A comparison of antigenic structure and phage pattern with biochemical properties of staphylococcus aureus strains isolated from horses.

This research looks at the antigenic structure, phage pattern and biochemical properties of the Staphylococcus aureus bacterium found in horses, revealing different strains, their identifiable properties, and patterns.

Isolation and Characterization of S. aureus Strains

• The study analysed S. aureus strains isolated from the anterior nares (the front part of the nostrils) of horses. Out of 70 isolated strains, 48 (69%) belonged to what is identified as the ‘E’ biotype.
• Approximately a third of these isolates were subjected to typing with factor serums and, of these, 35% displayed one of five different patterns.
• A notable finding was that almost all strains failed to be typable with the basic sets of phages used for typing staphylococci in humans and cattle, even at ‘RTD x 100’ — a high-intensity phage test.

Biotyping and Identifying Patterns

• All ‘E’ type staphylococci in these horses contained polysaccharide Aa — a component of their structure that can trigger immune responses. This was consistent across the tested sample.
• Other strains, although biochemically different, were also identified and were classed in biotypes A, B or C. These strains showed a variety of different serological (immune response) patterns and phage patterns.
• Unlike the ‘E’-type staphylococci, these carried the polysaccharide Ag.

Unclassified Cultures

• The researchers were unable to classify 6 cultures from tested samples. The reasons for this were not provided in the abstract. These strains could represent novel biotypes of the bacterium, or they may be anomalies that require further study.

Conclusion

• This study demonstrated a varied range of S. aureus strains in horses, each showing different biochemical characteristics, phage patterns, and antigenic structures.