Acid Fast Bacilli Smear Examination Research Articles

GeneXpert analysis of bronchoalveolar lavage (BAL) samples: promising diagnostic modality in patients with smear-negative pulmonary tuberculosis

PurposeThe aim of the study is to assess the diagnostic utility of bronchoalveolar lavage (BAL) samples with GeneXpert test in diagnosis of TB in smear-negative patients.MethodOne-hundred sixty-nine cases were included in this study, as they had a radiological finding suggested to have pulmonary tuberculosis, while the sputum direct smear examination for acid-fast bacilli was negative. All cases prepared to do fiber-optic bronchoscope with bronchoalveolar lavage collection after their consent and post bronchoscope sputum collection for further molecular and microbiological examination.ResultsThe combined diagnostic yield of all bronchoscopy procedures was 15.97% (27 cases of 169) and the final diagnosis of TB cases was established in 16 cases of 169 (9.4%) using BAL culture and in 20 cases of 169 (11.83%) by GeneXpert methods. Post bronchoscope direct sputum examination, culture, and GeneXpert evaluation gave diagnostic yield about 1.1%, 5.5%, and 7.1%, respectively. The specificity of GeneXpert examination of BAL and post bronchoscope sputum was 95.42% and 97.38%, respectively.ConclusionEarly detection of pulmonary tuberculosis using fiber-optic bronchoscope BAL examination and post bronchoscope sputum with GeneXpert method promotes the accurate decision to start antituberculous therapy in patients with smear negative.

Neuromeningeal tuberculosis in HIV-negative patients: a retrospective study in Rabat, Morocco

Neuro-Meningeal Tuberculosis (NMT) is a severe infection of the central nervous system which causes a public health problem in Morocco and in several countries in the world. In order to describe the epidemiological, clinical, paraclinical and outcome among NMT patients without HIV, we carried out a retrospective study at the neurology department of the Military Hospital of Rabat in Morocco, over a period of 17 years (2000-2017). Forty patients were included with a mean age of 44 years (± 18) and a sex ratio of 1.66. A history evoking the possibility of tuberculous origin was found in 8 patients (20%). Febrile confusion was the most common clinical manifestation and was observed in 22 patients (55%) followed by febrile meningeal syndrome in 12 patients (30%). The main abnormalities noted in brain magnetic resonance imaging (MRI) were: hydrocephalus in 13 cases (32.5%), intra-cranial tuberculomas in 10 patients (25%) and leptomeningitis in 9 cases (22.5%). Cerebrospinal fluid study found clear aspect in 29 patients (75%), direct acid fast bacilli smear examination was positive in 4 patients (10%) and positive culture in 4 patients (10%). The Polymerase chain reaction (PCR) study returned positive in 6 patients (35%) of the 17 patients tested. The outcome was good in 18 patients (45%) while 19 patients suffered from neurological sequelae (47.5%) and 3 cases of death recorded (7.5%). Febrile confusion was the most reported manifestation in our patients. Subacute onset of symptoms was the most predominant feature in our patients as reported in the literature. Our results are consistent with the literature and confirm the severity of this infectious disease, even in HIV-negative patients.

Neuromyelitis optica and concomitant pulmonary tuberculosis: a case report\xa0

BackgroundConcomitant diagnosis of neuromyelitis optica spectrum disease and pulmonary tuberculosis has rarely been reported.Case reportWe report a case involving a young Tunisian male patient who developed dry cough followed, 2 months later, by weakness in the lower limbs. The findings of central nervous system imaging and anti-aquaporin-4 antibody positivity were compatible with the diagnosis of neuromyelitis optica spectrum disease. Constellation of the clinical and the typical radiological pulmonary findings in our patient, coming from an endemic region, allowed the diagnosis of pulmonary tuberculosis, although sputum smear examination for acid-fast bacilli and cultures was negative. The patient received anti-tuberculous polytherapy associated with immunomodulation, consisting of methylprednisolone and intravenous immunoglobulins. Pulmonary infection symptoms initially improved but with no motor recovery. The patient suddenly died at home 4 months after the onset of the first symptoms. Current data regarding the clinical presentation of this underreported concomitant or associated condition, the possible pathophysiological mechanisms, and the therapeutic options were reviewed.ConclusionsThis case underscores the necessity to understand the exact mechanism of these coincident entities and to clarify the best immunomodulatory choice since immunosuppression targeting neuromyelitis optica spectrum disease can lead to dissemination of pulmonary tuberculosis.

