Cefazolin beneficial in infective endocarditis caused by methicillin-susceptible S aureus

In the treatment of patients with methicillin-susceptible S aureus (MSSA)-associated infective endocarditis, the cefazolin is as good as cloxacillin, with similar mortality and relapse rates, according to a study.

For the study, researchers conducted a retrospective analysis of a cohort of MSSA-associated infective endocarditis patients who were treated with cloxacillin and/or cefazolin. The outcomes evaluated included intra-hospital, overall, and endocarditis-related mortality, as well as relapse and adverse events. The risk of renal toxicity with each treatment was individually analysed.

The analysis included 631 infective endocarditis episodes caused by MSSA. Of these, 537 episodes (85 percent) were treated with cloxacillin only, 57 episodes (9 percent) were treated with cefazolin only, and 37 (6 percent) episodes were treated with both antibiotics.

Of note, patients who received cefazolin had significantly higher rates of comorbid conditions (median Charlson Index 7; p<0.01) and were more likely to have previous renal failure (57.9 percent; p<0.01). On the other hand, patients treated with cloxacillin had higher rates of septic shock (25 percent; p=0.033) and new-onset or worsening renal failure (47.3 percent; p=0.024), with significantly increased in-hospital mortality (38.5 percent; p=0.017).

One-year infective endocarditis-related mortality and rate of relapse did not significantly differ between the treatment groups. Moreover, neither cefazolin nor cloxacillin treatment emerged as a protective factor against both outcomes.

The findings suggest that cefazolin and cloxacillin are equally effective in the treatment of MSSA-associated infective endocarditis.