Department of Physical Sport Science, Nutrition and Food Science, Princess Nourah Bint Abdulrahman University, Saudi Arabia.
Department of Botany and Microbiology, College of Science, King Saud University, Saudi Arabia.
Biosci Rep. 2020 Apr 30;40(4). doi: 10.1042/BSR20193470.
Antibiotic- and heat-resistant bacteria in camel milk is a potential public health problem. Staphylococcus aureus (S. aureus) is an opportunistic pathogen in humans, dairy cattle and camels. We characterized the phenotype and genotype of methicillin-resistant staphylococcal strains recovered from pasteurized and raw camel milk (as control) distributed in the retail markets of Saudi Arabia. Of the 100 samples assessed between March and May 2016, 20 S. aureus isolates were recovered from pasteurized milk, 10 of which were resistant to cefoxitin, and as such, were methicillin-resistant. However, raw camel milk did not contain methicillin-resistant S. aureus (MRSA). Antimicrobial susceptibility tests showed that the resistance ratio for other antibiotics was 60%. We performed a polymerase chain reaction (PCR) assay using primers for the methicillin-resistant gene mecA and nucleotide sequencing to detect and verify the methicillin-resistant strains. Basic local alignment search tool (BLAST) analysis of the gene sequences showed a 96-100% similarity between the resistant isolates and the S. aureus CS100 strain's mecA gene. Ten of the methicillin-resistant isolates were heat-resistant and were stable at temperatures up to 85°C for 60 s, and three of these were resistant at 90°C for 60 or 90 s. The mean decimal reduction time (D85-value) was 111 s for the ten isolates. Sodium dodecyl sulfate (SDS)/polyacrylamide gel electrophoresis (PAGE) showed that there was no difference in the total protein profiles for the ten methicillin heat-resistant S. aureus (MHRSA) isolates and for S. aureus ATCC 29737. In conclusion, a relatively high percentage of the tested pasteurized camel milk samples contained S. aureus (20%) and MHRSA (10%).
骆驼奶中具有抗生素和耐热性的细菌是一个潜在的公共卫生问题。金黄色葡萄球菌（S. aureus）是人类、奶牛和骆驼中的机会性病原体。我们对从沙特阿拉伯零售市场中采集的巴氏杀菌和未加工骆驼奶（作为对照）中分离出的耐甲氧西林金黄色葡萄球菌（Methicillin-Resistant Staphylococcus aureus，MRSA）菌株进行了表型和基因型分析。在 2016 年 3 月至 5 月期间评估的 100 个样本中，从巴氏杀菌奶中分离出 20 株金黄色葡萄球菌，其中 10 株对头孢西丁耐药，因此为耐甲氧西林金黄色葡萄球菌。然而，未加工的骆驼奶中未检出耐甲氧西林金黄色葡萄球菌（MRSA）。抗生素药敏试验显示，其他抗生素的耐药率为 60%。我们使用耐甲氧西林基因 mecA 的引物进行聚合酶链反应（PCR）检测，并对耐药株进行核苷酸测序以进行检测和验证。mecA 基因序列的基本局部比对搜索工具（BLAST）分析显示，耐药分离株与金黄色葡萄球菌 CS100 株的 mecA 基因之间存在 96-100%的相似性。10 株耐甲氧西林金黄色葡萄球菌（MRSA）为耐热株，在 85°C 下 60s 时稳定，其中 3 株在 90°C 下 60 或 90s 时稳定。10 株耐热性耐甲氧西林金黄色葡萄球菌（MHRSA）的平均十进制减少时间（D85 值）为 111s。十二烷基硫酸钠（SDS）/聚丙烯酰胺凝胶电泳（PAGE）显示，10 株耐甲氧西林耐热性金黄色葡萄球菌（MHRSA）分离株和金黄色葡萄球菌 ATCC 29737 的总蛋白图谱没有差异。综上所述，检测的巴氏杀菌骆驼奶样本中金黄色葡萄球菌（20%）和耐甲氧西林耐热性金黄色葡萄球菌（10%）的比例相对较高。