Role of tuberculin skin test (Mantoux test) as an aid in the diagnosis of tuberculosis disease and to identify persons with latent tuberculosis in highly endemic hilly region of Jammu and Kashmir

Background: Tuberculosis (TB) is a chronic infectious disease caused by Mycobacterium tuberculosis and one of the major diseases affecting children throughout the world. Mantoux test and direct microscopic examination of acid-fast bacilli (AFB) by Ziehl–Neelsen staining are diagnostic and are widely being used. Objective: The objective of the study was to evaluate the efficacy of the Mantoux test and sputum smear examination as a diagnostic aid in latent TB. Materials and Methods: A prospective observational study was conducted, among 100 suspected cases of TB, over a period of 14 months from May 2019 to June 2020. After obtaining informed consent, patients were subjected to all three diagnostic tests including the Mantoux test, sputum smear examination for AFB, and cartridge-based nucleic acid amplification test (CBNAAT). Results of Mantoux and sputum tests were compared with CBNAAT to assess the sensitivity and specificity of individual tests. Results: In our study, most of the patients (32%) belonged to the age group of 21–30 years. There was a slight female predominance in the study population (52% females and 48% males). Mantoux test was positive in 41 (41%) patients and negative in 59 (59%) patients. On sputum examination, 42 (42%) patients tested positive and 58 (58%) patients were negative. On CBNAAT, 74 (74%) samples were positive, 26 (26%) were found to be negative. The sensitivity and specificity of the Mantoux test were 49.35% and 86.95%, respectively, and 53.33% and 92%, respectively, for sputum smear examination. Conclusion: Mantoux test, sputum smear, and CBNAAT test when performed together act as an aid in diagnosing TB in patients with latent TB.

Comparative evaluation of IS6110 and protein antigen b PCR in cerebrospinal fluid for rapid diagnosis of tuberculous meningitis in children.

Introduction. Childhood tuberculosis meningitis is a severe form of tuberculosis with high morbidity and mortality. The diagnosis is frequently missed and delayed due to lack of sensitive tests like acid-fast bacilli (AFB) smear and delayed results by culture.Aims. To compare the role of IS6110 and protein antigen b PCR in cerebrospinal fluid (CSF) for rapid diagnosis of tuberculous meningitis (TBM) in children.Methodology. Forty-five cases of TBM and 20 controls were enrolled in this prospective study.Results. The mean ages of cases and controls were 4.2±0.5 years and 4.5±0.7 years, respectively. In the TBM group, two-thirds of the children were <4 years of age, and 62 % were males. Sensitivities of AFB smear examination, Löwenstein-Jensen (LJ) medium and bactenecin (BACTEC) culture in cases were 4.4, 0 and 2.2%, respectively. The protein antigen b PCR was most sensitive as it was positive in 35 (77.8 %) of TBM patients; IS6110 PCR was positive in 27 (60 %) patients. Both PCR-based tests had higher positivity than conventional tests and BACTEC culture. No significant difference was seen between the PCR tests. Excellent agreement was observed between both PCR-based tests as they were concordant for 26 positive samples and 35 negative samples.Conclusion. Protein b PCR is a sensitive and rapid method for the diagnosis of TBM (sensitivity 77.8 %). Both PCRs were more sensitive than smear, LJ and BACTEC. The specificity of both PCR was 100 %.

