The Type of Coliform Bacilli Prevalent in Urine and their Significance, with Special Reference to the Sanitary Aspects

Abstract

1. 1000 urinary and 500 faecal cultures of coliform bacteria were studied by means of the methyl-red, citrate and indol tests and also by their fermentation reactions upon saccharose and dulcite.2. 8 per cent, of the faecal strains and 52 per cent, of the urinary strains were of theaerogenestype,i.e.methyl-red negative and citrate positive. Indol was produced in 94 per cent, and 43 per cent, of cases respectively.3. This would suggest additional evidence that thecoligroup are quickly outnumbered by theaerogenesgroup once they leave the faeces, and also that the presence of theaerogenestype is not confined even in large numbers to an extra-corporeal habitat.4. In water bacteriology the constancy or change in the relative proportions ofcoliandaerogenesstrains present is the goal at which to aim. Theaerogenesvariety cannot of itself be regarded as non-excretal or even non-faecal.5. From a sanitary standpoint, the classification of coliform bacteria by means of the methyl-red and citrate tests cannot be regarded as entirely free from error so long as (a) theaerogenesstrains are found in faeces, in however small numbers, (b) these strains occur as the predominant type in urine, and (c) intermediate strains are found in the faeces, urine, soil and water.6. The principal value of these tests lies in their comparative specificity in identifyingB. coliof immediate faecal origin. The presence of such an organism, interpreted together with the indol test, may be said to suggest dangerous faecal pollution if found prominently in a water sample. The presence of other types identified by the same tests cannot be regarded as having the same significant value in regard to a negative opinion.7. A plea is made for a further study of coliform bacteria by means of the tests described in relation to the biological behaviour of the bacteria under different environmental conditions.