GENETIC RELATEDNESS WITHIN AND BETWEEN SEROTYPES OF STREPTOCOCCUS-PNEUMONIAE FROM THE UNITED-KINGDOM - ANALYSIS OF MULTILOCUS ENZYME ELECTROPHORESIS, PULSED-FIELD GEL-ELECTROPHORESIS, AND ANTIMICROBIAL RESISTANCE PATTERNS

A collection of 54 isolates of invasive Streptococcus pneumoniae of se rotypes 3 and 14 and serogroups 6, 9, 19, and 23 was investigated. Mul tilocus enzyme electrophoresis and pulsed-field gel electrophoresis su ggested that two clones were represented in the collection, one of ser otype 14 isolates, most of which were resistant to erythromycin, and o ne of serotype 9V isolates, in which resistance to penicillin (MIC, 1 mu g/ml), cefotaxime, and co-trimoxazole was common. Among other isola tes there was only a limited correlation between genetic relatedness m easured by multilocus enzyme electrophoresis and expression of the sam e capsule type. However, isolates with highly related pulsed-field gel electrophoresis patterns always shared the same serotype and highly r elated allele profiles. Calculation of the index of association sugges ts a freely recombining population structure with epidemic spread of s uccessful clones.