Mycobacteria

Laboratory Diagnosis of Mycobacterium tuberculosis Infection

Laboratory Diagnosis of Mycobacterium tuberculosis Infection

Ziehl-Neelsen staining, culture in Lowenstein-Jensen medium and GeneXpert MTB/RIF assay are useful methods for the diagnosis of tuberculosis.

Löwenstein–Jensen (LJ) Medium: Preparation, Uses

Löwenstein–Jensen (LJ) Medium: Preparation, Uses

M. tuberculosis gives rough, raised, dry, non-pigmented (cream/buff colored) colonies on Lowenstein Jensen (LJ) medium.

GeneXpert MTB/RIF Assay

GeneXpert MTB/RIF Assay

GeneXpert MTB/RIF assay is a NAAT that simultaneously detects DNA of M.tuberculosis complex and resistance to rifampin (i.e. mutation of the rpoB gene).

Tuberculin Skin Test (Mantoux test): Principle, Procedure, Results

Tuberculin Skin Test (Mantoux test): Principle, Procedure, Results

Tuberculin skin test is the standard method of determining whether a person is infected with M.tuberculosis or has exposure to tubercle bacilli.

Tween 80 Hydrolysis Test: Principle, Procedure, Results

Tween 80 Hydrolysis Test: Principle, Procedure, Results

Mycobacterium species possess an enzyme-lipase, that splits Tween-80 and releases oleic acid and polyoxyethylated sorbitol.

Atypical Mycobacterial Infections

Atypical Mycobacterial Infections

Atypical mycobacteria include species such as M. avium, M. intracellularae, M. kansasii, M. xenopi, and M. fortuitum.

Ziehl-Neelsen Technique-AFB Staining

Ziehl-Neelsen Technique-AFB Staining

Ziehl-Neelsen acid fast stain is designed to stain bacterial cells containing long chain fatty (mycolid acids) such as Mycobacterium.

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Sodium Hypochlorite Centrifugation Technique to Concentrate AFB

Sodium hypochlorite centrifugation technique is used to concentrate the AFB present in the sputum, as it increases the chances of detecting AFB.

Biochemical Tests to identify Mycobacteria, NTM

Biochemical Tests to identify Mycobacteria, NTM

Tests are; Tween-80 hydrolysis test, niacin test, nitrate reduction test, tellurite reduction test, urea hydrolysis test and citrate utilization test.

Leprosy: Etiology, Pathogenesis, Lab Diagnosis

Leprosy: Etiology, Pathogenesis, Lab Diagnosis

Also known as Hansen’s disease, leprosy is a chronic infectious disease caused by an acid-fast bacillus, Mycobacterium leprae.