Identification of bacteria and fungi sampled from the conjunctival surface of normal horses in South-East Queensland, Australia.

The research examines the types of bacteria and fungi existing on the surface of healthy horse eyes, investigates potential risk factors for these microorganisms, and assesses their response to certain antimicrobial medicines. The study involved 95 horses within South-East Queensland, Australia.

Methodology

The researchers carried out the study on 95 client-owned horses in subtropical Australia. The sampling period ran from April 2012 to March 2013. They collected conjunctival swabs from each horse’s eye and cultured the samples to identify aerobic bacteria and fungi, determined by their colony morphology and phenotype. They then subjected the organisms to antimicrobial disk diffusion susceptibility testing, a laboratory method used to determine microbial resistance to antibiotics.

Results

From the study, 98.4% of the sampled eyes returned positive bacterial cultures, with the majority of the bacteria being Staphylococcus spp., Bacillus cereus, Bacillus spp., and Corynebacterium spp. These bacteria were predominantly susceptible to neomycin and fluoroquinolones, types of antibiotics.

Meanwhile, 58.4% of the eyes sampled returned positive fungal cultures, with the most common species being Penicillium spp., Aspergillus spp., and Scopulariopsis spp. Most of these molds showed susceptibility to fungal treatments like ketoconazole, voriconazole, itraconazole, and miconazole. Yeasts were particularly sensitive to ketoconazole.

The research found no significant connection between the breed, age, sex, purpose, or housing of the horse or climatic conditions and the bacterial or fungal culture status.

Conclusion

The researchers concluded that both bacteria and fungi are commonly found on the eyes of healthy horses. The susceptibility of the identified microorganisms can help guide empirical therapy (treatment based on observation and experience) following cytology (the study of cells under a microscope) in addressing corneal ulceration in horses.