New Scholar Award in Global Infectious Disease
Marc Lipsitch, D.Phil.
Harvard School of Public Health

Antibiotic Resistance in Streptococcus pneumoniae: Transmission Dynamics and Consequences for Public Health

Streptococcus pneumoniae is a leading cause of otitis media (middle ear infections), bacteremia (blood infection), pneumonia, and meningitis in both developed and developing countries. Extensive use of antibiotics has led to worldwide increases in the proportion of strains of Streptococcus pneumoniae that are resistant to major classes of antibiotics. This resistance makes treatment more difficult and more expensive, and raises the prospect that infections resistant to multiple antibiotics may be effectively untreatable. Although the trend towards increased resistance is occurring worldwide, the prevalence of resistance and its rate of increase vary dramatically between countries and even between regions in the United States.

The research proposed will aid in understanding the reasons for these trends and their consequences, and in planning interventions to slow the spread of resistance. Using animal models, we will assess the effect of resistance to clinically important antibiotics on the fitness (competitive ability) of S. pneumoniae; the prospects to reduce resistance by reducing antibiotic use depend on the magnitude of this cost. Using epidemiological databases, we will determine whether resistant strains cause a different spectrum of disease from sensitive strains, after controlling for such factors as age and bacterial serotype. Using these databases and mathematical models of the transmission of sensitive and resistant strains, we will attempt to determine the reasons for geographic variation in resistance, and we will project trends in resistance if current levels of antibiotic use continue. Using the findings from these studies and those of other investigators, we will further develop the mathematical models to assess alternative treatment policies for their effects in promoting or slowing the spread of resistance.

Contact Dr. Lipsitch.