Virulence Factors in <i>Staphylococcus</i> Associated with Small Ruminant Mastitis: Biofilm Production and Antimicrobial Resistance Genes

• Main Authors: Nara Cavalcanti Andrade, Marta Laranjo, Mateus Matiuzzi Costa, Maria Cristina Queiroga
• Format: Article
• Language: English
• Published: MDPI AG 2021-05-01
• Series: Antibiotics
• Subjects: mastitis; staphylococci; virulence factors; genes; biofilm; antimicrobial resistance
• Online Access: https://www.mdpi.com/2079-6382/10/6/633

Small ruminant mastitis is a serious problem, mainly caused by <i>Staphylococcus</i> spp. Different virulence factors affect mastitis pathogenesis. The aim of this study was to investigate virulence factors genes for biofilm production and antimicrobial resistance to β-lactams and tetracyclines in 137 staphylococcal isolates from goats (86) and sheep (51). The presence of <i>coa</i>, <i>nuc</i>, <i>bap</i>, <i>icaA</i>, <i>icaD</i>, <i>blaZ</i>, <i>mecA</i>, <i>mecC</i>, <i>tetK</i>, and <i>tetM</i> genes was investigated. The <i>nuc</i> gene was detected in all <i>S. aureus</i> isolates and in some coagulase-negative staphylococci (CNS). None of the <i>S. aureus</i> isolates carried the <i>bap</i> gene, while 8 out of 18 CNS harbored this gene. The <i>icaA</i> gene was detected in <i>S. aureus</i> and <i>S. warneri</i>, while <i>icaD</i> only in <i>S. aureus</i>. None of the isolates carrying the <i>bap</i> gene harbored the <i>ica</i> genes. None of the biofilm-associated genes were detected in 14 isolates (six <i>S. aureus</i> and eight CNS). An association was found between <i>Staphylococcus</i> species and resistance to some antibiotics and between antimicrobial resistance and animal species. Nine penicillin-susceptible isolates exhibited the <i>blaZ</i> gene, questioning the reliability of susceptibility testing. Most <i>S. aureus</i> isolates were susceptible to tetracycline, and no cefazolin or gentamycin resistance was detected. These should replace other currently used antimicrobials.