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

2009 to 2010 were screened for blaampC families andmobilizing elements (ISEcp1, IS26, ISCR1, and sul-1-type class 1 integrons) and their association with blaampC and for the occurrence of class A beta-lactamases (BLs) (CTX-M, TEM, and SHV). The concur-rent occurrences of two distinct AmpC families (blaCIT and blaEBC) 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 blaCTX-M genogroup 1; the remaining isolate carried blaCTX-M genogroup 9. The mobilizing elements occurred in different combinations in the study isolates. AmpCbeta-lactamases (BLs)were originally described as chro-mosomal, inducible enzymes in members of Enterobacteria-ceae; however, the plasmid-mediated AmpC beta-lactamases (pMAmpCs)were first discovered in the late 1980s (6). Since then, they have been detected in different regions around the globe (11, 13). pMAmpCs are assumed to be less common than extended-spectrum BLs (ESBLs) in Escherichia coli and Klebsiella isolates, but their importance should be noted, since they impart a broader spectrum of resistance, especially when present along with other classes of ESBLs. The data regarding the worldwide distribution and prevalence of AmpC-mediated resistance are fragmentar