Diagnosis of pulmonary tuberculosis by the amplicor test for Mycobacterium tuberculosis in induced sputum

The polymerase chain reaction (PCR) technique was compared with the conventional smear and culture method for the detection and identification of Mycobacterium tuberculosis in 25 induced sputa samples. Sputum induction was performed with an ultrasonic nebulizer using 3% hypertonic saline in 27 previously untreated patients suspected of active pulmonary tuberculosis clue to chest X-ray findings, but who were unable to spontaneously expectorate sputum. All patients received anti-tuberculosis drugs for at least 6 months after sputum induction. Two patients could not expectorate sputum after hypertonic saline inhalation. Microscopy failed to detect positive acid-fast bacilli in 25 induced sputa samples. Induced sputa were both PCR- and culture-positive for 10 patients, PCR-positive and culture-negative for 4 patients, and PCR-negative and culture-positive for 2 patients. These results suggest that the PCR method is useful in diagnosing tuberculosis in induced sputum, and that the results of PCR and culture Procedures can complement each other.     

Slide agglutination test for the diagnosis of pulmonary and extra-pulmonary tuberculosis

Nasal polyposis can be defined as a chronic inflammatory disease of the paranasal sinus mucosa, leading to a protrusion of benign edematous polyps from the meatus into the nasal cavities. Nasal polyps are histologically characterized by massive edema and accumulation of eosinophils. IgE-mediated allergy seems to play only a minor role in eosinophil accumulation, leaving the place for a new concept of non-allergic rhinitis with eosinophilia. The central question still remains, however, why eosinophils accumulate into nasal polyposis tissue. Some initial data show that tissue structural cells, i.e. epithelial cells or fibroblasts, could produce cytokines (GM-CSF) and play a role in eosinophil accumulation (micro-environmental theory). However, further studies showed, that GM-CSF was mainly produced by eosinophils themselves (autocrine theory), leading to the hypothesis of an intrinsic eosinophilic inflammatory process. Eosinophils may contribute to nasal polyp formation and growth not only through inflammation but also by exerting their effects on extracellular matrix including stimulation of collagen synthesis. Another feature associated with nasal polyposis is aspirin sensitivity. Some preliminary data indicate that eosinophils could also be involved in aspirin-sensitivity mechanisms.     

Clinical application of the Mycobacterium tuberculosis direct test: case report, literature review, and proposed clinical algorithm

PURPOSE: A prospective, multiinstitutional trial was initiated in 1991 to examine the tolerance to and efficacy of a program of preoperative chemoradiotherapy (CTRT) and surgical resection for patients with localized adenocarcinoma of the pancreas. PATIENTS AND METHODS: Fifty-three patients were assessable for analysis, with a median follow-up of 52 months for survivors. Radiation therapy (RT) totaling 5,040 cGy in 180 cGy fractions with mitomycin 10 mg/m2 day 2 and fluorouracil (5-FU) 1,000 mg/m2/d continuous infusion days 2 through 5 and 29 through 32 were given as preoperative adjuvant therapy. Twelve patients did not proceed to surgery (one death, one toxicity, three local progression, six distant metastases, one intercurrent illness), whereas 41 patients underwent surgery. Of these, 17 patients did not have resection (11, hepatic and/or peritoneal metastases and six local extension that precluded resection). Twenty-four patients had tumor resection (19 Whipple, four total pancreatectomy, one distal pancreatectomy). RESULTS: Treatment toxicity was primarily hematologic, although a comparable number suffered biliary tract complications, either from obstruction or cholangitis as a result of an occluded stent or the primary tumor. There was one postoperative death. Median survival for the entire group and for the 24 patients with resection was 9.7 and 15.7 months. This survival rate reflected the advanced state of most resected cancers (positive peritoneal cytology, three patients; margins within 2 mm, 13 patients; involved lymph nodes, four patients; and need for superior mesenteric vein (SMV) resection, four patients). Tumor progression was most frequent at metastatic sites. CONCLUSION: This preoperative CTRT protocol was feasible and safe in a cooperative group setting. Entry of patients with advanced tumors probably accounted for the suboptimal resectability and survival results.     

