Adjunctive azithromycin reduces risk of non-elective cesarean post-operative infection: The C/SOAP trial

1. Women receiving azithromycin in addition to standard antibiotic prophylaxis for cesarean section (c-section) were 49% less likely to develop endometritis and postoperative wound infections compared to those who received only placebo and standard antibiotic prophylaxis.

2. There were no significant differences in neonatal health outcomes in women who received adjunctive azithromycin in addition to standard antibiotic prophylaxis for c-section compared to those who received only placebo and standard antibiotic prophylaxis. 

Evidence Rating Level: 1 (Excellent)
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Study Rundown: Pregnancy-associated infection is a significant cause of maternal death and c-section is a notable risk factor for postpartum maternal infection. Previous literature has suggested that azithromycin, in addition to a standard cephalosporin prophylaxis, reduces the risk of such postoperative infections. In this randomized controlled trial, researchers investigated whether adjunctive azithromycin reduces the composite rate of endometritis, wound infection and other infections (abdominopelvic abscesses, maternal sepsis, pelvic septic thrombophlebitis, pyelonephritis, pneumonia or meningitis) in women undergoing non-elective cesarean infection. Their results showed that adding azithromycin to a standard cefazolin prophylaxis safely reduced the composite infection rate significantly. Additionally, they also found no differences in adverse neonatal outcomes in women receiving adjunctive azithromycin vs. placebo. This study, while reassuring of azithromycin adjunctive therapy, is limited by its exclusion of women undergoing scheduled c-sections and those with intrapartum chorioamnionitis.

Click to read the study, published today in NEJM

Relevant Reading: Antibiotic prophylaxis versus no prophylaxis for preventing infection after cesarean section

In-Depth [randomized controlled trial]: In this multicenter randomized controlled trial, 2013 women undergoing non-elective cesarean who were ≥28 weeks gestation were randomized to receive either 500mg of IV azithromycin (n = 1019) or placebo (n = 994). Both groups received standard cefazolin prophylaxis. The primary outcome was a composite of endometritis, wound infection or other infections up to 6 weeks after surgery occurring within 6 weeks. Secondary outcomes included a composite of neonatal death, suspected or confirmed sepsis and other medical complications. The primary outcome occurred in 62 women (6.1%) who received azithromycin and 119 (12.0%) who received placebo (RR 0.51; 95%CI 0.38-0.68, p < 0.001). Additionally, the azithromycin compared to the control group was 38% less likely to develop endometritis (3.8% vs. 6.1%, RR 0.62, 95%CI 0.22-0.56; p = 0.02) and 65% less likely to develop wound infections (2.4% vs. 6.6%, RR 0.35; 95%CI 0.22-0.56; p < 0.001). The NNT to prevent one primary outcome was 17 and 43 to prevent one event of endometritis. There were no significant differences between other infections between groups. Additionally, there were no differences between groups in terms of secondary neonatal composite outcomes including neonatal death and serious complications (14.3% vs. 13.6%, p = 0.63).

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