Association of the pneumococcal pilus with certain capsular serotypes but not with increased virulence.
The recent discovery of a mobile genetic element encoding a pilus-like structure in Streptococcus pneumoniae and the demonstration of a role for the pilus in virulence in mice have led to the proposal of the use of the pilus as a candidate pneumococcal vaccine. We examined the frequency of occurrence of the pneumococcal pilus, as determined by the presence of the rrgC gene, and analyzed its association with virulence, capsular serotypes, and multilocus sequence types in the American Indian pneumococcal collection and isolates of S. pneumoniae from blood cultures collected at Children's Hospital Boston. Overall, 21.4% of strains in the American Indian collection had the rrgC gene, but there was no difference between isolates obtained from the nasopharynx and those obtained from sterile sites (blood or cerebrospinal fluid). Vaccine-type strains were significantly more likely than non-vaccine-type strains to have this pilus gene (P < 0.001). Among isolates with identical multilocus sequence types, there was a high concordance (95%) between the multilocus sequence type and the presence or the absence of rrgC. Finally, in the era of the pneumococcal conjugate vaccine, the frequency of rrgC in isolates from Children's Hospital Boston has decreased significantly (42.8% before 2000 versus 21.3% after 2000; P = 0.019). Therefore, our data show that the pilus is present in a minority of strains and is associated with certain serotypes and that its frequency has been reduced by the conjugate pneumococcal vaccine.
Basset
Alan
A
Division of Infectious Diseases, Department of Medicine, Children's Hospital Boston, Enders 861.3, Boston, MA 02115, USA.
Trzcinski
Krzysztof
K
Hermos
Christina
C
O'Brien
Katherine L
KL
Reid
Raymond
R
Santosham
Mathuram
M
McAdam
Alexander J
AJ
Lipsitch
Marc
M
Malley
Richard
R
D002675:Child, Preschool; D010861:Fimbriae, Bacterial / Q000235:genetics*; D005798:Genes, Bacterial / Q000235:genetics*; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D007198:Indians, North American; D007223:Infant; D022401:Meningococcal Vaccines / Q000008:administration & dosage / Q000627:therapeutic use; D009305:Nasopharynx / Q000382:microbiology; D011008:Pneumococcal Infections / Q000453:epidemiology / Q000208:ethnology / Q000382:microbiology / Q000517:prevention & control; D022242:Pneumococcal Vaccines / Q000008:administration & dosage / Q000627:therapeutic use; D017422:Sequence Analysis, DNA; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification / Q000235:genetics / Q000276:immunology / Q000472:pathogenicity; D016896:Treatment Outcome; D014611:Vaccination; D014774:Virulence
D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022401:Meningococcal Vaccines; D022242:Pneumococcal Vaccines