Mycobacterium leprae PCR

Diagnostic Use

Leprosy (also known Hansen's disease) is a chronic infectious disease which is caused by Mycobacterium leprae and is an important global health concern. The disease affects the skin, the peripheral nerves, mucosa of the upper respiratory tract, and the eyes. Leprosy is curable and treatment in the early stages can minimize the likelihood of disability involving the eyes, hands, and feet due to neuropathy as these are often not reversible and may require lifelong care. Apart from the physical deformity, persons affected by leprosy also face stigmatization and discrimination.

The disease is transmitted through droplets from the nose and mouth. Prolonged, close contact over months with someone with untreated leprosy is needed to catch the disease. The disease is not spread through casual contact with a person who has leprosy like shaking hands or hugging, sharing meals, or sitting next to each other. Moreover, the patient stops transmitting the disease when they begin treatment.

The disease manifests commonly through skin lesion and peripheral nerve involvement. Leprosy is diagnosed by finding at least one of the following cardinal signs: (1) definite loss of sensation in a pale (hypopigmented) or reddish skin patch; (2) thickened or enlarged peripheral nerve, with loss of sensation and/or weakness of the muscles supplied by that nerve; (3) microscopic detection of bacilli in a slit-skin smear.

M. leprae is difficult to culture; PCR provides a faster and more reliable detection method.

Sources: Up-to-Date Leprosy: Epidemiology, microbiology, clinical manifestations, and diagnosis
WHO Leprosy fact sheet https://www.who.int/news-room/fact-sheets/detail/leprosy

Department

Microbiology - Virology

Delphic Registration Code

MLEP

Laboratory Handling

Laboratory

Testing is batched daily on routine weekdays at approximately 9.30am, with results available from mid-afternoon.

Test Adds

Add-ons can be made if an appropriate sample has already been received for other bacteriology or PCR testing. Please call Virology to discuss.

Synonyms

Hansen's disease
Leprosy
M. leprae PCR

Turnaround Time

3 days

Test Code

5087

Specimen Type

• Tissue
• Biopsy

Specimen Requirements

Tube/Container Type:

Preferred

• Pottle

Additional Specimen Information

Sample types: Tissue, Biopsy, Fluid from slit skin

After processing, samples are stored frozen for 4 weeks before discard. Add-on requests can be made for other appropriate tests during this time frame by contacting Virology.

Aliquot Instructions

Transport to Lab

Chilled (2 - 8 degrees Celsius)

Interpretation

Early diagnosis: PCR can aid in the early diagnosis of leprosy, especially in cases where clinical symptoms are ambiguous or where conventional methods like microscopy may yield negative results.

Monitoring treatment: PCR can be used to monitor the effectiveness of treatment by detecting changes in bacterial load over time. A decrease in PCR positivity correlates with successful treatment response.

Assessment of transmission risk: PCR can be used in epidemiological studies to assess the risk of transmission by detecting M. leprae in asymptomatic carriers or in environmental samples.

Differentiation of leprosy types: PCR can help differentiate between leprosy types (paucibacillary and multibacillary), which is crucial for appropriate treatment planning.

Test Method

Nucleic acid extraction, PCR amplification and detection.
Resistance testing by DNA sequencing analysis.

Non-Funded Test Cost

$116.60 (Exclusive of GST)

Billing Code

5110

Additional Costing Information

If resistance testing is performed there will be an additional charge.

Resistance testing can be performed on positive samples after discussion with and approval by a Microbiologist.

M. leprae cannot be cultured using routine (artificial) microbiological media therefore molecular techniques such as PCR and DNA sequencing are required to find point mutations conferring resistance.
Rifampicin resistance: Resistance in M. leprae is primarily associated with mutations in the rpoB gene, which encodes the beta subunit of RNA polymerase. Rifampicin resistance in leprosy is monitored by detecting mutations in this gene.
Dapsone resistance: Resistance to dapsone in M. leprae is typically associated with mutations in the folP1 gene (dihydropteroate synthase gene). Monitoring dapsone resistance involves detecting mutations in this gene.
Fluoroquinolone resistance: Fluoroquinolone resistance in M. leprae is associated with mutations in the gyrA gene (DNA gyrase subunit A). Molecular techniques can detect mutations in gyrA to assess resistance to fluoroquinolones.

Contact Information

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