Outcomes of β-Hemolytic Streptococcal Necrotizing Skin and Soft-tissue Infections and the Impact of Clindamycin Resistance

Clin Infect Dis. 2020 Nov 5;ciaa976. doi: 10.1093/cid/ciaa976. Online ahead of print.

Abstract

Background: β-Hemolytic streptococci are frequently implicated in necrotizing soft-tissue infections (NSTIs). Clindamycin administration may improve outcomes in patients with serious streptococcal infections. However, clindamycin resistance is growing worldwide, and resistance patterns in NSTIs and their impact on outcomes are unknown.

Methods: Between 2015 and 2018, patients with NSTI at a quaternary referral center were followed up for the outcomes of death, limb loss, and streptococcal toxic shock syndrome. Surgical wound cultures and resistance data were obtained within 48 hours of admission as part of routine care. Risk ratios for the association between these outcomes and the presence of β-hemolytic streptococci or clindamycin-resistant β-hemolytic streptococci were calculated using log-binomial regression, controlling for age, transfer status, and injection drug use-related etiology.

Results: Of 445 NSTIs identified, 85% had surgical wound cultures within 48 hours of admission. β-Hemolytic streptococci grew in 31%, and clindamycin resistance was observed in 31% of cultures. The presence of β-hemolytic streptococci was associated with greater risk of amputation (risk ratio, 1.80; 95% confidence interval, 1.07-3.01), as was the presence of clindamycin resistance among β-hemolytic streptococci infections (1.86; 1.10-3.16).

Conclusions: β-Hemolytic streptococci are highly prevalent in NSTIs, and in our population clindamycin resistance was more common than previously described. Greater risk of limb loss among patients with β-hemolytic streptococci-particularly clindamycin-resistant strains-may portend a more locally aggressive disease process or may represent preexisting patient characteristics that predispose to both infection and limb loss. Regardless, these findings may inform antibiotic selection and surgical management to maximize the potential for limb salvage.

Keywords: NSTI; clindamycin; necrotizing soft-tissue infection; resistance; β-hemolytic streptococci.