Evaluating the Relationship and Appropriateness of Treatment of Obese Patients with Group B Streptococcus Bloodstream Infections

Background:

Research on pregnant females has shown that women with high body mass index (BMI) may be at greater risk for Group B Streptococcus (GBS) colonization and neonatal sepsis. However, further investigation is needed on the relationship between obesity and invasive GBS infections in the general population. We hypothesized that obese adults with GBS bloodstream infections (BSIs) are at increased risk of having specific co-morbidities, are more likely to have inappropriate dosing of antibiotics, and overall, worse outcomes as compared to non-obese patients.

Methods:

Data was obtained through a retrospective chart review for patients aged 18 and older with a positive blood culture for Streptococcus agalactiae using electronic medical records from Long Island Jewish Medical Center from January 1, 2011 to December 31, 2014. Chi-square tests and analysis of variance was used to investigate hypotheses (p<.05).

Results:

Among 119 patients with GBS BSIs, 78 (65.5%) were obese (BMI ≥ 30). Immunosuppressed patients (defined as steroid use >14 days, immunosuppressive therapy, AIDS (CD4<200), history of organ and/or bone marrow transplant) with GBS BSI (n=10) had a significantly higher rate of obesity (90.0%) as compared to 52.3% in the immunocompetent group (p=0.022). Patients with diabetes mellitus (DM) had a significantly higher BMI (M=33.3, SD=9.6) compared to those without DM (M=29.4, SD=6.9; p=0.012). With regard to appropriate dosing of antimicrobials, 94.3% of non-obese patients were dosed appropriately compared to 75.8% of obese patients (p=0.006). Prior antibiotic use (≤3 months) was borderline significantly more common in obese patients (30.3%) compared to non-obese patients (15.1%; p=0.052). There were no statistically significant differences between obese and non-obese GBS patients on demographics, hospital length of stay, critical care unity stay, and 30-day mortality and readmission rates.

Conclusion:

Immunosuppressed and DM patients with GBS BSIs have increased rates of obesity. Further, recent antibiotic exposure and inappropriate weight-based dosing of antibiotics is more common among obese GBS patients, emphasizing the necessity for antimicrobial stewardship and adjusting antibiotics accordingly in patients with higher BMIs.