Current practices in mycobacteriology: results of a survey of state public health laboratories

Abstract

Fifty-six state and territorial public health laboratories were surveyed to determine whether currently available rapid methods for the identification and drug susceptibility testing of Mycobacterium tuberculosis were being performed. Forty (71%) laboratories use fluorochrome rather than conventional basic fuchsin stains for screening clinical specimens for acid-fast bacilli. Of the 55 laboratories that routinely culture for mycobacteria, 16 (29%) use the more rapid radiometric methods. Species identification of isolates is done by biochemical tests in 13 (23%) laboratories; 40 (72%) use nucleic acid probes, high-performance liquid chromatography, or the BACTEC p-nitro-alpha-acetylamino-beta-hydroxypropiophenone (NAP) test (rapid tests); 3 laboratories do not perform species identification. Drug susceptibility testing is performed with solid media by 36 of 45 (80%) laboratories, while the more rapid radiometric methods are used by 9 (20%) laboratories. Compared with the laboratories that use conventional methods, laboratories that use rapid methods report results more quickly: for species identification, 43 days (conventional) versus 22 days (rapid); for drug susceptibility testing, 44 days (conventional) versus 31 days (rapid) from specimen processing. Rapid technologies for microscopy and species identification are being used by many, but not all, state and territorial public health laboratories; however, most laboratories do not use the more rapid radiometric methods for routine culture or drug susceptibility testing of mycobacteria. Implementation of such rapid technologies can shorten turnaround times for the laboratory diagnosis of tuberculosis and recognition of drug resistance.