Abstract
A cross-sectional study on six dairy farms was conducted to ascertain the occurrence of carbapenem-resistant Escherichia coli in calves. Two-hundred and seventy-nine isolates of E. coli were recovered from 90 faecal samples from apparently healthy (45) and diarrhoeal (45) calves. The isolates were screened for phenotypic susceptibility to carbapenems and production of metallo β-lactamase, as well as five carbapenemase resistance genes by PCR, and overexpression of efflux pumps. Eighty-one isolates (29.03%) were resistant to at least one of three carbapenem antibiotics [meropenem (23.30%), imipenem (2.15%) and ertapenem (1.43%)], and one isolate was positive for the blaVIM gene which was located on an Incl1 plasmid of a novel sequence type (ST 297) by multilocus sequence typing. The majority (83.95%) of isolates had an active efflux pump. Calves housed on concrete floors were approximately seven times more likely to acquire meropenem-resistant isolates than those housed on earthen floors (95% CI 1.27-41.54). In India, carbapenem drugs are not used in food animal treatment, hence carbapenem-resistant strains in calves possibly originate from the natural environment or human contact and is of public health importance. To our knowledge, this is the first report of blaVIM carbapenemases gene in calves from India.