Molecular characterization of Klebsiella pneumoniae in clinical bovine mastitis in 14 provinces in China

Abstract

Abstract Klebsiella pneumoniae ( K. pneumoniae ) is a major common environmental pathogen which causes bovine mastitis. To investigate the epidemic of K. pneumoniae of China, 131 K. pneumoniae strains were isolated from 495 clinical mastitis milk samples from 14 provinces in China. The isolation rate of K. pneumoniae was 26.5%, and K57 was the dominant serotype (45.0%, 59/131). Nineteen (14.5%) isolates were identified as hypervirulent K. pneumoniae (hvKP) and nine of them belonged to the K57 serotype. The mrkA , entB , wabG and fimH genes were prevalent virulence genes while rmpA , magA and ycf were not found in K. pneumoniae . Furthermore, K. pneumoniae had serious drug resistance and multiple beta-lactamase genes were detected, including blaTEM , blaSHV , blaNDM , blaCTX-M , blaDHA and blaKPC . Biofilm was an important factor in bacterial resistance and persistent infection, and 77.1% isolates could form biofilm. Although acylated homoserine lactone (AHL, a Gram-negative bacterial quorum sensing signal molecule) was not confirmed among the K. pneumoniae isolates, exogenous AHLs could reduce the biofilm formation ability of the K. pneumoniae strains. In conclusion, the high rate of isolation and serious antibiotic resistance of K. pneumonia were found in this study and indicated a potential threat to public health from the food chain.