Distribution of 13-valent pneumococcal conjugate vaccine Streptococcus pneumoniae serotypes in US adults aged ≥50 years with community-acquired pneumonia.

BACKGROUND

Streptococcus pneumoniae causes a substantial proportion of community-acquired pneumonia (CAP) and healthcare-associated pneumonia (HCAP) in the United States. Limited data are available regarding the pneumococcal serotypes causing CAP and HCAP.

METHODS

Adults aged ≥ 50 years presenting to participating US hospitals with radiographically confirmed pneumonia between February 2010 and September 2011 were screened for inclusion. S. pneumoniae was identified using microbiological cultures, BinaxNOW® S. pneumoniae assay, or urine antigen detection (UAD) assay capable of detecting 13-valent pneumococcal conjugate vaccine (PCV13)-associated serotypes.

RESULTS

Among 710 subjects enrolled, the median age was 65.4 years; 54.2% of subjects were male, 22.4% of radiographically confirmed pneumonia cases were considered HCAP, and 96.6% of subjects were hospitalized. S. pneumoniae was detected in 98 subjects (13.8%) by any test, and PCV13-associated serotype(s) were identified by UAD in 78 (11.0%). Serotype 19A was most prevalent, followed by 7F/A, 3, and 5. Serotypes associated with 7-valent pneumococcal conjugate vaccine (PCV7) accounted for 25% of UAD-positive isolates.

CONCLUSIONS

Pneumococcal serotypes causing noninvasive pneumonia in adults may differ significantly from those causing invasive disease, with PCV7-associated serotypes overrepresented. Serotype 5, rarely seen in contemporary surveillance of invasive disease in the United States, substantially contributed to the observed cases of S. pneumoniae-positive CAP or HCAP.