Antimicrobial prophylaxis in urologic surgery: does it give some benefit?

Three types of antibiotic prophylactic regimens were evaluated versus a control without prophylaxis (group A: 3,912 cases) in urologic surgery. The antibiotic regimens were: group B = cefazolin 1 g/12 h/3 days (3,660 cases); group C = cefonicid 1 g/24 h/3 days (2,076 cases), and group D = cefonicid 1 g single dose (3,169 cases). The parameters used were the comparison of the corresponding rates of postsurgical sepsis and operative wound infections. Numeric investigations for the validity of a retrospective study (unpaired data) were performed: homogenicity test, relative risk point estimate and confidence limits (95%), and etiological fraction point estimate and confidence limits (95%). Chi-square for other purposes were performed. Endoscopic handling was considered homogeneous (same infective risk), while open surgery was heterogeneous (p < 0.001). In order to avoid probable bias, a correction factor was used. Although in different degrees, prophylaxis significantly reduced the morbidity of surgical wound infections (p < 0.001; etiological fraction > 90%). The differences (p < 0.01) between groups B and C/D were attributed to pharmacokinetic causes (short T 1/2 of cefazolin). To obtain the maximum protective effect, the use of antibiotics with a T 1/2 of > 4 h is suggested. There was no resistant mutans in previously sensitive strains. However, a significant selection of intrinsically resistant strains was observed. Monodose offers at lest the same advantages as multiple-dose therapy. In addition, the monodose selected in a lesser proportion both the resistant strains (p < 0.001) and the number of microbial associations (p < 0.01).