新疆奶牛养殖从业人员耐甲氧西林金黄色葡萄球菌定植、耐药及分子流行特征OA

[Background]Methicillin-resistant Staphylococcus aureus(MRSA)is an important pathogen for both human bloodstream infections and mastitis in cows.However,little attention has been paid to the cross-host transmission of MRSA from cows to high-risk groups in China. [Objective]To determine the MRSA colonization rates among dairy cows and dairy farm workers in Xinjiang,identify the antibiotic resistance profiles and molecular characteristics of the isolates,and provide scientific evidence for the formulation of targeted infection control strategies. [Method]A cross-sectional survey combined with laboratory pathogen analysis was conducted.From June to August 2024,large-scale dairy farms in Xinjiang region were selected as study sites.Nasal swabs(n=96)and skin swabs(n=39)were collected from workers,and bovine nasal swab samples(n=109)were collected simultaneously.All samples were subjected to MRSA isolation,cultivation,and identi-fication,followed by antibiotic susceptibility testing to characterize resistance phenotypes.Staphylococcus aureus protein A(Spa)typing was performed to determine strain genotypes and elucidate MRSA colonization rates and molecular epidemiological patterns. [Results]A total of 35 MRSA strains was successfully isolated from 244 samples.The MRSA colonization rates among dairy farm workers and dairy cows were 20.83%(20/96)and 12.84%(14/109),respectively,with an overall isolation rate of 14.34%(35/244).Among the workers,the nasal colonization rate was 16.67%(16/96),and the skin colonization rate was 12.82%(5/39).One worker exhibited MRSA colonization at multiple body sites.All MRSA strains were resistant to cefoxitin(100%,35/35).The resistance rates to erythromycin and clindamycin were 42.86%(15/35)and 34.29%(12/35),respectively.Thirteen strains showed a multidrug-resistant phenotype,whereas all strains were susceptible to vancomycin.The MRSA isolates exhibited high genetic diversity,with 13 Spa types identified,among which t441 was the most prevalent(8 strains).Both t441 and t034 types were detected in samples from both the dairy cows and their handlers.These two Spa types also carried and stably inherited specific resistance combinations,including erythromycin-clindamycin-cefoxitin and ciprofloxacin-erythromycin-clindamycin-gentamicin-cefoxitin-tetracycline,and a statistically significant association was also ob-served between the two resistance profiles and the bacterial types(P<0.001).In addition,one novel Spa type strain was identified. [Conclusion]MRSA colonization rates among dairy cows and dairy farm workers in Xinjiang are relatively high,with evidence of multi-site colonization.The isolates exhibit high levels of multidrug resistance and genetic diversity,indicating a potential risk of cross-host transmission.