Department of Microbiology, Faculty of Basic Science, Qom Branch, Islamic Azad University, Qom, Iran.
Bovine Tuberculosis Reference Laboratory, Agricultural Research, Education and Extension Organization (AREEO), Razi Vaccine and Serum Research Institute, Karaj, Iran.
Folia Microbiol (Praha). 2024 Feb;69(1):81-89. doi: 10.1007/s12223-023-01073-9. Epub 2023 Jul 29.
As an important source of human food, milk can be a carrier of human pathogenic bacteria, including tuberculous and nontuberculous mycobacteria (NTM), in its raw and unpasteurized state. In this research, 175 raw milk samples and 175 traditional cheese samples were collected from traditional dairy stores in 22 regions of Tehran in a 9- month period from August 2019 to May 2020. Samples were prepared and transferred to a specialized laboratory, where they were inoculated in Lowenstein-Jensen (LJ) medium containing glycerol or sodium pyruvate, as well as Herrold's egg-yolk with and without Mycobactin J. to determine the sample's identity of samples. The recommended 16S rRNA (1436 bp) and hsp65 (644 bp) gene fragments from the positive isolates identified in Ziehl-Neelsen (Z-N) staining were amplified and sequenced using PCR and compared with the sequences of the gene fragments of reference strains available in the global GenBank database. No mycobacterial species were isolated from traditional cheese samples in microbial culture. In case of raw milk samples, a total of four bacteria were collected, all of which were found in the genetic differential testing to be NTM, including n = 1 Mycobacterium heraklionense, n = 2 Mycolicibacterium fortuitum, and n = 1 Mycobacterium thermoresistibile. The analysis of the results obtained by isolate sequencing using the 16S rRNA gene showed higher discriminatory power and percentage similarities in the identification of the isolates than the hsp65 gene.
作为人类食物的重要来源，牛奶在未经巴氏消毒的原始状态下可能成为人类致病菌的载体，包括结核分枝杆菌和非结核分枝杆菌（NTM）。在这项研究中，我们在 2019 年 8 月至 2020 年 5 月的 9 个月期间，从德黑兰 22 个地区的传统乳品店收集了 175 份生奶样本和 175 份传统奶酪样本。将样本制备并转移到专门的实验室，在那里将其接种于含有甘油或丙酮酸钠的 Lowenstein-Jensen（LJ）培养基，以及含有和不含有 Mycobactin J 的 Herrold 蛋黄培养基中，以确定样本的身份。从 Ziehl-Neelsen（Z-N）染色阳性分离物中扩增并测序推荐的 16S rRNA（1436 bp）和 hsp65（644 bp）基因片段，使用 PCR 并将其与全球 GenBank 数据库中参考菌株的基因片段序列进行比较。在微生物培养中，传统奶酪样本中未分离出分枝杆菌。在生奶样本中，共收集到 4 株细菌，所有这些细菌在基因差异测试中均被鉴定为 NTM，包括 n=1 赫拉克利翁分枝杆菌、n=2 偶发分枝杆菌和 n=1 耐热分枝杆菌。使用 16S rRNA 基因对分离株测序结果的分析表明，在鉴定分离株方面，该基因的区分能力和百分比相似度均高于 hsp65 基因。
