Incidence of ESBL producers amongst Gram-negative bacilli isolated from intra-abdominal infections across India (based on SMART study, 2007 data).

OBJECTIVES This study was conducted in 9 centers spread over India from January 1 to December 31, 2007 to monitor in vitro susceptibility of Gram-negative bacilli to Group I carbapenem, ertapenem and other antimicrobials in intra-abdominal infections and to identify early changes in susceptibility pattern of community or hospital acquired organisms, with a focus on ESBL producers. MATERIAL AND METHODS Gram-negative bacilli isolated from intra-abdominal samples of patients with documented intra-abdominal infections were processed for identification by conventional/ automated methods and antimicrobial susceptibility by Micro-Scan (Siemens) MIC panel against 12 antimicrobials (3rd and 4th generation cephalosporins, Groups I and II carbapenems, amikacin, levofloxacin, amoxicillin-clavulanic acid and piperacillin-tazobactam). RESULTS A total of 588 isolates were identified, of which 351 (60%) were E. coli and 114 (19%) were Klebsiella spp. 79% of E. coli and 70% of Klebsiella spp. were ESBL producers in general. 110 of E. coli and 35 of Klebsiella isolates were from community-acquired intra-abdominal infections. 80% of E. coli and 63% of Klebsiella isolates from community-acquired infections were ESBL producers, against 79% of E. coli and 73% of Klebsiella isolates from hospital-acquired infections. Amongst the ESBL-positive isolates of E. coli, 94% were susceptible in vitro to ertapenem, 96% to imipenem and 76% to piperacillin-tazobactam. For ESBL-positive isolates of Klebsiella spp., the corresponding figures were 80%, 94% and 59% respectively. CONCLUSION The study showed a high incidence of ESBL-producers amongst Enterobacteriaceae isolates from intra-abdominal infections in both community-acquired and hospital-acquired settings across India. Ertapenem was comparable with imipenem against ESBL-positive E. coli isolates, while imipenem was more effective than ertapenem against ESBL-positive Klebsiella isolates.