Isolation of Corynebacterium group JK from clinical specimens with a semiselective medium

A semiselective medium for the detection of multiresistant lipophilic corynebacteria is described. The medium consisted of tryptose agar, supplemented with Tween 80, lecithin, histidine, glycerol, sodium thiosulfate, fosfomycin, ticarcillin, and 5-fluorocytosine. The medium was tentatively called lecithin-Tween medium (LT medium). It promoted mainly the growth of Corynebacterium group JK, which has recently been identified as a cause of serious infection in immunocompromised patients. The application of LT medium to 6,859 routine clinical specimens increased the percentage of Corynebacterium group JK isolation from 0.1 to 1.0%. Although a total of 72 isolates were found in 65 patients, on the basis of clinical criteria only 2 patients were regarded as having an infection with these bacteria. Consequently, Corynebacterium group JK infection can only be diagnosed through a combination of clinical and microbiological findings. In high-risk areas, however, the use of LT medium for surveillance may facilitate the early detection of these potentially dangerous organisms.