bombas de efluxo podem estar presentes nesses isolados.<br>Acinetobacter spp is an important pathogen that is responsible for nosocomial infections affecting immunocompromised patients, and it can easily acquire resistance to antimicrobial agents. Hospital sewage is an important means for disseminating genes for resistance to antimicrobial agents, to the microbiota of the environment. Within this context, 30 strains of Acinetobacter spp from the sewage of a hospital in Porto Alegre, Rio Grande do Sul, were analyzed regarding their profile of susceptibility to &#946;-lactams, quinolones and aminoglycosides, by means of an antibiogram and tests to screen for metallo-&#946;-lactamases and extended-spectrum &#946;-lactamases. The profile obtained revealed the presence of multidrug-resistant strains and showed that resistance mechanisms such as the production of extended-spectrum &#946;-lactamases and efflux pumps may be present in these strains

Detection of <it>P. aeruginosa </it> harboring <it>bla </it>_CTX-M-2, <it>bla </it>_GES-1 and <it>bla </it>_GES-5,<it>bla </it>_IMP-1 and <it>bla </it>_SPM-1 causing infections in Brazilian tertiary-care hospital

<p>Abstract</p> <p>Background</p> <p>Nosocomial infections caused by <it>Pseudomonas aeruginosa</it> presenting resistance to beta-lactam drugs are one of the most challenging targets for antimicrobial therapy, leading to substantial increase in mortality rates in hospitals worldwide. In this context, <it>P. aeruginosa</it> harboring acquired mechanisms of resistance, such as production of metallo-beta-lactamase (MBLs) and extended-spectrum beta-lactamases (ESBLs) have the highest clinical impact. Hence, this study was designed to investigate the presence of genes codifying for MBLs and ESBLs among carbapenem resistant <it>P. aeruginosa</it> isolated in a Brazilian 720-bed teaching tertiary care hospital.</p> <p>Methods</p> <p>Fifty-six carbapenem-resistant <it>P. aeruginosa</it> strains were evaluated for the presence of MBL and ESBL genes. Strains presenting MBL and/or ESBL genes were submitted to pulsed-field gel electrophoresis for genetic similarity evaluation.</p> <p>Results</p> <p>Despite the carbapenem resistance, genes for MBLs (<it>bla</it>_SPM-1 or <it>bla</it>_IMP-1) were detected in only 26.7% of isolates. Genes encoding ESBLs were detected in 23.2% of isolates. The <it>bla</it>_CTX-M-2 was the most prevalent ESBL gene (19.6%), followed by <it>bla</it>_GES-1 and <it>bla</it>_GES-5 detected in one isolate each. In all isolates presenting MBL phenotype by double-disc synergy test (DDST), the <it>bla</it>_SPM-1 or <it>bla</it>_IMP-1 genes were detected. In addition, <it>bla</it>_IMP-1 was also detected in three isolates which did not display any MBL phenotype. These isolates also presented the <it>bla</it>_CTX-M-2 gene. The co-existence of <it>bla</it>_CTX-M-2 with <it>bla</it>_IMP-1 is presently reported for the first time, as like as co-existence of <it>bla</it>_GES-1 with <it>bla</it>_IMP-1.</p> <p>Conclusions</p> <p>In this study MBLs production was not the major mechanism of resistance to carbapenems, suggesting the occurrence of multidrug efflux pumps, reduction in porin channels and production of other beta-lactamases. The detection of <it>bla</it>_CTX-M-2,<it>bla</it>_GES-1 and <it>bla</it>_GES-5 reflects the recent emergence of ESBLs among antimicrobial resistant <it>P. aeruginosa</it> and the extraordinary ability presented by this pathogen to acquire multiple resistance mechanisms. These findings raise the concern about the future of antimicrobial therapy and the capability of clinical laboratories to detect resistant strains, since simultaneous production of MBLs and ESBLs is known to promote further complexity in phenotypic detection. Occurrence of intra-hospital clonal dissemination enhances the necessity of better observance of infection control practices.</p