M FORTUITUM - ITS IDENTIFICATION, INCIDENCE, AND SIGNIFICANCE IN FLORIDA

Abstract

This study indicates that, in Florida, rapidly growing mycobacteria are not uncommonly isolated from human sources. Of 407 unclassified mycobacterial cultures obtained during one year, 46 (11%) were rapid growers, 32 (70%) of which were M. fortuitum (8% of the total unclassified strains). This is a higher incidence than that found in Florida for M. kansasii and about the same as that found for Group II scotochromogens (3% and 12%, respectively). The fact that 18 (95%) of 19 Group IV strains exhibiting the unique ability to absorb malachite green from Lowenstein-Jensen medium were subsequently identified as M. fortuitum strongly suggests that the property, when present, is characteristic of this organism. However, not all strains of M. fortuitum demonstrated this property. Three of 43 patients had two isolations each of Group IV mycobacteria, and both cultures were M. fortuitum in 2 of these patients, LAN 37 and OP 80. The M. fortuitum was clinically significant for patient LAN 37, and is probably significant for patient OP 80. Since subsequent isolations of Group IV organisms have been obtained, there was roentenographic evidence of a disease process, and no other etiologic agent was identified.