Risk Factors for Relapse in Acute Bacterial Prostatitis: the Impact of Antibiotic Regimens

The aim of the study was to analyze the risk factors for relapse in patients with acute bacterial prostatitis (ABP), focusing on the impact of different antibiotic regimens. We conducted an observational study of all patients diagnosed with ABP (irritative and/or obstructive urinary symptoms, temperature of >37.8°C, and the presence of bacteriuria in urine culture, in the absence of data suggesting pyelonephritis) from January 2017 to December 2018. The main outcome was relapse. We performed a multivariate analysis to identify the risk factors associated with relapse. A propensity score with inverse weighting was applied to attenuate antibiotic selection bias. We included 410 patients. The mean age was 68 years; 28.8% had diabetes mellitus, and 61.1% benign prostatic hyperplasia. The most common isolated bacteria were Escherichia coli (62.4%) and Klebsiella spp. (10%). The overall resistance rate was 39.5% to quinolones. The mortality rate was 1.2%, and the relapse rate was 6.3%. The only independent risk factor for relapse was inadequate antibiotic therapy (odds ratio [OR] 12.3; 95% confidence interval [95% CI], 3.5 to 43.1). When the antibiotic was modified according to the susceptibility pattern, the rates of relapse were 1.8% in those treated with ciprofloxacin, 3.6% with intravenous beta-lactam, 9.3% with co-trimoxazole, and 9.8% with oral (p.o.) beta-lactam (P = 0.03). Treatment with oral beta-lactam (OR, 5.3; 95% CI, 1.2 to 23.3) and co-trimoxazole (OR, 4.9; 95% CI, 1.1 to 23.2) were associated with a risk of relapse. In this large real-life observational study, a significantly higher relapse rate was observed when antibiotic treatment was inadequate. When the antibiotic was tailored, quinolones and intravenous beta-lactams had a lower relapse rate than co-trimoxazole and oral beta-lactams. IMPORTANCE In the manuscript, we report a large series of acute bacterial prostatitis cases and describe data about the etiology, antibiotic resistance rate, and outcome, specially focused on the risk factors for relapse. We found high rates of resistance to the most frequently used antibiotics and a high relapse rate in patients whose treatment was not adjusted according to their microbiological susceptibility. We did not observe differences, though, in mortality or relapse according to appropriate or inappropriate empirical treatment. What is new in this article is the different relapse rates observed depending upon the definitive adequate antibiotic used. Quinolones and intravenous (i.v.) beta-lactam have lower rates of relapse (1.8% and 3.6%, respectively) compared to co-trimoxazole and oral (p.o.) beta-lactam (3.3% and 9.8%, respectively). Clinicians should carefully choose an adequate antibiotic for definitive ABP treatment depending on the results of microbiological isolation, using quinolones as the first option. Whenever quinolones cannot be administered, i.v. beta-lactams seem to be the second-best option.