Delayed hypersensitivity reactions in patients with Mycobacterium chelonei and Mycobacterium fortuitum infections

Delayed hypersensitivity reactions to skin test antigens prepared from rapidly growing mycobacteria were measured in patients with postoperative wound infections due to Mycobacterium chelonei and M. fortuitum. Sixteen of 19 patients with M. chelonei infection had more than 10 mm of induration to the M. chelonei purified protein derivative antigen (PPD-CG) and were significantly more likely to react to PPD-CG than patients or hospital personnel who had no evidence of infection. All but one patient had more induration with PPD-CG than with the antigen prepared from M. fortuitum (PPD-F). Three of 4 patients with M. fortuitum infection had greater than or equal to 9mm of induration with PPD-F and were significantly more likely than noninfected patients to react to PPD-F. Three of the 4 patients also had at least as much induration with PPD-F as with PPD-CG. In an outbreak of infections due to M. chelonei, testing with PPD-CG may be useful epidemiologically. Although the data are less clearly defined for PPD-F, testing with this antigen may be of value in an outbreak caused by M. fortuitum.