Serodiagnosis of intestinal tuberculosis by enzyme immunoassay and soluble antigen fluorescent antibody tests using a saline extracted antigen

Abdominal tuberculosis

Tuberculosis has staged a global comeback and forms a dangerous combination with AIDS. The abdomen is one of the common sites of extrapulmonary involvement. Patients with abdominal tuberculosis have a wide range and spectrum of symptoms and signs; the disease is therefore a great mimic. Diagnosis, mainly radiological and supported by endoscopy, is difficult to make and laparotomy is required in a large number of patient. Management involves judicious combination of antitubercular therapy and surgery which may be required to treat complications such as intestinal obstruction and perforation. The disease, though potentially curable, carries a significant morbidity and mortality.

Potential value of serology for diagnosis of extrapulmonary tuberculosis

The possible benefits for improved diagnosis of extrapulmonary tuberculosis were evaluated by means of a modified serological competition assay. Antibodies to the 38 kD Mycobacterium tuberculosis antigen were detected in 73% of cases of extrapulmonary tuberculosis and 70% of smear-negative cases of pulmonary tuberculosis at a chosen specificity of 98%. Of 55 patients (45%) whose diagnosis of tuberculosis was not made until 7 days or longer after admission, 76% were positive for the antibody. In this group the serological test would have allowed chemotherapy to be started on average 12.5 days earlier and would have obviated the need for 80% of diagnostic biopsies.

ELISA--its evaluation in diagnosis of tuberculosis meningitis

Diagnostic utility of an enzyme linked immunosorbent assay (ELISA) in hospitalised patients with clinical symptoms suggestive of tuberculous meningitis (94 cases) was studied. CSF Anti-tubercular IgG antibody levels were estimated by ELISA in 44 cases of proven tuberculous meningitis, 24 proven pyogenic meningitis and in 48 non-tuberculous cases. The cut off dilution was established at a CSF dilution of 1 : 1 (undiluted) with positive and negative controls. The ELISA test had a sensitivity of 97.72% and a specificity of 95.35% using MSE antigen. When compared with conventional smear examination and culture isolation from specimens, the ELISA test proved statistically superior in the detection rate or diagnosis of clinically suspected tuberculous meningitis cases (P less than 0.05).