title: Methicillin-Resistant Staphylococcus aureus in Raw Milk: Prevalence, SCCmec Typing, Enterotoxin Characterization, and Antimicrobial Resistance Patterns.
abstract: Staphylococcus aureus is a known major cause of foodborne illnesses, and raw milk and dairy products are often contaminated by enterotoxigenic and antimicrobial-resistant S. aureus strains. In the present study, 35 S. aureus strains were isolated from 383 raw milk samples collected from various dairy herds in the province of Milan (northern Italy). The isolates were characterized based on their antimicrobial susceptibility patterns and the presence of genes encoding staphylococcal enterotoxins (sea, seb, sec, sed, and see). About half (45.7%) of the strains were enterotoxigenic, and 37.1% were resistant to at least one of the antimicrobial drugs tested. Seven (20%) of 35 isolates were identified as methicillin-resistant S. aureus (MRSA), and SCCmec typing performed with a multiplex PCR assay revealed the presence of gene cassettes IV and V, typical of community-acquired MRSA, and I and II, characteristic of health care-associated MRSA. The MRSA strains were evaluated for the presence of the Panton-Valentine leukocidin gene, but this gene was not found. The results of the present study revealed the presence of toxin-producing S. aureus and MRSA strains in raw milk. MRSA and enterotoxigenic S. aureus in dairy farms are an important risk factor for the spread of staphylococcal infections; therefore, further studies are needed to find strategies for monitoring and controlling the presence of S. aureus, especially MRSA, in dairy products.
authors.affiliation: Department of Health Sciences, Università degli Studi di Milano, Via di Rudinì 8, 20142 Milan, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Riva
authors.affiliation: Department of Health Sciences, Università degli Studi di Milano, Via di Rudinì 8, 20142 Milan, Italy. elisa.borghi@unimi.it.
authors.forename: Elisa
authors.initials: E
authors.lastname: Borghi
authors.affiliation: Department of Health Sciences, Università degli Studi di Milano, Via di Rudinì 8, 20142 Milan, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Cirasola
authors.affiliation: Istituto Zooprofilattico della Lombardia e dell'Emilia Romagna, Via Celoria 12, 20133 Milan, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Colmegna
authors.affiliation: Department of Health Sciences, Università degli Studi di Milano, Via di Rudinì 8, 20142 Milan, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Borgo
authors.affiliation: Department of Health Sciences, Università degli Studi di Milano, Via di Rudinì 8, 20142 Milan, Italy.
authors.forename: Ettore
authors.initials: E
authors.lastname: Amato
authors.affiliation: Department of Health Sciences, Università degli Studi di Milano, Via di Rudinì 8, 20142 Milan, Italy.
authors.forename: Mirella Maria
authors.initials: MM
authors.lastname: Pontello
authors.affiliation: Department of Health Sciences, Università degli Studi di Milano, Via di Rudinì 8, 20142 Milan, Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Morace
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry; D001427:Bacterial Toxins / Q000235:genetics; D002417:Cattle; D003612:Dairying; D004768:Enterotoxins / Q000235:genetics*; D005098:Exotoxins / Q000235:genetics; D005260:Female; D005516:Food Microbiology; D007558:Italy; D007956:Leukocidins / Q000235:genetics; D008712:Methicillin / Q000737:chemistry; D055624:Methicillin-Resistant Staphylococcus aureus / Q000235:genetics / Q000302:isolation & purification*; D008826:Microbial Sensitivity Tests / Q000662:veterinary*; D008892:Milk / Q000382:microbiology*; D015995:Prevalence; D013203:Staphylococcal Infections / Q000662:veterinary*
chemical_list: D000900:Anti-Bacterial Agents; D001427:Bacterial Toxins; D004768:Enterotoxins; D005098:Exotoxins; D007956:Leukocidins; C078284:Panton-Valentine leukocidin; D008712:Methicillin