Preventing Obesity, Diabetes, Might Also Reduce Adult Invasive GBS Infection

PHILADELPHIA, PA—Efforts to prevent obesity and diabetes might also reduce incidence of adult invasive group B streptococcal (GBS) infection, investigators reported at IDWeek 2014.

The study found that “morbid obesity and diabetes were associated with a substantially increased risk of invasive GBS infection, with a smaller effect of morbid obesity among diabetics,” said Samantha Pitts, MD, MPH, of Johns Hopkins University in Baltimore, MD.

Incidence of invasive GBS in U.S. adults is increasing, and Dr. Pitts and her colleagues “hypothesized that both obesity and diabetes are independently associated with an increased risk of invasive GBS infection.”

Between January 1, 2010 and December 31, 2011, they conducted population-based surveillance for invasive GBS disease—defined as an isolation of GBS from a normally sterile site, such as blood—in adults 18 years of age and older documented at 9 Active Bacterial Core surveillance (ABCs) sites.

Medical conditions, height, weight, and body mass index (BMI), were abstracted from patient medical records. “We identified 3,135 eligible cases of invasive GBS infection,” Dr. Pitts reported.

From models adjusted for age, sex, race, and diabetes, when compared with BMI 18.5–<25kg/m² (eg, normal weight), the relative risks for invasive GBS for BMI ≥40 (morbid obesity) was 3.1 (95% CI 2.2–4.5); for BMI 30–<40, 1.0 (95% CI 0.7–1.4); and for BMI 25–<30, 0.7 (95% CI 0.5–0.9). The RR for diabetes was 6.2 (95% CI 4.8–7.8). 

When analyzed by age groups, patients aged 45–64 years showed 3 times increased risk, whereas patients aged ≥65 years showed 5 times increased risk of developing invasive GBS infection. Race was not significantly associated with increased risk. However, females were at a reduced risk of developing invasive GBS infection (RR 0.6). 

Overall, increased risk of GBS infection was seen in with increased age, class III obesity, and diabetes. “Stratified analyses showed that morbid obesity was less predictive of GBS among those with diabetes,” Dr. Pitts concluded. She added that future prevention studies should evaluate patient with concomitant class III obesity and diabetes.