Isolation of Pathogenic Bacteria from Dairy Cow Mastitis and Correlation of Biofilm Formation and Drug Resistance of Klebsiella pneumoniae in Jiangsu, China

According to recent investigations, the proportion of mastitis caused by environmental pathogens, such as K. pneumoniae, has increased. In this research, the epidemiology of pathogens in milk samples collected from four farms in the Jiangsu Province was carried out. The results show that 16 pathogens were detected in 186 positive milk samples. It was found that K. pneumoniae had the lowest sensitivity to penicillin (0%) and amoxicillin (4%) compared to its sensitivity to gentamicin (92%) and piperacillin (89%). A total of eight ESBL-producing strains were detected. Crystal violet staining showed that 46 of the 68 isolates of K. pneumoniae had strong biofilm-forming ability, which was related to the tetracycline resistance phenotype (p < 0.05). The detection rate of the ESBL-resistant gene (bla(SHV)) reached 100%. The results show that resistance genes bla(VIM), bla(OXA-10), and bla(TEM) were correlated with drug-resistance phenotypes to varying degrees. The present study indicates the prevalence of bovine mastitis-derived pathogens in part of Jiangsu Province and reveals the distribution of beta-lactam resistance genes and the strong biofilm-forming ability of K. pneumoniae and its relationship with tetracycline resistance. This study provided theoretical support and guidance for rational drug use and disease prevention and control on farms.