title: Prevalence of Staphylococcus aureus and of methicillin-resistant S. aureus clonal complexes in bulk tank milk from dairy cattle herds in Lombardy Region (Northern Italy).
abstract: Staphylococcus aureus is the most important causative agent of subclinical mastitis in cattle resulting in reduced milk production and quality. Methicillin-resistant S. aureus (MRSA) strains has a clear zoonotic relevance, especially in the case of occupational exposure. The aim of the study was to evaluate the prevalence of S. aureus and MRSA in bulk tank milk (BTM) from dairy cattle herds in the Lombardy Region (Northern Italy) and to identify the main MRSA circulating genotypes. MRSA strains were characterized by susceptibility testing, multi-locus sequence typing (MLST), spa typing and SCCmec typing. A total 844 BTM samples were analysed and S. aureus and MRSA were detected in 47·2% and 3·8% of dairy herds, respectively. MLST showed that the majority (28/32) of isolates belonged to the typical livestock-associated lineages: ST398, ST97 and ST1. Interestingly, in this study we report for the first time the new ST3211, a single locus variant of ST(CC)22, with the newly described 462 aroE allele. Our study indicates high diffusion of S. aureus mastitis and low, but not negligible, prevalence of MRSA in the considered area, suggesting the need for planning specific control programmes for bovine mastitis caused by S. aureus, especially when MRSA is implicated.
authors.affiliation: Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna,Lodi,Italy.
authors.forename: C
authors.initials: C
authors.lastname: Cortimiglia
authors.affiliation: Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna,Lodi,Italy.
authors.forename: M
authors.initials: M
authors.lastname: Luini
authors.affiliation: Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna,Lodi,Italy.
authors.forename: V
authors.initials: V
authors.lastname: Bianchini
authors.affiliation: Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna,Lodi,Italy.
authors.forename: L
authors.initials: L
authors.lastname: Marzagalli
authors.affiliation: Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna,Lodi,Italy.
authors.forename: F
authors.initials: F
authors.lastname: Vezzoli
authors.affiliation: Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna,Sorveglianza Epidemiologica Lombardia,Brescia,Italy.
authors.forename: D
authors.initials: D
authors.lastname: Avisani
authors.affiliation: Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna,Sorveglianza Epidemiologica Lombardia,Brescia,Italy.
authors.forename: M
authors.initials: M
authors.lastname: Bertoletti
authors.affiliation: Istituto Zooprofilattico Sperimentale del Lazio e della Toscana 'M. Aleandri',Rome,Italy.
authors.forename: A
authors.initials: A
authors.lastname: Ianzano
authors.affiliation: Istituto Zooprofilattico Sperimentale del Lazio e della Toscana 'M. Aleandri',Rome,Italy.
authors.forename: A
authors.initials: A
authors.lastname: Franco
authors.affiliation: Istituto Zooprofilattico Sperimentale del Lazio e della Toscana 'M. Aleandri',Rome,Italy.
authors.forename: A
authors.initials: A
authors.lastname: Battisti
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology* / Q000382:microbiology*; D003612:Dairying; D005260:Female; D007558:Italy / Q000453:epidemiology; D008712:Methicillin / Q000494:pharmacology; D016106:Methicillin Resistance; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification / Q000187:drug effects / Q000302:isolation & purification; D008892:Milk / Q000382:microbiology*; D015995:Prevalence; D013211:Staphylococcus aureus / Q000145:classification / Q000187:drug effects / Q000302:isolation & purification*
chemical_list: D000900:Anti-Bacterial Agents; D008712:Methicillin
keywords: 
                 Staphylococcus aureus
              ; Bulk tank milk; MRSA; dairy cattle; genotyping