MANTOUX TEST

PRAKASH DHAKAL

Public Health Microbiology

Tribhuvan University

OUTLINE OF PRESENTATION

IntroductionPrincipleRequirementsProcedurePrecautions

INTRODUCTION Tuberculosis is important communicable disease and

is a problem in developing countries as well as developed countries.

It can develop in different parts of the body.

The main reservoir is the human population from which it is mainly transferred by respiratory route.

If any part of the body is infected by Mycobacterium tuberculosis, it sensitizes T cell which can be detected by Mantoux test i.e. delayed type hypersensitive reaction of tuberculin type( reaction seen after 12-48 hrs).

PRINCIPLE

In this test, a small amount of mycobacterial antigen in the form of tuberculin or a purified protein derivative (PPD) is injected intradermally, it reacts with sensitized T cells and produce hypersensitivity reaction.

It results in local hardening at the site of injection which is called indurations and swelling.

Redness appearing around the injected part is called erythema.

The diameter of induration is directly proportional to the degree of sensitization.

PPD can be injected in different doses i.e. 1-5 Tuberculin unit (TU).

After injecting 0.1 ml of TU PPD intradermally, the characteristic skin reaction develops fully after 48- 72 hrs. The result is interpreted as follows:

Area of induration 10 mm and more Reactive case

Area of induration 5-9 mm Intermediate

Area of induration less than 5 mm Non reactive

The test is though useful in diagnosis of tuberculosis, it is not sufficient for interpreting the exact result. The test should be correlated with clinical signs and symptoms, clinical history and lab diagnosis .

Conditions like Mumps, Polio, Measles and malnutrition of corticosteroids may give false positive result.

REURIEMENTS

Tuberculin PPD ( 5TU) 70 % ethanol 26 Gauze syringe or tuberculin syringe Sterile cotton

PROCEDURE Select preferred site of injection , left hand forearm

dorsal surface, about 4 inches below the elbow joint without vein using disinfectant 70 % ethanol around 5 cm area.

With the help of 26 G needle , draw 0.1 ml of 5 TU PPD without trapping any air bubbles.

Penetrate superficial layer of skin with an angle of 30° with needle bevel pointing upwards and then inject parallel to skin.

Pull the skin slowly with next hand and release the solution, take out the syringe and mark the area.

Read the result after 72 hrs. Measure the diameter of indurations and erythema using a ruler along the axis of forearm in mm.

PRECAUTIONS

PPD solution should not enter the subcutaneous level.

Exposure to soap, water,scratching,rubbing or touching the site of injection should be aovided.

The vial should not be vigorously shaken before use to avoid the formation of air bubbles.

THANK YOU