Although an acid fast smear (AF smear) can provide an important clue to the nature of the causative agent for a patient's disease, a positive result does not necessarily indicate the presence of M. tuberculosis complex (MTBC).
The presence of acid fast bacilli (AFBs) in clinical specimens can be simply due to the growth of common water contaminants such as M. chelonae and M. fortuitum.
For an accurate detection of the presence of MTBC in clinical specimens, the UWMC Molecular Diagnosis Section utilizes a nested PCR protocol that targets heat shock protein 65 gene (hsp65). Utilization of species-specific fluorescent probes on a real-time PCR platform facilitates rapid and highly sensitive detection of M. tuberculosis complex-specific DNA in clinical specimens.
