Determining the contribution of Streptococcus pneumoniae to community-acquired pneumonia in Australia.

Objective: To evaluate trends in the proportion and severity of community-acquired pneumonia (CAP) attributable to Streptococcus pneumoniae (pneumococcus) in Australians aged 18 years and over.

Study Design: Systematic review with unpublished data from the largest study.

Data Sources: Multiple key bibliographic databases to June 2016.

Study Selection: Australian studies on the aetiology of CAP in adults.

Data Synthesis: In the 12 studies identified, pneumococcus was the most common cause of CAP. Four studies were assessed as being of good quality. Participants in two studies were predominantly non-Indigenous (n = 991); the proportion of pneumococcal CAP cases declined from 26.4% in 1987-88 to 13.9% in 2004-06, and the proportion with bacteraemia decreased from 7.8% to 3.8%. In two studies with predominantly Indigenous participants (n = 252), the proportion with pneumococcal bacteraemia declined from 6.8% in 1999-2000 to 4.2% in 2006-07. In the largest study (n = 885; 2004-06), 50.8% (60/118) of pneumococcal CAP occurred in people who were ≥ 65 years old. Among patients aged ≥ 65 years, intensive care unit admission and death were more common in patients who were ≥ 85 years old compared with younger patients (12.5% v 6.8%; 18.8% v 6.8% respectively), and also more common in the 19 patients with bacteraemia than in those without it (15.8% v 2.6%; 10.5% v 7.9% respectively). Of 17 cases of bacteraemia serotyped, 12 were due to 13-valent pneumococcal conjugate vaccine (13vPCV) serotypes and three to additional serotypes in 23-valent pneumococcal polysaccharide vaccine (23vPPV).

Conclusions: Available data suggest that the proportion of CAP attributable to pneumococcus (both bacteraemic and non-bacteraemic) has been declining in Australian adults. Should 13vPCV replace the 23vPPV currently funded by the National Immunisation Program for persons aged ≥ 65 years, surveillance to track non-bacteraemic pneumococcal CAP will be essential to evaluate the impact.