Discussion

The most important finding of this study is that AAP among patients undergoing TURP was associated with a significant reduction in the incidence of 30-day post-TURP UTI. The benefit of preoperative urine culture procurement, together with targeted AAP, was associated with a 51% reduction in the incidence of UTI in patients with preoperative asymptomatic bacteriuria. The incidences of postoperative UTI were also significantly higher in the patients who received inactive prophylactic antibiotics and in those receiving prophylactic antibiotics that were too broad-spectrum compared to those receiving AAP. Notably, receiving inactive antibiotic prophylaxis was confirmed as an independent risk factor associated with post-TURP UTI in the multivariable regression analysis. Our findings are consistent with the prior studies that have reported benefit of urine culture-guided, targeted, antibiotic prophylaxis for reduction of post-TURP fever and bacteremia, ^{Reference Cafferkey, Falkiner, Gillespie and Murphy1,Reference Murphy, Stassen, Carr, Gillespie, Cafferkey and Falkiner4} and these findings provide additional evidence in support of the current guideline recommendations. ^{Reference Nicolle, Gupta and Bradley5,Reference Bratzler, Dellinger and Olsen8,Reference Lightner, Wymer, Sanchez and Kavoussi9}

In our study, the high procurement rate (95%) of pre-TURP urine culture within 14 days of the scheduled surgery is consistent with a prior 90% reported rate. ^{Reference Khaw, Oberle and Lund10} However, the prescribed IAP rate of 51% is higher than that reported in the same prior study (29%). ^{Reference Khaw, Oberle and Lund10} As a comparative benchmark for future studies, this higher IAP rate in our study may be attributed to at least 3 reasons. First, expanded criteria for IAP by adding too broad spectrum of prescribed drug and incorrect drug dosing. Although these were not identified as the independent factors associated with post-TURP UTI, prescribing antibiotic prophylaxis that was too broad-spectrum was associated with the higher rate of subsequent UTIs due to MDR pathogens compared to prescribing AAP. Second, the antibiotic-resistant rates of the Enterobacteriaceae to the commonly prescribed prophylactic antibiotics, such as third-generation cephalosporins, fluoroquinolones, and TMP-SMX, are high in our regional setting. Although prescribing ciprofloxacin as a prophylactic agent is the second most common practice in the study, it contributed the most to IAP given no activity against most of the uropathogens. Lastly, one-quarter of the study patients had urine culture performed <3 days prior to TURP, and the culture results were not available at the time of TURP. Together, these factors inform on the clinically meaningful impact of timely procurement of preoperative urine culture and targeted AAP.

Post-TURP UTI within 30 days in this study was common (37%), and most cases had lower UTI. Notably, we assessed the lower UTI instead of bacteriuria as the post-TURP outcome. The rate of lower UTI in this study was lower than the rate of post-TURP bacteriuria (40%–74%) reported in previous studies. ^{Reference Grabe, Forsgren and Hellsten2,Reference Grabe, Forsgren, Björk and Hellsten3} Our definition of lower UTI may be a more accurate clinically meaningful outcome than bacteriuria given that this definition considers the new onset of lower UTI symptoms but excludes irritative or discomfort symptoms that commonly occur right after TURP and during urinary catheter retention.

In this study, we identified cerebrovascular disease and prior UTI within 3 months of TURP as independent factors associated with post-TURP UTI. Underlying cerebrovascular disease may be attributed to limited post-TURP ambulation, bladder overflow, or urinary and fecal incontinence. In contrast, UTI within 3 months prior to TURP may represent risk for UTI recurrence. Patients with these risk factors should be carefully monitored for post-TURP UTI.

This study, to the best of our knowledge, is the first comparative assessment of the post-TURP UTI incidence for patients who received AAP versus IAP. In addition, it reports on the contribution of each prophylactic antibiotic to IAP, and changes in types and susceptibility profiles of the uropathogens isolated from the pre- and post-TURP urine cultures. Nonetheless, there were some recognizable limitations. First, the study design was a prospective observational cohort with some differences in baseline characteristics between the groups. Notably, a randomized controlled design to assign patients to receive AAP and IAP is not ethically feasible. However, most of the baseline characteristics associated with the study outcomes were not significantly different between the 2 groups. Second, the findings were from a single tertiary-care center with local uropathogen susceptibility patterns and might have limited generalizability. However, the principle of AAP for reduction in post-TURP UTI should be generalizable to other settings. Lastly, duration of antibiotic prophylaxis was not considered a criterion for AAP given there is no definitive consensus recommendation for the duration in current guidelines. ^{Reference Nicolle, Gupta and Bradley5,Reference Bratzler, Dellinger and Olsen8,Reference Lightner, Wymer, Sanchez and Kavoussi9} However, the median durations of the antibiotic prophylaxis were not significantly different between the 2 groups.

In conclusion, AAP significantly reduced the incidence of 30-day post-TURP UTI compared to IAP. Timely preoperative urine culture procurement and AAP is a strategic, patient-centric approach to minimize risk for post-TURP UTI in the era of antibiotic resistance. Use of antibiotic prophylaxis that is too broad-spectrum may be associated with development of the MDR-associated UTIs. Patients undergoing TURP who have underlying cerebrovascular disease or preoperative UTI within 3 months should be closely evaluated for post-TURP UTI. Further studies are needed to assess interventions to improve the practice of prescribing AAP for patients undergoing TURP.