Pasteurella multocida subsp multocida and P. multocida subsp septica - Differentiation by PCR fingerprinting and alpha-glucosidase activity

Pasteurella mulfocida is composed of three subspecies that are often differ entiated by fermentation of sorbitol and dulcitol. We studied 35 dulcitol-n egative P. multocida isolates from infected dog and cat bite wounds, 16 of which yielded weak and/or conflicting fermentation reactions in Andrades so rbitol, thus making it difficult to distinguish between the two dulcitol-ne gative subspecies of P. multocida, i,e., P. multocida subsp. multocida and P. multocida subsp. septica. All isolates and two control strains were furt her analyzed using a PCR fingerprinting technique with a single primer (M13 core) and assessed for cr-glucosidase (alpha -Glu) activity. Although the PCR fingerprint patterns and alpha -Glu activity did not correlate well wit h the sorbitol fermentation reactions, they did correlate well with each ot her. All strains identified as P. multocida subsp. septica were positive fo r alpha -Glu activity and exhibited the group I PCR fingerprint profile. Al l strains categorized as P. multocida subsp. multocida displayed either the group n or group III PCR fingerprint profile; 9 of 11 of these isolates we re alpha -Glu negative. These data suggest that both PCR fingerprinting and alpha -Glu activity provide reliable means for differentiating P. mulfocid a subsp. multocida from P. multocida subsp. septica, particularly in strain s that produce weak and/or discrepant sorbitol fermentation reactions.