Microbiology. 1999 Nov;145 ( Pt 11):3283-93. Unique Identifier :
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.
JOURNAL ARTICLE Adolescence Adult Antibiotics/PHARMACOLOGY Bacterial
Typing Techniques Base Sequence Carrier
State/EPIDEMIOLOGY/*MICROBIOLOGY Child Child, Preschool Drug
Resistance, Microbial Epidemiology, Molecular Female Genes,
Bacterial/GENETICS Genetics, Population Human HIV Seropositivity
Molecular Sequence Data Oropharynx/*MICROBIOLOGY Pneumococcal
Infections/EPIDEMIOLOGY/*MICROBIOLOGY Polymorphism, Restriction
Fragment Length Streptococcus pneumoniae/*CLASSIFICATION/DRUG
EFFECTS/GENETICS Support, Non-U.S. Gov't Variation (Genetics)
Virulence