October 28, 2013
1 min read

Rare pneumococcal serotype may be more prevalent than previously thought

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Serotype-5 infections contributed significantly to the burden of Streptococcus pneumoniae-positive pneumococcal infections in the United States, according to recent study findings.

The researchers said there are limited data on the pneumococcal serotypes that cause community-acquired and health care-associated pneumonia.

Eligible participants in the current study were aged at least 50 years and presented with radiographically confirmed pneumonia. The enrollment duration was February 2010 to September 2011.

Screening for S. pneumoniae was performed using microbiological cultures, BinaxNOW S. pneumoniae assay or urinary antigen detection assay capable of detecting 13-valent pneumococcal conjugate vaccine-associated (Prevnar13, Pfizer) serotypes, according to the results.

The analysis included 710 patients with a median age of 65.4 years. Twenty-two percent of patients with radiographically confirmed disease were considered for health care-associated infections. The hospitalization rate was 97%.

Clinicians detected S. pneumonia by any test in 13.8% of the cohort. Urinary antigen detection effectively identified PCV13-associated serotypes in 11% of participants.

The most frequently observed serotype was 19A, followed by 7F/A, 3 and 5. One-quarter of isolates were 7-valent pneumococcal conjugate vaccine-associated (Prevnar, Pfizer) serotypes among those positive in the urinary antigen detection assay group.

“Pneumococcal serotypes causing noninvasive pneumonia in adults may differ significantly from those causing invasive disease, with PCV7-associated serotypes overrepresented,” the researchers said, adding that the rare serotype 5 was a substantial contributor to the S. pneumoniae-positive infections in the United States.

Disclosure: The study was supported by Wyeth, which was acquired by Pfizer in October 2009. All of the researchers report various financial ties or former ties to Pfizer.