Potentiated Aminoglycosides in Postoperative Urinary Tract Infection Prophylaxis

Overview

Urinary tract hardware such as pig-tail catheters are are frequently used for management of urolithiasis or other obstructive pathologies. They are readily colonized by urogenital flora leading to asymptomatic bacteriuria. While asymptomatic bacteriuria is not per se a problem for patients, it may lead to severe infections in the context of hardware manipulation leading to mucosal damage (e.g. catheter exchanges or stone extraction). Such interventions therefore warrant an antibiotic prophylaxis. However, bacteria rapidly form biofilms on hardware; aside of fluoroquinolones, antibiotics have limited anti-biofilm activity. Furthermore, the widespread use of antibiotics has lead to resistant strains. Hence, novel antimicrobial strategies are needed. Recently, metabolism-based potentiation of aminoglycoside has shown high antimicrobial activity against persistent forms of bacteria such as biofilms in the context of murine catheter-associated urinary tract infections. Because of the highly favorable pharmacodynamic profile of aminoglycoside in the urinary tract and the metabolic potentiation, aminoglycosides can be reduced to levels with minimal toxicity. UROPOT aims to compare the efficacy of potentiated aminoglycoside to standard of care for (i) prophylaxis of asymptomatic bacteriuria during urinary hardware manipulations with mucosal trauma (Pig-tail catheter exchange, stone surgery with prior in-dwelling catheter, etc.) and (ii) sustained microbiological eradication through antibiofilm activity. UROPOT will compare the rate of post-interventional urinary tract infections (primary outcome). It will also assess safety and eradication potency (microbiological outcome).

UROPOT is a randomized, single-centre, double-blind, pilot trial comparing a combination of aminoglycosides and mannitol to standard of care or aminoglycosides alone for the peri-operative antimicrobial prophylaxis of endourological procedures with mucosal trauma in the presence of hardware. Adults (≥18 years) scheduled for such procedures with mucosal trauma (stone surgery with hardware, pig-tail catheter exchanges) and having an asymptomatic bacteriuria E. coli or K. pneumoniae as identified 10 days prior to surgery, will be randomly assigned (1:1:1) to receive standard prophylaxis (gen. Ceftriaxone 2 g) for 24 hours, a single dose of amikacin (6mg/kg i.v.) or a single dose of mannitol (pres. 2.5g i.v. bolus)/amikacin (3mg/kg i.v.). Sample size for the three groups will be constructed to demonstrate a non-inferiority for the clinical outcome (absence of infectious complication within 48 hours from operation) with a power of 80%. Complications in the absence of antimicrobial prophylaxis range from 2-10%. Patients will be excluded if baseline urine culture has another bacterial pathogen or E. coli or K. pneumoniae are documented to be aminoglycoside resistant. The primary endpoint will be the prevention of complications(clinical) that will be evaluated for non-inferiority compared to the accepted standard of care. i.e., within a 6% margin Assuming a rate of complication as low as 2%, the new treatments will be considered non-inferior if the corresponding rate of complication is not above 8% (i.e., 6% margin). This non-inferiority margin can be evaluated with a total for 128 patients per treatment arm, at 1-sided alpha of 5%, with power 80%, through an exact two-sample test for proportions. Two comparisons will be performed of arm A and of arm B versus standard of care (SoC). In addition, a microbiological outcome will be included to document higher biofilm eradication rate. This will be documented by sonication of extracted hardware as well as repeat urine culture at post-operative days 7 and 14 days (secondary outcomes). Safety will be monitored with a specific focus on nephrotoxicity and ototoxicity. If highly efficient, this novel antimicrobial strategy would be expanded to treatment of complicated urinary tract infections.