Although studies have investigated bacteremia in the critically ill neonatal foal, none specifically investigated bacteremia in neonatal foals with diarrhea. These animals are likely to have a compromised gastrointestinal tract, and be at increased risk of bacteremia, perhaps with different organisms than in foals with other disease conditions.
Records of all neonatal (<30d of age) foals presenting with diarrhea between January 1990 and September 2007 were examined. Foals that developed diarrhea > 12 hours after admission were excluded. 153 records were available for inspection with 133 admission blood culture results recorded. 66 foals (50%) were bacteremic at admission, with 75 isolates. Blood culture from a further 18 foals (14%) grew Corynebacterium spp, interpreted as skin contamination. 9 foals (14%) had 2 or more organisms isolated. One foal had 5 different organisms, interpreted as contamination. Forty-eight foals (36%) had no growth. Excluding Corynebacterium spp, 43 isolates (57%) were gram-negative organisms, and 32 isolates (43%) were gram-positive organisms. Enterococcus spp (22 isolates, 29%) was most common, many resistant to multiple antimicrobials, followed by Pantoea agglomerans (13 isolates, 17%).
The high prevalence of bacteremia, dominated by Enterococcus spp and Pantoea agglomerans isolates, contrasts previous studies of critically ill foals. Bacteremia appears to be more common in neonatal foals with diarrhea than other critically ill neonatal foals. Foals with diarrhea may be predisposed to gram-positive or gram-negative bacteremia with a multiply resistant pathogen early in the clinical course. Decisions regarding antimicrobial selection should be made with these differences in mind.