Molecular characterization and clonal diversity of methicillin-susceptible Staphylococcus aureus in milk of cows with mastitis in Brazil.
J Dairy Sci
; 96(11): 6856-6862, 2013.
Article
de En
| MEDLINE
| ID: mdl-24054305
ABSTRACT
Mastitis is an important disease for the dairy industry worldwide, causing economic losses and reducing milk quality and production. Staphylococcus aureus is a worldwide agent of this intramammary infection, which also causes foodborne diseases. The objective of this study was to determine the frequency of methicillin-susceptible Staphylococcus aureus (MSSA) isolates in milk of mastitis cows in Brazil and to analyze the genetic lineages and the content of antimicrobial resistance genes and virulence factors among these isolates. Fifty-six MSSA isolates were recovered from 1,484 milk samples (positive for the California mastitis test) of 518 cows from 11 different farms in Brazil (representing 51% of total Staph. aureus obtained), and they were further characterized. Methicillin-susceptible Staphylococcus aureus were isolated from 3.7% of California mastitis test-positive tested milk samples and from 6.2% of tested mastitic cows. Methicillin-susceptible Staphylococcus aureus isolates were characterized by spa typing, agr typing, and multilocus sequence typing, and resistance and virulence traits were investigated by PCR. Seven spa types were identified among MSSA (% of isolates) t127 (44.6), t605 (37.5), t002, t1784, t2066 (1.8), and 2 new ones t10856 (10.7) and t10852 (1.8). Five distinct sequence types (ST) were detected (% of isolates) ST1 (46.4), ST126 (37.5), ST133 (10.7), ST5 (3.6), and a novel ST registered as ST2493 (1.8). Resistances were detected for streptomycin, chloramphenicol, and tetracycline. One strain contained the chloramphenicol resistance gene (fexA; included within transposon Tn558) and 3 strains contained the tetracycline resistance gene [tet(K)]. Methicillin-susceptible Staphylococcus aureus strains were susceptible to most of the antibiotics studied and lacked the virulence genes of Panton-Valentine leukocidin (lukF/S-PV), toxic shock syndrome toxin 1 (tst), exfoliative toxin A (eta), and exfoliative toxin B (etb), as well as the genes of the immune evasion cluster. Methicillin-susceptible Staphylococcus aureus isolates were detected in a relatively low proportion of cows with mastitis (6.2%) and recovered isolates presented high diversity of genetic lineages, with CC1 and CC126 the predominant clonal complexes, and CC133 also being detected. Larger epidemiological studies with molecular characterization of isolates are required to deepen the knowledge on the circulating genetic lineages among the cow population with mastitis.
Mots clés
Texte intégral:
1
Collection:
01-internacional
Base de données:
MEDLINE
Sujet principal:
Infections à staphylocoques
/
Staphylococcus aureus
/
Variation génétique
/
Lait
/
Mammite bovine
Type d'étude:
Prognostic_studies
Limites:
Animals
Pays/Région comme sujet:
America do sul
/
Brasil
Langue:
En
Journal:
J Dairy Sci
Année:
2013
Type de document:
Article
Pays d'affiliation:
Brésil