Persistence of Pneumococcal Serotype 3 in Adult Pneumococcal Disease in Hong Kong

The epidemiology of hospitalised pneumococcal disease in adults following the introduction of universal childhood pneumococcal immunisation in 2009 was assessed. Culture-confirmed Streptococcus pneumoniae (SP) from adults hospitalised between 2009 to 2017 were examined. The cases were categorised into invasive pneumococcal disease (IPD) and pneumonia (bacteraemic, non-bacteraemic, and that associated with other lung conditions). The isolates were serotyped and antimicrobial susceptibilities were determined by microbroth dilution. Patient characteristics, comorbidities, and outcomes were analysed. Seven hundred and seventy-four patients (mean age, 67.7 years, SD +/- 15.6) were identified, and IPD was diagnosed in 110 (14.2%). The most prevalent serotype, 19F, was replaced by serotype 3 over time. Penicillin and cefotaxime non-susceptibilities were high at 54.1% and 39.5% (meningitis breakpoints), 19.9% and 25.5% (non-meningitis breakpoints), respectively. The overall 30-day mortality rate was 7.8% and 20.4% for IPD. Age >= 75 years (OR:4.6, CI:1.3-17.0, p < 0.02), presence of any complications (OR:4.1, CI:1.02-16.3, p < 0.05), pleural effusion (OR:6.7, CI:1.2-39.4, p < 0.03) and intensive care unit (ICU) admission (OR:9.0, CI:1.3-63.4, p < 0.03) were independent predictors of 30-day mortality. Pneumococcal disease by PCV 13 covered serotypes; in particular, 19F and 3 are still prominent in adults. Strengthening targeted adult vaccination may be necessary in order to reduce disease burden.

Automated summary

The epidemiology of hospitalised pneumococcal disease in adults was assessed following the introduction of universal childhood pneumococcal immunisation in 2009. It was found that invasive pneumococcal disease and pneumonia cases existed, with serotype 19F being replaced by serotype 3 over time.