Occurrence and sensitivity profile of extended spectrum beta-lactamase-producing Enterobacteriaceae at a tertiary hospital in Southern Brazil

Introduction: Nosocomial infections are closely associated with antimicrobial drug resistance. One of the most important mechanisms of resistance to beta-lactam antibiotics is the production of extended spectrum beta-lactamases (ESBLs). The objective of the present study was to evaluate the prevalence and antimicrobial susceptibility profile of ESBL-producing strains and to assess the evolution of antimicrobial drug resistance between 2007 and 2013 at the Hospital Sao Vicente de Paulo, Passo Fundo, State of Rio Grande do Sul, Brazil. Methods: We conducted a descriptive, observational, cross-sectional study. Bacterial culture was performed from January to December 2013. The antimicrobial susceptibility profile of these cultures was determined using the disk diffusion method. Phenotypic screening for ESBL production was performed using the disk approximation method. Results: We analyzed a total of 19,112 cultures, 11.5% of which were positive for Enterobacteriaceae. Of these, 30.3% of the isolates were positive for ESBL production, and the most prevalent species was Klebsiella sp. (37.5%). Over 95% of these isolates showed reduced susceptibility to all cephalosporins, aztreonam, and amoxicillin/clavulanic acid. The isolates also showed high sensitivity to the following antimicrobials: amikacin, meropenem, and piperacillin/tazobactam. Overall, the resistance rates among ESBL-producing Enterobacteriaceae decreased from 2007 to 2013. Conclusions: In our hospital, the increased sensitivity to certain antimicrobial agents seems to be directly related to the implementation of improvements in the methods to prevent and control nosocomial infections in addition to the natural development of other resistance mechanisms.