Occurrence of Multi-Resistant Staphylococcus aureus in Artisan Goat Coalho Cheese in Northeastern Brazil

Resumo

Background: The artisanal goat coalho cheese is one of the products obtained that stand out in 11 the dairy goat farming of the Northeast of Brazil. Despite its importance, goat cheese is often 12 made under inadequate hygienic-sanitary conditions and usually uses raw goat's milk, 13 increasing the risk of product contamination. Among the pathogens carried by goat coalho 14 cheese, Staphylococcus aureus stands out, being responsible for cases of food poisoning and 15 persistent infections that are difficult to treat. This study aimed to evaluate the contamination, 16 genotypic and phenotypic resistance of Staphylococcus aureus isolated from artisanal coalho 17 cheese made with goat milk produced in the Northeast region of Brazil.

Materials, Methods & Results: This study analyzed only artisanal coalho cheeses made with  raw goat's milk and purchased directly from farms. Twelve samples of artisanal coalho cheeses  made with raw goat's milk were collected (1 sample per property) in 8 municipalities in the  state of Pernambuco, Northeast region of Brazil. For microbiological analysis of enumeration  of Colony Forming Units (CFU/g) of Staphylococcus spp. the methodology recommended by the International Organization for Standardization (2019) and recognized by the Ministry of Agriculture, Livestock and Supply was used. After enumeration, 5 colonies were selected per enumerated plate, a total of 180 Staphylococcus spp. was obtained. These were subjected to thermal extraction of genetic material to search for the nuc gene by Polymerase Chain Reaction, the isolates carrying the nuc gene were subjected to genotypic and phenotypic evaluation of  antimicrobial resistance. After the phenotypic analysis, the Multiple Antimicrobial Resistance Index was evaluated. In all samples, Staphylococcus spp. and were considered unfit for consumption, with the lowest count being 9.4x103 CFU/g and the highest 6.4x106 CFU /g. Of the 180 isolates, 28.34% (51/180) were positive for the detection of the nuc gene. All resistance  genes except mecA, mecC, and norB were detected. Of the 51 S. aureus isolates, 31.37% (16/51) were considered multi-resistant and presented a Multiple Antimicrobial Resistance Index above 0.2.

Discussion: After microbiological analysis it was found that all samples of coalho cheese were out of standards and unfit for human consumption in accordance with Ordinance n° 146/1996 of the Ministry of Agriculture, Livestock and Supply of Brazil. Furthermore, the contamination of goat coalho cheeses is a risk to public health. During sample collection were found inadequate hygiene conditions in the environment used for cheese production. The presence of Staphylococcus aureus can be attributed to hygienic-sanitary failures in cheese production. From a health point of view, it is even more alarming when it comes to S. aureus carrying resistance genes. Although the 51 S. aureus isolates did not carry the mecA, mecC, norB genes and did not show phenotypic resistance to cefoxitin and oxacillin, all other genes were detected, indicating the circulation of S. aureus carrying the tet(L) genes, tet(M), tet-38, msrA, norA, and norC, which so far had not been reported in the production chain of goat coalho cheese in Brazil. Furthermore, the evaluation of the Multiple Antimicrobial Resistance Index identified the occurrence of multiple resistance to antimicrobials in 31.37% (16/51) of S. aureus at high risk to human health. The results obtained are quite worrying and serve as a warning to the scientific community and the Food Safety and Hygiene Inspection Services.

Keywords: goat cheese, contamination, resistance, one health