Role of endoscopic ultrasound guided fine needle aspiration/biopsy in the evaluation of intra-abdominal lymphadenopathy due to tuberculosis

BACKGROUNDIntra-abdominal lymphadenopathy due to tuberculosis (TB) poses a diagnostic challenge due to difficulty in tissue acquisition. Although endoscopic ultrasound guided fine needle aspiration/biopsy (EUS-FNA/B) has shown promise in the evaluation of mediastinal lymph nodes, its role in the evaluation of intra-abdominal lymphadenopathy is not clear. AIMTo assess the role of EUS-FNA/B in the evaluation of intra-abdominal lymphadenopathy due to TB.METHODSThis was a retrospective study where patients with intra-abdominal lymphadenopathy who underwent evaluation with EUS-FNA/B were included. TB was diagnosed if the patient had any one of the following: (1) Positive acid fast bacilli (AFB) stain/TB GeneXpert/TB-polymerase chain reaction/AFB culture of tissue sample; and (2) Positive Mantoux test and response to anti-tubercular therapy. EUS-FNA reports, clinical reports and imaging characteristics of patients were recorded for a detailed analysis of patients with TB. RESULTSA total of 149 patients underwent an EUS-FNA/B from lymph nodes (mean age 51 ± 17 years, M:F = 1.2). Benign inflammatory reactive changes were seen in 45 patients (30.2%), while 54 patients (36.2%) showed granulomatous inflammation with/without caseation. Among these, 51 patients (94.4%) were confirmed to have TB as per pre-defined criteria. Patients with TB were more likely to have hypoechoic and matted nodes [40 patients (67.7%)]. EUS-FNA/B was found to have a sensitivity and specificity of 86% and 93% respectively, with a diagnostic accuracy of 88% in the evaluation of intra-abdominal lymphadenopathy due to TB.CONCLUSIONEUS-FNA/B has a high diagnostic yield with a good sensitivity and specificity in the evaluation of intra-abdominal lymphadenopathy due to TB. However, the validity of these findings in populations with low prevalence of TB needs further evaluation.     

A rare case of primary sinonasal tuberculosis presented with phlyctenular keratoconjunctivitis in a pediatric patient: A case report and literature review

Rationale:Tuberculosis is a common cause of phlyctenular keratoconjunctivitis, especially for patients who live in a high endemic area of tuberculosis. We report a rare case of pediatric phlyctenular keratoconjunctivitis associated with primary sinonasal tuberculosis.Patient concerns:A 7-year-old boy presented with a 5-month history of redness of the left eye accompanied by mild visual impairment. Physical examination revealed elevated pinkish-white nodules with a circumcorneal hypervascularized lesion on the left conjunctiva.Diagnosis:Computed tomography revealed an enhancing soft tissue mass in the left maxillary sinus with bone destruction. Histopathology of maxillary tissue showed chronic inflammation without granuloma. Special stain, culture and polymerase chain reaction for mycobacterium were initially negative. Left maxillary sinus tuberculosis was diagnosed by positive Mycobacterium tuberculosis polymerase chain reaction from formalin-fixed paraffin-embedded maxillary tissue.Interventions:Two month of oral isoniazid, rifampicin, pyrazinamide, and ethambutol, followed by 10 months of oral isoniazid and rifampicin without topical eye drops agent were prescribed.Outcomes:Two months after initiation of treatment, the phlyctenular lesion had significantly improved. A follow-up computed tomography showed a significant reduction in the size of the maxillary sinus lesion and the extent of adjacent bone destruction.Lessons:Primary sinonasal tuberculosis is an uncommon cause of phlyctenular keratoconjunctivitis in children. When microbiological and histopathological evidences are absent, polymerase chain reaction analysis has a crucial role in the diagnosis of tuberculosis, especially in patient with uncommon presentation.     

