Staphylococci outside the hospital. Staphylococcus aureus in sheep

Area of Science:

• Veterinary Microbiology
• Bacterial Pathogenesis

Background:

• Staphylococcus aureus is a significant pathogen in both human and animal health.
• Understanding the biochemical properties of S. aureus strains in livestock is crucial for disease control and prevention.

Purpose of the Study:

• To biochemically characterize Staphylococcus aureus strains isolated from sheep, differentiating between healthy animals and those with mastitis.
• To compare the properties of sheep-derived S. aureus with strains from other species and hosts.

Main Methods:

• Isolation and cultivation of S. aureus from ovine anterior nares and mastitic udders.
• Biochemical profiling including pigment production, hemolysin activity (alpha, beta), fibrinolysin activity, crystal violet agar growth, plasma coagulation (human and bovine), and mannitol fermentation.
• Antibiotic sensitivity testing.

Main Results:

• The majority (89.3%) of 84 S. aureus isolates were identified as the C biotype, adapted to sheep, producing pigment and beta hemolysin, but lacking fibrinolysin and alpha hemolysin.
• All C biotype strains coagulated human plasma rapidly but showed variable coagulation times in bovine plasma.
• Mannitol fermentation was observed in 44% of C biotype strains, and all strains were sensitive to tested antibiotics.
• Two strains were classified as C biotype variants lacking pigment, while A and E biotypes (likely from human and dog, respectively) were also identified.

Conclusions:

• The C biotype represents the predominant, sheep-adapted S. aureus, sharing biochemical characteristics with cattle-derived strains.
• The presence of A and E biotypes suggests potential cross-species transmission of S. aureus to sheep.
• All studied ovine S. aureus strains demonstrated antibiotic sensitivity, indicating a potential for effective treatment strategies.