PHILADELPHIA – Obesity and diabetes are independent risk factors for invasive group A Streptococcus infections, with the highest risk among those with diabetes and morbid obesity.
The relative risk of invasive group A Streptococcus (iGAS) infection was 15 times higher in adults with diabetes and grade 3 morbid obesity (body mass index ≥ 40 kg/m2) than in those of normal weight, Dr. Gayle Langley reported at Infectious Diseases Week 2014.
Dr. Gayle Langley
Moreover, grades 1-2 obesity and morbid obesity increased the odds of ICU admission and death from an iGAS infection in multivariable logistic regression.
The adjusted odds ratios for ICU admission and death were 1.46 and 1.55 for patients with grades 1-2 obesity (BMI 30 < 40 kg/m2) and 2.07 and 1.62 for those with morbid obesity, she said.
Diabetes was not associated with an increased risk for either ICU admission (odds ratio, 1.06) or death (OR, 0.77) in the analysis.
Skin and soft tissue infections, which were significantly more common in obese and diabetic patients, appear to be driving the increased risk for iGAS in these groups, Dr. Langley of the Centers for Disease Control and Prevention said in an interview.
“Based on the literature, I’m not all that surprised because we definitely know that they are at increased risk for these skin and soft tissue infections, and that is a common manifestation of strep,” she said. “The mortality is slightly increased, but not to the extent of the incidence.”
The study was prompted by the limited number of prevention strategies for what Langley described as a “really serious infection” and by the rise in obesity and diabetes in the United States.
Data from select counties in 10 of the CDC’s Active Bacterial Core surveillance sites were used to identify 2,927 cases of 2010-2012 community onset iGAS. Cases were defined by isolation of GAS from a normally sterile site or from a wound in a patient with necrotizing fasciitis or streptococcal toxic shock syndrome in a resident in the surveillance area. Clinical data were obtained from medical records, with height and weight used to calculate BMI.
Diabetes was present in 859 patients (29.3%), grades 1-2 obesity in 743 (25.4%), grade 3 obesity in 399 patients (13.6%), and skin/soft tissue infections in 976 (33.3%). Most patients were aged 18-49 years (37.6%) and male (55%).
Among diabetic patients, the relative risk of an iGAS infection was 4.09 for those who were underweight (BMI < 18.5), 1.23 for the overweight (BMI 25 < 30), 3.14 for those with grade 1-2 obesity, and 15.6 for the morbidly obese. Among nondiabetics, the corresponding relative risks were 3.29, 0.87, 1.15, and 2.95, the authors reported in the poster presentation.
Dr. Langley said the next step is to look at treatment options and whether antibiotic dosing is important and “Long term, if we have a vaccine, this might be a group that needs to be targeted for vaccination.”
ID Week is a joint meeting of the Infectious Diseases Society of America, Society for Healthcare Epidemiology of America, HIV Medicine Association, and Pediatric Infectious Diseases Society.