Relationship Between the Detection Rate of <I>Streptococcus pneumoniae</I> in Adults with Acute Otitis Media and Presence of a Cohabitating Child Attending Group Nursery Care

<p>　　The frequency of detection of drug-resistant Streptococcus pneumoniae (DRSP) infections has decreased after the introduction of the pneumococcal conjugate vaccine (PCV). This study was aimed at investigating the changes in the DRSP detection trends among cases of acute otitis media (AOM) in adults following introduction of the PCV. The study population included 135 adults with S. pneumoniae was detected in middle ear fluid specimens obtained through myringotomy between 2000 and 2009 (period I, before introduction of the PCV) and 75 adults with S. pneumoniae detected in middle ear fluid specimens obtained by myringotomy between 2013 and 2022 (period II, 3 years after introduction of the PCV). Throughout both the phases, penicillin antibiotics (PCs) were the treatment of first-choice for upper respiratory infections at our institution and nearby medical facilities. The results showed a significant decrease in the detection frequency of DRSP after introduction of the PCV and an improvement in the susceptibility of the pathogens to amoxicillin. Prior to introduction of the PCV, significant differences were noted in drug susceptibilities to PCs based on cohabitation with children in group childcare settings and the age groups of the cohabitating children (cases cohabitating with and not cohabitating with children under 2 years old). However, these differences disappeared after introduction of the PCV. The study also confirmed a reduction in the number of adult cases of AOM after introduction of the PCV and a significant decrease in the proportion of adult cases of AOM caused by S. pneumoniae requiring myringotomy. While herd immunity from the PCV was suggested, further research is needed to investigate the relationship between the serotypes covered by PCV, the non-covered serotypes, and the serotypes of S. pneumoniae detected in adult cases of AOM.</p>