Multiplex PCR reveals a high rate of nasopharyngeal pneumococcal 7-valent conjugate vaccine serotypes co-colonizing indigenous Warao children in Venezuela.
Knowledge of co-colonization with multiple pneumococcal serotypes is becoming very important in the light of both serotype replacement and switching as a result of vaccination. Co-colonization has been reported to occur in up to 30% of carriers, especially in populations with high Streptococcus pneumoniae carriage rates. For the determination of co-colonization, single colonies of nasopharyngeal specimens are serotyped with the Quellung method, a costly method with a low sensitivity. Here we explore the use of a multiplex PCR to identify simultaneous carriage of the capsular serotypes targeted by the 7-valent conjugate vaccine. We applied this multiplex PCR to 50 primary cultures from the nasopharyngeal swabs of healthy Warao Amerindian children, a population with a high pneumococcal carriage rate, most of them with vaccine serotypes, and we identified a second serotype in 20% (n=10) of the pneumococci carriers. These results were confirmed by detailed serotyping of multiple colonies isolated from the primary culture with the Quellung method. We conclude that the multiplex PCR is a sensitive, simple and cost-effective method for detecting multiple serotypes in nasopharyngeal cultures, and thus might be useful for the monitoring of pneumococcal colonization over time, especially in the surveillance of nasopharyngeal colonization after conjugate vaccination.
Rivera-Olivero
Ismar A
IA
Laboratorio de Tuberculosis, Instituto de Biomedicina, Caracas, Venezuela.
Blommaart
Martijn
M
Department of Paediatrics, Nijmegen Medical Centre, Radboud University, Nijmegen, The Netherlands.
Bogaert
Debby
D
Department of Epidemiology, Harvard School of Public Health, Boston, MA, USA.
Hermans
Peter W M
PWM
Department of Paediatrics, Nijmegen Medical Centre, Radboud University, Nijmegen, The Netherlands.
de Waard
Jacobus H
JH
Laboratorio de Tuberculosis, Instituto de Biomedicina, Caracas, Venezuela.
D002648:Child; D006801:Humans; D009305:Nasopharynx / Q000382:microbiology*; D011008:Pneumococcal Infections / Q000276:immunology; D022242:Pneumococcal Vaccines / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D016133:Polymerase Chain Reaction / Q000379:methods*; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification / Q000302:isolation & purification*; D018074:Vaccines, Conjugate / Q000302:isolation & purification; D014687:Venezuela
D022242:Pneumococcal Vaccines; D018074:Vaccines, Conjugate