Endoscopic ultrasound-guided fine-needle aspiration for the diagnosis of peripancreatic tuberculous lymphadenitis

The percentage of patients with atypical extrapulmonary forms of tuberculosis has been increasing. Among extrapulmonary tuberculosis cases, tuberculosis of the pancreas and peripancreatic lymph nodes is a rare clinical entity. Here, we present a case of peripancreatic tuberculous lymphadenitis diagnosed by endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) both cytologically and microbiologically. A 23-year-old man had a 1-week history of epigastralgia and low-grade fever. Subsequently, he was found to have an abnormality on abdominal ultrasound. A computed tomography scan of the abdomen showed a solitary mass consisting of multiple cystic components with rim enhancement in the peripancreatic portion contiguous to the gall bladder. Endoscopic ultrasound-guided fine-needle aspiration was performed to confirm the diagnosis. The cytological examination revealed epithelioid cells with caseous necrosis, indicating tuberculosis. The aspirated fluid was positive by polymerase chain reaction (PCR) analysis and culture for Mycobacterium tuberculosis. Antituberculosis therapy with isoniazid, rifampicin, ethambutol, and pyrazinamide was started based on the PCR and cytology results, and a good response to the treatment was noted. Endoscopic ultrasound-guided fine-needle aspiration cytology with PCR analysis is very useful for the diagnosis of peripancreatic tuberculosis.     

Nested polymerase chain reaction in the diagnosis of negative Ziehl-Neelsen stained Mycobacterium tuberculosis fistula-in-ano: report of four cases

PURPOSE: Mycobacterium is one of the causes of granulomatous diseases within the anorectal region. Early diagnosis of Mycobacterium infection is important before the use of antituberculosis chemotherapy. Clinical diagnosis is usually dependent on microscopic detection using Ziehl-Neelsen stain and mycobacterial culture, but the sensitivity and specificity of these two methods are low. In this study nested polymerase chain reaction was used to detect mycobacterial infection in anal fistulas. METHODS: Paraffin-embedded specimens from three patients and discharge from one patient were used. DNA extraction was performed using phenol/chloroform techniques. IS6110-based nested polymerase chain reaction, yielding a 259-bp amplicon, for the diagnosis of Mycobacterium infection was done to facilitate treatment. RESULTS: Four cases of suspected Mycobacterium tuberculosis fistulas-in-ano presented with persistent fistula or unhealed wound. Histopathologic examination revealed granulomatous inflammation with failed microscopic detection of acid-fast bacilli using Ziehl-Neelsen stain. Nested polymerase chain reaction confirmed the presence of M. tuberculosis in all cases. The anal lesions healed rapidly following a course of antituberculosis therapy. CONCLUSION: Molecular diagnosis of M. tuberculosis fistula-in-ano by nested polymerase chain reaction is useful for clinically highly suspected Mycobacterium infection despite a negative Ziehl-Neelsen stain.     

Does Crohn's disease need differentiation from tuberculosis?

Crohn's disease (CD) and tuberculosis (TB) of the gastrointestinal tract pose major diagnostic problems for clinicians where these conditions coexist. Clinically and radiologically, the diseases are similar. In the West, TB is considered in the differential diagnosis of all suspected cases of CD, particularly among Asian migrants. Earlier age of presentation, perianal disease and enteric fistulae favour a diagnosis of CD. Aphthoid ulceration, pseudopolyps and filliform mucosa at endoscopy are suggestive of CD and a negative tuberculin test is useful. The final diagnosis depends largely on histopathology and the presence or absence of acid fast bacilli. Tuberculosis is more common in developing countries and intestinal TB frequently coexists with pulmonary tuberculosis. TB is known to affect all age groups and fistulous communication, although uncommon, does occur. In addition to radiology and endoscopy, laparotomy may be required to establish the diagnosis. In developing countries, CD is uncommon and remains largely a diagnosis of exclusion. A trial of anti-tuberculosis therapy may often be prescribed before definitely diagnosing CD. The development of molecular biology techniques has led to a revival of interest in mycobacteria as a possible aetiological agent in CD. DNA from Mycobacterium paratuberculosis and Mycobacterium kansaii have both been identified in CD cases but the significance of this finding has not been established. However, in the near future polymerase chain reaction will become increasingly useful in differentiating CD from intestinal TB because it allows the amplification and identification of very small quantities of mycobacterium DNA.     

Tuberculosis: diagnostics

While microscopy and culture are still the major backbone for laboratory diagnosis of tuberculosis (TB), new methods including molecular diagnostic tests have evolved over the last two decades. The majority of molecular tests have been focused on: (i) detection of nucleic acids both DNA and RNA, which are specific to Mycobacterium tuberculosis, by amplification techniques such as polymerase chain reaction (PCR); and (ii) detection of mutations in the genes which are associated with resistance to anti-tuberculosis drugs by sequencing or nucleic acid hybridization. In the session of the conference on diagnosis of TB, there were two presentations: one on the development of new diagnostic tools for drug resistant M. tuberculosis, and the other on issues involved in the application of new diagnostic tools for multidrug resistant (MDR)-TB, pediatric TB and HIV-TB.     

