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

Abstract

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. Systematic review with unpublished data from the largest study. Multiple key bibliographic databases to June 2016. Australian studies on the aetiology of CAP in adults. 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). 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.