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Microscopic examination of sputum smears (search for acid-fast bacilli or AFB) is the most rapid procedure for diagnosis of contagious tuberculosis. Gene amplification is not yet reliable for direct detection of M. tuberculosis in clinical specimens that are AFB smear-negative. Culture (3 to 8 weeks on Lowenstein-Jensen medium or 1 to 4 weeks in liquid media) remains essential to identify AFB and conduct antibiotic susceptibility testing. AFB from culture can be identified in a few hours by molecular approaches with specific DNA probes. Results of susceptibility testing, even in liquid media, are not available until 2 to 4 weeks after the recovery of specimens, although mutations of the rpoB and katG 315 genes, which confer resistance to rifampin and isoniazid, can be detected within hours by molecular hybridization with specific probes fixed on strips. Immunologic tests that measure the interferon gamma produced by sensitized lymphocytes are promising tools for the diagnosis of latent tuberculosis.

Tuberculosis may affect several organs and its prevalence is continuously increasing. Laboratory diagnosis still remains difficult. Adenosine deaminase (Ada) is an enzyme which contributes to purine metabolism and its presence in lymphocyte, monocyte and macrophage cells is associated with T cells mediated immunity. Many studies have shown the usefulness of Ada determination in various biological fluids for the diagnosis of tuberculosis. In pleural fluid, cutoff vary from 33 to 48 U/L, with sensitivity higher than 80% and specificity near 100%. In peritoneal fluid the cutoff value is 30 U/L. In cerebrospinal fluid, the value of 7 U/L can make discriminate negative and positive cases with a good sensitivity and specificity. The data from the literature show that 50 U/L in pericardic fluid is a reliable threshold for tuberculosis diagnosis. Ada determination in serum is not as relevant as in others fluids because of its low specificity. Ada measurement in biological fluids, easy and not expensive, may be add to other biological tests for tuberculosis diagnosis.

Background: Extrapulmonary manifestations of tuberculosis are increasing in incidence. Abdominal tuberculosis may mimic a variety of gastrointestinal disorders. The diagnosis of abdominal tuberculosis is still difficult to establish before surgery., Case Reports: We report 3 cases of abdominal tuberculosis in immunocompetent individuals. One patient presented with an ileocecal mass mimicking cancer. The second one presented with fever, ileocecal mass and ascites leading to the diagnosis of appendiceal peritonitis. The last patient was admitted for ascites, ovarian mass and high CA 125 serum level simulating ovarian cancer with peritoneal carcinomatosis., Comments: In cases of abdominal tuberculosis when standard investigations are unhelpful, a PCR should be performed. Estimation of adenosine deaminase in ascitic fluid is an easy and reliable method for diagnosing tuberculous ascites. With these non invasive diagnostic procedures, surgery should be reserved only to patients with complications.

Adenosine desaminase activity was measured in the pericardiac fluid of 35 patients with pericarditis of undetermined origin who were operated upon for diagnostic or therapeutic purposes. The causes of pericarditis fell into 6 categories: I, tuberculosis (8 cases); II, idiopathy (17 cases); III, neoplasia (6 cases); IV, purulent bacterial infection (2 cases); V, constriction (2 cases) and VI, radiotherapy (1 case). The highest mean adenosine desaminase value (143 U/l) was found in group I. Other values were 34 in group II, 48 in group III and 45 in groups IV to VI. There was a statistically significant difference in this respect between group I and the other groups (P less than 0.0001). If 60 U/l is taken as discriminant value for the diagnosis of tuberculous pericarditis, then the adenosine desaminase value has a 100 percent sensitivity and an 80 percent specificity. Measuring this value therefore is a very promising procedure.

The activity of adenosine deaminase has been measured in 295 specimens of pleural fluid from 248 patients. The effusions were due in part to pleural tubercle (n = 8), rheumatoid arthritis (n = 2) empyema (n = 4), or malignant lymphoma (n = 5); the remainder were due to effusions of other aetiologies (n = 229). The disorders of the first group of patients are known to be associated with an elevated level of ADA. The two groups of patients were compared by fixing the upper limit of normal at 50 U/l. There was a 97% specificity even though the sensitivity was only 42%. However the relative smallness of the group of patients who were suffering from tuberculosis, rheumatoid arthritis, empyema and malignant lymphoma means that the interpretation of the sensitivity of the test should be subject to caution.