Identification of a multi-resistant Enterobacter cloacae strain from diseased crayfish (Procambarus clarkii)

Abstract Diseases of crayfish in May often result in severe economic losses to crayfish farming in Qianjiang, China. Several bacterial pathogens have been identified that responsible to the diseases. In our present study, a virulent strain named L21 was separated from diseased crayfish. The strain was identified as Enterobacter cloacae (E. cloacae) by phenotypical and molecular identification. Then the susceptibility of the strain was examined by K-B method, and the minimum inhibitory concentrations were acquired by broth micro-dilution method. Moreover, carbapenemase and mcr-1 genes were detected. The results showed that L21 strain was multi-resistant strain carrying carbapenemase genes and mcr-1 gene. L21 strain showed susceptibility to cefotaxime, enrofloxacin and tetracycline among all the tested antibiotics. These results demonstrated that E. cloacae was a novel pathogen to farmed crayfish in China.