The Eijkman test for faecal coli in the bacteriological examination of water supplies

Abstract

1. A historical survey is given of work upon the Eijkman method.2. A total of 104 water samples were examined by methods I and III. These yielded 602 cultures obtained from the 44 and 37° C. presumptive series, and of these 357 were 44° C.-positive. The only types capable of fermenting lactose at 44° C. wereBact. colitype I and Irregular type II, with the addition of three cultures of intermediate type I and two ofaerogenestype I.3. The relative efficiencies in the detection ofBact. coliof the 44° C. method by direct inoculation and of the 37° C. presumptive test with plating and differentiation were compared. Out of 104 samples, sixty-eight were shown to contain faecalBact. coli, and in 19% of these the 44° C. method detectedBact. coliwhen it was not recovered at 37° C. The converse was true in only 13% of samples.4. The results obtained by other workers in regard to the specificity of incubation at 44° C. and to the various methods hitherto proposed for employing it have been collected and discussed; technical advantages and disadvantages have also been considered.5. It is concluded: (1) That false positives at 44° C. are a negligible quantity for practical purposes. (2) That the best all-round method to use is Wilson's method IV. (3) That 48 hr. incubation should be given, but that 24 hr. is sufficient when rapidity is desired. (4) That the test should be officially recognized and standards laid down for use with it.6. Cellobiose was found to be inferior to citrate for the identification of the I.A.C. group.