Karzis Joanne, Petzer Inge-Marié, Donkin Edward F, Naidoo Vinny, Etter Eric M C
Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa.
Department of Animal and Wildlife Sciences, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa.
Antibiotics (Basel). 2020 Sep 18;9(9):616. doi: 10.3390/antibiotics9090616.
Antibiotic resistance has been reported since the 1940s in both human and veterinary medicine. Many years of monitoring milk samples in South Africa led to identification of a novel maltose-negative ( strain, which appears to be an emerging pathogen. In this study, the susceptibility of this strain to antibiotics was evaluated over time, during diverse seasons in various provinces and according to somatic cell count (SCC) categories. A data set of 271 maltose-negative isolates, from milk samples of 117 dairy herds, was examined using the disk diffusion method, between 2010 and 2017. This study also compared the susceptibility testing of 57 maltose-negative and 57 maltose-positive isolated from 38 farms, from three provinces using minimum inhibitory concentration (MIC). The MIC results for the maltose-negative isolates showed highest resistance to ampicillin (100%) and penicillin (47.4) and lowest resistance (1.8%) to azithromycin, ciprofloxacin and erythromycin. The maltose-negative isolates showed overall significantly increased antibiotic resistance compared to the maltose-positive strains, as well as multidrug resistance. Producers and veterinarians should consider probability of cure of such organisms (seemingly non-chronic) when adapting management and treatment, preventing unnecessary culling.
自20世纪40年代以来，人类医学和兽医学领域均已报道了抗生素耐药性问题。在南非，多年来对牛奶样本的监测发现了一种新型的麦芽糖阴性菌株，它似乎是一种新出现的病原体。在本研究中，对该菌株在不同时间、不同省份的不同季节以及根据体细胞计数（SCC）类别对抗生素的敏感性进行了评估。在2010年至2017年期间，使用纸片扩散法对来自117个奶牛场牛奶样本中的271株麦芽糖阴性分离株数据集进行了检测。本研究还比较了从三个省份38个农场分离出的57株麦芽糖阴性和57株麦芽糖阳性菌株的药敏试验，采用最低抑菌浓度（MIC）进行检测结果分析。麦芽糖阴性分离株的MIC结果显示，对氨苄青霉素的耐药性最高（100%），对青霉素的耐药性为47.4%，对阿奇霉素、环丙沙星和红霉素的耐药性最低（1.8%）。与麦芽糖阳性菌株相比，麦芽糖阴性分离株总体上显示出明显更高的抗生素耐药性以及多重耐药性。生产者和兽医在调整管理和治疗措施时应考虑此类生物体（看似非慢性）的治愈可能性，避免不必要的淘汰。