A Dynamic Reinfection Hypothesis of Latent Tuberculosis Infection

Abstract Background:   It has been traditionally postulated that individuals, once infected by Mycobacterium tuberculosis, will retain throughout their entire lifetime latent bacilli which will remain dormant in old lesions. This bacillus would then be the source of a later reactivation of active tuberculosis (TB), with the aid of resuscitation factors. Unfortunately, the presence of these bacilli can only be predicted by indirect immunological methods, such as the tuberculin skin test (TST) or T cell interferon–gamma release assays. Other evidence shows that a 9-month isoniazid treatment of TST+ individuals converting to TB reduces the incidence of TB by approximately 90%. Questions:   Taking into account this widely accepted framework, I suggest that there are at least three relevant questions to answer: (1) How can dormant bacilli remain in the lungs for an entire lifetime, taking into account constant cellular turnover and the healing of damaged tissues? (2) What provides the resuscitation factor to dormant bacilli, assuming that these latent bacilli are indeed present inside old lesions? (3) Why can a 9-month treatment with isoniazid eliminate dormant bacilli? As isoniazid is active only against growing bacilli, and thus is only able to destroy them after reactivation of latent bacilli, this treatment should have to be provided for life if the traditionally accepted postulate is correct. Hypothesis:   For a better understanding of latent TB infection. I propose a hypothesis that describes a dynamic scenario of constant endogenous reinfection with M. tuberculosis which explains the efficacy of the current standard of treatment. If this hypothesis is true, new strategies for the management of TB may arise.     

Epidermal growth factor receptor-mutant pulmonary adenocarcinoma coexisting with tuberculosis: A case report

Rationale:Lung cancer and pulmonary infections can have similar clinical and radiographic manifestations. Treatment for the coexistence of epidermal growth factor receptor (EGFR)-mutant pulmonary adenocarcinoma and tuberculosis remains unclear.Patient concerns:We reported a case of EGFR-mutant lung adenocarcinoma (mimicking pulmonary infections) that coexisted with pulmonary tuberculosis during the course of the disease.Diagnoses:The patient was initially diagnosed with pneumonia-like pulmonary adenocarcinoma with EGFR exon 19 deletions based on computed tomography scan, fiberoptic bronchoscopy, pathology, and genetic analysis, and then coexistence with active tuberculosis (TB) was confirmed via laboratory examinations and TB-DNA polymerase chain reaction.Interventions:Antibiotics and gefitinib were administered initially. A combination of gefitinib and anti-TB treatment was then administered when active TB was confirmed, and osimertinib was then prescribed because the disease was progressive and EGFR T790 M mutation was detected.Outcomes:The patient has survived with a stable disease status to date.Lessons:Exploring and ruling out differential diagnoses between pulmonary malignancies and infectious diseases is vital for treatment decisions and outcomes. The combined gefitinib-anti-TB regimen was safe, though it needed modification.     

Application of loop-mediated isothermal amplification and next-generation sequencing in the diagnosis of maternal tuberculosis with multiple negative tests: A case report

Rationale:Tuberculosis (TB) is one of the top 10 causes of death worldwide and is the leading infectious cause of death. The incidence of TB, especially active TB, is increased in pregnant and postpartum women. Newborns can be infected with TB from their mothers through several routes. Diagnosis of TB in pregnant women and infants is difficult. Here, we report the simultaneous postdelivery diagnosis of TB in a mother and infant pair.Patient concerns:A 28-year-old woman presented with a sudden onset of convulsions, loss of consciousness, coughing, fever, and breathing difficulty. Her 18-day-old infant daughter developed cough and wheezing.Diagnosis:The mother''s chest computed tomography showed diffuse interstitial changes and both lungs’ exudation. Enhanced cranial magnetic resonance imaging showed scattered nodular intracranial lesions. A tuberculin skin test and an interferon-gamma release assay were negative. Xpert MTB/RIF (Xpert) testing and acid-fast bacilli smear of bronchoalveolar lavage (BAL) fluid of the mother were negative. Loop-mediated isothermal amplification of BAL fluid was positive for Mycobacterium tuberculosis, and next-generation sequencing confirmed the diagnosis of TB. A biopsy specimen also showed characteristic TB findings. The mother was diagnosed with TB and TB encephalitis. The infant''s BAL fluid was positive for acid-fast bacilli and Xpert and, therefore, was diagnosed with TB.Interventions:The mother was treated with rifampicin and isoniazid for 9 months, ethambutol and pyrazinamide for 3 months, and prednisolone acetate for 8 weeks. The infant received ventilator-assisted ventilation for 10 days and anti-tuberculous therapy for 11 months.Outcomes:After anti-tuberculous therapy, the mother and infant both gradually recovered. The mother''s chest computed tomography showed significant recovery 9 months after discharge. The infant developed normally during the 11-month follow-up.Lessons:This mother-child case pair highlights the value of loop-mediated isothermal amplification and next-generation sequencing as new diagnostic technologies for diagnosing TB in patients with multiple negative tests.     

