Finding
The trays are also satisfactory for macroscopic agglutinations using other bacterial antigens such as Shigella, Salmonella, and Brucella.
Paper
DIRECT PERFORMANCE AND DARKFIELD READINGS OF LEPTOSPIRA TESTS IN PLASTIC TRAYS WITH DEPRESSIONS
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Semantic ScholarAbstract
The use of clear disposable plastic trays with depressions provides a new method of performing and reading Leptospira agglutination and agglutination-lysis tests. The performance of these macroscopic tests with Leptospira antigens has been complicated by the necessity for reading the tests microscopically under darkfield illumination. To accomplish this, a drop or loopful must be removed from each tube of the test to a microscopic slide. Dry low power examination has made the preparations easier to read but has not eliminated the time consuming and tedious procedure. In addition, the use of live organisms in the agglutination-lysis test poses a hazard in the reading of the tests. For the Leptospira tests the trays are cut into four pieces, 4 by 6 in each. This size fits well on the ordinary microscope stage. Serial dilutions of serum are made in 0.2 ml saline directly in the cups and a little practice avoids both bubbling and spattering. Equal amounts of antigen suspension are added to the cups and the plastic tray placed on a serology rotator for 3 min at 120 to 180 rpm. Quantities up to 1 ml have been used successfully. The trays are then covered with a glass plate and placed in a 37 C incubator. There is very little evaporation in trays which have been tested in the incubator for as long as 72 hr. Trays are easily removed from the incubator and examined at intervals or after 24 hr for a final reading. The trays are stiff enough to handle easily and may be placed on glass plates for stacking. The most striking advantage of the use of the trays is that the preparations may be read directly by dry darkfield examination under low power magnification. It is not necessary to remove a portion of the contents. Test tubes with expensive and time consuming washing are eliminated. The trays (Linbro Chemical Co., 681 Dixwell Avenue, New Haven, Conn.) are inexpensive and may be used for other serological, microbiological, and chemical tests such as virus assays. They may be discarded or easily washed for additional use. They do not withstand autoclaving but may be disinfected in alcohol or other germicides. Agglutination tests and agglutination-lysis tests performed in this laboratory have corresponded to tests performed in test tubes and incubated for 2 hr at 50 C and in the refrigerator overnight. The trays are also satisfactory for macroscopic agglutinations using other bacterial antigens such as Shigella, Salmonella, and Brucella. These tests are read with ease over a dark background.
Authors
N. Hirschberg
Journal
Journal of Bacteriology