For patients with uncomplicated Pseudomonas aeruginosa bloodstream infections, the odds of recurrent infection or death within 30 days were similar for long- or short-course therapy, according to results of a study published in Clinical Infectious Diseases.  

The study used an observational propensity scored-weighted cohort of 249 adult patients with a positive blood culture for P aeruginosa. The primary exposure was a short-course (7-11 days) of antimicrobial therapy. Patients were then observed for 30 days following the end of therapy and 2 physicians blinded to the duration of therapy prescribed independently determined whether subsequent blood cultures were true infections or colonization.

Short-course therapy was received by 28% of the cohort and lasted a median of 9 days (interquartile range [IQR] 8-10 days). Prolonged therapy, of a median 16 days (IQR 14-17 days), was given to 72% of patients. The types of antibiotics prescribed as culture-directed therapy included piperacillin/tazobactam (31%), cefepime (29%), ciprofloxacin (24%), meropenem (12%), and ceftazidime (4%).

Recurrent infection at any site or mortality within 30 days occurred in 14% of those who received a short course of treatment and in 13% of those who received the long course of treatment (odds ratio [OR], 1.06; 95% CI, 0.42-2.68; P =.91). Looking at the outcomes separately, recurrent infection occurred in 7% and 11% of the short- and long-course groups, respectively, and mortality in 7% and 4% (P >.05 for both). Patients in the short-course group spent, on average, 4 days fewer in the hospital compared with the other group (4.04 days; 95% CI, 1.25-6.83 days; P =.005).

As a result of the retrospective nature of the study, imbalances between groups may have persisted despite the application of propensity score-weighting aimed at reducing selection bias. The study investigators also noted that they were unable to make inferences regarding optimal duration of therapy because of the small number of patients, less than 7% of the weighted cohort, who did not have source control.

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Researchers concluded that for bloodstream infections with Pseudomonas spp, receiving roughly 10 days of treatment resulted in outcomes similar to those attained with longer treatment courses and carried the extra benefit of earlier hospital discharge. Because of the rising rate of antibiotic resistance, the study authors emphasized the importance of re-evaluating frequently prescribed durations of antibiotic therapy. Researchers also cautioned that, “further interventional studies are necessary to evaluate the reproducibility of our findings.”

Reference

Fabre V, Amoah J, Cosgrove SE, Tamma PD. Antibiotic therapy for Pseudomonas aeruginosa bloodstream infections: How long is long enough? [published online March 18, 2019]. Clin Infect Dis. doi:10.1093/cid/ciz223