Prevalence of Extended Spectrum Beta-Lactamases among Enterobacteriaceae Isolated from Intrahospital Patients in Serbia

The aim of this study was to determine the prevalence of extended spectrum beta-lactamases (ESBLs) production in hospital strains of Enterobacteriaceae isolated from various clinical specimens (urine, blood and wound swabs) from hospitalized patients at the Military Medical Academy, Belgrade, Serbia. During six months of study, a total of 1034 isolates of Enterobacteriaceae were tested for antimicrobial susceptibility and screened for ESBL production according to standard methods. The overall prevalence of ESBL production in the hospital isolates of Enterobacteriaceae was 57.4%. Among the isolates, minimum frequency of resistance was found for amikacin (25.2%), and maximum for ampicillin (84.5%). The strain resistant to imipenem could not be isolated. Resistance to the tested antibiotics was higher in ESBL producers than non-producers (P < 0.05). Among Escherichia coli isolates, the prevalence of ESBL production was less than 50% (33.9%). ESBLs were most often produced by isolates of Serratia spp. (85.2%) and Klebsiella spp. (81.8%). Blood specimens were the most common sources of ESBL-producing isolates (84.0%). These findings might help clinicians in deciding the appropriate empirical treatment for intrahospital patients and emphasize the increasing problem of antimicrobial resistance in Serbia.