Comparison of the amplified Mycobacterium tuberculosis (MTB) direct test, Amplicor MTB PCR, and IS6110-PCR for detection of MTB in respiratory specimens

Several nucleic acid amplification techniques (NAAT) have been developed for rapid and direct detection of Mycobacterium tuberculosis (MTB) from clinical specimens. This study compared the performances of the Gen-Probe Amplified MTB Direct Test (AMDT), Roche Amplicor MTB PCR test, and an IS6110-PCR assay with acid-fast smear and culture in the detection of MTB from 428 respiratory specimens from 259 patients. Patients' charts were reviewed for clinical correlation. Of 98 specimens that were clinically positive for MTB, acid-fast smear was positive in 50% of cases, culture in 93%, IS6110-PCR in 83%, AMDT in 84%, and Amplicor MTB PCR in 80%. Of 337 specimens that were negative for MTB, 117 (35%) were positive for nontuberculous mycobacteria. Specificities were as follows: smear, 89%; culture, 100%; IS6110-PCR, 99%; AMDT, 98%; and Amplicor MTB PCR, 96%. The accuracies of the tests were 80%, 98%, 96%, and 92%, respectively. MTB culture-positive specimens that were smear-negative were detected by AMDT and IS6110-PCR in 77% of cases and by Amplicor MTB PCR in 70%. NAAT was less sensitive than was culture for detection of MTB, but all these techniques had acceptable accuracy and were completed within hours. NAAT may be useful for rapid screening of respiratory specimens to distinguish MTB from nontuberculous mycobacteria infection in order to isolate patients.     

Differential diagnosis of pulmonary tuberculosis

Differential diagnosis of pulmonary tuberculosis is discussed. Chest X-ray findings of pulmonary tuberculosis may be greatly varied, because tuberculosis may cause three different lesions: an exudative lesion, a proliferative lesion, and a fibrotic lesion, and because it may invade all the structure. Thus, the differential diagnosis of pulmonary tuberculosis includes very many diseases. The most important differential diagnosis of nodule is tuberculoma and lung cancer. The clue of the diagnosis is the feature of the nodule and surrounding structure, such as pleural indentation, or knotching. There is, however, the limitation of the diagnosis by imaging: some tuberculoma may show the identical feature with the pulmonary adenocarcinoma. It is important to gather the pathological or bacteriological evidences by means of suitable procedures.     

Predictive factors of Mycobacterium tuberculosis infection and pulmonary tuberculosis in prisoners

BACKGROUND: Tuberculosis currently represents a serious problem in prison populations. METHODS: With the aim of studying the predictive factors for, and the prevalence of, Mycobacterium tuberculosis infection and pulmonary tuberculosis in a Spanish prison, all those admitted during 1991 and 1992 were included (N = 1314). The tuberculin skin test, HIV serology, chest X-ray and bacteriological examination of sputum were carried out. Statistical analysis was done by univariant tests, stratified analysis and logistic regression. RESULTS: The prevalence of M. tuberculosis infection was 55.5% (95% confidence interval [CI] 52.5-58.5). An association was found with sex, imprisonment more than once, HIV infection and age. The co-infection rate (tuberculosis plus HIV) was 9.2%. Logistic regression showed a greater risk with age (4.4% per year), time spent in prison and for males. The prevalence of pulmonary tuberculosis was 1.26% and an association was found with M. tuberculosis infection, HIV infection (odds ratio [OR] = 13.7), intravenous drug users (OR = 17.2) and imprisonment more than once (OR = 7.3). Logistic regression showed an association with HIV co-infection (OR = 20.2). CONCLUSIONS: The prevalence of M. tuberculosis infection and pulmonary tuberculosis is high when compared with similar studies. The influence of age, time spent in prison and co-infection with HIV is relevant to recommendations for specific tuberculosis prevention programmes in correctional facilities.     

Infection with Mycobacterium tuberculosis complicating a pulmonary sequestration

Pulmonary sequestration is a relatively rare malformation. Infection with common pyogenes is a frequent feature in the evolution of this disease. We report a case of intralobar sequestration infected with Mycobacterium tuberculosis in the absence of any other site of tuberculous infection. The patient underwent surgical removal of the affected lobe and subsequent antituberculous chemotherapy. At 1-year follow-up his clinical status is excellent.     

Rapid diagnosis of Mycobacterium tuberculosis bacteremia by PCR

A method based on DNA amplification and hybridization has been used for the rapid detection of Mycobacterium tuberculosis in blood samples from 38 hospitalized patients (15 human immunodeficiency virus [HIV] positive and 23 HIV negative) in whom localized or disseminated forms of tuberculosis were suspected. In 32 of these patients, the diagnosis of tuberculosis was eventually confirmed by conventional bacteriological or histological procedures. M. tuberculosis DNA was detected with the PCR technique in the peripheral blood mononuclear cells from 9 of 11 (82%) HIV-infected patients and in 7 of 21 (33%) HIV-negative patients (P < 0.01), while M. tuberculosis blood cultures were positive in 1 of 8 (12.5%) and 1 of 18 (5.5%) patients, respectively. PCR was positive in all cases with disseminated disease in both HIV-negative and HIV-positive patients and also in the HIV-positive patients with extrapulmonary tuberculosis. Seven samples from patients with documented illness other than tuberculosis and 12 specimens from healthy volunteers, including seven volunteers with a recent positive purified protein derivative test, were used as controls and had a negative PCR. These results suggest that detection of M. tuberculosis DNA in peripheral blood mononuclear cells may be a useful tool for rapid diagnosis of disseminated and extrapulmonary forms of tuberculosis, especially in an HIV-positive population.     

