New Patterns in the Otopathogens Causing Acute Otitis Media Six to Eight Years After Introduction of Pneumococcal Conjugate Vaccine

Department of Pediatrics, University of Rochester, Rochester, NY, USA.
The Pediatric Infectious Disease Journal (Impact Factor: 2.72). 11/2009; 29(4):304-9. DOI: 10.1097/INF.0b013e3181c1bc48
Source: PubMed


To describe NP and AOM otopathogens during the time frame 2007 to 2009, 6 to 8 years after the introduction of 7-valent pneumococcal conjugate (PCV7) in the United States and to compare nasopharyngeal (NP) colonization and acute otitis media (AOM) microbiology in children 6 to 36 months of age having first and second AOM episodes with children who are otitis prone.
Prospectively, the microbiology of NP colonization and AOM episodes was determined in 120 children with absent or infrequent AOM episodes. NP samples were collected at 7 routine visits between 6 and 30 months of age and at the time of AOM. For first and subsequent AOM episodes, middle ear fluid (MEF) was obtained by tympanocentesis. Eighty otitis prone children were comparatively studied. All 200 children received age-appropriate doses of PCV7.
We found PCV7 serotypes were virtually absent: (0.9% isolated from both NP and MEF) in both study groups. However, non-PCV7 serotypes replaced PCV serotypes such that the frequency of isolation of S. pneumoniae (Spn) was nearly equal to that of non-typeable Haemophilus influenzae (NTHi). M. catarrhalis (Mcat) was less common and Staphylococcus aureus infrequent in the NP and MEF from the 2 groups. The proportion of Spn, NTHi and Mcat causing AOM was similar in children with first and second AOM episodes compared to otitis prone children. However, oxacillin-resistant Spn isolated from the NP and MEF was 19% for the absent/infrequent and 58% for the otitis prone groups, P < 0.0001. Beta-lactamase producing NTHi occurred more frequently in the otitis prone group, P = 0.04.
Six to 8 years after widespread use of PCV7, Spn strains expressing vaccine-type serotypes have virtually disappeared from the NP and MEF of vaccinated children. NP colonization and AOM has changed to non-PCV7 strains of Spn. NTHi continues to be a major AOM pathogen. The otopathogens in first and second AOM and in otitis prone children are very similar although Spn and NTHi are more often antibiotic resistant in the otitis prone.

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    • "Analysis of national Hospital Episode Statistics (HES) data also revealed 20% reduction in hospitalizations for pneumonia and empyema in England following PCV7 introduction [6]. The reduction in PCV7-type pneumococcal infections, however, was associated with an increase in non-vaccine serotypes in carriage and, consequently, in invasive disease, led to replacement of PCV7 in national immunization schedules with a 13-valent vaccine (PCV13) that provided protection against six additional serotypes (1, 3, 5, 6A, 7F and 19A) [7] [8].In the UK, PCV13 replaced PCV7 in April 2010 without a catch-up for older children. In other developed countries in Europe and North America, the success of PCV7 in reducing community acquired-pneumonia and OM has been demonstrated in a number of clinical trials and observational studies [9] [10] [11] [12] [13] [14] [15] [16] [17]. "
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    • "Marchese et al. [36] using blood PCR, showed that more than 47% of Bacteremic pneumonia cases in children less than 5 years old were due to non-PCV7 serotypes. Concerning non invasive diseases, Casey et al. [22] reported that non-PCV7 serotypes like 19A and 6A were among the most common causes of pneumococcal otitis media in the post-PCV7 era. However, care should be taken when assuming a causal relationship between PCV7 vaccination and an increase in 19A diseases, since recent reports describe an increase in 19A even in countries without routine PCV7 vaccination [37,38]. "
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