Resistance of Escherichia coli and Salmonella Isolated from Marine and Freshwater Fishes towards Carbapenems

Abstract

The carbapenems are beta-lactam antimicrobial agents with an exceptionally broad spectrum of activity and are active against most Enterobacteriaceae including those that produce ampC β-lactamase. Resistance to carbapenems, especially carbapenems-resistant-Enterobacteriaceae (CRE) is a serious issue worldwide as it is extremely difficult to combat bacteria resistant to carbapenems. Fifty two isolates of Escherichia coli and twelve isolates of Salmonella (invA and stn gene positive) isolated from marine fish and freshwater fish were tested for their susceptibility to carbapenems namely meropenem, imipenem and ertapenem. A low percentage (3.9%) of E.coli showed resistance to meropenem, while 11.5 & 17% of E.coli and 8.3 & 25% of Salmonella showed intermediate sensitivity to meropenem and ertapenem, respectively. However, 100% of E. coli and Salmonella were sensitive to imipenem. Importantly, meropenem resistant E.coli was also found to be resistant to other antibiotics such as ciprofloxacin, gentamicin, nalidixic acid, norfloxacin and tetracycline. The results indicate that carbapenem resistance in E. coli and Salmonella isolated from fish was marginal but nevertheless needs continuous monitoring.