Differentiation of Mycobacterium tuberculosis Complex and Nontuberculous Mycobacterial Liquid Cultures by Using Peptide Nucleic Acid-Fluorescence In Situ Hybridization Probes

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.