## 4 Discussion  
In addition to the use of raw milk for production, artisanal cheeses undergo several processing steps where contact with handlers is unavoidable, and so, contamination with _S. aureus_ can be expected [20; 23]. Cross-contamination at retail locations can also be a source of _S. aureus_, as whole cheeses are cut into smaller pieces for sale, and cutting boards and utensils can transfer microorganisms from one cheese to another. Handlers with poor personal hygiene practices, in retail environments, can be additional sources of contamination [30]. \begin{table}
\begin{tabular}{c c} \hline \hline
**Enterotoxin Gene** & **Prevalence \%** \\ \hline _sea_ & 15 (11.6\%) \\ _seb_ & 4 (3.1\%) \\ _sec_ & 5 (3.9\%) \\ _sed_ & 0 \\ _sea_ & 7 (5.4\%) \\ _seg_ & 97 (75.2\%) \\ _seh_ & 119 (92.2\%) \\ _sei_ & 35 (27.1\%) \\ _sej_ & 0 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Distribution of enterotoxin genes among 129 _Staphylococcus aureus_ isolates positive for at least one gene. A worrisome percentage (38.2%) of the _S. aureus_ isolates obtained from Minas artisanal cheese samples collected from retail establishments in Sao Paulo was tolerant to at least one biocide, mainly to quaternary ammonium compounds (QACs), benzalkonium chloride (BC), and hexadecylpyridinium chloride (HDP). The wide use of BC in the formulations of products destined for cleaning utensils and other surfaces in the food industry may explain these results [31]. BC is also used as a component in pesticides, disinfectants, and detergents in animal husbandry, mainly dairy cattle [32]. HDP is used in personal hygiene products, and is also approved for decontaminating raw poultry, so its use in food processing environments is possible [33]. The frequent use and overuse of biocides in the food processing system can create selective pressure, resulting in the proliferation and abundance of disinfectant-tolerant strains [9], besides the appearance of strains tolerant to multiple biocides, as evidenced in this study and reported by other authors [34; 35]. The reported tolerance to biocides suggests that any use that may provide a sublethal exposure represents a risk of developing adaptation to these compounds. A high prevalence of the QAC efflux pump _smr-qacC/D_ gene among the _S. aureus_ isolates tolerant to biocides (89.6%) was detected, confirming previously published results [36; 37]. Some studies have shown that efflux pumps decreased the effectiveness of QAC biocides, phenolic parabens, and intercalating agents, most notably in _S. aureus_ expressing pumps such as QacA-D, QacG, and QacH [38]. In this study, none of the CD-tolerant isolates were positive for the _qacA/B_ and _smr_ genes, suggesting that these genes do not play an important role in tolerance to this biocide, as also reported in other studies [35]. Most biocide-tolerant _S. aureus_ isolates harbored at least one antibiotic resistance gene (92.3%). This phenomenon has been observed for _Salmonella_ from chicken eggshells: isolates tolerant to benzalkonium chloride, cetrimide, hexadecylpyridinium chloride, triclosan, hexachlorophene, and \(\Gamma\)3-oxonia were resistant to ampicillin (90.5%), chloramphenicol (61.9%), tetracycline (47.6%), and trimethoprim-sulfamethoxazole (38.1%) [17]. _Salmonella_ sp. (_S. Derby, S. typhimurium and S. infants_) isolates from a pig slaughterhouse, presenting multidrug resistance (amoxicillin, chloramphenicol, florfenicol, doxycycline, cefalcor, azithromycin, and enforloxacin), were also tolerant to 0.5% benzalkonium chloride [39]. The co-existence of tolerance to biocides and potential resistance to antibiotics found in the _S. aureus_ isolates obtained from artisanal cheeses can be explained by the positivity for _smr_ and _qacA/B_ genes encoding QAC efflux pumps. Despite having different mechanisms of action, studies indicate that the genetic systems for antibiotic and biocide resistance are similar [40].