Adenosine deaminase estimation and multiplex polymerase chain reaction in diagnosis of extra-pulmonary tuberculosis

SETTING: Extra-pulmonary tuberculosis (EPTB), including mycobacteriosis, contributes 15-20% of all tuberculosis (TB) cases. The diagnosis of EPTB remains elusive because of the inadequate sensitivity of routine and conventional bacteriological methods for the detection of Mycobacterium tuberculosis and related organisms in clinical specimens such as cerebrospinal fluid (CSF), pleural fluid and peritoneal fluid. OBJECTIVE: To develop a better diagnostic marker for EPTB. DESIGN: In our study, 179 cases of EPTB were analysed for acid-fast bacilli (AFB) smear, adenosine deaminase activity (ADA) and multiplex polymerase chain reaction (PCR). Although estimation of ADA is helpful, its sensitivity and specificity varies widely. On the other hand, a multiplex PCR using amplicons such as IS6110, dnaJ gene and hsp65 genes has high sensitivity (60-88%) and specificity (81-100%). RESULTS: On comparing AFB and ADA results with PCR, the PCR is clearly more effective than AFB (P < 0.001) and ADA estimation (P < 0.02) in CSF. The same result was observed with peritoneal fluid (P < 0.001 vs. P < 0.05) and pleural fluid (P < 0.001 and P < 0.05). CONCLUSION: The study shows that multiplex PCR remains the best tool and is a much better marker for diagnosing EPTB.     

Ultrasound guided fine needle aspiration biopsy in mediastinal tuberculosis.

SETTING: Diagnosis of mediastinal tuberculosis (TB) is difficult due to non-specific clinical features and lack of characteristic radiographic features. Histopathological confirmation has often required computed tomography guided fine needle aspiration biopsy (FNAB) or even invasive procedures such as mediastinoscopy or open/surgical biopsy. FNAB under ultrasound (US) guidance can also be performed in this clinical setting. OBJECTIVE: To define the role of percutaneous US guided FNAB in the diagnosis of mediastinal tuberculosis. DESIGN: Twenty-six patients with a proven diagnosis of mediastinal TB formed the study group. Chest radiographs and sputum examination were negative. FNAB was performed via suprasternal (n = 20) and parasternal (n = 6) route under sonographic guidance using 22G spinal needle. Aspirates were considered positive for TB when epithelioid cell granuloma with caseation necrosis and/or the presence of Mycobacterium tuberculosis by acid-fast bacilli (AFB) or culture was demonstrated, indeterminate when epithelioid cell granulomas were seen but without caseation necrosis or AFB, and negative when aspirate contained non-representative material. RESULTS: A total of 30 biopsies were performed in the 26 patients, including repeat biopsy and biopsy of different sites in two patients each. FNAB was positive for TB in 20 of the 26 patients. In four, AFB were demonstrated, and in seven culture was positive for M. tuberculosis; in the remaining six patients, cytologic diagnosis was indeterminate in four and negative in two. No procedure related complications were noted. CONCLUSION: Ultrasound guided FNAB is a safe, effective technique in the diagnosis of mediastinal TB.     

Real-time PCR assay for improved detection of Mycobacterium tuberculosis complex in paraffin-embedded tissues.

OBJECTIVE: To test the usefulness of a commercially available real-time polymerase chain reaction (PCR) kit for the detection of Mycobacterium tuberculosis complex (MTBC) in formalin-fixed, paraffin-embedded tissues. RESULTS: The examination of 24 specimens of patients with a final diagnosis of TB shows that the real-time PCR assay exhibits a higher sensitivity (66.7%) for the detection of MTBC DNA than an alternative in-house IS6110 PCR (33.3%), whereas staining detected acid-fast bacilli in only two cases (8.3%). CONCLUSION: The real-time PCR assay provides a highly sensitive and specific means for the detection of MTBC DNA in histopathological specimens.     

