Fast plaque assay technique for detection of mycobacterium tuberculosis in sputum samples of newly diagnosed cases of pulmonary tuberculosis

Tuberculosis [TB] is a serious public health problem that especially prevalent in developing countries. An essential element in the control of TB is the rapid, sensitive and specific identification of the causative agent. Mycobacteriophages constitute a potentially useful approach for detecting viable Mycobacterium tuberculosis bacilli as well as for susceptibility studies. The aim of this study is to evaluate the diagnostic value of the Phage Tek MB kit for pulmonary tuberculosis in comparison with standard Lowenstein-Jensen [LJ] media and staining techniques for respiratory specimens. Sputum specimens submitted for diagnosis of mycobacterial disease at Ain Shams University hospital from August to November 2004 were included in the study. Specimens were studied using both of the conventional methods [direct microscopic examination and culture in LJ medium] and the Phage Tek MB assay. The sensitivity, specificity, positive and negative predictive value for the FAST Plaque TB assay relative to that of culture were 65.52, 100, 100 and 52.38%, respectively. The sensitivity was much higher in smear positive samples in comparison to smear negative ones [73.91% and 33.33%, respectively]. FAST Plaque TB proved to be specific, and rapid. It is able to detect M. tuberculosis in clinical samples within 1 day with 100% specificity, long before culture results]. Also it is cheap technology in comparison to PCR and would be suitable for use by routine microbiology laboratories, especially in developing countries

Neopterin in pulmonary tuberculosis and lung cancer patients

Neopterin is produced and released by human macrophages in response to stimulation with interferon-gamma, and changes in neopterin concentrations indicate cellular immune activation. To assess the usefulness of serum, urine and pleural fluid neopterin levels as an index of disease activity in patients with pulmonary tuberculosis and lung cancer. Serum, urine and pleural fluid neopterin levels were evaluated in 30 patients with pulmonary tuberculosis and 30 patients with lung cancer while serum and urine neopterin levels were evaluated in 20 healthy controls by enzyme linked imunosorbent assay [ELISA] technique. The neopterin levels [mean +/- SD] in the serum and urine of 30 tuberculous patients [54 +/- 13.9 n mol/L, 675 +/- 230.7 n mol/mol criatinine respectively] were significantly higher when compared with those in lung cancer patients [29 +/- 5 n moUL, 312 +/- 74.5 n mol/ mol criatnine respectively, P < 0.001] and when compared with those in control subjects [6 +/- 2 n mol/L, 128 +/- 39.8 u mol/mol criatinine respectively]. In tuberculosis patients with faradvanced disease pleural fluid, serum and urine neopterin levels were significantly higher when compared with those in patients with moderately and minimally advanced disease [p < 0.001]. In lung cancer group serum and urine neopterin levels were significantly higher [p < 0.001] in adenocarcinoma, squanous cell carcinoma, and small cell carcinoma than that in the control group. But there was no significant difference between the serum, urine and pleural fluid neopterin from one cell type to another. Serum urine and pleural fluid neopterin levels may reflect the degree of activity in pulmonary tuberculosis before exact diagnosis of the disease by culture results. In addition serum, urine and pleural fluid neopterin levels are elevated in patients with lung cancer whatever the cell type

Serum level of transforming growth factor-beta in patients with pulmonary tuberculosis

Pulmonary tuberculosis [TB] is a major cause of morbidity and mortality allover the world. Owing to the complex interaction between the Mycobacterium tuberculosis [MTB] and the specific host cell mediated immune response, the clinical spectrum of TB ranges from a few foci affecting the upper parts of the lungs to intense tissue destruction and caseous necrosis. TGF-beta is one of the inhibitory cytokines that, among other functions, is responsible for deactivation of the T-cell response that is important in host defense against MTB, suggesting its role in the pathogenesis of PTB.The aim of this study was to determine the serum level of TGF-beta1 in patients with active pulmonary tuberculosis [cavitary and non cavitary], in comparison to healthy controls and to chronic obstructive airway disease [COAD] patients as disease controls, as well as investigating the correlation between its level and disease severity. Tuberculous patients were followed up during the course of anti-tuberculous chemotherapy to assess the changes in TGF-beta1 level. Three groups were studied, including 24 pulmonary tuberculosis patients [9 patients were cavitary and 15 patients were non cavitary] that were selected according to the diagnostic standards and classification of tuberculosis. [New York NY: National Tuberculosis and Respiratory disease Association, 1969]. Twenty two patients with [COAD] were taken as a disease control group and 13 apparently healthy individuals with matching age and sex were included as normal controls. All patients were subjected to full history taking, clinical examination, laboratory diagnosis of TB by examination of sputum for the presence of acid fast bacilli [AFB] by film or culture and radiological diagnosis by chest X-rays. Serum from all patients and controls was examined for the level of TGF-beta1 using ELISA technique. Patients with PTB were followed up for the post treatment level of TGF-beta1 3 months after the onset of anti-tuberculous treatment. Statistical analysis for the results showed significant elevation of TGF-beta1 serum level in patients with PTB when compared to normal controls but not when compared to the disease controls. No significant difference was found between TGF-beta1 level on comparing the cavitary and non cavitary groups, or on comparing the pre and the post treatment levels. In conclusion TGF-beta1 is suggested to play an important role in the pathogenesis of pulmonary tuberculosis. Further studies can be done to evaluate the correlation between the TGF-beta1 level and the severity of tuberculous disease, or with the course of anti tuberculous treatment. Controlling TGF-beta1 production may be the key to prevent scarring and fibrosis in progressive pulmonary disease as tuberculosis and chronic obstructive pulmonary disease. Also using anti-TGF-beta1 antibodies may be promising anti-tuberculous agents with their anti-fibrotic actions that may prevent the progress of fibrosis during the course of the disease

Directigen Flu A + B test versus viral culture and reverse transcription-PCR for diagnosis of influenza virus type A and type B

In our study, 60 sputum specimens were collected from patients suffering from upper and lower respiratory tract manifestations with a mean age of 44.5 years. Out of the 60 patients, 49 patients had developed pneumonia as a complication. In addition to 20 specimens were collected from apparently healthy subjects matching in age with the patient group. All specimens were subjected to Directigen Flu A+B assay, viral culture on Madin Darby canine kidney cell and reverse transcription-PCR [RT-PCR] for demonstration of influenza type A and B. Directigen Flu test had a detection rate of 18.3% for influenza type A and 26.6% for influenza B. Viral culture had a detection rate of 20% and 26.6% for influenza type A and influenza type B respectively. While RT-PCR had a detection rate of 16.6% and 25% for influenza virus type A and B respectively. The sensitivity, specificity and positive and negative predictive value was[66%, 0%, 72.7%, 0% for influenza A virus and 75%, 0%, 75%, 0% for influenza type B by Directigen Flu A + B test. While the resolved sensitivity, specificity and positive and negative predictive value of RT-PCR was 100%, 83.3%, 100%, 60% for influenza A virus and 100%, 93.7%, 100%, 80% for influenza type B. Directigen Flu test is rapid, easy, reliable test that can be used for diagnosis and discrimination between influenza type A and type B infections. But it lacks specificity in some patients, thus, it requires confirmation by tissue culture and RT-PCR to rule out false-positive results