Antimicrobial Susceptibility of Klebsiella pneumoniae Producing Extended-Spectrum beta-lactamase (ESBL) Isolated in Hospitals in Brazil.

The prevalence of klebsiella pneumoniae producing extended-spectrum beta-lactamase (ESBL) has been increasing all over the world. Infections caused by ESBL producing isolates are difficult to detect with current susceptibility tests, and are difficult to treat. ESBLs confer resistance to all currently available beta-lactam, except carbapenems. In addition, ESBL production is usually associated with resistance to other classes of antimicrobial agents such as aminoglycosides and quinolones. The objective of this study was to evaluate the in vitro susceptibility patterns of ESBL producing K pneumoniae isolated in Brazil. Seventy-two strains were tested using E test against 30 antimicrobial agents, including carbapenems, second and third generation cephalosporins, aminoglycosides, quinolones, and some new compounds. The most active compounds (i.e. 100% susceptibility) were meropenem (MIC90, 0.125µg/mL), imipenem (MIC90, 0.25µg/mL), and cefotetan (MIC90, 2µg/mL). Ciprofloxacin (MIC90, 1µg/mL, 94% susceptibility) and cefepime (MIC90, 6µg/mL, 92% susceptibility), were also very active against our collection of ESBL producing K pneumoniae. None of the six aminoglycosides showed good activity against these strains (16% to 41% susceptibility) and only 39% of the isolates were susceptible to piperacillin/tazobactam. The results of our study indicated that the carbapenems are the most active compounds against ESBL producing L pneumoniae in Brazil, and ciprofloxacin remains very active against these strains. Cefotetan and cefepime were also very active against ESBL producing K.pneumoniaein Brazil; however, further studies are necessary to evaluate the role of these cephalosporins in the treatment of infections due to ESBL producing strains.