The level of evidence is downgraded by imprecise results (wide confidence intervals).
A Cochrane review included six studies with a total of 789 subjects. All trials compared antibiotic prophylaxis versus no prophylaxis.
The primary outcome of bacteriuria was less common in the prophylaxis group amongst surgical patients with asymptomatic bacteriuria (RR 0.20; 95% CI 0.13 to 0.31) . Two non-surgical studies could not be combined in a meta-analysis due to heterogeneity and only one showed significantly fewer cases of bacteriuria (RR 0.19; 95% CI 0.09 to 0.37).
Two trials of surgical patients with asymptomatic bacteriuria only (255 participants) compared one type of antibiotic prophylaxis with another and neither study showed a significant difference in cases of bacteriuria. One study (78 participants) compared antibiotic prophylaxis in patients at catheterisation only versus antibiotic prophylaxis throughout catheterisation period with asymptomatic bacteriuria. Antibiotics at catheterisation only, resulted in significantly fewer cases of bacteriuria than giving prophylaxis throughout the catheterisation period (RR 0.29 95% CI 0.09 to 0.91).
Secondary data of pyuria were provided by two surgical studies (255 participants). When studies were pooled, pyuria occurred in significantly fewer cases in the prophylactic antibiotic group (RR 0.23, 95% CI 0.13 to 0.42). The number of gram-negative isolates in patients' urine just before catheter removal in one study (RR 0.05, 95% CI 0.00 to 0.79) and six weeks after hospital discharge (RR 0.36, 95% CI 0.23 to 0.56) were significantly lower. There were no events in the treatment group before catheter removal. When pooled data from two studies showed significantly reduced febrile morbidity in those receiving antibiotic prophylaxis (RR 0.53 95% CI 0.31 to 0.89).
In one trial comparing antibiotic prophylaxis with giving antibiotics when clinically indicated amongst female surgical patients who had a urethral catheter for more than 24 hours, symptomatic urinary tract infection was less common in the prophylaxis group (RR 0.20, 95% CI 0.06 to 0.66). Five trials compared antibiotic prophylaxis with giving antibiotics when microbiologically indicated, bacteriuria, pyuria and gram-negative isolates in patients' urine were less common in the prophylaxis group amongst surgical patients with bladder drainage for at least 24 hours postoperatively. Bacteriuria rates were also about five-fold lower in the prophylaxis group in trials involving urological surgery patients and non-surgical patients.Comment: The trials involved varying patient populations and various models of antibiotic prophylaxis. However, given the general consistency of the results, this variation enhances the generalizability of the review findings. None of the reports provided any information about allergic adverse drug reactions. Another concern is the development of antibiotic resistant strains of bacteria that calls for limiting the use of antibiotic prophylaxis.