Predictability of Methenamine Efficacy Based on Type of Urinary Pathogen and pH

Abstract

This study involved 27 geriatric patients with asymptomatic chronic bacteriuria; all had indwelling Foley catheters. The treatment regimens (daily oral dosage) were: methenamine mandelate (MM) granules, 4 gm; MM, 4 gm, plus ascorbic acid, 4 gm; and MM, 4 gm, plus ascorbic acid, 4 gm, plus cranberry cocktail, 1 liter--administered according to a cross-over design. Proteus vulgaris, Pseudomonas aeruginosa and E. coli were the most common urinary organisms. Proteus organisms were more often found in alkaline than in acidic urines, but the type of pathogen had no influence on urinary pH. Urinary formaldehyde concentration [HCHO] was lower in patients with Proteus infection (17.7 micrograms/ml) than in those with Pseudomonas (21.9 micrograms/ml) or E. coli infection (21.8 micrograms/ml). However, for Proteus infection, [HCHO] was higher in patients receiving MM plus ascorbic acid than in those receiving MM alone. Addition of cranberry cocktail to ascorbic acid did not enhance urinary pH, [HCHO] or methenamine efficacy. Our data suggest that in Foley catheter patients with chronic asymptomatic bacteriuria secondary to Proteus, Pseudomonas or E. coli infection, the type of urinary pathogen or the urinary pH cannot be used to predict the efficacy of methenamine therapy either with or without urinary acidifying agents.

Safety and efficacy of methenamine hippurate for the prevention of recurrent urinary tract infections in adult renal transplant recipients: A single center, retrospective study

“…We did not have any reliable way to assess medication compliance of patients in our study. Because an acidic urine is required for the conversion of methenamine into formaldehyde, and some pathogens that split urea and cause a more basic urine pH will have lower levels of formaldehyde, methenamine is also given with ascorbic acid to help acidify the urine . When patients had a breakthrough UTI, methenamine was stopped and appropriate antibiotics based on the culture data were utilized.…”

Current clinical status on the preventive effects of cranberry consumption against urinary tract infections

“…Moreover, both cranberry powder and PAC-rich extract have been shown to inhibit the adherence of E coli to vaginal epithelial cells in a dose-dependent manner [32]. Such an effect may be relevant to the prevention of UTIs, since in vitro bacteria adherence is significantly higher in vaginal epithelial cells from women with recurrent UTIs compared to controls [33]. Certainly, clinical studies are strongly recommended in order to confirm such a hypothesis.…”

Methenamine Prophylaxis for Recurrent Urinary Tract Infections in a Tertiary Referral Center

“…To our knowledge, the only, the only comparative trials of MH with vs without vitamin C were conducted on patients using indwelling catheters. 10,11 Except for 1 center that used MH+vitamin C, 5 most studies have used MH alone. 6–9 In our practice we use MH alone to keep the regimen simple.…”