Characterization and identification of 95 diphtheroid (group JK) cultures isolated from clinical specimens.

Ninety-five cultures of group JK bacteria isolated from clinical specimens were characterized morphologically and biochemically. The microorganisms were isolated primarily from blood cultures. The bacterial cultures produced positive reactions when tested for catalase, Tween hydrolysis, and carbohydrate fermentation. Glucose and galactose were fermented by more than 90% of the organisms. Gas-liquid chromatography of trimethylsilyl derivatives of whole-cell hydrolysates of some of the group JK cultures yielded nearly identical elution profiles. The group JK microorganisms were susceptible to vancomycin but were resistant to most of the other 17 antimicrobial agents tested. A method is presented for differentiating the group JK microorganisms from other similar bacteria encountered in clinical specimens. Although these bacteria rarely occur in clinical specimens, they are capable of producing fatal infections (endocarditis and sepsis) in humans.