Incidence and severity of invasive Streptococcus pneumoniae, group A Streptococcus, and group B Streptococcus infections among pregnant and postpartum women.

BACKGROUND: The epidemiology of streptococcal infection in pregnant and postpartum women is poorly described in recent literature. We used data from multistate surveillance for invasive Streptococcus pneumoniae, group A Streptococcus (GAS), and group B Streptococcus (GBS) infections to estimate disease incidence and severity in these populations.
METHODS: Cases were reported through the Centers for Disease Control and Prevention Active Bacterial Core surveillance, an active population- and laboratory-based system. A case was defined as illness in a woman aged 15-44 years with streptococcus isolated from a normally sterile body site during 2007-2009. Pregnant or postpartum status was recorded at the time of culture. Incidence was calculated as cases per 1000 woman-years with use of national Census data; 95% confidence intervals were calculated on the basis of λ distribution. We used multivariable logistic regression to explore associations between pregnant or postpartum status and hospital length of stay, a marker of disease severity.
RESULTS: We identified 1848 cases in women; 6.0% of women were pregnant, and 7.5% were postpartum. Pregnant women had a higher mean incidence of GBS disease, compared with nonpregnant women (0.04 cases per 1000 woman-years [range, 0.03-0.05 cases per 1000 woman-years] vs 0.02 cases per 1000 woman-years [range, 0.02-0.02 cases per 1000 woman-years]). Postpartum women had elevated mean incidence of all 3 pathogens, compared with nonpregnant women (S. pneumoniae: 0.15 cases per 1000 woman-years [range, 0.09-0.25 cases per 1000 woman-years] vs 0.052 cases per 1000 woman-years [range, 0.049-0.056 cases per 1000 woman-years]; GAS: 0.56 cases per 1000 woman-years [range, 0.42-0.70 cases per 1000 woman-years] vs 0.019 cases per 1000 woman-years [range, 0.017-0.021 cases per 1000 woman-years]; GBS: 0.49 cases per 1000 woman-years [range, 0.36-0.64 cases per 1000 woman-years] vs 0.018 [range, 0.016-0.020 cases per 1000 woman-years]). Neither pregnancy nor postpartum status was associated with longer length of stay among women infected with any of the 3 pathogens.
CONCLUSIONS: Although invasive streptococcal infections do not appear to be more severe in pregnant or postpartum women, postpartum women have a 20-fold increased incidence of GAS and GBS, compared with nonpregnant women.