Adjunctive Clindamycin Improves Outcomes of Invasive Group A Streptococcal Infection: Best Evidence to Date

Patients with invasive group A strep infections who received clindamycin in addition to beta-lactam antibiotics were significantly less likely to die in the hospital than those who did not.

Clindamycin decreases production of exotoxins that underlie many manifestations of invasive group A streptococcal (iGAS) infections. Although this protein synthesis inhibitor is recommended for management of iGAS infections, data are limited — and the benefit of clindamycin in other beta-hemolytic strep infections is even more uncertain. Using health record data, investigators assessed outcomes among 1956 patients at 118 U.S. hospitals with invasive beta-hemolytic strep infections (1079 with iGAS and 877 with invasive non–group A/B beta-hemolytic strep [iNABS]) who received beta-lactam therapy. Within these groups, patients who received adjunctive clindamycin were matched 1:2 with those who did not. The primary outcome was inpatient mortality.

When adjusted for proven invasive disease, vasopressor use, and intensive care unit stay, patients with iGAS who received adjunctive clindamycin were significantly less likely to die in the hospital than those who did not receive clindamycin (adjusted odds ratio, 0.44). This benefit persisted in patients without shock or necrotizing fasciitis. Among those with iNABS, a trend toward increased inpatient mortality with use of adjunctive clindamycin was seen but did not achieve statistical significance.

Comment

Clindamycin is recommended based on animal and in vitro data, but research involving humans has been limited to small observational studies. As the largest series thus far, the present study, although observational, includes matched controls and statistical rigor. The inpatient mortality benefits noted in those with iGAS infection provide the best evidence to date that adjunctive clindamycin should be used routinely in these cases, but not in those with iNABS infection. Because patients with group B streptococcal infections were excluded, the results cannot be extrapolated to that population.

Reviewing Author

Wendy S. Armstrong, MD

Disclosures

Consultant/Advisory BoardNIH Therapeutics and Prevention Data Safety Monitoring Board

Leadership Positions in Professional SocietiesAmerican Board of Internal Medicine Infectious Diseases Subspecialty Board (member), Infectious Diseases Society of America (Vice President)