Occurrence of Nontuberculous Mycobacteria, Salmonella, Listeria monocytogenes, and Staphylococcus aureus in Artisanal Unpasteurized Cheeses in the State of Michoacan, Mexico.

ABSTRACT: This study investigated the presence of nontuberculous mycobacteria (NTM) for the first time in two types of unpasteurized fresh cheese produced in the state of Michoacan, Mexico. We tested for this pathogen, along with the others, to broaden the study of microbiological quality in 60 samples of cheese, 30 fresh and 30 Adobera, which were collected from six artisanal cheese factories (ACFs). The hygienic conditions of these establishments and the practices of cheese manufacture were generally poor. Although Mycobacterium bovis was not detected, four cheese samples harbored NTM isolates. The four NTM isolates were identified using three molecular markers (hsp65, rrs, and rpoB genes) that corresponded to Mycolicibacterium fortuitum (n = 3) and Mycolicibacterium mageritense (n = 1). All 60 cheese samples analyzed had unsatisfactory microbiological quality according to the Mexican Official Guideline. Regarding fresh cheeses, all 30 samples analyzed were positive for aerobic mesophilic bacteria, total coliforms, fecal coliforms, and yeasts and molds. Escherichia coli and Staphylococcus aureus were present in 23 and 21 samples, respectively. Listeria monocytogenes was identified in a sample and was isolated from a bulk milk tank in the same ACF. With regard to Adobera cheeses, all samples were positive for aerobic mesophilic bacteria, total coliforms, fecal coliforms, yeasts and molds, and S. aureus. E. coli was isolated from 28 samples. Salmonella was isolated from a sample and from a wooden shovel used in the manufacture of the cheeses in the same ACF. Thus, the consumption of unpasteurized fresh cheese may represent a public health risk. Because of this, health authorities should enforce the legislation that forbids the processing of cheese with unpasteurized milk and encourage producers to follow good manufacturing practices from original ingredients, through the production process of the cheese, to its sale to assure a safe product.

A new species of the genus Centruroides Marx (Scorpiones, Buthidae) from western Michoacán State, México using molecular and morphological evidence.

A new species of scorpion belonging to the genus Centruroides Marx, 1890 is described from the Coalcomán mountain range, western Michoacán State, Mexico. Its general aspect resembles Centruroidesruana Quijano-Ravell & Ponce-Saavedra, 2016, and C.infamatus (C. L. Koch, 1844), but it is a smaller species having lower pectinal tooth counts; also, males of C.ruana have the pedipalp chelae slightly thicker, whereas C.infamatus has a subaculear tubercle nearer to the base of the aculeus. Another species with similar aspect is Centruroidesornatus Pocock, 1902; however, a preliminary molecular analysis of the mitochondrial gene mRNA 16S showed genetic divergence (measured as p-distance) near to 10% between these species, and lower differences between the new species with respect to C.infamatus (4.63%) and C.ruana (5.07%). The molecular evidence together with the morphological characters (integrative taxonomy) are sufficient for recognizing the Coalcomán population as a separate and valid species.