Population biology of Streptococcus pneumoniae isolated from oropharyngeal carriage and invasive disease.
The population structure of Streptococcus pneumoniae in a sample of 134 carried antibiotic-susceptible isolates, and 53 resistant and susceptible invasive isolates, was examined using a DNA-based version of multilocus enzyme electrophoresis: multilocus restriction typing (MLRT). This involved RFLP analysis of PCR products generated from nine loci of housekeeping genes located around the pneumococcal chromosome. The combination of alleles at each of the nine loci gave an allelic profile or restriction type (RT). All carried (throat or nasopharyngeal) isolates from children or adults in Oxford and Manchester, UK, and from an HIV-seropositive cohort in Nairobi, Kenya, showed an epidemic population structure. Twelve carried clonal groups, each with different serotypes, were identified at both locations within the UK. Almost all of the carried clones examined (16/17) were found to possess identical RTs or sequence types (STs) to invasive isolates, indicating that frequently carried clones are also associated with cases of invasive disease. As expected from previous studies, the population of 53 invasive, mainly penicillin-resistant, isolates was also found to be at linkage equilibrium. Serotype switching was identified among 14% of RTs that possessed two or more members, or 5.7% of individual isolates within these RTs. In support of a population structure in which there is frequent recombination, there is also clear evidence that the trpA/B locus within pneumococci has evolved by horizontal gene transfer. A non-serotypable isolate from an HIV-seropositive patient in Kenya was clearly genetically distinct from other strains studied, with unique alleles at eight out of nine loci examined. However, it was initially identified as a pneumococcus by a 16S RNA gene probe (Gen-Probe), optochin susceptibility and the presence of pneumolysin and autolysin.
Müller-Graf
Christine D M
CDM
Department of Biological Sciences, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK1.
Whatmore
Adrian M
AM
Department of Biological Sciences, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK1.
King
Samantha J
SJ
Department of Biological Sciences, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK1.
Trzcinski
Krzysztof
K
Department of Biological Sciences, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK1.
Pickerill
A Paul
AP
Department of Biological Sciences, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK1.
Doherty
Neil
N
Department of Biological Sciences, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK1.
Paul
John
J
Public Health Laboratory, Royal Sussex County Hospital, Brighton BN2 5BE, UK2.
Griffiths
David
D
John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK3.
Crook
Derek
D
John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK3.
Dowson
Christopher G
CG
Department of Biological Sciences, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK1.
D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015373:Bacterial Typing Techniques; D001483:Base Sequence; D002353:Carrier State / Q000453:epidemiology / Q000382:microbiology*; D002648:Child; D002675:Child, Preschool; D004352:Drug Resistance, Microbial; D005260:Female; D005798:Genes, Bacterial / Q000235:genetics; D014644:Genetic Variation; D005828:Genetics, Population; D006679:HIV Seropositivity; D006801:Humans; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D009960:Oropharynx / Q000382:microbiology*; D011008:Pneumococcal Infections / Q000453:epidemiology / Q000382:microbiology*; D012150:Polymorphism, Restriction Fragment Length; D013296:Streptococcus pneumoniae / Q000145:classification* / Q000187:drug effects / Q000235:genetics; D014774:Virulence
D000900:Anti-Bacterial Agents