Molecular characterization of extended-spectrum β-lactamases in clinical Escherichia coli and Klebsiella pneumoniae isolates from Surabaya, Indonesia

Abstract

No detailed reports regarding extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae are currently available from Indonesia, the fourth most populous country in the world. A survey was carried out to investigate the molecular epidemiology and genetic characteristics of clinical ESBL-producing Escherichia coli and Klebsiella pneumoniae isolates originating from the Dr. Soetomo Academic Hospital in Surabaya, Indonesia, over a 4 month period (January to April 2005). ESBLs were characterized by isoelectric focusing and PCR assays. Clonality of the isolates was assessed by PFGE and repetitive-sequence-based PCR (rep-PCR). Phylogenetic grouping was performed among CTX-M-15-producing E. coli. In total, 73 consecutive non-duplicate ESBL-positive E. coli and 72 K. pneumoniae strains were isolated. The bla(CTX-M-15) gene was found to be highly prevalent (69/73 strains, 94.5%) among the 73 ESBL-positive E. coli isolates. The gene was detected in both clonal and non-clonal isolates, as defined by PFGE and rep-PCR. Sixteen CTX-M-15-positive E. coli could be assigned to a single rep-PCR type and phylogenetic group B2 and belonged to the well-known O25b-ST131 clone. Among the 72 ESBL-positive K. pneumoniae isolates, bla(CTX-M-15) was again the most prevalent ESBL (40/72, 55.6%). Several SHV-type enzymes were also frequently detected: SHV-5 (n = 28); SHV-12 (n = 13); and SHV-2 (n = 6). TEM-type ESBLs were not detected in any of the isolates. Indonesia is another developing country affected by the emergence and spread of bacterial strains harbouring ESBL genes, including the CTX-M-15-producing B2-E. coli O25b-ST131 clone.