Contamination of rat urine with gut flora using all-glass metabolism cages for collection of urine and faeces

Abstract

1. In rat urine collected in all-glass metabolism cages, at least four strains of intestinal microflora were found: two types of E. coli, Enterobacter cloaceae and Proteus vulgaris. The number of bacteria of each strain increased with time.

2. The pH of the urine increased from 6·9 after 24 h to 8·95 after 120 h. The pH of the urine of neomycin-treated rats remained nearly constant over a period of two days.

3. Nitroreductase activity was present in the rat urine. Added p-nitro-benzoic acid was reduced within the first 24 h. Nitroreductase activity in the urine of neomycin-treated rats was significantly lower than in the urine of normal rats, during the second 24-h period only.

4. Collection of urine at -10° prevented the consequences of contamination.