Pasteurella multocida subsp. multocida and P. multocida subsp. septica differentiation by PCR fingerprinting and...

Pasteurella multocida is composed of three subspecies that are often differentiated by fermentation of sorbitol and dulcitol. We studied 35 dulcitol-negative P. multocida isolates from infected dog and cat bite wounds, 16 of which yielded weak and/or conflicting fermentation reactions in Andrades sorbitol, thus making it difficult to distinguish between the two dulcitol-negative subspecies of P. multocida, i.e., P. multocida subsp. multocida and P. multocida subsp. septica. All isolates and two control strains were further analyzed using a PCR fingerprinting technique with a single primer (M13 core) and assessed for alpha-glucosidase (alpha-Glu) activity. Although the PCR fingerprint patterns and alpha-Glu activity did not correlate well with the sorbitol fermentation reactions, they did correlate well with each other. All strains identified as P. multocida subsp. septica were positive for alpha-Glu activity and exhibited the group I PCR fingerprint profile. All strains categorized as P. multocida subsp. multocida displayed either the group II or group III PCR fingerprint profile; 9 of 11 of these isolates were alpha-Glu negative. These data suggest that both PCR fingerprinting and alpha-Glu activity provide reliable means for differentiating P. multocida subsp. multocida from P. multocida subsp. septica, particularly in strains that produce weak and/or discrepant sorbitol fermentation reactions.