当院における肺炎球菌ワクチン施行前後の中耳炎の推移

抄録

Purpose

A 7-valent pneumococcal conjugate vaccine (PCV7) was placed on the market in 2010. We conducted a survey comparing changes in the clinical status of pediatric acute otitis media diagnosed in our hospital by dividing the period into a pre-PCV era and post-PCV era.

Subjects

Survey 1: The subjects were the 0–6-year-old pediatric otitis media patients examined in our hospital between 2008 and 2016.

Period: The 9-year period was divided into 3 eras: a pre-vaccine era (pre-PCV era: 2008–2009), a Prevenar 7 era (PCV7 era: 2010–2013), and a Prevenar 13 era (PCV13 era: 2014–2016).

Survey 2: In the same period we investigated the course of changes in bacterial strains isolated from the nasopharynx and middle ear effusions of pediatric acute otitis media patients (0–15 years of age) and their pneumococcal capsular serotypes.

Results

Survey 1: In the age range of the subjects of this survey we observed effusions in the middle ears of 1746 children (32.2%). The acute otitis media prevalence rate was significantly lower in the PCV7 era than in the pre-PCV era (P<0.01), and in the PCV13 era than in the pre-PCV era (P<0.05). The bilateral acute otitis media prevalence rate was significantly lower in the PCV7 era than in the pre-PCV era (P<0.01), and in the PCV13 era than in the pre-PCV era (P<0.01).

Survey 2: A total of 4250 strains of bacteria were isolated by bacterial culture tests. The proportion of pneumococci was 37.7% in 2008, but subsequently declined, and was 21.7% in 2016. There was a statistically significant trend for detection of pneumococci to decrease over the 3 eras. The proportion of drug-resistant pneumococci decreased from 2012 onward. Serotype replacement occurred among the capsular serotypes, but type 3, which was a vaccine type, was detected. The frequency of β-lactamase-positive Haemophilus influenzae isolation increased.

Conclusions

Significant decreases in the prevalence of acute otitis media and bilateral otitis media were seen between the pre-PCV era and post-PCV era. A decrease in the number of drug-resistant pneumococci was also seen.