Afb Detection Rrna Reflex Rapid Culture Sputum

Mycobacterium tuberculosis (MTB) is a pathogenic bacterial species in the genus Mycobacterium and the causative agent of most cases of tuberculosis (TB). M. tuberculosis has an unusual, waxy coating on its cell surface (primarily mycolic acid), which makes the cells impervious to Gram staining, so acid-fast detection techniques are used, instead. The physiology of M. tuberculosis is highly aerobic and requires high levels of oxygen. Primarily a pathogen of the mammalian respiratory system, MTB infects the lungs. The most frequently used diagnostic methods for TB are the tuberculin skin test, acid-fast stain, and chest radiographs. The Mycobacterium tuberculosis complex (MTBC) is a taxonomic group of Mycobacterium that includes M. tuberculosis, M. bovis, M Bovis BCG, M. africanum, M caprae, M. microti, M canettii, M pinnipedii, M mungi, and M orygis. Their nucleotide sequences only differ from each other by .01 to .03% and though they are so genetically similar they differ widely in epidemiology. To differentiate the species of mycobacterium polymerase chain reaction (PCR) is used to analyze the presence or absence of the regions of difference (RD) of the genomes. There are 16 regions of difference that have been identified and can be analyzed to determine the species of the mycobacterium. In one study, initial screenings of isolates only required analysis of RD1, RD9 and RD10. If the results of the RD1, RD9 and RD10 were all negative, then RD3, RD5 and RD11 were tested and able to identify the remaining species.