Effect of nitrofurantoin and methenamine hippurate prophylaxis on bacteria and yeasts in the urine of patients with an indwelling catheter

Nitrofurantoin or methenamine hippurate was given prophylactically to elderly patients without urinary tract infection at the beginning of long-term catheterization (mean 81 days), but it only delayed the appearance of bacteriuria. Escherichia coli was most frequently the first species to appear (≥10⁴/ml) in the urine of 40 patients given methenamine hippurate as well as in the control group (41 patients), whereas in 42 patients treated with nitrofurantoin more resistant species, such as Proteus mirabilis, Providencia spp. and Pseudomonas aeruginosa most often appeared first. Weekly tests made during the course of catheterization showed that E. coli disappeared from the nitrofurantoin-treated patients, while pseudomonas increased in this group and providencia in the control group. Pseudomonas was isolated more frequently in the nitrofurantoin than other groups. With the exception of klebsiellae, the bacterial strains isolated from the nitrofurantoin group were as sensitive to various antibiotics as were those from other groups. Significantly more samples with growth of yeasts (≥10⁴/ml) were obtained from nitrofurantoin treated than from methenamine hippurate treated patients. Candida albicans was the species of yeasts most often isolated.