Inter- and intra-strain variants in the genus Brucella.

Inter strain variation among the species and biotypes in this genus was determined by examining 1 800 separate isolates by all the conventional identification methods and also by the manometric method to determine the oxidative metabolic pattern of each isolate. Included among this pool of 1 800 strains are isolates from all reported hosts and from world wide geographic areas, including most countries. Intra strain variation was studied by randomly selecting and transferring to slants 50 well isolated colony forming units from plates streaked with saline suspensions of the following organisms: 2 strains each of B. melitensis biotypes 1, 2, 3; 2 strains each of B. suis biotypes 1, 2, 3; 2 strains each of B. abortus biotypes 1, 2, 3, 5; and 2 strains of B. neotomae. Each of the 1 100 slants than were examined by the conventional determinative methods and manometrically for its species metabolic patterns. There were essentially no variants found among the CFUs from B. melitensis or B. neotomae. Many variants in dye sensitivities were found among CFUs from the strains of B. abortus and variants in both the conventionally measured characteristics and in metabolic patterns were found in the strains of B. suis. Implications of these findings will be discussed.