Performance of newer and conventional diagnostic methods in detection of drug sensitive and resistant tuberculous meningitis

ObjectiveTo compare the performance of traditional and newer diagnostic methods for diagnosis of tuberculous meningitis (TBM) along with detection of drug resistant TBM. MethodsSingle cerebrospinal fluids sample from 281 suspected TBM patients was processed during August 2011 to July 2012 for acid fast bacilli (AFB) examination by Ziehl-Neelsen and auramine staining methods, AFB culture on Lowenstein-Jensen culture media, by microscope observation of drug susceptibility testing assay, and nucleic acid amplification tests by in-house conventional PCR and in-house real time PCR targeting IS6110 insertion sequence. All the isolates were subjected to drug susceptibility testing for isoniazid, rifampicin, ethambutol and streptomycin by 1% proportion method. ResultsThe percentage positivity by AFB smear examination and culture on Lowenstein-Jensen media was 21% (59/281), 11.4% (32/281) respectively. The detection rate by conventional PCR was 33.1% (93/281). The real time PCR showed positivity rate of 44.8% (126/281). The extra detection by real time PCR was 11.7%. Only one isolate was multiple drug resistant and 22 (68.8%) were pan-susceptible. Remaining eight isolates showed either mono/poly drug resistant to first line antitubercular drugs. ConclusionsReal time PCR is a more sensitive and rapid method if it is appropriately adopted in clinical practice for diagnosis of TBM. Prevalence of multiple drug resistance Mycobacterium tuberculosis causing TBM is low.

Tuberculosis: Laboratory Diagnosis and Dots Strategy Outcome in an Urban Setting: A Retrospective Study

Pulmonary Tuberculosis (TB) is a global public health threat. It has a worldwide distribution with a very high prevalence in Asian countries. A correct diagnosis forms an important and indispensable part of proper and timely treatment. Detection of acid fast bacilli in direct smears has considerable clinical and epidemiological value and remains the most widely used rapid diagnostic test. In smear negative cases, radiography has an important role to play. Directly Observed Treatment Short Course (DOTS) strategy is one of the most cost-effective health interventions to treat tuberculosis. Samples from clinically suspected cases of TB were screened for the presence of Acid Fast Bacilli (AFB). Radiography and culture was done for the AFB negative cases. 760 cases of pulmonary TB were diagnosed by smear examination and 412 by radiography. 270 cases of pulmonary TB were diagnosed in the study. Of the 1422 patients put on DOTS, out of which 1138 (80.1%) were successfully treated. Thus, smear examination for AFB and radiography should go hand in hand for correct diagnosis and treatment of TB by DOTS which is a very successful regimen for developing countries like India.

Evaluation of BACTEC Micro MGIT with Lowenstein Jensen Media for Detection of Mycobacteria in Clinically Suspected Patients of Extra Pulmonary Tuberculosis in a Tertiary Care Hospital at Mullana (Ambala)

Background and objectives: Tuberculosis continues to be an important public health problem in India and globally. Extra pulmonary mycobacterial infections are more often smear negative than pulmonary cases which makes the diagnosis difficult. With this in background, this study aimed at the isolation of Mycobacteria from clinical specimens of patients suspected of extra pulmonary tuberculosis using BACTEC Micro MGIT, Lowenstein Jensen (LJ) media and Direct acid fast bacilli smear examination. Methods- A total of 200 samples were processed for direct AFB smear examination, and culture on M960 and LJ media. Acid fast staining of the specimens was done using the Ziehl-Neelsen method. Results and Interpreation - Of the 24 positive specimens, the highest rate of Mycobacterial recovery was by MGIT (91.6%) as compared to LJ media (58.3%).From smear negative samples LJ and MGIT media detected 6.06 % and 10.10 % isolates respectively. For smear-positive specimens, the mean turnaround time was 8 days by MGIT whereas on LJ medium, it was 36 days. For smear-negative specimens, the same was 18 days for MGIT and 40 days for LJ medium. Conclusion-The MGIT system is a good system for, especially in the diagnosis of extra pulmonary samples. The MGIT system was found to be more sensitive in detecting mycobacterium in smearnegative samples. The MGIT system detected mycobacterium significantly earlier than the LJ medium.

