Detection of mycobacteria in coalho cheese sold in Northeastern Brazil

Abstract

The aim of the present study was to detect and identify Mycobaterium spp. in 50 samples of coalho cheese sold in the Northeast region of Brazil. Of the 50 analyzed samples, 35 were produced by the artisanal process, using raw milk, and 15 originated from industrialized establishments that pasteurize milk. Conventional and real-time nested PCR for the rv2807 gene of the M. tuberculosis complex was performed directly from the 50 analyzed samples. Samples of coalho cheese were grown simultaneously in Stonebrink medium, and conventional PCR was performed from the bacterial isolates with primers that flank differentiation region 4 (DR4), specific to M. bovis, mb400F. Bacterial isolates negative by PCR for RD4 were subjected to PCR for hsp65 of Mycobacterium spp., with subsequent DNA sequencing. The cultures were negative for the M. tuberculosis complex, but two samples (4%) from the artisanal process (with raw milk) exhibited identity with hsp65 of Mycobacterium lehmanii (Sequence ID: KY933786.1, identities: 312/363 [86%]); and Mycobacterium rutilum (sequence ID: LT629971.1, identities: 331/371 [89%]), showing to be indicative environmental contamination. Non-tuberculous mycobacteria are emergent and ubiquitous microorganisms; therefore, they deserve greater attention in the cheese production chain, both in terms of Good Agricultural Practices (GAP) and food Good Manufacturing Practices (GMP).

Artisanal Brazilian Cheeses—History, Marketing, Technological and Microbiological Aspects

“…Medeiros et al [ 18 ] reported an analysis of 50 different samples of Coalho cheese from the Northeastern regions of Brazil in which they were screened for the presence of different representatives of mycobacteria based on conventional and RT nested PCR. Even though all studied cheese samples were negative for M. tuberculosis , two cheeses (both artisanally produced with raw milk) showed positive evidence for the presence of Mycobacterium lehmanii and Mycobacterium rutilum , most probably as a result of environmental contamination [ 18 ].…”

“…Moreover, Albuquerque et al [ 43 ] and Medeiros et al [ 18 ] detected the DNA of mycobacteria ( M. avium subsp. paratuberculosis , M. lehmanii , and M. rutilum ), and not the bacterial cells of the pathogen itself; also, they did not provide evidence that showed if the DNA was from dead or living cells.…”

“…The number of studies dedicated to characterizing the historical, technological, and microbiological characteristics of artisanal Brazilian cheese has increased over the last few years, demonstrating their importance. Some papers, theses, and books feature artisanal Minas cheese, such as Canastra [ 5 , 6 , 7 ], Serro [ 8 , 9 , 10 ], Campo das Vertentes [ 11 , 12 , 13 ], Serrano [ 14 , 15 , 16 ], Coalho [ 17 , 18 ], and Colonial [ 1 , 19 , 20 , 21 ] cheeses. Currently, however, Brazil offers a wide variety of artisanal cheeses, generally distributed regionally, which are still little known, even among Brazilians.…”