The efficacy and safety of a shortened duration of antimicrobial therapy for Group A Streptococcus bacteraemia

Objectives: To determine if shorter courses of antibiotic therapy for group A Streptococcus (GAS) bacteremia are associated with excess mortality.

Methods: In this retrospective study of consecutive cases of GAS bacteremia in tropical Australia, the duration of antibiotic therapy was correlated with 90-day all-cause mortality.

Results: There were 286 episodes of GAS bacteremia; the patients' median (interquartile range) age was 60 (48-71) years and 169/286 (59.1%) patients identified as an Indigenous Australian. There were 227/286 (79.4%) patients with a significant comorbidity. The all-cause 90-day mortality was 16/286 (5.6%); however, 12/16 (81.3%) patients died while still receiving their initial course of antibiotics and only 7/16 (43.8%) deaths were directly attributable to the GAS infection. After excluding patients who died while taking their initial course of antibiotics and those in whom the duration of therapy was uncertain, there was no difference in 90-day mortality between patients receiving ≤5 days of intravenous antibiotics and those receiving longer courses (1/137 [0.7%] vs 3/107 [2.8%], P-value = 0.32) nor in patients receiving ≤10 days of total therapy and those receiving longer courses (1/67 [1.5%] vs 3/178 [1.7%], P-value = 1.0).

Conclusion: Even among patients with significant comorbidity, shorter antibiotic courses for GAS bacteremia are not associated with excess mortality.

Keywords: Antibiotic therapy; Bacteremia; Clinical management; Group A Streptococcus; Indigenous health; Streptococcus pyogenes.