Abstract & Commentary
Nasopharyngeal Bacterial Changes with Antimicrobials and Pneumococcal Vaccine
By Hal B. Jenson, MD, FAAP, Dean, School of Medicine, Western Michigan University School of Medicine, Kalamazoo, MI., is Associate Editor for Infectious Disease Alert.
Dr. Jenson reports no financial relationships relevant to this field of study.
Synopsis: Antimicrobial use and heptavalent pneumococcal vaccine induce significant changes in the nasopharyngeal microbiota of young children, with reduced prevalence of Streptococcaceae and Corynebacteriaceae and increased prevalence of Enterobacteriaceae and Pasteurellaceae.
Source: Hilty M, Qi W, Brugger SD, et al: Nasopharyngeal microbiota in infants with acute otitis media. J Infect Dis 2012;205:1048-1055.
A total of 153 nasopharyngeal swabs were collected as part of a nationwide study in Switzerland from children <2 years of age treated for acute otitis media from 2004-2009. Approximately one-quarter of young children with acute otitis media had been treated recently with antimicrobials, approximately one-third attended day care, and approximately half had received heptavalent pneumococcal vaccine (PCV7). An additional 10 specimens were collected from young children without acute otitis media as controls. Nasopharyngeal microbiota was characterized using multiplexed pyrosequencing targeting the variable regions 3—5 of the 16S rRNA gene.
Operational taxonomic units of microbiota were identified with a minimum of 97% sequence identity, and were grouped into 58 bacterial families. The median Shannon Diversity indices were 0.69 for young children with acute otitis media and 1.31 controls (P = 0.002), indicating that young children with acute otitis media have fewer microbiota taxonomic units and that were less evenly distributed than for controls. The most commonly identified bacterial families were Moraxellaceae (present in 154 of 163 specimens), non-pneumococcal Streptococcaceae (122 of 163), and Pasteurellaceae (97 of 163). Commensal families were more frequent in controls than in young children with acute otitis media, such as Staphylococcaceae (P = 0.001), Flavobacteriaceae (P = 0.0004), Carnobacteriaceae (P = 0.02), and Comamonadaceae (P = 0.003). Young children with recent exposure to microbials also less frequently carried Streptococcaceae (P = 0.02) and Corynebacteriaceae (P = 0.001), and more frequently carried Enterobacteriaceae (P = 0.03). Young children who had received PCV7 less frequently carried Corynebacteriaceae (P = 0.02) than did unvaccinated children. Further analysis showed that the differences of microbiota between children with acute otitis media and controls were due to the prevalence of bacterial families (unweighted analysis) rather than their relative abundance (weighted analysis).
Colonization density was estimated by measuring the DNA concentration of the PCR application product. Significantly lower quantities of total DNA were observed from controls (median, 12 ng/µL) compared to young children with acute otitis media (median, 38 ng/µL; P = 0.005).
There was no influence of age, history of recurrent acute otitis media, sex, or day care attendance on the microbiota of young children with acute otitis media.
Commentary
Normal nasopharyngeal microbiota among young children is characterized by commensal bacterial families and non-pneumococcal Streptococcaceae. Among young children with recent antimicrobial exposure, classic otitis media pathogens predominate over the commensals, resulting in reduced richness and evenness but higher overall colonization density. Vaccination with PCV7 changed the community structure of microbiota towards reduced prevalence of commensals, especially Streptococcaceae and Corynebacteriaceae.
Antimicrobial treatment of acute otitis media, and for that matter antimicrobials used for other reasons, has important effects on the nasopharyngeal microbiota among young children. Antimicrobials lead to the displacement of a broad array of nonpathogenic nasopharyngeal commensals with a narrower spectrum of pathogenic organisms and with higher density of organisms. This is a vicious circle, in which treatment of the initial episode of otitis media results in nasopharyngeal microbiota changes that are likely predisposed to subsequent episodes.
Reference
Weinberger, DM , et al. Impact of the 2009 Influenza Pandemic on Pneumococcal Pneumonia Hospitalizations in the United States. J Infect Dis 2012:205:458-465
A total of 153 nasopharyngeal swabs were collected as part of a nationwide study in Switzerland from children <2 years of age treated for acute otitis media from 2004-2009.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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