Presence of Classical Enterotoxin Genes, agr Typing, Antimicrobial Resistance, and Genetic Diversity of Staphylococcus aureus from Milk of Cows with Mastitis in Southern Brazil

• Published in: Journal of food protection 2018-05, Vol.81 (5), p.738-742
• Main Authors: Kroning, Isabela S, Iglesias, Mariana A, Mendonça, Karla S, Lopes, Graciela V, Silva, Wladimir P
• Format: Article
• Language: English
• Subjects: Animals; Anti-Bacterial Agents; Antibiotics; Antiinfectives and antibacterials; Antimicrobial agents; Antimicrobial resistance; Bacterial Proteins - genetics; Brazil - epidemiology; Cattle; Cow's milk; Dairy cattle; Dairy farming; Dairy farms; Dairy products; Drug resistance; Drug Resistance, Bacterial; Electrophoresis; Enterotoxins; Enterotoxins - analysis; Enterotoxins - genetics; Farms; Female; Food contamination & poisoning; Food processing industry; Food safety; Foodborne diseases; Gel electrophoresis; Genes; Genetic diversity; Genetic Variation; Gram-positive bacteria; Laboratories; Mastitis; Mastitis, Bovine - microbiology; Milk; Milk - chemistry; Molecular Epidemiology; Molecular Typing; Multilocus sequence typing; Outbreaks; Ovis aries; Pathogens; Penicillin; Pulsed-field gel electrophoresis; Staphylococcal Infections - epidemiology; Staphylococcal Infections - microbiology; Staphylococcal Infections - veterinary; Staphylococcus; Staphylococcus aureus; Staphylococcus aureus - drug effects; Staphylococcus aureus - genetics; Staphylococcus aureus - isolation & purification; Trans-Activators
• ISSN: 0362-028X; 1944-9097
• DOI: 10.4315/0362-028X.JFP-17-436

Staphylococcus aureus is a common causative agent of bovine mastitis in dairy cows and commonly associated with foodborne disease outbreaks. The aim of this study was to evaluate the presence of enterotoxin genes, agr typing, antimicrobial resistance, and genetic diversity of S. aureus isolated from milk of cows with mastitis in dairy farms from southern Brazil. Results showed that 7 (22.6%) of 31 S. aureus isolates were positive for enterotoxin genes. Specifically, the genes encoding for enterotoxins A ( n = 4), C ( n = 2), and B ( n = 1) were detected. Isolates belonging to the agr group III (10 of 31, 32.2%) and agr group I (7 of 31, 22.5%) were the most common. To our knowledge, this is the first report of both agr I and III in the same S. aureus isolate from milk of cows with bovine mastitis. The antimicrobial resistance test showed that 54% of the isolates were multiresistant to antimicrobial agents. The macrorestriction analysis produced 16 different major SmaI pulsed-field gel electrophoresis patterns, with up to two subpatterns. Moreover, the presence of some S. aureus clones in a distinct area was observed. Although this study characterized a limited number of S. aureus isolates, the presence of classical enterotoxin genes and resistance to multiple antimicrobial agents reinforces the importance of this microorganism to animal and human health. In addition, similar genetic profiles have been identified in distinct geographic areas, suggesting clonal dissemination of S. aureus in dairy herds from southern Brazil.