Prevalence of TB in India continues to be alarming.

Many cases in India are neglected due to poor diagnosis and evaluation making them critical points to be resolved. Good TB control is critical to prevent the emergence of drug resistance in the first place, and proper treatment of MDR-TB prevents the emergence of XDR-TB.

Current situation in India

In their recent (March 2017) clinical research (India's fight against tuberculosis: How can chest physicians help?) published in Lung India, Madhukar Pai and Parvaiz Koul have reported as follows: 

“At the level of general practitioners (GPs), there is evidence that patients with classic TB symptoms rarely get investigated for TB. Instead, GPs give broad-spectrum antibiotics (e.g., fluoroquinolones) and nonspecific drugs such as cough syrups and steroids. Even when TB is considered likely, GPs tend to order tests such as complete blood count, erythrocyte sedimentation rate, Mantoux test, and chest X-rays. They rarely seek microbiological confirmation through sputum smear microscopy, culture, or polymerase chain reaction tests. All these result in diagnostic delays, and patients often bounce from one doctor to another before TB is eventually picked up.”

Infectious Diseases Society of America (IDSA) Recommendations

Infectious Diseases Society of America (IDSA) along with American Thoracic Society, Centers for Disease Control and Prevention (CDC) have recommended certain guidelines for the diagnosis of tuberculosis in adults and children using an efficient Grading, Recommendations, Assessment, Development and Evaluation - GRADE approach.

Tuberculosis, displaying all the signs and symptoms of the disease, may be present as

1. Latent tuberculosis infection (LTBI) or
2. Acive infection
    

Guidelines for latent tuberculosis infection

• Interferon-γ release assay (IGRA) is recommended over tuberculin skin test (TST) for individuals who are 5 years or older with the criteria of disease condition as: likely to get affected, risk of progression, diagnosed with latent tuberculosis infection or did not return for the TST test.
• If one of the two tests –IGRA or TST is positive, then the second diagnostic test has to be performed as a confirmatory test.
• Healthy children below 5 years of age are recommended TST rather than IGRA when it is decided that diagnostic testing for LTBI is warranted.
• Both TST and IGRA can diagnose Mycobacterium tuberculosis infection but cannot distinguish between active and latent infection. Hence, active TB has to be confirmed first by looking for symptoms and by performing a chest radiograph. If nothing is observed in the chest radiograph then treatment for LTBI should be started.

Guidelines for active TB

• An acid-fast bacilli (AFB) smear microscopy should be performed at least thrice to avoid the possibilities of false results which are very common due to poor sample quality. Use of fluorescence microscopy and concentrated respiratory specimen should be preferred.
• Instead of using only one culture method, both liquid and solid mycobacterial cultures should be performed for individuals suspected with TB. If not feasible, at least a liquid culture should be performed as it is the gold standard microbiologic test for the diagnosis of TB.
• Patient suspected with pulmonary TB should be recommended for a nucleic acid amplification test (NAAT) on the respiratory sample obtained from the patient.
   

• Respiratory specimens of AFB positive or NAAT positive patients who have been treated in the past for TB, born or lived in a country with a moderate TB incidence for an year or if HIV infected, should be checked with rapid molecular drug susceptibility for rifampin with or without isoniazid.
• For adults with suspected pulmonary TB who are unable to expectorate sputum or who have a negative AFB smear, sputum induction should be done rather than flexible bronchoscopic sampling.
• Fluid collected from patients with suspected pleural TB, TB meningitis, peritoneal TB, or pericardial TB should be checked for levels of
  • Adenosine deaminase 
  • Free IFN-γ levels

• ABF smear microscopy, NAAT test and mycobacterial cultures have to be performed for specimen isolated from suspected extra-pulmonary sites.

These guidelines will help the healthcare professionals to make rational decisions while evaluating the possibility of an active or latent TB infection in patients.