From Big Medical Encyclopedia

KRUGER METHOD (And. P. Krueger, amer. the bacteriologist, a sort in 1901) — kinetic method of titration of a bacteriophage. It is developed on the basis of the pattern which is experimentally established by Kruger and J. H. Northrop, according to a cut at constant initial concentration of bacteria time necessary for approach of a lysis, in direct ratio to a logarithm of initial concentration of the added phage; it is modified by M. N. Fischer.

To. the m is seldom applied though in certain cases it did not lose the value. It allows to compare (to the mistake which is not exceeding 5 — 20%) lytic activity of the studied drug of a phage with activity of another randomly of the chosen phage called by standard.

As a standard phage choose drug, highly active and steady at long-term storage. Take the minimum cultivation for its conventional unit, at Krom the initial quantity of bacteria completely lyses at t ° 36 ° on a rocking chair. Credits of the studied phages express in these units by comparison of speeds of a lysis of the same initial concentration of bacteria the studied phage and three-four consecutive tenfold cultivations of a standard phage. The kinetics of a lysis is defined, comparing a turbidity of mixes a phage — bacteria with bacterial standard (see) a turbidity.

As well as at Appelman's method (see. Appelmana method ), the data obtained by titration on To. m, though differ in bigger accuracy, but characterize only lytic activity of drug. The caption of a standard phage can correspond to a caption on dense environments (see. Gratsia method ), determine concentration of active phage corpuscles by Krom, only at defined (not too low and not too high) initial concentration of bacteria and provided that this phage gives high performance of crops.

Compliances between credits investigated and standard phages, on the one hand, and concentration of active phage corpuscles, with another, can not be since the speed of the lysis caused by different phages depends not only on their initial concentration (that is the basis To. m), but also from distinctions in adsorbability, duration of the periods of intracellular reproduction and a lysis, an average exit (harvest) of a phage to a cell (see. Bacteriophage ).

Bibliography: Fischer M. N. A kinetic method of titration of a bacteriophage according to Kruger and his theoretical justification, Zhurn, mikr., epid, and immun., t. 20, century 2, page 5, 1938.

A.S. Krivisky.