Based on partial sequencing of the 16S rRNA gene V-factor dependent Pasteurellaceae (Haemophilus), strains from rat and guinea pig were assigned to the Rodent cluster or the Haemophilus parainfluenzae complex. PCRs for the detection of biotype Heyl or Jawetz [P.] pneumotropica detected none of the strains and only two Haemophilus strains assigned to the Rodent cluster respectively. All Haemophilus strains were positive by a PCR developed for detection of all Pasteurellaceae taxa. The Pasteurellaceae PCR detected infection in all 76 rats and 40 guinea pigs from 3 and 6 colonies respectively reported to be free from Pasteurellaceae infection. ELISAs, using two Haemophilus antigens and culture, detected infection with similar frequency but both methods were inferior to PCR. The Pasteurellaceae PCR should be the new ‘gold standard’ for comparison of the sensitivity of other test methods for Pasteurellaceae infection in rodents.
