A national diagnostic service identified M. tuberculosis and rifampin resistance in primary clinical specimens faster than conventional techniques.

A blinded comparison of peptide nucleic acid-fluorescence in situ hybridization (PNA-FISH) with routine identification methods was performed on 74 consecutively positive mycobacterial liquid cultures. All Mycobacterium tuberculosis cultures (48 of 48) and 22 of 27 (81.5%) nontuberculous cultures were correctly identified (including one mixed culture). Five isolates yielded no reaction with either probe and were identified as Mycobacterium xenopi , Mycobacterium fortuitum , or Mycobacterium flavescens .