Occurrence of mycobacteria in bovine milk samples from both individual and collective bulk tanks at farms and informal markets in the southeast region of Sao Paulo, Brazil

Abstract

BackgroundMycobacterium 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.ResultsOf 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.ConclusionThe 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.

Isolation and molecular characterization of Mycobacterium tuberculosis complex isolated from raw milk in some dairy farms in Egypt

“…Moreover, similar results were obtained by [10] In Tunisia who proved that, out of 102 SCITT positive cows, 5 were detected as shedders of M. bovis in their milk. Also, similar results were detected by [24] who mentioned that, in Brazil mycobacteria isolated from 24 (8%) out of examined 300 milk samples. All samples were tested and confirmed using real time PCR.…”

“…However, it is not likely that cattle infected with M. tuberculosis would excrete the bacillus in their milk since they rarely develop TB due to M. tuberculosis. Lower results were detected in Brazil by [24] who detected only one M. bovis among examined 300 milk samples. Moreover, [3] mentioned that M. bovis infection in cattle may involve in some cases udder lesion and the bacilli excreted in milk or sheded in their milk due to septicemic and cutaneous infections.…”

Isolation and identification of Mycobacterium bovis in milk from cows in northeastern Brazil

“…The increasing number of individuals infected with HIV predisposes an increase in the number of cases of emerging and re-emerging diseases, especially those caused by opportunistic agents, such as Mycobacterium spp. In this context, non-pasteurized milk infected with mycobacteria poses a serious risk to individuals with HIV (FRANCO et al, 2013).…”

“…in two samples, probably nontuberculous environmental mycobacteria (NTM), which are present in the environment and can be transmitted to animals and humans (FRANCO et al, 2013) through inhalation or ingestion, resulting in permanent or temporary colonization of the respiratory and digestive tracts (PRIMM et al, 2004). The increasing number of individuals infected with HIV predisposes an increase in the number of cases of emerging and re-emerging diseases, especially those caused by opportunistic agents, such as Mycobacterium spp.…”

“…In São Paulo, PARDO et al (2001) isolated M. bovis in one sample of raw milk; LEITE et al (2003), using milk samples from the states of São Paulo, Paraná, Santa Catarina, Goiás and Pará, isolated M. bovis in one sample of raw milk. FRANCO et al (2013), in the southeast region of São Paulo, isolated M. bovis from one milk sample from an individual cooling tank.…”