Pneumococcal Meningitis in the Conjugate Vaccine Era

Deborah Lehman, MD reviewing Olarte L et al. Clin Infect Dis 2015 Sep 1.

No significant decrease has occurred in pneumococcal meningitis, but fewer cases are caused by PCV13 serotypes and antibiotic resistance has declined.

Introduction of a 7-valent pneumococcal conjugate vaccine in the U.S. in 2000 dramatically reduced invasive pneumococcal disease (IPD) in young children. A 13-valent vaccine (PCV13) was introduced in 2010; one year later, data from an ongoing prospective surveillance study of IPD in eight U.S. children's hospitals showed that the incidence of bacteremia and pneumonia, but not meningitis, had decreased. Using the most recent surveillance data from that study, industry-supported researchers compared epidemiologic trends in pneumococcal meningitis before (2007–2009) and after (2011–2013) PCV13 introduction.

Among 1207 episodes of IPD identified between 2007 and 2013, 173 were meningitis cases. Overall, 7% of patients with meningitis were aged <2 months, and patients aged ≥24 months were twice as likely as those aged <24 months to have an underlying condition (48% vs. 24%). Serotype 19A was the most common serotype (22%). Changes between the pre-PCV13 and post-PCV13 periods included the following:

Because the overall number of IPD cases decreased, the proportion of meningitis cases among all IPD cases increased by 50%.

The proportion of PCV13 serotypes decreased by 50% (from 54% to 27%), and 73% of isolates in the post-PCV13 period were non-PCV13 serotypes, the most common being 35B, 22F, and 33F.

The incidence of penicillin resistance did not change, but ceftriaxone resistance decreased from 13% to 3%, and no isolates in the post-PCV13 period had a ceftriaxone minimum inhibitory concentration ≥2.0 μg/mL.

Citation(s):

Olarte L et al. Impact of the 13-valent pneumococcal conjugate vaccine on pneumococcal meningitis in US children. Clin Infect Dis 2015 Sep 1; 61:767.