SENSITIVITY AND SPECIFICITY OF BRONCHOALVEOLAR LAVAGE AND PROTECTED CATHETER BRUSH METHODS FOR ISOLATING BACTERIA FROM FOALS WITH EXPERIMENTALLY-INDUCED PNEUMONIA CAUSED BY KLEBSIELLA-PNEUMONIAE

One indication for referral of horses to veterinary hospitals is for d iagnosis of the microbiologic cause of pneumonia, particularly when th e initial treatment fails. Although endoscopic methods have long been available for microbiologic sample collection, accuracy of these metho ds under these conditions have not been studied in detail. We compared the bacteria isolated from samples obtained by bronchoalveolar lavage (BAL) with those obtained by protected catheter brush (PCB) from foal s with unilateral pneumonia induced by inoculation with Klebsiella pne umoniae. As part of previously described clinical trials, foals were a dministered antimicrobial therapy IM (n = 15) or vehicle IM (n = 7), a nd collection of distal airway secretion samples was conducted during the treatment period. Sensitivity and specificity of the sample collec tion methods were assessed by comparison of the isolates from BAL or P CB samples with isolates from tissue of the inoculated lung lobe, whic h was the most severely affected lung region. Sensitivity and specific ity of BAL for recovery of K pneumoniae (challenge strain) and Strepto coccus zooepidemicus (common secondary pathogen) was 90 and 69%, respe ctively, compared with 76 and 85%, respectively, for the PCB method. S ensitivity was significantly (P = 0.03) higher for BAL (100%) than for PCB (69%) for recovery of K pneumoniae (P = 0.03) from lungs. However , difference in the sensitivity of these methods for recovery of S zoo epidemicus was not significant. In conclusion, BAL was a more reliable method for recovery of bacteria from the lungs in chronically infecte d foals that received antimicrobial treatment.