Pneumococcal disease: emergence of serotypes 19A and 7F following conjugate pneumococcal vaccination in a Mexican hospital.
BACKGROUND
Mexico was the country to initiate massive vaccination with heptavalent pneumococcal conjugate vaccine (PCV-7) in children. There is no information regarding pneumococcal invasive disease (PID) in children before and after implementation of PCV-7 in Mexico or elsewhere in Latin America.


METHODS
During October 2005 to September 2010, active surveillance for pediatric PID was initiated at Tijuana General Hospital. Only culture-confirmed cases from sterile fluids were included in the study. Serotype identification was also performed.


RESULTS
Twenty-eight pediatric PID cases were confirmed. Streptococcus pneumoniae was the main cause of pleural empyema (n = 13). It was also the second most common cause of confirmed bacterial meningitis (n = 10), followed by Neisseria meningitidis (n = ?), and the only cause of otomastoiditis with bacterial isolation (n = 5). Vaccine-associated serotypes decreased from 54% before PCV-7 introduction to the vaccination schedule, to only 5.6% after PCV-7 implementation. Serotypes 19A and 7F (47% and 33% respectively were predominant following PCV-7 vaccination.


CONCLUSIONS
Serotype substitution in PID is present in the northern border of Mexico following PCV-7 vaccination in children.
Department of Pediatric Infectious Diseases, General Hospital of Tijuana, Mexico. echacon88@hotmail.com
Enrique
E
Chacon-Cruz
Yazbeck
Y
Velazco-Mendez
Samuel
S
Navarro-Alvarez
Rosa M
RM
Rivas-Landeros
Maria Luisa
ML
Volker
Graciano
G
Lopez-Espinoza
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004653:Empyema / Q000453:epidemiology / Q000382:microbiology; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006776:Hospitals, Pediatric; D006801:Humans; D007223:Infant; D008297:Male; D008417:Mastoiditis / Q000453:epidemiology / Q000382:microbiology; D016920:Meningitis, Bacterial / Q000453:epidemiology / Q000382:microbiology; D008800:Mexico / Q000453:epidemiology; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000382:microbiology*; D022242:Pneumococcal Vaccines / Q000008:administration & dosage* / Q000276:immunology*; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification* / Q000302:isolation & purification*
D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022242:Pneumococcal Vaccines