Molecular characterization of pneumococcal nasopharynx isolates collected from children during their first 2 years of life.
Pneumococcal colonization was studied in 19 children monitored from birth through the age of 2 years. For this purpose, pneumococcal isolates were characterized by capsular typing, restriction fragment end labeling (RFEL), and penicillin-binding protein (PBP) genotyping. Fifty-eight isolates were collected and were found to belong to 10 capsular types, 31 RFEL types, and 7 PBP genotypes. Thirty-nine percent of the isolates had reduced susceptibility to penicillin. All seven highly resistant strains (MICs, > 1 microgram/ml) were identical to the pandemic clone 23F. Children were culture positive between one and eight times at 13 scheduled visits. Although the infants were frequently recolonized with different strains, colonization with one particular strain often persisted for several months. Isolation of a previously detected capsular type was common, and the chromosomal homogeneity tended to be high when it occurred. Horizontal transfer of capsular genes between strains of different RFEL types was demonstrated in one child. The ecological advantage of transfer of capsular genes is unclear unless survival of the organism on a mucosal surface may be linked to immunoprotective pressure against particular capsular types.
Department of Pediatrics, Erasmus Medical Center Rotterdam, Erasmus University Rotterdam, The Netherlands.
M
M
Sluijter
H
H
Faden
R
R
de Groot
N
N
Lemmens
W H
WH
Goessens
A
A
van Belkum
P W
PW
Hermans
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins; D015373:Bacterial Typing Techniques; D002352:Carrier Proteins / Q000235:genetics; D002675:Child, Preschool; D015331:Cohort Studies; D016172:DNA Fingerprinting; D005260:Female; D006602:Hexosyltransferases; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008826:Microbial Sensitivity Tests; D002267:Muramoylpentapeptide Carboxypeptidase / Q000235:genetics; D009305:Nasopharynx / Q000382:microbiology*; D010403:Penicillin Resistance; D046915:Penicillin-Binding Proteins; D010458:Peptidyl Transferases; D010802:Phylogeny; D012150:Polymorphism, Restriction Fragment Length; D012091:Repetitive Sequences, Nucleic Acid; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification* / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002352:Carrier Proteins; D046915:Penicillin-Binding Proteins; D010458:Peptidyl Transferases; D006602:Hexosyltransferases; D002267:Muramoylpentapeptide Carboxypeptidase