Drug Resistance in Mycobacterial Isolates From Meningitis Cases

To the Editors: In countries with high burden of pulmonary tuberculosis (TB), the incidence of extrapulmonary TB (EPTB) is high. There has been a rising trend of tuberculous meningitis (TBM) in developing countries in the past 2 decades. There are few published reports on drug susceptibility profiling of EPTB, particularly TBM.1 Early and rapid detection of drug resistance in TBM is not always possible because bacterial load in cerebrospinal fluid (CSF) is too low to detect the resistance by both culture and molecular methods. Hence, it is important to have surveillance of drug resistance in EPTB to help in planning the treatment regimen. Here, we report the prevalence of drug resistance in Mycobacterium tuberculosis isolates from CSF of TBM cases. CSF samples from 370 clinically suspected pediatric TBM cases were referred to the TB laboratory, Department of Microbiology, Chhatrapati Shahuji Maharaj Medical University, Lucknow, India, for laboratory confirmation of TBM. Each CSF sample was processed for acid-fast bacilli smear examination, mycobacterium culture2 and demonstration of mycobacterial DNA by in-house nucleic acid amplification method.3 All M. tuberculosis isolates were subjected to drug susceptibility testing for first-line drugs: isoniazid, rifampicin, streptomycin and ethambutol by conventional 1% proportion method.2 The laboratory is under external quality control for first-line drug susceptibility testing (provided by the National JALMA Institute for Leprosy and Other Mycobacterial Diseases, Agra, India). Of the 370 cases, 106 (28.6%) patients had laboratory-proven TBM. CSF samples from all 106 laboratory-proven patients were polymerase chain reaction positive whereas 60 (16.2%) patients were positive by smear examination for acid-fast bacilli and 51 (13.7%) patients were culture positive for M. tuberculosis. Among 106 samples, 32 (30.2%) samples were positive by all the 3 tested methods. Of the 51 M. tuberculosis isolates, 34 (66.7%) isolates were pan-susceptible whereas resistance to isoniazid or streptomycin was detected in 7 (13.7%) and 5 (9.8%) isolates, respectively. Multidrug resistance (MDR) was detected in 1 isolate. Almost 50% of MDR-TB pulmonary cases worldwide are estimated to occur in China and India. Drug resistance in M. tuberculosis isolates from TBM cases is low despite the fact that, among pulmonary cases, prevalence of MDR in our setting was higher (19.8%)4 than other parts of the country.5 MDR among cases of pulmonary TB is well documented, but reports on MDR–EPTB and MDR–TBM are limited. Continuous surveillance of drug resistance in EPTB is needed. Amita Jain, MD Pratima Dixit, MSc Indu Jaiswal, MSc Department of Microbiology C.S.M. Medical University Ravindra Kumar Garg, MD, DM Department of Neurology C.S.M. Medical University Rashmi Kumar, MD Department of Pediatrics, C.S.M. Medical University Lucknow, India

