Abstract
Background: Percutaneous drainage is the cornerstone of source control for pelvic abscess, yet the microbiology and resistance burden of the drained fluid remain underexplored. Methods: We retrospectively analyzed data from 149 patients who underwent image-guided percutaneous drainage of a pelvic abscess at a single center. Third-generation cephalosporin resistance (3GCR) was evaluated as the primary outcome, with documented resistance across at least three antimicrobial categories (DR ≥ 3) as a secondary descriptor. Results: Cultures were positive in 74/101 sampled aspirates (73%), Gram-negative-predominant (73%), with Escherichia coli most frequent (50% of isolates). At least one Enterobacterales isolate was recovered from 50 patients, of whom 32 (64%) had documented resistance to ceftriaxone or ceftazidime; among patients with E. coli, 27/41 (66%) were 3GCR-positive. This proportion applies to the culture-positive subset with an available antibiogram. It cannot be extrapolated to all drained pelvic abscesses, since culture acquisition was selective and strongly associated with macroscopic purulence. Median abscess volume was higher in 3GCR-positive patients (213 vs. 88 cc), but the association did not reach statistical significance (OR 1.60 per 100 cc, 95% CI 0.94–2.71; p = 0.081; AUC 0.70) and attenuated further when restricted to adults (OR 1.49, 95% CI 0.91–2.45; p = 0.114). Postoperative etiology was not associated with 3GCR (14/22, 64%, vs. 9/16, 56%; OR, 1.36; 95% CI, 0.37–5.07; p = 0.74). Overall clinical success was 128/148 (86%), and 47/50 (94%) in the primary analysis set. Conclusions: In a selected subset of culture-positive pelvic abscesses, two-thirds of Enterobacterales were resistant to third-generation cephalosporins. Neither abscess volume nor postoperative origin predicted resistance.