DNA probe technology for detection of Haemophilus influenzae.

A 5 kb Haemophilus influenzae DNA fragment involved in penicillin-binding proteins expression was used as a probe for specific detection of H. influenzae strains. The 32p-labeled probe specificity was assessed by hybridization to bacterial dots and 75 strains were tested. All H. influenzae (18) and H. aegyptius (1) strains reacted very strongly with the probe. The H. influenzae serotypes tested (a, b, and non-typable strains) did not differ in their hybridization. Some hybridization was also found with the 12 other Haemophilus species tested as well as other Pasteurellaceae such as Actinobacillus lignieresii and Pasteurella multocida. Two other less related species (Klebsiella ozaenae and Providencia stuartii) also showed low hybridization. The probe detected as low as 10(5)-10(6) H. influenzae cells and 0.1 microgram of DNA in a dot sensitivity test. Hybridization to electroblotted, digested DNA from different species which reacted in the bacterial dot test revealed strong hybridization to H. influenzae and H. aegyptius only. This DNA probe should prove useful for H. influenzae and possibly H. aegyptius detection due to its high specificity and sensitivity under stringent hybridization conditions.