Microbiology quality, detection of enterotoxin genes and antimicrobial resistance of Staphylococcus aureus isolated from milk and Coalho cheese

Abstract

This study evaluated the microbiological quality of milk and Coalho cheese, the prevalence of enterotoxin genes, antimicrobial resistance and determined an inducible MLSB resistance phenotype by the D-test in strains of Staphylococcus aureus isolated from these products. Seventy samples of milk and Coalho cheese were analyzed. S. aureus strains were identified by biochemical tests. The presence of se genes (sea-see) was tested by polymerase chain reaction. The antimicrobial sensitivity of S. aureus strains was evaluated for 13 antimicrobial drugs using the disk diffusion technique and the double-disk diffusion test (D-test) was performed to determine inducible resistance to lincosamide phenotype. The amount of toxin sufficient to cause foodborne diseases is generally observed when Staphylococcus populations exceed 105 CFU mL-1 g-1. In this study, none of the milk samples analyzed showed these counts; however, 73.3% (22/30) of Coalho cheese samples exceeded this value. A total of 109 isolates were identified as S. aureus. The presence of enterotoxin genes was detected in 25.7% of these isolates and amplified only for the sec gene. Most of the isolates (78.5%) were resistant to one or more antimicrobial agents. The D test showed that 25.0% of erythromycin-resistant isolates had the constitutive resistance phenotype, and 3.8% had the inducible resistance phenotype to clindamycin. These results indicate that these dairy products represent a health risk since these bacteria can cause foodborne diseases or may be a possible route for the transfer of antimicrobial resistance to humans.

Staphylococcus aureus Exotoxins and Their Detection in the Dairy Industry and Mastitis

“…Typically, S. aureus SE food poisoning is associated with inappropriate handling of cooked foodstuffs, or improper storage, resulting in bacterial growth and toxin production [ 11 ]. These enterotoxins are mainly found in foods with high amounts of starch and protein, such as meat products, eggs, and dairy products [ 35 , 36 ]; but enterotoxin production is also affected by other factors, such as pH, water activity, temperature. The SEA, SEB, SEC, SED, and SEE classic enterotoxins are responsible for 95% of SFP; with SEA and SED as the most common causes of food poisoning, due to their stability under a wide range of water activities and pH conditions [ 34 , 37 ].…”

Prevalence, characterization and antibiotic resistance of Staphylococcus aureus isolated from traditional cheeses in Turkey

“…[10] It has been widely reported that the consumption of contaminated food with enterotoxinproducing strains of S. aureus is one of the most common causes of staphylococcal food-poisoning outbreaks worldwide. [11,12] The critical density of S. aureus higher than 10 5 CFU of coagulase-positive S. aureus per gram is required for assumptive enterotoxin production. [7,8,13,14] To date, 24 different staphylococcal enterotoxins (SEc and SEls) have been determined and classified into several evolutionary groups based on a comparison of their nucleotide and amino acid sequences.…”

Determinação Do Potencial Antimicrobiano De Óleos Essenciais De Lavanda (Lavandula Dentata L.) E Manjericão (Ocimum Basilicum L.) Sobre Cepas De Pseudomonas Aeruginosa Isolada De Leite Mastitíco Bovino

“…Dentro desta grande expectativa da utilização de óleos essenciais para o tratamento de mastites, em substituição ao uso de antibióticos, surge um importante benefício: o fato de evitar a ingestão de produtos lácteos contendo resíduos de antibióticos, o que reduz os riscos à saúde pública (PEREIRA et al, 2018), e também dificulta o processo de aquisição de resistência bacteriana (FERRO; MOURA; GERON, 2016).…”