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Fellow tracks post-vaccination bacterial trends

Oct. 17, 2013, 10:18 AM

Pediatric Infectious Diseases fellow Annabelle de St. Maurice, M.D., has been awarded a grant to determine the relationship between pneumococcal vaccination and the emergence of certain strains of pneumococcal bacteria not covered by vaccines.

Annabelle de St. Maurice, M.D.

The Pfizer ASPIRE Award in adult vaccine research provides $100,000 to support her work to examine statewide trends of invasive pneumococcal disease (IPD) caused by Streptococcus pneumoniae, also referred to as pneumococcus.

“In this past year, we have taken care of five children with pneumococcal meningitis, and unfortunately, two of them died,” de St. Maurice said. “It’s hard because we have these vaccines and they are great, but most of these patients had strains not covered by their immunization. We would like to learn more about these infections so we can improve prevention as well as identification and treatment.”

Her mentors at Vanderbilt have published several studies regarding pneumococcal infections. It is a hot topic because childhood vaccines to prevent serious IPD are relatively new, with the first pneumococcal vaccine being introduced in 2001, covering seven of the most common serotypes causing IPD. A broader version of the vaccine, with six additional serotypes, was released in 2010.

Natasha Halasa, M.D., MPH, associate professor of Pediatric Infectious Diseases, said this grant is important to help document the impact of this new vaccine on IPD trends in adults and children.

“A previous study we completed showed that between 38 and 58 percent of disease was caused by strains not covered in the first version that were added to the 2010 version of the vaccine,” Halasa said. “While that is significant additional coverage, it still leaves a good portion not covered by this vaccine. Therefore, continued surveillance is important to know which strains are causing invasive disease.”

There are more than 90 types of pneumococcus, and while it is expected infection rates will continue to drop, other strains might emerge as increasingly common. de St. Maurice said this has already been shown to be a national trend, and she hopes a closer look at local rates will add to the understanding of this trend.

Tennessee is one of 10 states participating in active bacterial surveillance to track different strains of pneumococcus, with William Schaffner, M.D., professor of Preventive Medicine, as the principal investigator of this Centers for Disease Control and Prevention (CDC)-funded grant. Positive lab reports for the bacteria are reported to the CDC and are sent for identification of the strain.

The ASPIRE grant will support de St. Maurice’s efforts to determine IPD trends in Tennessee, geographic differences, and antibiotic susceptibility of IPD. She will compare the strains seen in 2001 to 2009, and after the introduction of the expanded vaccine in 2010. She will work closely with Halasa, Schaffner, Carlos Grijalva, M.D., MPH, assistant professor of Preventive Medicine, and Christopher Fonnesbeck, assistant professor of Biostatistics, to achieve the objectives of this grant.

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