Rapid Diagnosis of Genital Tuberculosis by Real-time Polymerase Chain Reaction

ABSTRACT Objective Rapid diagnosis of genital tuberculosis (GTB) is essential as it is an important cause of infertility among women. Diagnosis can be done by imaging techniques, direct visualization by endoscopy, serology, histopathology, culture and polymerase chain reaction (PCR) tests. Laparoscopy detects macroscopic changes only; histology is only suggestive and not confirmatory unless acid fast bacilli (AFB) are demonstrated in the lesion but sensitivity is poor in paucibacillary disease. Culture methods are the gold standard but slow growth of most pathogenic mycobacteria delays the diagnosis. PCR can rapidly detect even few copies of DNA with high sensitivity and specificity. Aim Comparative evaluation of AFB smear examination, culture in Middlebrook 7H9 media and IS6110 based real-time PCR assay for the detection of mycobacteria in various female genital samples. Materials and methods A total of 555 female genital samples like endometrial and fallopian tube biopsies, menstrual blood and vaginal discharge were processed by modified Petroff's method. The deposit was used for detection of mycobacteria by AFB smear, culture on Middlebrook 7H9 media and IS6110 based real-time PCR. Results Out of 555 samples, 25.22 % (140/555) were positive by the combination of all the methods used. Overall positivity by real-time PCR alone was 23.78% (132/555), by culture 8.28% (46/555) and 2.70% (15/555) by AFB smear examination. Out of total positives, 94.28% (132/140) were positive by PCR alone, 32.85% (46/140) by culture and 10.71% (15/140) by AFB smear. Eight (5.71%) culture positive samples were negative by smear and PCR, six of these were nontubercular mycobacteria (NTM) and two samples had PCR inhibitors as confirmed by spiking with positive DNA. Contamination was observed in 25/555 (4.5%) which were reported negative by culture but three of these were PCR positive. AFB smear results were available in 1 hour, PCR in 1 day and culture in 4 to 6 weeks. Conclusion PCR was found to be the most rapid and sensitive (94.28%) method, 9-fold more sensitive than smear examination and 3-fold than the culture for detection of mycobacteria. Results were available in 4 to 6 weeks time for culture but in only 1 day by PCR. IS6110 PCR can detect only MTB and not the NTM. Use of multiplex PCR with genus and MTB specific primers will increase the sensitivity of test but care needs to be taken to prevent false positivity due to cross contamination and false negative due to PCR inhibitors. How to cite this article Malhotra B, Sinha P, Hooja S, Vyas L. Rapid Diagnosis of Genital Tuberculosis by Real-time Polymerase Chain Reaction. J South Asian Feder Obst Gynae 2012;4(1):39-42.

Multiplex PCR technique could be an alternative approach for early detection of leprosy among close contacts - a pilot study from India

BackgroundImplementation of Multi drug Therapy (MDT) regimen has resulted in the decline of the total number of leprosy cases in the world. Though the prevalence rate has been declining, the incidence rate remains more or less constant and high in South East Asian countries particularly in India, Nepal, Bangladesh, Pakistan and Srilanka. Leprosy, particularly that of multibacillary type spreads silently before it is clinically detected. An early detection and treatment would help to prevent transmission in the community. Multiplex PCR (M-PCR) technique appears to be promising towards early detection among contacts of leprosy cases.MethodsA total of 234 paucibacillary (PB) and 205 multibacillary (MB) leprosy cases were studied in a community of an endemic area of Bankura district of West Bengal (Eastern India). They were assessed by smear examination for acid-fast bacilli (AFB) and M-PCR technique. These patients were treated with Multidrug Therapy (MDT) as prescribed by WHO following detection. A total of 110 MB and 72 PB contacts were studied by performing M-PCR in their nasal swab samples.Results83.4% of MB patients were observed to be positive by smear examination for AFB and 89.2% by M-PCR. While 22.2% of PB patients were found to be positive by smear examination for AFB, 80.3% of these patients were positive by M-PCR. Among leprosy contacts (using M-PCR), 10.9% were found to be positive among MB contacts and 1.3% among PB contacts. Interestingly, two contacts of M-PCR positive MB cases developed leprosy during the period of two years follow up.ConclusionThe M-PCR technique appears to be an efficient tool for early detection of leprosy cases in community based contact tracing amongst close associates of PB and MB cases. Early contact tracing using a molecular biology tool can be of great help in curbing the incidence of leprosy further.