Hepatobiliary tuberculosis

Tuberculosis is known to involve the liver in different ways. The term hepatobiliary tuberculosis refers to the localized form of hepatic tuberculosis as a distinct clinical entity, with signs and symptoms related to the hepatobiliary tract. Its clinical features and the different diagnostic aids used in its diagnosis are reviewed. Plain abdominal radiographs showing diffuse hepatic calcifications seen in approximately 50% of cases are almost diagnostic for hepatobiliary tuberculosis. Liver biopsies obtained either by ultrasound, computed tomography or laparoscopy, showing caseating granuloma usually establish the diagnosis. In the absence of caseation necrosis, a positive acid-fast bacillus (AFB) or culture for Mycobacterium tuberculosis is needed to establish the diagnosis. A polymerase chain reaction assay for the identification of Mycobacterium tuberculosis in liver biopsy specimens is a new development. Treatment is similar to that used for pulmonary tuberculosis. Quadruple therapy (using four anti-tuberculosis drugs) is recommended, generally for 1 year. For patients with obstructive jaundice, in addition to anti-tuberculous treatment, biliary decompression should be performed either by stent insertion during endoscopic retrograde cholangiopancreatology, by percutaneous transhepatic biliary drainage or by surgical decompression whenever feasible.     

The use of the paediatric tuberculosis score chart in an HIV-endemic area

BACKGROUND: Diagnosing tuberculosis (TB) in a human immunodeficiency virus (HIV)-endemic area is extremely difficult, as the clinical symptoms of HIV-seropositive children can be easily confounded with TB. The paediatric tuberculosis score chart (TSC) was developed for resource-poor countries and its use continues to be promoted despite the fact that this scoring system has not been evaluated in countries with a high HIV prevalence. OBJECTIVE: To assess the utility of the TSC in an HIV-endemic area. METHOD: A prospective cohort study conducted between January and December 1999 at St Theresa's Mission Hospital, Copperbelt Province, Zambia. Results of the TSC (TB score) were compared with the results of a diagnostic algorithm, incorporating sputum smear microscopy, culture and polymerase chain reaction of Mycobacterium tuberculosis, tuberculin skin test, chest X-ray and histology eventually. RESULTS: A total of 147 children were enrolled in the study. On the basis of HIV-serology and clinical findings they were divided into four groups: children with TB (23 HIV-seropositive; 52 HIV-seronegative), 21 HIV-infected children without TB and 51 HIV-seronegative children without TB. The differences in TB scores between the groups were not significant. The sensitivity of the TSC to diagnose TB in this study was 88%; but the specificity was only 25%. CONCLUSION: The TSC should not be used as a diagnostic tool in countries with a high HIV prevalence. The low specificity of this scoring system leads to overdiagnosis of TB and unnecessary use of costly, antituberculous drugs. New tools for TB diagnosis in children in HIV-endemic areas are urgently needed.     

Polymerase chain reaction for Mycobacterium tuberculosis: impact on clinical management of refugees with pulmonary infiltrates

STUDY OBJECTIVES: Screening for pulmonary tuberculosis (TB) in war refugees entering low-prevalence countries for TB is a common policy, but workup strategies are difficult and expensive. DESIGN: Prospective screening of war refugees for TB by chest radiograph and evaluation of the impact of additional polymerase chain reaction (PCR) testing for Mycobacterium tuberculosis complex (MTB) on clinical management in case of pulmonary infiltrates suspicious for TB. SETTING: Academic university medical center. PATIENTS: A total of 3,119 adult war refugees from the Kosovo war were screened by chest radiograph on arrival. Refugees with pulmonary infiltrates suspicious for TB were hospitalized, and a standardized diagnostic workup was performed. MEASUREMENTS AND RESULTS: Of 3,119 adult war refugees screened for TB, 29 patients (0.9%) were identified with pulmonary infiltrates suspicious for TB; 103 specimens (76 sputa; 27 BAL fluids) were collected for acid-fast smear (AFS), PCR, and culture. The prevalence of culture-proven TB infection in this population was 27.6%. Sensitivity for PCR was higher compared with AFS for all specimens (64% vs 20%; p < 0.01) and also for each refugee with at least one positive specimen finding (100% vs 37.5%; p = 0.025). More important, the negative predictive value for three consecutive PCRs (in two sputa and one BAL) was 100%. CONCLUSIONS: Repeated PCR testing for MTB in a population of asymptomatic war refugees with pulmonary infiltrates highly suggestive of TB is significantly more sensitive than AFS. Three negative PCR results allow discharge from isolation, thus reducing the economic burden of isolation strategies.     

