EVALUATION OF A PCR ASSAY FOR IDENTIFICATION AND DIFFERENTIATION OF CAMPYLOBACTER-FETUS SUBSPECIES

Objective To evaluate a polymerase chain reaction assay for identifica tion of Campylobacter fetus and differentiation of the defined subspec ies. Design Characterisation of bacterial strains by traditional pheno typing, polymerase chain reaction, a probabilistic identification sche me and macrorestriction profiling using pulsed field gel electrophores is. Procedure The results of identification of 99 bacterial strains as determined by conventional phenotyping or by polymerase chain reactio n were compared. Two of these were type strains of C fetus subsp fetus and C fetus subsp venerealis; the remaining strains were field isolat es putatively identified as C fetus. In cases where the subspecies ide ntity was disputed, isolates were identified by means of a probabilist ic identification scheme and by macrorestriction profiling. Results Th e agreement between strain identities initially suggested by tradition al phenotypic methods and the PCR assay was found to be 80.8%. The pol ymerase chain reaction proved to be a reliable technique for the speci es and subspecies identification of C fetus; equivocal results were ob tained in only two instances. Initial misidentifications by convention al phenotyping methods were attributed to methodological differences u sed in various laboratories. Conclusion Our results indicate that misi dentification of C fetus in routine diagnostic laboratories may be rel atively common. The PCR assay evaluated gave rapid and reproducible re sults and is thus a valuable adjunctive method for the identification of C fetus and subsequent subspecies differentiation.