Tuberculosis en una cohorte de pacientes con lupus eritematoso sistémico

Objectives 1) To study tuberculosis (TB) infection in a cohort of patients with systemic lupus erythematosus (SLE) and to compare its frequency and characteristics with that of others series. 2) To look for differential characteristic among SLE patients with and without TB. 3) To investigate if there was any relationship between TB's most severe forms and higher doses of glucocorticoids (GC) or other immunosuppressants. Patients and Method Retrospective review of medical records of 789 SLE patients and description of the clinical characteristics of 13 cases of active TB infection among them. Bibliographical search in MEDLINE-PubMed of the SLE/TB series published, using the terms: infection, tuberculosis, systemic lupus erythematosus. Comparative study of clinical, biological and therapeutic differences between cases (SLE/TB+) and controls (SLE/TB) using χ 2 and Fisher exact test. Results Thirteen patients with active tuberculosis were detected (10 women, average age 36 years/SD 11,2/prevalence 1,6%). Nine (69,2%) of them were primary infections and 4 (30,8%) reactivations. Microbiological diagnosis (smear examination for acid-fast bacilli and/or culture on Lowestein-Jensen medium) was established in 11 patients (84,6%). TB Pulmonary manifestations was present in 9 patients (69,2%) and extra-pulmonary manifestations were found in 8 [(61,5%); 6 of them (46%) were disseminated forms]. Nine (69,2%) patients were on GC therapy at the moment TB was diagnosed. Four of the TB patients died (30,8%). Myositis was more frequent in TB cases (p < 0,05). This data is similar to that reported in the literature. Conclusions In our series, TB mortality was high (30,8%) in a patients with SLE. Frequency of extrapulmonary forms was double than that described in the Spanish population. Patients with higher GC dose had more severe forms of TB.

Tuberculosis in a cohort of patients with systemic lupus erythematosus

Objectives1) To study tuberculosis (TB) infection in a cohort of patients with systemic lupus erythematosus (SLE) and to compare its frequency and characteristics with that of others series. 2) To look for differential characteristic among SLE patients with and without TB. 3) To investigate if there was any relationship between TB's most severe forms and higher doses of glucocorticoids (GC) or other immunosuppressants. Patients and methodRetrospective review of medical records of 789 SLE patients and description of the clinical characteristics of 13 cases of active TB infection among them. Bibliographical search in MEDLINE-PubMed of the SLE/TB series published, using the terms: infection, tuberculosis, systemic lupus erythematosus. Comparative study of clinical, biological and therapeutic differences between cases (SLE/ TB+) and controls (SLE/TB) using χ2 and Fisher exact test. ResultsThirteen patients with active tuberculosis were detected (10 women, average age 36 years/SD 11.2/prevalence 1.6%). Nine (69.2%) of them were primary infections and 4 (30.8%) reactivations. Microbiological diagnosis (smear examination for acid-fast bacilli and/or culture on Lowestein-Jensen medium) was established in 11 patients (84.6%). TB Pulmonary manifestations was present in 9 patients (69.2%) and extrapulmonary manifestations were found in 8 [(61.5%); 6 of them (46%) were disseminated forms]. Nine (69.2%) patients were on GC therapy at the moment TB was diagnosed. Four of the TB patients died (30.8%). Myositis was more frequent in TB cases (P<.05). This data is similar to that reported in the literature. ConclusionsIn our series, TB mortality was high (30.8%) in a patients with SLE. Frequency of extrapulmonary forms was double than that described in the Spanish population. Patients with higher GC dose had more severe forms of TB

A COMPARATIVE STUDY FOR THE DETECTION OF MYCOBACTERIA BY BACTEC MGIT 960, LOWENSTEIN JENSEN MEDIA AND DIRECT AFB SMEAR EXAMINATION

