Occurrence of aac(6')-Ib variants among Enterobacteriaceae: Is aac(6')-Ib-cr the most predominant variant?

at codon 102 in the “cr” variant, it does not possess the BtsC1 restriction site. Hence, the PCR amplicons were digested with BtsC1 and the fragments were visualised in agarose gel electrophoresis. Strains harbouring wild-type variants of aac(6’)‐Ib gene shows fragments of 272 bp and 210 bp on gel electrophoresis and those which harbour aac(6’)‐Ib‐cr gene shows a single undigested DNA fragment of 482bp. The strains that harbour both the variants simultaneously show three fragments of 482 bp, 272 bp and 210 bp of DNA on the gel electrophoresis [Figure 1]. ATCC BAA 2146 K.pneumoniae was used as a positive control.[4] PCR assay to confirm the presence of the “cr” variant was done according to published method[5] using ATCC BAA 2146 as the positive control and a sequenced wild-type variant of the aac‐(6’)‐Ib gene as the negative control (KF744024) obtained in our study.