October 9, 2013
Tuberculosis Diagnosis with Tuberculin skin test (TST)
The IDR is essentially the basis for the diagnosis of latent tuberculosis infection.
The skin test is a test that involves injecting a liquid droplet containing mycobacterial antigen (tuberculin) in the dermis (anterior surface of the forearm). The inflammatory response obtained (read 72 hours) determines whether the subject was previously in contact with the bacillus or the vaccine, according to the diameter of induration observed, but it is not always an effective witness protection vis- à-vis the tubercle bacillus.
The IDR should be performed:
- to verify the absence of TB infection or TB disease before the first vaccination. However infants are vaccinated without testing. We must remember that a positive test, vaccination is not necessary to be performed.
- during the investigation about a case of tuberculosis. In this context, the IDR is an element among others (chest radiography, clinical examination, patient follow-up …) to determine if contamination has occurred. It should be recalled that an investigation is always necessary that the index case or not bacillary and whether it is an adult or a child.
- as ad hoc aid in the diagnosis of tuberculosis, for example in extra pulmonary tuberculosis, or whenever it may be an element of diagnostic orientation required the doctor.
- as a reference test under the supervision of members of the health professions or social exposed to tuberculosis (occupations listed in sections R and R 3112-1 3112-2 Code of Public Health). We must remember that in the case of professional presentations, removing revaccination makes it even more interesting this IDR hiring, which provide a baseline for future monitoring aims.
Chest radiography to diagnose pulmonary forms (and contagious) disease.
The chest x-ray is the basis for the diagnosis of tuberculosis disease and allows early diagnosis when screening for tuberculosis.
Bacteriological allow definitive diagnosis because they highlight the tuberculosis bacillus. Respiratory tests were performed on sputum or samples such as gastric aspirate or when bronchoscopy.
Other deductions are possible depending on the location of TB disease (lumbar puncture, bone samples …)