Abstract
The following is a simplified technic of the so-called Castellani-Taylor mycologieal method, 1 which I have found most useful in practice. The urine is collected in a clean bottle or other clean vessel, if possible sterile, but this is not essential; if it cannot be examined at once, it can be kept for some hours or even a day or two in the ice-box.
A portion of the urine is boiled for 2 minutes; I have found that boiling for 2 minutes does not apparently alter the chemical structure of lactose in the urine; the boiled urine is then distributed into 2 fermentation tubes, 1 and 2. As soon as the urine has cooled down, No. 1 tube is inoculated with B. coli from an agar culture: 2 or 3 large loopfuls; No. 2 tube is inoculated with B. paratyphosus B in the same way. The 2 tubes are placed in the incubator at 35-37° for 12-24 hours. The results are then read. If tube No. 1 (B. coli) shows presence of gas and tube No. 2 (B. paratyphosus B) does not show presence of gas, the inference is that the urine contained lactose.
The explanation is the following: with regard to Fehling reducing sugars which may be found in the urine, viz., glucose, levulose, maltose, galactose, pentose—B. coli and B. paratyphosus B have the same fermentative reactions except on lactose which is fermented by B. coli and not by B. paratyphosus B. If a Fehling reducing sugar, therefore, is fermented by B. coli and not by B. paratyphosus B the inference is that it is lactose. The test may be employed also as a roughly quantitative test using graduated fermentation tubes.
If both tubes show fermentation there are several possibilities: as a rule it is glucose, but it may be levulose or galactose or maltose or pentose or a mixture of them or it may be one or several of these sugars + lactose.
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