Oral Beta-Lactams in Acute Prostatitis

Evidence

Two independent retrospective cohorts examined oral step-down therapy after initial treatment for acute bacterial prostatitis. Both reported lower observed clinical cure with an oral beta-lactam regimen than with comparator regimens, but neither randomly assigned treatment. The newer study provides a small Japanese cohort and 30-day outcomes. The larger Spanish study provides commercially reusable full text, a more narrowly defined Escherichia coli population, and 90-day follow-up.

The Japanese single-center study included adult men whose acute bacterial prostatitis was attributed to Enterobacteriaceae. All received intravenous antibiotic therapy before switching to an oral regimen. The analysis covered 66 episodes in 65 patients: 15 patients were placed in the oral beta-lactam group and 51 in a group receiving a fluoroquinolone or trimethoprim-sulfamethoxazole. Clinical cure was the primary outcome; secondary outcomes included Clostridioides difficile infection, sepsis, and all-cause mortality within 30 days.

The abstract reports clinical cure in 61.5% of the beta-lactam group and 87.2% of the comparator group. The between-group result reached the study's significance threshold in its main analysis, with p=0.049. That difference did not remain in a sensitivity analysis, however, and the authors identified oral treatment duration as a suspected major confounder. No C. difficile infection, sepsis, or death occurred in either group during the reported 30-day window. Because only the abstract was ingested, details of eligibility, treatment allocation, cure assessment, missing data, and the sensitivity analysis cannot be audited here.

The Spanish study retrospectively reviewed 326 episodes of culture-confirmed E. coli acute bacterial prostatitis at one Barcelona teaching hospital from 2010 through 2023. Its case definition required fever, urinary symptoms, another compatible feature, and a urine culture with substantial E. coli growth. After initial therapy, 158 episodes received oral cefuroxime and 168 received oral ciprofloxacin. Follow-up extended to 90 days, with clinical failure defined as lack of cure, recurrence with the same strain, or reinfection with a different organism or strain.

Clinical cure occurred in 85.7% of cefuroxime episodes and 96.9% of ciprofloxacin episodes. Recurrence occurred in 6.96% of the cefuroxime group and none of the ciprofloxacin group, while reinfection and mortality were similar. An adjusted model retained an association between treatment group and clinical failure, and a urinary tract infection in the preceding year was also associated with failure. Yet the groups differed substantially before outcomes were measured: cefuroxime recipients were younger and had fewer comorbidities, whereas ciprofloxacin recipients were hospitalized more often and had more bacteremia, recent urological manipulation, and benign prostatic hyperplasia.

Analysis — Converging signals, unresolved causality

The cross-study pattern is a replicated association, not a treatment verdict. In two hospitals, two time windows, and partly different bacterial populations, oral beta-lactam step-down groups had lower observed cure than groups receiving fluoroquinolone-based or mixed comparator therapy. The larger study also found recurrence only in its cefuroxime group. That convergence makes the outcome gap a credible research signal rather than an isolated percentage.

The studies also converge on the reason the signal remains uncertain: treatment was selected in routine care. The Japanese result changed under sensitivity analysis and may have been influenced by different oral treatment durations. The Spanish groups differed in age, comorbidity, hospitalization, bacteremia, and urological history, even before considering unmeasured prescribing decisions. Its adjusted analysis reduces but cannot eliminate this problem. The analysis therefore suggests that drug class, tissue exposure, duration, organism susceptibility, and patient selection may all contribute to the observed gap. A prospective comparison using one case definition, predefined susceptibility criteria, standardized outcome assessment, and balanced treatment pathways would be needed to separate those factors.

Limitations

Both studies were single-center, retrospective, and observational. They show associations between selected oral regimens and outcomes, not that one regimen caused better or worse results. Neither was randomized, and prescribing decisions may have reflected culture results, expected tissue penetration, illness severity, discharge timing, clinician preference, or patient characteristics that the reported models did not capture.

The Japanese evidence is abstract-only and particularly small, with just 15 patients in the beta-lactam group. Its comparator combines two drug classes, its main result was borderline, and its sensitivity analysis did not preserve the difference. The source pack does not expose the detailed sensitivity method or cure adjudication.

The Spanish full text offers more detail but focuses only on E. coli, compares cefuroxime with ciprofloxacin, spans more than a decade of changing practice, and uses a single hospital's diagnostic process. Its treatment groups were imbalanced, and the paper notes that acute bacterial prostatitis lacks fully standardized diagnostic criteria. The two studies also used different follow-up windows and comparator definitions, so their cure percentages should not be pooled. Neither study establishes a general rule for other beta-lactams, other pathogens, other resistance settings, or individual patient care.