RESUMO
INTRODUCTION: Extended-spectrum - beta lactamases (ESBLs) are increasingly detected globally among Escherichia coli and Klebsiella pneumoniae. The correlation between antibiotics use and resistance, though not fully described, has been addressed and shown in several studies. In this study, the profiles of ESBLs in E. coli and K. pneumoniae isolated from two Lebanese hospitals and their relationship to antibiotic consumption were determined. METHODOLOGY: A total of 205 E. coli and 67 K. pneumoniae isolates resistant to third- or fourth-generation cephalosporins were collected between January 2011 and January 2012. Antibiotic susceptibility and consumption data were also collected from 2010-2012. Double-disk synergy and Etest ESBL assays were performed, followed by PCR for ESBL genes. Pulsed-field gel electrophoresis (PFGE) was performed for representative isolates. Statistical analysis for consumption and susceptibility data over 3 years was performed. RESULTS: As expected, CTX-M-15 was predominant. In both hospitals, strains of E. coli and K. pneumoniae harbored at least one ESBL, and in some cases (23%) harboured four different ESBLs. A significant correlation was detected between total use of antimicrobial agents and resistance to various antibiotics. This was obvious for the use of penicillins and resistance to aztreonam, ceftazidime and ciprofloxacin, and use of third- and fourth-generation cephalosporins and resistance to ceftazidime, cefuroxime, cefoxitin and ciprofloxacin in both bacteria. CONCLUSIONS: This study shows the predominance of CTX-M-15 among cephalosporin-resistant E. coli and K. pneumoniae in Lebanese hospitals and highlights the direct relationship between the use of antibiotics and the emergence of resistance in bacteria.