Molecular epidemiological study of Haemophilus influenzae serotype b strains obtained from children with meningitis in Japan

We report an epidemiological study of 30 Haemophilus influence serotype b ( Hib) strains derived from the cerebrospinal fluid of children with meningit is. The Hib strains were biotyped, tested for beta-lactamase production, an d genotyped by long PCR-ribotyping, random amplified polymorphic DNA (RAPD) analysis, and genomic DNA restriction fragment length polymorphism (RFLP) analysis by pulsed-field gel electrophoresis (PFGE), The phenotypic study c haracterized 22 of the strains (73%) as biotype I. A genotypic study using long PCR-ribotyping with HaeIII restriction digestion showed no polymorphis ms among these 30 Hib strains, but RAPD analysis,vith two sets of primers d emonstrated two distinctive subtypes: one typical of the strains of biotype group II and the second characteristic of the strains of biotype groups I and IV, Each RAPD group was subtyped into several genotypic groups by PFGE- RFLP with SmaI digestion. The genotyping of clinically isolated Hib strains may help to elucidate transmission routes in community infections, endemic ity, and the reasons for vaccine failure.