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.