Department of Veterinary Hygiene and Public Health, School of Veterinary Medicine and Animal Science, UNESP - Univ Estadual Paulista, Box 56018618-970, Botucatu, State of Sao Paulo, Brazil.
BMC Vet Res. 2013 Apr 24;9:85. doi: 10.1186/1746-6148-9-85.
Mycobacterium spp. is one of the most important species of zoonotic pathogens that can be transmitted from cattle to humans. The presence of these opportunistic, pathogenic bacteria in bovine milk has emerged as a public-health concern, especially among individuals who consume raw milk and related dairy products. To address this concern, the Brazilian control and eradication program focusing on bovine tuberculosis, was established in 2001. However, bovine tuberculosis continues to afflict approximately 1,3 percent of the cattle in Brazil. In the present study, 300 samples of milk from bovine herds, obtained from both individual and collective bulk tanks and informal points of sale, were cultured on Löwenstein-Jensen and Stonebrink media. Polymerase chain reaction (PCR)-based tests and restriction-enzyme pattern analysis were then performed on the colonies exhibiting phenotypes suggestive of Mycobacterium spp., which were characterized as acid-fast bacilli.
Of the 300 bovine milk samples that were processed, 24 were positively identified as Mycobacterium spp.Molecular identification detected 15 unique mycobacterial species: Mycobacterium bovis, M. gordonae, M. fortuitum, M. intracellulare, M. flavescens, M. duvalii, M. haemophilum, M. immunogenum, M. lentiflavum, M. mucogenicum, M. novocastrense, M. parafortuitum, M. smegmatis, M. terrae and M. vaccae. The isolation of bacteria from the various locations occurred in the following proportions: 9 percent of the individual bulk-tank samples, 7 percent of the collective bulk-tank samples and 8 percent of the informal-trade samples. No statistically significant difference was observed between the presence of Mycobacterium spp. in the three types of samples collected, the milk production profiles, the presence of veterinary assistance and the reported concerns about bovine tuberculosis prevention in the herds.
The microbiological cultures associated with PCR-based identification tests are possible tools for the investigation of the presence of Mycobacterium spp. in milk samples. Using these methods, we found that the Brazilian population may be regularly exposed to mycobacteria by consuming raw bovine milk and related dairy products. These evidences reinforces the need to optimize quality programs of dairy products, to intensify the sanitary inspection of these products and the necessity of further studies on the presence of Mycobacterium spp. in milk and milk-based products.
分枝杆菌属是最重要的人畜共患病病原体之一，可从牛传播到人。这些机会性、致病性细菌存在于牛的牛奶中，引起了公共卫生关注，尤其是在食用生牛奶和相关乳制品的人群中。为了解决这一问题，巴西于 2001 年建立了专注于牛结核病的控制和根除计划。然而，牛结核病仍在巴西约 1.3%的牛群中流行。在本研究中，从个体和集体大容量罐以及非正式销售点采集了 300 份牛奶样本，在 Löwenstein-Jensen 和 Stonebrink 培养基上培养。然后，对表现出分枝杆菌属特征的菌落进行基于聚合酶链反应（PCR）的测试和限制性内切酶图谱分析，这些菌落被鉴定为抗酸杆菌。
在处理的 300 份牛奶样本中，有 24 份被确认为分枝杆菌属。分子鉴定检测到 15 种独特的分枝杆菌物种：牛分枝杆菌、戈登分枝杆菌、偶然分枝杆菌、胞内分枝杆菌、微黄分枝杆菌、杜氏分枝杆菌、嗜血分枝杆菌、免疫分枝杆菌、微黄分枝杆菌、黏液分枝杆菌、新型分枝杆菌、副偶然分枝杆菌、耻垢分枝杆菌、土壤分枝杆菌和牛分枝杆菌。从不同地点分离出的细菌比例如下：9%的个体大容量罐样本、7%的集体大容量罐样本和 8%的非正式贸易样本。从三种采集的样本中分离出分枝杆菌属的存在、牛奶生产概况、兽医协助的存在以及牛群中预防牛结核病的关注情况之间，没有观察到统计学上的显著差异。
与基于 PCR 的鉴定测试相关的微生物培养是调查牛奶样本中分枝杆菌属存在的可能工具。使用这些方法，我们发现巴西人可能通过食用生牛牛奶和相关乳制品而经常接触分枝杆菌。这些证据加强了优化乳制品质量计划、加强对这些产品的卫生检查以及进一步研究牛奶和牛奶制品中分枝杆菌属存在的必要性。
