Community-wide vaccination with the heptavalent pneumococcal conjugate significantly alters the microbiology of acute otitis media.
BACKGROUND
Community-wide use of conjugated heptavalent pneumococcal vaccine (PCV7) in children <2 years of age could affect the microbiology of acute otitis media (AOM) in vaccinees, particularly for penicillin-nonsusceptible Streptococcus pneumoniae (PNSP).


METHODS
Since Summer 2000, 94% of young children cared for by this 7-clinician, pediatric practice in rural central Kentucky received 3 or 4 doses of PCV7 in the first 18 months of life.


OBJECTIVE
To determine changes in microbiology of AOM before and after community-wide routine implementation of PCV7.


METHODS
Among children 7-24 months old with severe or refractory AOM, we compared 336 AOM isolates from 1992-1998 with 83 AOM isolates from 2000-2003 in children who had received 3 or 4 doses of PCV7.


RESULTS
Comparing each cohort (1992-1998 versus 2000-2003), the proportion of S. pneumoniae decreased from 48% to 31% (P = 0.009; relative risk, 0.754; 95% confidence interval, 0.628-0.906), and nontypable Haemophilus influenzae increased from 41% to 56% (P = 0.01; relative risk, 1.87; 95% confidence interval, 1.15-3.04; beta-lactamase-positive, 56% versus 64%, not significant). The proportions of intermediate PNSP and resistant PNSP, respectively, were 16% and 9% versus 13% and 6% pre- and post-PCV7, respectively. Vaccine and vaccine-related serotypes, respectively, comprised 70% and 8% versus 36% and 32% of S. pneumoniae strains (P = 0.003). Post-PCV7, Gram-negative bacteria and beta-lactamase-producing organisms accounted for two-thirds and one-half of all AOM isolates, respectively.


CONCLUSIONS
The overall proportion of S. pneumoniae isolates and vaccine serotypes in AOM were significantly reduced by community-wide use of PCV7 vaccine in our practice. The proportion of Gram-negative bacteria became 2-fold more frequent than S. pneumoniae in AOM in PCV7-vaccinated young children where PCV7 uptake was community-wide and supply was adequate.
Block
Stan L
SL
Kentucky Pediatric Research, Inc., Bardstown, KY, USA.
Hedrick
James
J
Harrison
Christopher J
CJ
Tyler
Ron
R
Smith
Alan
A
Findlay
Rebecca
R
Keegan
Eileen
E
D000208:Acute Disease; D000704:Analysis of Variance; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D006090:Gram-Negative Bacteria / Q000302:isolation & purification; D006094:Gram-Positive Bacteria / Q000302:isolation & purification; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D007115:Immunization Schedule; D015994:Incidence; D007223:Infant; D008297:Male; D022401:Meningococcal Vaccines / Q000008:administration & dosage*; D010033:Otitis Media / Q000453:epidemiology / Q000382:microbiology* / Q000517:prevention & control; D011008:Pneumococcal Infections / Q000453:epidemiology / Q000517:prevention & control*; D022242:Pneumococcal Vaccines / Q000008:administration & dosage*; D011336:Probability; D011379:Prognosis; D011446:Prospective Studies; D018570:Risk Assessment; D013296:Streptococcus pneumoniae / Q000276:immunology; D014611:Vaccination / Q000592:standards* / Q000639:trends; D018074:Vaccines, Conjugate / Q000008:administration & dosage
D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022401:Meningococcal Vaccines; D022242:Pneumococcal Vaccines; D018074:Vaccines, Conjugate