Purpose: To compare BACTEC MGIT 960 (M960) with conventional culture on Lowenstein Jensen (LJ) media and direct acid fast bacilli (AFB) smear examination for the detection of Mycobacteria in clinical samples obtained from suspected cases of pulmonary and extra pulmonary tuberculosis (TB). Methods: A total of 500 samples were processed for direct AFB smear examination, and culture on M960 and LJ media. Results: Two hundred fifty-eight out of 500 (51.6%) isolates of Mycobacteria were obtained by combined use of the two culture methods. Two hundred and fifty-three (50.6%) were positive in culture by M960 and LJ media and 28% (140/500) by direct AFB smear examination. The positivity rate of M960 system alone was 34.10% (88/258) and of LJ alone was 1.93% (5/258). Average time to detect growth (TTD) was 9.66 days by M960 and 28.81 days by LJ. Conclusions: M960 system is a rapid and sensitive method for early diagnosis of pulmonary and extrapulmonary TB. But for maximum recovery of Mycobacteria, a combination of both M960 and LJ media should be used.

A comparative study for the detection of mycobacteria by bactec MGIT 960, lowenstein jensen media and direct AFB smear examination

To compare BACTEC MGIT 960 (M960) with conventional culture on Lowenstein Jensen (LJ) media and direct acid fast bacilli (AFB) smear examination for the detection of Mycobacteria in clinical samples obtained from suspected cases of pulmonary and extra pulmonary tuberculosis (TB). A total of 500 samples were processed for direct AFB smear examination, and culture on M960 and LJ media. Two hundred fifty-eight out of 500 (51.6%) isolates of Mycobacteria were obtained by combined use of the two culture methods. Two hundred and fifty-three (50.6%) were positive in culture by M960 and LJ media and 28% (140/500) by direct AFB smear examination. The positivity rate of M960 system alone was 34.10% (88/258) and of LJ alone was 1.93% (5/258). Average time to detect growth (TTD) was 9.66 days by M960 and 28.81 days by LJ. M960 system is a rapid and sensitive method for early diagnosis of pulmonary and extrapulmonary TB. But for maximum recovery of Mycobacteria , a combination of both M960 and LJ media should be used.

Association of Human Leukocyte Antigen-A11 With Resistance and B40 and DR2 With Susceptibility to HIV-1 Infection in South India

Association of Human Leukocyte Antigen-A11 With Resistance and B40 and DR2 With Susceptibility to HIV-1 Infection in South India

Infectious bulla of the lung caused by Mycobacterium intracellulare

A healthy 24-year-old man who was admitted to our hospital was suspected of having an infectious bulla of the lung because an intrabullous effusion was seen on a chest radiograph. A bulla of the right lung had been found 2 years earlier during a periodic health examination. On a chest radiograph, a bullous lesion with a niveau-like shadow (14 x 7 cm) was noted in the right lower lobe of the lung. On puncture aspiration, the bulla fluid was found to be exudative and contained mostly lymphocytes. A smear examination for acid-fast bacilli was positive, as was polymerase chain reaction (PCR) examination for Mycobacterium intracellulare. Therefore, a diagnosis of infectious lung bulla caused by M. intracellulare was made. A right lower lobectomy was performed. On macroscopic examination of the resected lesion, the area surrounding the bulla was whitish in color, and microscopic examination of this area showed a caseating epitheloid granuloma with acid-fast bacilli. We report this case because there have been no previous reports in the literature of infectious lung bulla caused by M. intracellulare although there have been several reports dealing with lung bulla caused by Mycobacterium tuberculosis.

Diagnostic value of gastric aspirate smear and polymerase chain reaction in smear-negative pulmonary tuberculosis.

