Multiple Streptococcus pneumoniae Serotypes in Aural Discharge Samples from Children with Acute Otitis Media with Spontaneous Otorrhea

Abstract

e Among 55 children with cultures positive for acute otitis media with spontaneous otorrhea, 28 (51%) had cultures positive for aural Streptococcus pneumoniae, and in 10 of these, two distinct strains were detected, in which 5 had pairs of strains that were both capsule-bearing serotypes. Such cases were more likely to have cultures positive for other otopathogens than those with only one pneumococcus present. The most common bacteria causing acute otitis media (AOM) in children are Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pyogenes. Spontaneous otorrhea can complicate AOM, and S. pyogenes may be found in higher percentages and H. influenzae and M. catarrhalis in lower percentages among such patients than among those with AOM and intact tympanic membranes (1).Nasopharyngeal colonization by potential middle-ear pathogens is presumed to precede AOM. There is an association between nasal bacterial load and the presence and severity of ear disease (2), and aural S. pneumoniae shows a close genetic relatedness with its nasopharyngeal counterpart (3).Understanding of the etiopathogenesis of AOM is increasing. Viral and bacterial causation are no longer seen as alternatives. Intercurrent respiratory viral infections may render the middle ear susceptible to symptomatic infection with bacteria that normally colonize the nasopharynx. Ruohola et al. suggest that the majority of acute middle-ear infections in children are due to bacterial and viral coinfection (4).More than one bacterial species can simultaneously infect the middle ear in AOM (1, 4). Multibacterial species biofilm formation may be involved in chronic recurrent otitis media pathogenesis, perhaps explaining the demonstrated effectiveness of conjugate pneumococcal vaccines against AOM but not recurrent disease (5).Conventional S. pneumoniae culture and serotyping methodologies underestimate multiple-serotype carriage. Molecular serotyping improves detection of multiple serotypes and determines the relative abundance of each (6, 7) but has not previously been applied to the middle ear.The pneumococcal conjugate vaccine (PCV) became available in Portugal in 2001 but has not been included in the national immunization program. Coverage from private market sales data was around 65% in 2011, following a peak of around 79% in 2007 (oral communication, Pfizer). Since 2010, 13-valent PCV (PCV13) has been used predominantly.Tympanocentesis is not routinely performed in the investigation and management of AOM in Portugal. To obtain data on the etiology of AOM, we studied children with AOM with spontaneous otorrhea (AOMSO). We hypothesized that just as simultaneous nasal colonization with multiple pneumococcal serotypes and strains occurs (7), this may also be the case in the ear.The study was conducted at Coimbra Children's Hospital, a 120-bed tertiary care center in central Portugal, with more than 60,000 emergency service (ES) visits each year. It was approved by the hospital ethics committee. Parents or guardians provid...

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