Study: Pneumococcal Carriage Prevalence Is Higher Among Those With Contact to Children

The prevalence of invasive pneumococcal disease carriage was particularly high among individuals who had contact with school-age children, according to investigators of a study published in Microbiology Spectrum.

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However, they found that carriage was not limited to this group.

Between October 2020 and August 2021, couples in the greater New Haven area in Connecticut were enrolled in the study. They were included if they were both aged 60 years or older and no one under aged 60 years lived in the household.

Investigators collected saliva samples and questionnaires, including contacts, medical history, and social activities, every 2 weeks for 10 weeks.

The extracted DNA was tested with a quantitative polymerase chain reaction for pneumococcus-specific sequences piaB and lytA. The individuals were considered positive for carriage when the cycle threshold (Ct) value was 40 or greater for piaB.

Investigators collected 567 saliva samples from 95 individuals in 47 household pairs and 1 singleton. They found that 7.1% of the samples tested positive for pneumococcus, which represented 23.2% of individuals and 33.3% of households.

Investigators reported that samples that were both positive for piaB and lytA, there was a concordance in the Ct value. The results showed that in some samples, the concentration of lytA was higher than piaB, which could indicate the presence of non-pneumococcal Streptococci spp and a simultaneous pneumococcus infection.

Because the sensitivity of the tests was slightly higher for piaB, some samples were near the limit of detection and were negative for lytA and positive for piaB. Investigators relied on piaB for this study.

Further, they found that individuals attended a few social events during this period, but many had continued to have regular contact with children. Those who had regular contact with preschool and school-aged children (ranging from aged 2 to 9 years), had a higher prevalence of carriage at 15.9% compared with 5.4% for those who did not have continued contact with children.

Investigators also found that individuals who reported contact with children older than aged 10 years did not have a higher prevalence. Those with contact with children younger than aged 5 years had a higher prevalence, with 11.9% for those under aged 12 months, 13.3% for those aged 12 to 23 months, and 20.5% for those aged 24 to 59 months.

During the period, individuals continued to partake in social activities outside their homes, 40% of whom were with family and 29% of whom were with friends. Just 6% of individuals reported participating in activities at a community center and 8% in fitness activities.

The prevalence of pneumococcal carriage was modestly higher for those who reported activity with their families, at 13.5%, compared with 8.1% for those reporting no social activity.

Investigators also found that a large proportion of older individuals continued to carry pneumococcus during the COVID-19 pandemic.

A study limitation was the difficulty in isolating individual pneumococci, because of the high polymicrobial nature of saliva, according to investigators.

Reference

Wyllie AL, Mbodj S, Thammavongsa DA, Hislop MS, et al. Persistence of pneumococcal carriage among older adults in the community despite COVID-19 mitigation measures. Microbiol Spectr. 2023;e0487922. doi:10.1128/spectrum.04879-22