Antimicrobial resistance and clinical outcome of bacteroides bacteremia: Findings of a multicenter prospective observational trial

There is debate regarding the correlation between in vitro susceptibility t esting and clinical response to therapy for bacteroides bacteremia. We cond ucted a prospective multicenter observational study of 128 patients with ba cteroides bacteremia. Outcome was correlated with results of in vitro susce ptibility testing of Bacteroides isolates recovered from blood and/or nonbl ood sites, determined with use of 3 end points: mortality at 30 days, clini cal response (cure vs, failure), and microbiological response (eradication vs. persistence). The mortality rate among patients who received inactive t herapy (45%) was higher than among patients who received active therapy (16 %; P = .04). Clinical failure (82%) and microbiological persistence (42%) w ere higher for patients who received inactive therapy than for patients who received active therapy (22% and 12%, respectively; P = .0002 and .06, res pectively). In vitro activity of agents directed at Bacteroides species rel iably predicts outcome: the specificity was 97%, and positive predictive va lue was 82%. Antimicrobial susceptibility testing may be indicated for pati ents whose blood specimens yield Bacteroides species.