PCR AMPLIFICATION AND RESTRICTION-ENDONUCLEASE ANALYSIS OF A 65-KILODALTON HEAT-SHOCK PROTEIN GENE SEQUENCE FOR TAXONOMIC SEPARATION OF RAPIDLY GROWING MYCOBACTERIA

A total of 129 reference and clinical strains of rapidly growing mycob acteria (RGM) belonging to 10 taxonomic groups were studied for restri ction fragment length polymorphism patterns from a PCR-amplified 439-b p segment of the 65-kDa heat shock protein (HSP) gene. Of 24 endonucle ases evaluated, restriction fragment length polymorphism patterns prod uced by HaeIII and BstEII and then by AciI and CfoI gave the best sepa ration. Sixty percent of all RGM taxa studied were differentiated by H aeIII digests alone. Single unique patterns were observed with HaeIII and/or BstEII for Mycobacterium fortuitum (100%), M. chelonae (94%), M . abscessus (96%), M. smegmatis (100%), M. mucogenicum (formerly the M . chelonae-like organism) (100%), and the sorbitol-negative third biov ariant of M. fortuitum (100%). Evidence is presented in support of two subgroups within M. peregrinum, M. smegmatis, and the unnamed third b iovariant of M. fortuitum (sorbitol positive and sorbitol negative). P CR based technology provides a rapid, accurate system for the identifi cation of clinically important species of RGM which should be particul arly useful for reference laboratories.