Concurrent occurrence of blaampC families and blaCTX-M genogroups and association with mobile genetic elements ISEcp1, IS26, ISCR1, and sul1-type class 1 integrons in Escherichia coli and Klebsiella pneumoniae isolates originating from India.

Cefoxitin-resistant Escherichia coli (n = 109) and Klebsiella pneumoniae (n = 16) isolates collected from patients in India in 2009 to 2010 were screened for bla(ampC) families and mobilizing elements (ISEcp1, IS26, ISCR1, and sul-1-type class 1 integrons) and their association with bla(ampC) and for the occurrence of class A beta-lactamases (BLs) (CTX-M, TEM, and SHV). The concurrent occurrences of two distinct AmpC families (bla(CIT) and bla(EBC)) and of class A with class C beta-lactamase were observed. All but one of the isolates harboring CTX-M extended-spectrum BLs (ESBLs) were carrying bla(CTX-M) genogroup 1; the remaining isolate carried bla(CTX-M) genogroup 9. The mobilizing elements occurred in different combinations in the study isolates.