Smear-Negative Pulmonary Tuberculosis

Abstract

Tuberculosis (TB) is the second leading cause of death from an infectious disease worldwide, after the human immunodeficiency virus. There are almost 2.5 million new smear-positive pulmonary TB cases and 1.9 million new smear-negative pulmonary TB cases in the world in 2012 according to the World Health Organization (WHO) Global Tuberculosis Report 2013. Smear negativity in pulmonary TB is a common clinical problem. Clinicians have difficulty in diagnosing smear-negative pulmonary TB without bacteriological confirmation. It is very important to decide whether or not to treat a patient with smear negative pulmonary TB when the culture results are pending or negative. New diagnostic methods are required for the diagnosis of smear-negative pulmonary TB. In addition to the development of new microbiological and serological diagnostic tests, clinical prediction scoring systems and algorithms including clinical and radiological findings of smear-negative pulmonary TB patients in our country, should be established to facilitate the diagnosis of smear-negative pulmonary TB.

High Positivity Rate of Urinary Mycobacterium tuberculosis Antigens Cocktail (ESAT-6, CFP-10, and MPT-64) in Active Tuberculosis Patients With and Without Human Immunodeficiency Virus Infection: A Cross-Sectional Study

“…Although the microscopic investigation is the fastest diagnostic method, the performance of sensitivity is relatively low. 20 In our study, only 40% of the TB-HIV group had positive smear results, meanwhile, the urinary Mtb antigen cocktail test result in this group was 93.3%. Our previous study mentioned the added value of urinary Mtb antigen cocktail, we found the sensitivity of AFB staining was 45.4% to 90% when combined with urinary Mtb antigen cocktail assay.…”

Comparison of the Performance of Urinary Mycobacterium tuberculosis Antigens Cocktail (ESAT6, CFP10, and MPT64) with Culture and Microscopy in Pulmonary Tuberculosis Patients

“…Although the microscopic investigation is the fastest diagnostic method, the performance of sensitivity is relatively low. For a positive result, samples must contain more than 10.000 bacilli per milliliter [ 5 ]. This is shown in our study for the performance of AFB stain against mycobacterial culture, as high as 45.4% for sensitivity and 67% for specificity.…”

“…First, mycobacterial culture is still the reference standard method for pulmonary tuberculosis diagnosis. The culture needs the presence of 10–100 bacilli in a milliliter of the sample to obtain the culture sensitivity of 81.5% and the specificity of 98.4% [ 5 ]. This shows that culture positivity depends on the number of bacilli in a milliliter of sample.…”

“…A microscopic investigation using acid-fast bacilli (AFB) stain is the primary laboratory tool for Mycobacterium species, which is inexpensive, fast, and specific [ 4 ]. Difficulties of Mycobacterium species detection are as follows: (1) the sensitivity of the sputum microscopy is 20–60%; this test has high specificity but some mycobacteria other than M. tuberculosis may also stain acid [ 5 ]; (2) the result of culture technique requires 2-3 weeks, and positivity of the culture depends on number of viable bacteria. Therefore, it may cause delay to provide a definitive diagnosis for tuberculosis [ 6 ].…”