Novel catheter design enables transurethral catheterization of male mice

A novel technique for atraumatic transurethral catheterisation of male rats

Transurethral catheterisation of male rats is technically difficult owing to anatomical peculiarities. In the male rat, the urethral striated sphincter consists of two lateral fascicles separated by an anterior and a posterior strip of connective tissue, which impedes the smooth insertion of a urinary catheter. For rat studies requiring continuous collection of urine, bladder irrigation, or measurement of bladder pressure, investigators either have to exclude the male population (be limited to the female population) or perform percutaneous (suprapubic) bladder puncture in male rats, which is more traumatic and invasive than transurethral catheterisation. This paper describes a novel, atraumatic method of transurethral catheterisation in the male rat, with the aid of a microscope and microsurgical instruments. Six Wistar rats were used for this experiment, all of which were catheterised successfully, with no evidence of bladder or urethral injury. The study shows that male rats can be safely catheterised via the urethra with the aid of a microscope and microsurgical instruments for both visual and tactile feedback. This is a relatively straightforward technique to learn and can allow for inclusion of male rats in future studies requiring urinary analysis or bladder irrigation, without the need for traumatic percutaneous (suprapubic) bladder puncture.

Investigating inhibitors of 1-deoxy-d-xylulose 5-phosphate synthase in a mouse model of UTI

The rising rate of antimicrobial resistance continues to threaten global public health. Further hastening antimicrobial resistance is the lack of new antibiotics against new targets. The bacterial enzyme, 1-deoxy-d-xylulose 5-phosphate synthase (DXPS), is thought to play important roles in central metabolism, including processes required for pathogen adaptation to fluctuating host environments. Thus, impairing DXPS function represents a possible new antibacterial strategy. We previously investigated a DXPS-dependent metabolic adaptation as a potential target in uropathogenic Escherichia coli (UPEC) associated with urinary tract infection (UTI), using the DXPS-selective inhibitor butyl acetylphosphonate (BAP). However, investigations of DXPS inhibitors in vivo have not been conducted. The goal of the present study is to advance DXPS inhibitors as in vivo probes and assess the potential of inhibiting DXPS as a strategy to prevent UTI in vivo. We show that BAP was well-tolerated at high doses in mice and displayed a favorable pharmacokinetic profile for studies in a mouse model of UTI. Further, an alkyl acetylphosphonate prodrug (homopropargyl acetylphosphonate, pro-hpAP) was significantly more potent against UPEC in urine culture and exhibited good exposure in the urinary tract after systemic dosing. Prophylactic treatment with either BAP or pro-hpAP led to a partial protective effect against UTI, with the prodrug displaying improved efficacy compared to BAP. Overall, our results highlight the potential for DXPS inhibitors as in vivo probes and establish preliminary evidence that inhibiting DXPS impairs UPEC colonization in a mouse model of UTI.IMPORTANCENew antibiotics against new targets are needed to prevent an antimicrobial resistance crisis. Unfortunately, antibiotic discovery has slowed, and many newly FDA-approved antibiotics do not inhibit new targets. Alkyl acetylphosphonates (alkyl APs), which inhibit the enzyme 1-deoxy-d-xylulose 5-phosphate synthase (DXPS), represent a new possible class of compounds as there are no FDA-approved DXPS inhibitors. To our knowledge, this is the first study demonstrating the in vivo safety, pharmacokinetics, and efficacy of alkyl APs in a urinary tract infection mouse model.