Characteristics of Bacterial Isolates Before and After PCV13 Introduction

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In 2016, the proportion of <i>H influenzae</i> strains producing β-lactamase increased to 23.6% from 11.7% in 2012.
In 2016, the proportion of H influenzae strains producing β-lactamase increased to 23.6% from 11.7% in 2012.

Among bacteria isolated from nasopharyngeal samples collected from children with acute otitis media, penicillin-resistant Streptococcus pneumoniae prevalence decreased between 2001 and 2016, and β-lactamase-producing Haemophilus influenzae increased during the same time period, according to the results of a study published in the Pediatric Infectious Disease Journal.

In this cross-sectional study, 12,973 nasopharyngeal samples collected between 2001 and 2016 from young children with acute otitis media were analyzed for S pneumoniae, H influenzae, and Moraxella catarrhalis. Isolates were tested for penicillin susceptibility and for the production of β-lactamase. The prevalence and characteristics of the bacterial strains were compared before and after the introduction of the 13-valent pneumococcal conjugate vaccine (PCV13).

After the introduction of PCV13, global S pneumoniae carriage significantly decreased by 18.2% (P <.001). Similarly, M catarrhalis carriage decreased from 53.2% to 49.3% between 2006 and 2016 (P =.034). In contrast, H influenzae carriage increased significantly from 46.6% to 57.0% between 2001 and 2016 (P <.001).

The proportion of penicillin-resistant S pneumoniae isolates was significantly reduced by 46.4% over the course of the study (P <.001). After the introduction of PCV13, fully penicillin-resistant strains comprised 0.8% of S pneumoniae isolates. Daycare attendance was associated with increased odds for penicillin-resistant S pneumoniae in multinomial analysis (odds ratio [OR] 2.7).

In 2016, the proportion of H influenzae strains producing β-lactamase increased to 23.6% from 11.7% in 2012. In multinomial analysis, daycare attendance (OR 2.7), conjunctivitis (OR 6.0), having siblings (OR 1.7), history of acute otitis media (OR 1.4), and bilateral acute otitis media (OR 1.4) were associated with an increased odds for β-lactamase H influenzae carriage.

Based on the study results, the researchers concluded that “for children with [acute otitis media] and conjunctivitis, because of the role of [H influenzae] and the frequency of β-lactamase-producing [H influenzae] carriage, the treatment should remain [amoxicillin-clavulanate], especially for children attending a [daycare center].”

Reference

Rybak A, Levy C, Bonacorsi S, et al. Antibiotic resistance of potential otopathogens isolated from nasopharyngeal flora of children with acute otitis media before, during and after pneumococcal conjugate vaccines implementation [published online December 8, 2017]. Pediatr Infect Dis J. doi: 10.1097/INF.0000000000001862

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