Detection of A/B toxin and isolation of Clostridium difficile and Clostridium perfringens from foals.
Authors: Silva R O S, Ribeiro M G, Palhares M S, Borges A S, Maranhão R P A, Silva M X, Lucas T M, Olivo G, Lobato F C F
Journal: Equine veterinary journal
Summary
# Editorial Summary Clostridium difficile and Clostridium perfringens are recognised enteric pathogens in foals, yet their epidemiological significance in equine diarrhoea remains poorly characterised. This cross-sectional study examined 153 faecal samples (139 from farm foals and 14 from hospitalised cases) using cytotoxicity assays to detect A/B toxins and molecular techniques to identify pathogenic strains and antimicrobial resistance profiles. C. difficile toxin was isolated from 4.6% of samples overall, but notably from 35.7% of hospitalised diarrhoeic foals compared to only 3.2% of farm-based diarrhoeic foals (P = 0.002), suggesting hospital environments may represent a significant risk factor; C. perfringens was recovered from 20.3% of all foals, with higher isolation rates in diarrhoeic animals (27.6%) than non-diarrhoeic controls (13.2%, P = 0.045), though only 4 isolates carried the β2-encoding gene associated with severe disease. Both organisms demonstrated universal susceptibility to metronidazole and vancomycin, supporting these as reliable therapeutic choices. For practitioners, these findings underscore the importance of laboratory confirmation when clostridial infection is suspected—particularly distinguishing C. difficile toxigenic disease from other causes of foal diarrhoea—whilst acknowledging that C. perfringens isolation alone does not confirm pathogenicity, necessitating further investigation into strain virulence and host factors in naturally occurring disease.
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Practical Takeaways
- •Foals presenting with diarrhoea in hospital settings have significantly higher risk of C. difficile infection (35.7%) compared to farm cases (3.2%); laboratory confirmation is essential to guide appropriate antimicrobial selection
- •C. perfringens is commonly isolated from foals (20.3%) but appears to be a secondary rather than primary pathogen, as it was found in both diarrhoeic and non-diarrhoeic animals; isolation alone does not confirm it as the cause of diarrhoea
- •Both C. difficile and C. perfringens remain reliably susceptible to metronidazole and vancomycin, making these agents appropriate empirical choices while awaiting culture results and toxin detection in hospitalised foals with diarrhoea
Key Findings
- •C. difficile A/B toxin detected in 4.6% of samples (7/153), all from diarrhoeic foals; 35.7% of hospitalised diarrhoeic foals versus 3.2% of farm diarrhoeic foals (P=0.002)
- •C. perfringens isolated from 20.3% of foals (31/153), significantly more common in diarrhoeic foals (27.6%) than nondiarrhoeic foals (13.2%, P=0.045)
- •Only 4 C. perfringens strains carried the β2-toxin encoding gene (cpb2), suggesting limited pathogenic potential in this population
- •All C. difficile and C. perfringens isolates were susceptible to metronidazole and vancomycin, supporting their use as first-line antimicrobial therapy