Khasapane Ntelekwane George, de Smidt Olga, Lekota Kgaugelo Edward, Nkhebenyane Jane, Thekisoe Oriel, Ramatla Tsepo
Centre for Applied Food Safety and Biotechnology, Department of Life Sciences, Central University of Technology, 1 Park Road, Bloemfontein 9300, South Africa.
Unit for Environmental Sciences and Management, North-West University, Potchefstroom 2531, South Africa.
Animals (Basel). 2025 Jul 5;15(13):1980. doi: 10.3390/ani15131980.
Subclinical mastitis (SCM) is a stealthy but devastating challenge in the dairy industry, leading to economic losses and hindering efforts to achieve milk self-sufficiency. This study investigated the prevalence of SCM, antimicrobial resistance, and virulence profiles of . A total of 174 milk samples were analyzed using the California mastitis test (CMT), somatic cell counts (SCCs), bacteriological culture, MALDI-TOF MS, and polymerase chain reaction (PCR). The findings revealed that the SCM prevalence was 68/174 (39.08%) based on CMT and SCC. Among SCM-positive samples, 60/68 (88.23%) were identified as confirmed by MALDI-TOF MS and PCR assay. The most frequently detected serogroups were 0113 (11.6%) and 0113 (3.3%). Additionally, the genes for and were also detected in nine (15%) and one (1.7%), respectively. Antimicrobial susceptibility tests showed widespread resistance, with isolates demonstrating resistance to penicillin in 43 (71.6%), followed by ciprofloxacin in 42 (70%) and gentamicin in 18 (30%). A larger proportion of the strains (100%) harbored the gene, while 23 (38.3%), 20%, 20%, and 1.47% contained , , , and . Thirty (50%) isolates were considered multidrug-resistant (MDR). These findings underscore the urgent need for enhanced surveillance and antibiotic stewardship in dairy farming. The presence of MDR in SCM poses a dual threat of potential transmission to humans and treatment failures in mastitis management. This study highlights the importance of proactive control strategies to mitigate the spread of antimicrobial resistance in livestock and beyond.
亚临床型乳腺炎（SCM）是乳制品行业中一个隐蔽但极具破坏性的挑战，会导致经济损失并阻碍实现牛奶自给自足的努力。本研究调查了SCM的患病率、抗菌药物耐药性及毒力特征。总共使用加利福尼亚乳腺炎检测法（CMT）、体细胞计数（SCC）、细菌培养、基质辅助激光解吸电离飞行时间质谱（MALDI-TOF MS）和聚合酶链反应（PCR）对174份牛奶样本进行了分析。研究结果显示，基于CMT和SCC，SCM患病率为68/174（39.08%）。在SCM阳性样本中，经MALDI-TOF MS和PCR检测确认，60/68（88.23%）被鉴定为[具体细菌名称未给出]。最常检测到的血清型是0113（11.6%）和0113（3.3%）。此外，[具体基因名称未给出]和[具体基因名称未给出]的基因也分别在9份（15%）和1份（1.7%）样本中被检测到。抗菌药物敏感性测试显示广泛耐药，[具体细菌名称未给出]分离株中43份（71.6%）对青霉素耐药，其次是42份（70%）对环丙沙星耐药，18份（30%）对庆大霉素耐药。较大比例的[具体细菌名称未给出]菌株（100%）携带[具体基因名称未给出]基因，而23份（38.3%）、20%、20%和1.47%的菌株分别含有[具体基因名称未给出]、[具体基因名称未给出]、[具体基因名称未给出]和[具体基因名称未给出]。30份（50%）分离株被认为是多重耐药（MDR）。这些发现强调了在奶牛养殖中加强监测和抗生素管理的迫切需求。SCM中MDR[具体细菌名称未给出]的存在对人类构成了潜在传播和乳腺炎治疗失败的双重威胁。本研究强调了采取积极控制策略以减轻抗菌药物耐药性在牲畜及其他领域传播的重要性。
