Stewardship / Resistance Scan for Aug 28, 2017

Resistant ear infections in Angola
Analysis of antibiotic duration

Rare, resistant bacteria linked to chronic ear infections in Angola

Researchers have discovered that more than 10% of patients with chronic ear infections at an ear, nose, and throat clinic in Angola were co-colonized with a fluoroquinolone-resistant bacterium commonly found in bird feces.

In a new study in Emerging Infectious Diseases, the researchers report that analyses of samples from 188 patients at a clinic in Luanda, Angola, who had ear discharge related to chronic suppurative otitis media (CSOM), found that 20 patients (10.6%) were colonized by the gram-negative bacillus Alcaligenes faecalis, which was resistant to both ciprofloxacin and levofloxacin. Pseudomonas aeruginosa was the predominant species in 50% of those patients, and Proteus mirabilis the second most common.

Although the presence of A faecalis was originally a mystery, the researchers learned that, to prevent ear discharge from CSOM, a common condition in many developing countries, patients occasionally filled their external auditory canals with dove or pigeon feces. The authors note that it remains to be confirmed whether A faecalis plays a crucial role for disease progression or is merely a contaminant. CSOM is generally caused by P aeruginosa and P mirabilis.

Because the A faecalis isolates were resistant to fluoroquinolones, they authors suggest an alternative strategy of colistin as topical treatment or supplement with orally administered amoxicillin/clavulanic acid for treatment of more severe cases.
Aug 25 Emerg Infect Dis research letter

Study finds short-duration antibiotics superior for intra-abdominal infection

Findings from a new analysis that uses novel methods of evaluating data from antibiotic trials suggest that a short duration of antibiotic therapy is superior to a longer duration of therapy for patients with complicated intra-abdominal infections.

In a study today in Clinical Infectious Diseases, a team of researchers retrospectively applied desirability of outcome ranking (DOOR) and response adjusted for duration of antibiotic risk analyses (RADAR) to data from the Trial of Short-Course Antimicrobial Therapy for Intra-abdominal Infection (STOP-IT), a multisite, randomized controlled trial that evaluated short-duration antibiotic therapy for treating abdominal infections after initial source control. While the initial trial concluded that short, fixed-duration therapy (approximately 4 days) is non-inferior to traditional, longer-duration therapy (approximately 8 days), the researchers theorized that using the DOOR/RADAR approach—which categorizes patients into a list of potential clinical outcomes and ranks them by the desirability of the associated outcome and duration of therapy—could provide stronger conclusions.

Using the DOOR analysis, all 518 STOP-IT patients were categorized as having one of five mutually exclusive outcomes: (1) recovery, with no complications; (2) recovery, with extra-abdominal infection (including Clostridium difficile); (3) recovery with surgical site/wound infection; (4) recovery with recurrent intra-abdominal infection requiring procedure; or (5) death.  Then RADAR was applied to DOOR results to further stratify patients with similar outcomes.

Analysis based on this five-tiered scoring system showed that the probability that randomly selected patients would have a better DOOR score if receiving short-course antibiotics was 49.33%. The probability that randomly selected patients undergoing traditional-duration therapy would have a better DOOR score was 50.6%. Application of RADAR showed that the probability that randomly selected patients would have a better DOOR score if receiving short-course therapy was 63.4%. In addition, analysis of a smaller sample size of patients (150) using DOOR/RADAR showed that the probability of an improved DOOR score was 66.3% for patients in the short-course group.

The authors conclude, "In summary, DOOR/RADAR analysis can be used in antibiotic trials to globally evaluate for superiority of new antibiotic strategies that previously might have been reportable only as noninferior." 
Aug 28 Clin Infect Dis study

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