The aim of this study was to determine the validity of acid-fast bacilli (AFB) smear and polymerase chain reaction (PCR) from gastric aspirates for the diagnosis of smear-negative pulmonary tuberculosis. A cross-sectional study was conducted in a university hospital. One hundred and nine patients with suspected pulmonary tuberculosis in whom either sputum smears were negative or who were not producing sputum were recruited to the study. All patients underwent gastric aspiration after an overnight fast followed by standard fibreoptic bronchoscopy. Specimens were subjected to AFB smear, culture, and pathological examination. PCR was performed on culture filtrate after 1 week of incubation. Eight patients did not complete the follow-up schedule. Of the 101 patients with final outcomes, a diagnosis of pulmonary tuberculosis from microbiological evidence was established in 54 patients. The gastric aspirate smear, PCR, or either one of them was positive in 34, 30, and 39 tuberculosis patients, respectively. There were 13 false positive smears from 47 non-tuberculosis patients, with five resulting from non-tuberculous mycobacteria (NTM). The PCR was falsely positive in eight patients, five of whom had previous histories of tuberculosis. The overall sensitivity, specificity, positive predictive value, and negative predictive value of gastric aspirate examination by combined smear and PCR were 72, 58, 66, and 64%, respectively. Gastric aspiration is a useful tool for the diagnosis of smear-negative pulmonary tuberculosis warranting institution of antituberculosis treatment. Interpretation of the results should be cautious in those who have had tuberculosis in the past or who have been at risk for acquisition of NTM.

Detection of Mycobacterium tuberculosis in bronchoalveolar lavage from patients with sputum smear-negative pulmonary tuberculosis using a polymerase chain reaction assay.

The objective of this study was to evaluate the utility of a polymerase chain reaction (PCR) assay in detecting Mycobacterium tuberculosis in bronchoalveolar lavage (BAL) specimens of patients suspected of having active pulmonary tuberculosis (TB) but who were sputum smear-negative. Patients undergoing investigation for suspected pulmonary TB at the University Hospital, Kuala Lumpur, and who were sputum smear-negative underwent fibreoptic bronchoscopy and BAL. One portion of each lavage specimen was submitted for smear examination for acid-fast bacilli and mycobacterial culture and the other portion assayed by PCR for the presence of a 562-base pair DNA segment belonging to the insertion sequence IS986, unique to the M. tuberculosis complex. As controls, lavage specimens from patients with other lung lesions were also similarly tested. The PCR assay gave a positivity rate of 80.9% (55 of 68) compared with 8.8% of smear examination and 7.4% of culture for detecting M. tuberculosis in BAL specimens. The assay was positive in two of 45 BAL specimens from 35 control subjects. The PCR assay was more sensitive than smear and culture in detecting M. tuberculosis in BAL specimens of patients with sputum smear-negative pulmonary TB.

Microbiological Diagnosis of Tuberculosis: A Comparison of Old and New Methods

The aim of our study was to evaluate the diagnostic value of various methods widely used in microbiological diagnosis of tuberculosis: direct smear examination for acid-fast bacilli, cultural identification in Lowestein-Jensen (L-J) medium, the radiometric BACTEC 460 system, and Polymerase Chain Reaction (PCR).Three hundred and ninety-three clinical samples of sputum (375), gastric aspirate (3), pleural fluid (12) and urine (3) were taken from 125 patients hospitalized at our Institute for suspected pulmonary tuberculosis, between January 1995 and June 1997. On completion of diagnosis, 35 were found to be affected by active tuberculosis (30 pulmonary, 4 pleural and 1 urinary) and 90 by other non-tubercular diseases (pneumonia, lung cancer, non-tubercular pleural effusion, etc.).In our study, direct smear examination for acid-smear bacilli gave diagnostic value results of 88% and positive predictive value of 91.67%. Cultural identification in L-J and BACTEC 460 TB radiometric system media resulted in diagnostic values of 96.80% and 94.40%, respectively, and positive predictive values of 100% for both of them. Finally, One-Tube Nested-PCR, a variant which uses specific primers for the IS6110 insertion sequence specific for Mycobacterium tuberculosis, gave us 88.80% (91.43% sensitivity and 87.78% specificity) diagnostic value results, and 74.42% (11 false-positives) positive predictive value.On the basis of our results, we can affirm that PCR is a good method for microbiological diagnosis of tuberculosis, given its high sensitivity and specificity and unparalleled rapidity. However, the high number of false-positives that we found suggests that results obtained should be confirmed with BACTEC, which considerably reduces the time required for identification, and makes it possible to carry out an antibiotic assay rapidly.