Retrospective study of blood culture isolates, antimicrobial sensitivity, and survival factors from 243 neonatal foals in Normandy (France).

Aminoglycosides remain the most effective empirical option; ceftiofur resistance warrants strict antimicrobial stewardship in neonatal foals.

This retrospective cohort study analyzed blood culture isolates, antimicrobial susceptibility patterns, and survival factors in 243 neonatal foals (under 7 days old) admitted to two equine intensive care units in Normandy, France. Blood cultures were positive in 43% of cases, with pretreatment not significantly affecting culture positivity rates (P=.62). Contrary to older literature emphasizing Gram-negative predominance, Gram-positive organisms accounted for 65% of isolates, with Staphylococcus spp. (25%), Escherichia coli (11%), and Streptococcus spp. (11%) being most prevalent. Multidrug-resistant (MDR) bacteria comprised 26% of isolates, predominantly Gram-positive, yet MDR presence was not significantly associated with in-hospital mortality (P=.52). Aminoglycosides demonstrated the lowest resistance rates, with amikacin at 17% and gentamicin at 19%, supporting their continued empirical use. In contrast, resistance to penicillin was notably high (53%), and ceftiofur resistance reached 33%, raising significant concerns given its classification as a critically important antimicrobial for human medicine. Trimethoprim-sulfamethoxazole resistance was approximately 35% for Gram-positive and 26% for Gram-negative isolates. These findings reinforce the importance of regional antimicrobial stewardship programs and suggest that aminoglycosides remain reliable empirical options for neonatal foal bacteremia, while ceftiofur use should be minimized to preserve efficacy and protect public health interests.

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