Cesarean section prophylaxis: comparison of two doses with three doses of mezlocillin.

A prospective randomized double-blind comparison of two doses, with three doses of mezlocillin for nonelective cesarean section prophylaxis was performed. One hundred seven (107) patients were evaluated. Mezlocillin (4 g) was given post-cord clamping and then at 4-h intervals for a total of two doses or three doses. The incidence of febrile morbidity was lower in the three-dose group (2 of 46, 4%) than the two-dose group (14 of 61, 23%) (P less than 0.02). However, the incidence of infectious morbidity was not different between the three-dose group (3 of 46, 7%) and the two-dose group (10 of 61, 16%), and the incidence of endomyometritis was similar in the two groups (6.5% vs 9.8%). Among failures of prophylaxis there were no differences compared to successes in the number of potential commensals or potential pathogens cultured from amniotic fluid. However, the proportion of failures among patients with both commensals and potential pathogens isolated (10/58) was significantly greater than among patients with none or only commensals isolated (1/37) (P less than 0.03). We found mezlocillin to be an effective agent for perioperative cesarean section prophylaxis with two doses as effective as three doses. The presence of clinically important organisms in the amniotic fluid at the time of operation typified patients with postoperative infectious complications despite perioperative prophylaxis.