Ability of ciprofloxacin but not pipemidic acid to differentiate all three biovariants of Mycobacterium fortuitum from Mycobacterium chelonae.

When tested against 312 clinical isolates of rapidly growing mycobacteria, the quinolone pipemidic acid correctly separated Mycobacterium chelonae (M. chelonei) from Mycobacterium fortuitum biovar fortuitum but not from biovar peregrinum or the third biovar complex. The new 4-quinolone ciprofloxacin correctly separated all three biovars of M. fortuitum from M. chelonae and appears to provide a better taxonomic test.