title: Analysis of the prevaccine population of noncapsulate Haemophilus influenzae and identification of a putative epidemic clone.
abstract: For six months prior to the introduction of Haemophilus influenzae serotype b vaccines, all noncapsulate Haemophilus influenzae received by our laboratory were characterised by biotyping, antibiogram, outer-membrane protein profiling, and ribotyping. Simpson's index of diversity (SID) showed the population was heterogeneous with multiple clones. The study identified a clone within noncapsulate Haemophilus influenzae biotype II that caused more disease than other strains. This clone was shown to have previously caused two outbreaks of respiratory disease and to possess a small extrachromosomal plasmid encoding ampicillin resistance. The study shows that describing the diversity within a bacterial population with SID may negate the need for retrospective subtyping comparisons.
authors.affiliation: Haemophilus Reference Laboratory, Oxford Public Health Laboratory, John Radcliffe Hospital, Headington, UK.
authors.forename: N I
authors.initials: NI
authors.lastname: Leaves
authors.forename: J Z
authors.initials: JZ
authors.lastname: Jordens
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015373:Bacterial Typing Techniques; D006192:Haemophilus Infections / Q000517:prevention & control; D018073:Haemophilus Vaccines; D006193:Haemophilus influenzae / Q000145:classification* / Q000302:isolation & purification; D006801:Humans; D008826:Microbial Sensitivity Tests; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D006113:United Kingdom
chemical_list: D000900:Anti-Bacterial Agents; D018073:Haemophilus Vaccines