Georgia
Veterinary Scholar
Program

Bacterial isolates and antibiotic sensitivity patterns from septicemic neonatal foals: a 15 Year retrospective study (1986-2000).

Septicemia is the leading cause of acquired illness in neonatal equines. The purpose of this study was to identify the major organisms cultured from septicemic foals, to identify trends in Gram staining characteristics and antibiotic sensitivities, and to determine if culture results correlated with clinical data. We reviewed records of 507 foals < 14 days of age that were admitted to the University of Georgia from 1986 to 2000. Foals were included in the study if they met at least one of three criteria: a positive sepsis score, a positive blood culture, or > 3 focal infections (49%; 250/507). The tissue from which bacteria were most frequently isolated was blood, with 61% (112/184) positive cultures. There was a significant correlation between the sepsis score and blood culture outcomes. The overall case fatality was 56% (138/244), and was significantly greater in foals in which a gram negative organism was isolated from the blood. If the blood culture was positive, the same organism was cultured from another site 50% of the time (43/72). The number of gram positive organisms cultured from blood samples rose significantly over time from 21% (1986-1990) to 54% (1996-2000). Amikacin, TMS, gentamicin, and chloramphenical were most effective against gram negative organisms (90%, 79%, 75%, and 75% sensitive, respectively) cultured from blood, synovial fluid, CSF, and feces. Chloramphenical, erythromycin, cephalothin, rifampin, and tetracycline were most effective against gram positive organisms (90%, 85%, 82%, 81%, and 77%, respectively). Chlorampenical and tetracycline were most effective against all bacteria (80% and 74%, respectively). In conclusion, a positive blood culture correlates with both a positive sepsis score and survival. Due to the fact that gram positive isolates have increased over time, septicemic foals should be treated with antibiotics effective against both gram negative and gram positive bacteria until culture results can be obtained.