blaCTX-M, blaTEM, and blaSHV in Enterobacteriaceae from North-Indian tertiary hospital: high occurrence of combination genes

Abstract

OBJECTIVE: To delineate the frequency of occurrence of bla(CTX-M), bla(TEM), and bla(SHV) in Enterobacteriaceae from North-Indian tertiary hospital. METHODS: A random collection of a subset of 45 Escherichia coli (E. coli) and 28 Klebsiella pneumoniae (K. pneumoniae) that was resistant to a third generation cephalosporin and obtained during 2007-2008 was selected for detailed screening for bla(CTX-M), bla(TEM), and bla(SHV) by monoplex PCRs. The isolates demonstrating the presence of bla(CTX-M) alleles were characterized for the specific CTX-M-genogroup by using a multiplex PCR. RESULTS: Resistance to cefoperazone, ceftazidime, ceftriaxone, cefotaxime, cefoxitin and piperacillin was 100% each in K. pneumoniae isolates, whereas these resistance-rates for E. coli isolates were 93.1%, 83.8%, 91.9%, 93.6%, 97.3% and 97.1%, respectively. Concomitant resistance to aminoglycosides, quinolones and aztreonam was also noticed. Presence of any of the bla genes (bla(CTX-M), bla(TEM), and bla(SHV)) was noticed in a total of 28 (38.4%) isolates of the 73 isolates studied. Many isolates demonstrated occurrence of these genes in various combinations. bla(CTX-M), bla(TEM), and bla(SHV) were noticed in 28.8%, 10.9% and 13.7% isolates, respectively. Multiplex PCR in bla(CTX-M) harboring isolates demonstrated the presence of CTX-M-Genogroup-1 and sequencing for the specific CTX-M-type revealed presence of CTX-M-15 type. RAPD typing showed wide diversity in isolates. CONCLUSIONS: This is amongst the premier report describing the simultaneous occurrence of bla(TEM), bla(SHV), and bla(ampC) in Indian Enterobacteriaceae and that wider dissemination of these genes, as demonstrated by diversity of isolates, raises concern and emphasizes a need for extensive search for the presence of these gene pools in Indian subcontinent.