BACKGROUND: The potential risk for infection is a common concern of transrectal ultrasound prostate biopsies. The current AUA White paper recommends single dose antibiotic prophylaxis and culture-directed antimicrobial therapy if rectal swab is performed. Concern has also been raised for increased prevalence of antibiotic resistant organisms. In this study, we aimed to assess whether the presence of a positive fluroquinolone resistant gram-negative rod (GNR) rectal swab culture is associated with an increased risk of infection despite culture-guided prophylaxis.
METHODS: We retrospectively analyzed patients who underwent an in-office transrectal prostate biopsy from October 2022 through January 2024. Antibiotic prophylaxis was administered in-line with AUA recommendations for all patients. Decision to perform MRI-fusion was operator & patient dependent. Resistant GNR rectal swab culture data was collected. Primary outcome was post-operative infection within 10 days after biopsy. Secondary outcomes were procedure specific and any-cause ED visit within 30 days after biopsy. Logistic regression was performed to determine whether a positive rectal swab was a predictor of post-biopsy infection.
RESULTS: : A total of 1876 patients underwent transrectal prostate biopsy, of which 1836 (97.9%) had a rectal swab performed. Of these patients, 305 patients (16.6%) had a positive resistant GNR rectal swab, with E. coli being the most common organism (80.7%). The average time between rectal swab to biopsy was 36.6 ± 30.0 days. Twenty eight (1.5%) patients had post-procedure infection. On logistic regression, patients with appropriately treated rectal swab did not have an increased risk of post-procedure infection (OR: 1.69, 95% CI: 0.71 - 4.00, p = 0.24). Procedure-specific ED visits and any-cause ED visit within 30 days of biopsy was higher for patients with a positive rectal swab (OR: 2.94, 95% CI: 1.62 - 5.30, p=0.021). Incidence of ED visits and their associated primary reason are listed in Table 1.
CONCLUSIONS: Our results validate the benefit of identification of patients with resistant organisms and appropriate culture-guided antibiotic prophylaxis in preventing post-prostate biopsy infection. However, patients with a positive rectal swab despite antibiotic prophylaxis are more likely to require post-biopsy medical care related to the procedure. Finally, these data suggest modification to the post-biopsy protocol may be indicated for patients with quinolone resistant organisms but would benefit from further investigation.
Table 1. Incidence of Procedure Related and Unrelated Emergency Department Visits of Patients with and without Positive Resistant GNR Rectal Swabs
| Visit Reason | Positive Swab | Negative Swab |
| Procedure Related Visits | ||
| Urinary Retention | 6 (1.97%) | 5 (0.33%) |
| Urinary Tract Infection | 3 (0.98%) | 8 (0.52%) |
| Dizziness/Syncope | 3 (0.98%) | 4 (0.26%) |
| Sepsis | 2 (0.66%) | 4 (0.26%) |
| Post-Operative Infection | 1 (0.33%) | 2 (0.13%) |
| Hematuria | 0 (0%) | 3 (0.20%) |
| Fever | 0 (0%) | 4 (0.26%) |
| Procedure Unrelated Visits | ||
| Gastrointestinal | 2 (0.66%) | 6 (0.39%) |
| Musculoskeletal/Fall | 1 (0.33%) | 2 (0.13%) |
| Neurologic/Psychiatric | 1 (0.33%) | 3 (0.20%) |
| Acute Kidney Injury | 1 (0.33%) | 0 (0%) |
| Hydrocele | 1 (0.33%) | 0 (0%) |
| Cardiac | 1 (0.33%) | 7 (0.46%) |
| Fatigue | 0 (0%) | 2 (0.13%) |
| Dental | 0 (0%) | 1 (0.07%) |
| Nephrolithiasis | 0 (0%) | 1 (0.07%) |
| COVID-19 Infection | 0 (0%) | 1 (0.07%) |
| Paronychia | 0 (0%) | 1 (0.07%) |
