Escherichia coli Isolates Harboring bla NDM Variants and 16S Methylases Belonging to Clonal Complex 131 in Southern Punjab, Pakistan.

The emergence of carbapenem-resistant Escherichia coli (CREC) especially harboring the New Delhi Metallo-β-lactamase ( bla NDM ) variants are increasingly being reported from many countries, however, the data from Pakistan is limited. In the present study, 109 CREC isolates were obtained from 4,091 E. coli isolates in five tertiary care hospitals in southern Punjab, Pakistan. The antimicrobial susceptibility profiling and screening for the resistance determinants were performed followed by bla NDM typing and multilocus sequence typing (MLST) to characterize the CREC strains. Among the carbapenemases, 57 CREC isolates were found to harbor bla NDM . The bla NDM-1 , bla NDM-5 , bla NDM-7 , and bla NDM-4 variants were identified in 30 (52.6%), 18 (31.6%), (12.3%), 2 (3.5%) isolates, respectively. The ESBL genes, such as bla CTX-M and bla TEM, were also found in different combinations, whereas the 16S methylases that is, rmtB and armA were found in 69 (63.3%) and 55 (50.5%) CREC isolates, respectively. The MLST of bla NDM carrying E. coli revealed eight different sequence types (STs) with ST131 belonging to 21 isolates being the most prevalent. The clonal complex 131 was the predominant complex corresponding to 47 (82.5%) of bla NDM -positive strains. Large-scale surveillance studies coupled with active infection control policies are suggested on an urgent basis to avoid an epidemic in the future.