Ertapenem susceptibility of extended spectrum a-lactamase-producing Enterobacteriaceae at a tertiary care centre in India

Behera B, Mathur P, Das A, Kapil A
Correspondence: Dr Purva Mathur, purvamathur@yahoo.co.in

ABSTRACT
Introduction Infections caused by multidrug-resistant organisms such as extended spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae have come to assume widespread proportions. Carbapenems (imipenem and meropenem) are the drugs of choice for the treatment of infections caused by ESBL-producing organisms. There is limited clinical data regarding the efficacy of the latest carbapenem, called ertapenem, against these organisms in the Indian subcontinent. In this study, ertapenem susceptibility in ESBL-producing clinical isolates was evaluated. The in vitro activities of the three carbapenems were compared in ertapenem-resistant isolates.
Methods A total of 205 ESBL-producing Enterobacteriaceae collected from inpatients and outpatients at the All India Institute of Medical Sciences, were identified and tested for antimicrobial susceptibility by the disc diffusion method and Vitek 2 advanced expert system. Ertapenem susceptibility was performed by disc diffusion and Vitek 2 in all the isolates and by E-test in 100 isolates.
Results 191 (93 percent) of the ESBL-producing isolates tested were susceptible to ertapenem. All ertapenem-susceptible isolates were also susceptible to imipenem and meropenem. Isolates with low-level ertapenem resistance retained their susceptibility to imipenem and meropenem, whereas those with high-level ertapenem resistance were resistant to both imipenem and meropenem.
Conclusion Our results suggest that ertapenem may be a viable alternative to other carbapenems for the treatment of infections caused by ESBL-producing clinical isolates. Clinical outcome studies are required to determine if ertapenem is effective for the treatment of infections caused by these organisms.

Keywords: Enterobacteriaceae, ertapenem, extended spectrum ß-lactamase, multidrug-resistant organisms
Singapore Med J 2009; 50(6): 628-632