Mycobacterial Diseases
Open Access

Clinical Methods of Mycobacteriology in Detecting TB

Macroni Laco^{* *}Correspondence: Macroni Laco, Department of Surgery, University of California, Irvine, USA, Email:

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Description

Mycobacteriology is the study of the Mycobacterium, which includes several species known to cause human diseases. These diseases include tuberculosis, leprosy, and other atypical infections. Clinical mycobacteriology involves the identification and diagnosis of these diseases in patients, as well as the study of the molecular biology and epidemiology of the causative agents. It is caused by the Mycobacterium tuberculosis, which is spread through the air when an infected person coughs or sneezes. Tuberculosis is a major global health problem, with an estimated 10 million people developing the disease each year, and 1.4 million dying from it.

The diagnosis of tuberculosis requires the detection of the bacterium in clinical specimens, such as sputum, blood, or urine. Microscopy and culture are the traditional methods used to diagnose tuberculosis, with culture being the gold standard. In recent years, molecular methods such as Polymerase Chain Reaction (PCR) and Nucleic Acid Amplification Tests (NAATs) have been developed to provide rapid and sensitive diagnosis. Culture remains the cornerstone of mycobacteriology, allowing the isolation and identification of the organism, as well as providing the necessary material for susceptibility testing. The culture of mycobacteria is challenging, requiring special media and a long incubation period of up to eight weeks. Identification of mycobacteria is based on a combination of phenotypic and genotypic methods. Phenotypic methods include microscopy, culture characteristics, and biochemical tests, while genotypic methods involve the detection of specific genetic markers using PCR or DNA sequencing. The most commonly used phenotypic tests for mycobacterial identification include the niacin test, the nitrate reduction test, and the catalase test. However, these tests can be time-consuming and may not provide definitive identification. Molecular methods, such as PCR and DNA sequencing, have revolutionized mycobacteriology in recent years. These methods allow for rapid and sensitive detection of mycobacteria, as well as the identification of species and strains. PCR is a powerful tool for the diagnosis of tuberculosis, with several commercial PCR assays available for use in clinical laboratories. These assays target specific genetic markers, such as the IS6110 insertion sequence of Mycobacterial tuberculosis DNA in a clinical sample.

DNA sequencing is another important tool for mycobacterial identification, allowing for the detection of genetic mutations associated with drug resistance. The sequencing of the 16S rRNA gene is commonly used for species identification, while the sequencing of the rpoB, katG, and inhA genes can provide information on drug resistance in Mycobacterial tuberculosis. Drug susceptibility testing is critical for the management of tuberculosis, as drug-resistant strains of the bacterium are a growing problem. Traditional drug susceptibility testing involves the use of agar-based methods, such as the proportion method and the BACTEC MGIT system. These methods require the growth of the bacterium in culture, which can take several weeks, and can be subject to technical variability. Molecular methods, such as PCR-based assays and DNA sequencing, have been developed to provide rapid and accurate drug susceptibility testing for Mycobacterial tuberculosis. These methods can detect specific genetic markers associated with drug resistance, such as mutations in the rpoB gene that confer resistance to rifampicin. They can also be used to detect mutations associated with resistance to other drugs.