Certain factors associated with higher mortality risk in invasive group B strep infection

In a study of patients with invasive group B Streptococcus infections, all-cause 30-day mortality was highest for those with peritonitis and pneumonia or empyema and lowest among those with osteomyelitis or joint infection.

Poor long-term glycemic control was associated with increased risk for invasive group B Streptococcus (GBS) infections, while peritonitis and pneumonia or empyema were associated with the highest risk for death, a recent study found.

To investigate risk factors and mortality rates associated with specific invasive GBS infectious syndromes, researchers conducted a cohort study using Veterans Health Administration data from January 2008 through December 2017. They evaluated specific infectious syndromes and comorbid conditions among patients with an invasive GBS infection. Results of the study were published Dec. 27 by JAMA Network Open.

In the study, 5,175 patients in the Veterans Affairs system experienced 5,497 invasive GBS infections. All-cause 30-day mortality was 8.7% (451 of 5,175 patients). The most common infections were osteomyelitis (1,171 patients [21.3%]), bacteremia without focus (1,009 patients [18.4%]), skin or soft-tissue infections (919 patients [16.7%]), and pneumonia or empyema (694 patients [12.6%]). All-cause 30-day mortality following the index infection for each patient was highest among those with peritonitis (38 [27.5%] of 138 patients) and pneumonia or empyema (116 [17.5%] of 664 patients) and lowest among those with osteomyelitis (15 [1.4%] of 1,075 patients) or joint infection (17 [3.4%] of 501 patients).

Diabetes (3,364 patients [65.0%]), obesity (2,669 patients [51.6%]), and chronic heart conditions (1,633 patients [31.6%] ) were the most common comorbid conditions in patients with invasive GBS infections. Invasive GBS infections increased from 9.23 to 11.67 cases per 100,000 person-years over the study period (P=0.049). Stratification by body mass index (BMI) showed the highest incidence of infections among patients at either extreme (BMI <18.5 kg/m2, 25.1 cases per 100,000 person-years; BMI ≥40 kg/m2, 31.0 cases per 100,000 person-years). Incidence among patients with diabetes and poor long-term glycemic control, defined as an HbA1c level of 9.5% or greater, was four times higher than among patients with diabetes and good glycemic control, defined as an HbA1c level below 7.5% (78.3 cases vs. 19.0 cases per 100,000 person-years; unadjusted incident rate ratio, 4.1 [95% CI, 3.7 to 4.4]; P<0.001).

The authors noted that their study was done in U.S. veterans and cannot be generalized to the U.S. population as a whole, among other limitations, but concluded that poor long-term glycemic control is an important modifiable risk factor for invasive GBS infections. “Efforts to reverse the increasing rates of invasive GBS infections in adults should continue to address diabetes, obesity, and other chronic medical conditions,” they concluded. “Among those with diabetes, improving glycemic control may help mitigate the risk of invasive GBS infection.”