CLINICAL-SIGNIFICANCE, BIOCHEMICAL FEATURES, AND SUSCEPTIBILITY PATTERNS OF SPORADIC ISOLATES OF THE MYCOBACTERIUM-CHELONAE-LIKE ORGANISM

Mycobacterium chelonae-like organisms are nonpigmented rapidly growing mycobacteria whose clinical significance is unknown. We evaluated 87 sporadic isolates encountered in a clinical laboratory. Most isolates (62%) were respiratory; only 2 of 54 (4%) (both from patients with AID S) were clinically significant. Among 33 nonrespiratory isolates, 20 o f 33 (or 61%) were clinically significant. Clinical diseases included posttraumatic wound infections and catheter-related sepsis. Routine bi ochemical features included growth inhibition by 5% NaCl (100%), a smo oth colony morphology (94%), positive 3-day arylsulfatase reaction (84 %), no color or a light tan color on iron uptake (100%), and variable nitrate reduction (45%). Additional characteristics that helped to sep arate this group from M. chelonae and Mycobacterium abscessus were sus ceptibility to cephalothin (90%) and ciprofloxacin (100%), utilization of mannitol (94%) and citrate (83%) as carbon sources, and unique pat terns of mycolic acid esters by high-performance liquid chromatography . This group was quite drug susceptible, with 100% of isolates inhibit ed by amikacin, imipenem, cefoxitin, cefmetazole, and the newer quinol ones ciprofloxacin and ofloxacin. Three examples of this group, includ ing a proposed type strain, have been deposited in the American Type C ulture Collection.