Diversities of antimicrobial resistance patterns across Staphylococcus aureus and Coagulase-Negative Staphylococci isolated from dairy herbs in Jiangsu province, China
Background As mastitis major causing agents, Coagulase-Negative Staphylococci (CNS) and Staphylococcus aureus (SA), are important and their connections are special and worth comparing. The overall aim of this study is to investigate antimicrobial resistance patterns of CNS and SA. Understanding the special characters of staphylococci is essential for finding the precise strategies or directions against them. Results Staphylococci (47.63%) were the commonest pathogens in subclinical mastitis in
... inical mastitis in Jiangsu province. 73.34% and 45.78% of CNS respectively were extensively drug-resistant (XDR) strains and multiple drug-resistant (MDR) strains, mainly resisting penicillin (77.78%) and ceftazidime (55.95%); for SA, 62.52% of them were MDR strains and resistant to penicillin (94.05%) and norfloxacin (58.33%). Notably, 4 CNS were pandrug-resistant (PDR) strains. According to the chi-square test results, we summary and find that SA was more resistant to quinolones (ciprofloxacin, levofloxacin, and norfloxacin) and co-trimoxazole antibiotics than CNS, significantly; on the other hand, CNS were significantly more resistant to lincomycins (clindamycin), macrolides (including erythromycin and clarithromycin), tetracycline, and nitrofurantoin antibiotics than SA" in total. Resistance genes were detected more frequently in CNS than SA; nearly a third of CNS resit penicillin by β-lactamase coded by blaZ and CNS resist tetracycline mainly by protein pump mechanism. For SA, blaZ was detected out 27.2%, and the other five resistance genes were rare to be found. Conclusion Responding to antibiotics interfering with metabolisms of nucleotide, SA might be more resistant than CNS; while CNS strains are more likely to become mutations to survive under the stress of antibiotics interfering with protein synthesis. These might provide the advantages for CNS to represent like a reservoir of resistance genes for other staphylococci as the previous researches' assumption.