THE ROLE OF THE MICROBIOLOGY LABORATORY IN DIAGNOSING MYCOBACTERIAL DISEASES

Recent surveys show that many mycobacteriology laboratories continue t o use less-than-optimal culture and susceptibility methods. This revie w summarizes available methods to diagnose Mycobacterium tuberculosis. Although the local epidemiologic characteristics of M tuberculosis wi ll partially determine what diagnostic measures are used, all laborato ries should use a broth culture method in addition to a solid medium w hen culturing for M tuberculosis. Laboratories serving communities whe re drug resistance is common should use the BACTEC system for suscepti bility testing or send isolates to a laboratory that uses it. Conventi onal testing in this setting must be aggressively discouraged. Rapid g enetic amplification methods to detect mycobacteria in clinical specim ens can greatly reduce the time needed to diagnose tuberculosis, espec ially if these methods can reliably detect M tuberculosis in smear-neg ative specimens. Many other diagnostic methods are being developed and clinicians and laboratories must regularly reassess whether a new met hod would be beneficial to their patients and the public.