Limits of commercial molecular tests for diagnosis of pulmonary tuberculosis

Several studies report high specificity, but variable sensitivity, of Amplified Mycobacterium tuberculosis Direct Test (AMTDT, Gen-Probe) based on ribosomal ribonucleic acid (rRNA) amplification and Amplicor Mycobacterium tuberculosis test (Amplicor, Roche) based on deoxyribonucleic acid (DNA) amplification for diagnosis of pulmonary tuberculosis. We have retrospectively evaluated these assays on selected acid-fast bacilli (AFB)-positive and -negative smear specimens and compared the results obtained from nucleic acid amplification with those of AFB staining of semi-quantitative cultures as determined by radiometric Bactec and L?wenstein-Jensen cultures. In comparison to cultures, Amplicor and AMTDT assays exhibited identical overall sensitivities of 80%, while the staining had a lower sensitivity of 62%. The sensitivities of Amplicor and AMTDT were 98% and 100%, respectively, for the AFB-positive specimens, and 50 and 46%, respectively for the AFB-negative specimens in comparison to cultures. The sensitivities of both assays appeared similar, and were directly related to the number of bacilli in the specimens studied. The low sensitivity (50%) for smear-negative specimens showed that current amplification assays may be unsuitable to replace cultures for diagnosis of tuberculosis. The decision to perform these molecular techniques should result from close co-operation between clinicians and microbiologists, taking into account the sensitivity results reported here, as well as the expense of the assays.     

Performance characteristics of the BDProbeTec system for direct detection of Mycobacterium tuberculosis complex in respiratory specimens

GABABR1 clones were isolated from a human cerebellum library. The human sequence is very similar to rat GABABR1 with the cDNAs sharing 91.3% sequence identity and the receptors sharing 98.6% amino acid sequence identity. Northern blotting has shown that the receptor is brain-specific with a widespread distribution throughout the brain but none detected in the spinal cord.     

Clinical utility of an amplification test based on ligase chain reaction in pulmonary tuberculosis

We evaluated the sensitivity and specificity of a new semiautomated direct amplification test (DAT), the LCx-MTB, for the diagnosis of pulmonary tuberculosis (TB) and assessed its positive predictive value by focusing on patients with high clinical and radiologic suspicion of pulmonary TB. Respiratory tract specimens from 32 consecutive patients with high suspicion of active pulmonary TB (case patients) and from 204 control patients were cultured for Mycobacterium tuberculosis and tested by LCx-MTB. Sensitivity and specificity of LCx-MTB when compared with culture was, respectively, 80 and 98%. Pulmonary TB was confirmed in the 32 case patients without knowledge of the LCx results: 18 patients were smear- and culture-positive for M. tuberculosis, and all gave at least one specimen that was LCx-positive. Eight patients were smear-negative culture-positive, and seven gave at least one LCx-positive specimen. LCx-MTB was negative in all the specimens obtained from six patients with smear- and culture-negative TB. A positive LCx-MTB result in a smear negative specimen was 100% predictive that at least one of the case patients' specimens would yield M. tuberculosis. As a consequence, knowledge of the LCx-MTB results at the time of specimen collection could have hastened the start of the antituberculosis therapy in three (21%) smear-negative case patients and could have avoided unnecessary invasive diagnostic procedures in four (29%). We conclude that the sensitivity of LCx-MTB in detecting M. tuberculosis DNA in respiratory tract specimens is similar to other DATs, that LCx-MTB is a reliable test for confirmation of TB in smear-positive patients and that LCx-MTB could be beneficial as a diagnostic step in smear-negative patients with a high suspicion of pulmonary TB.     

PCR-based rapid detection of Mycobacterium tuberculosis in blood from immunocompetent patients with pulmonary tuberculosis

A PCR test based on insertion sequence IS1081 was developed to detect Mycobacterium tuberculosis complex organisms in the peripheral blood. The method was applied to blood samples from immunocompetent individuals with localized pulmonary tuberculosis. Seven of 16 (43.75%) blood samples were found to be positive for the circulating DNA copies of M. tuberculosis complex.     

The direct agglutination test: a non-specific test specific for the diagnosis of visceral leishmaniasis?

Serology has an important role to play in the diagnosis of the severe clinical syndrome of visceral leishmaniasis (VL). The direct agglutination test (DAT), a simple agglutination test which requires no laboratory facilities, has become the preferred test, particularly for field studies. The nature of the antigens responsible for the agglutination of leishmanial promastigotes by the serum of VL patients is not known. A series of experiments which provide some clues to the molecular basis for the test and which indicate that there might be more in DAT than meets the eye is reported.