Primary Tuberculosis of the Pancreas Mimicking a Pancreatic Tumor

Summary Background. Diagnosis of tuberculosis of the pancreas is often missed, and may present to the clinician as a difficult diagnostic problem. Methods. We report an extremely rare case of a 35-year-old woman who admitted for acute pain in the right upper quadrant, jaundice, fever 38°C and chills. During the last 8 mo, she developed increasing fatigue and a weight loss of approx 10 kg. Results. Computed tomography (CT) of the abdomen showed a mass in the head of the pancreas, and upper gastrointestinal endoscopy revealed a stenosis of the second part of duodenum and a pancreatico-duodenum fistula. Frozen sections by direct trucut needle biopsy raised suspicions of a malignancy, and a Whipple procedure was performed as a radical procedure. The final histopathology revealed a chronic granulomatous lesion with caseating necrosis. Mycobacterium of tuberculosis was detected using the polymerase chain reaction-based assay. Conclusion. This unusual case emphasizes that in suspected cases of pancreatic carcinoma with an atypical presentation, an attempt should be made to confirm the diagnosis by CT-guided needle biopsy, or by ultrasound endoscopic fine-needle aspiration.     

Diagnosis and treatment of tuberculous pleural effusion in 2006

Tuberculous (TB) pleural effusion occurs in approximately 5% of patients with Mycobacterium tuberculosis infection. The HIV pandemic has been associated with a doubling of the incidence of extrapulmonary TB, which has resulted in increased recognition of TB pleural effusions even in developed nations. Recent studies have provided insights into the immunopathogenesis of pleural TB, including memory T-cell homing and chemokine activation. The definitive diagnosis of TB pleural effusions depends on the demonstration of acid-fast bacilli in the sputum, pleural fluid, or pleural biopsy specimens. The diagnosis can be established in a majority of patients from the clinical features, pleural fluid examination, including cytology, biochemistry, and bacteriology, and pleural biopsy. Measurement of adenosine deaminase and interferon-gamma in the pleural fluid and polymerase chain reaction for M tuberculosis has gained wide acceptance in the diagnosis of TB pleural effusions. Although promising, these tests require further evaluation before their routine use can be recommended. The treatment of TB pleural effusions in patients with HIV/AIDS is essentially similar to that in HIV-negative patients. At present, evidence regarding the use of corticosteroids in the treatment of TB pleural effusion is not clear-cut.     

First Susceptibility Testing of Mycobacterium tuberculosis for Second-line Anti-tuberculosis Drugs in Ghana

We performed drug susceptibility testing on first- and second-line drugs in Mycobacterium tuberculosis (M. tuberculosis) for the first time in Ghana to obtain preliminary data on drug-resistant tuberculosis. Of 21 isolates (4 new cases and 17 treated cases), 5 (23.8%) were multi-drug resistant tuberculosis (MDR-TB) and 19 (90.5%) were resistant to at least one drug, but no extensively drug-resistant TB (XDR-TB) was identified. Since the target patients were Category II, IV or smear positive at follow-up microscopy, it is understandable that there were many drug-resistant TB cases. Six isolates were resistant to one or two second-line drugs, but the second-line drugs were not approved in Ghana. It is considered that the bacilli were imported from abroad. Preventing the import of drug-resistant TB bacilli is probably one of best ways to control TB in Ghana.     

A simple,rapid and economic method for detecting multidrug-resistant tuberculosis

ObjectiveTo evaluate multiplex allele specific polymerase chain reaction as a rapid molecular tool for detecting multidrug-resistant tuberculosis.MethodsBased on drug susceptibility testing, 103 isolates were multidrug-resistant tuberculosis and 45 isolates were sensitive to isonicotinylhydrazine and rifampin. Primers were designed to target five mutations hotspots that confer resistance to the first-line drugs isoniazid and rifampin, and multiplex allele specific polymerase chain reaction was performed. Whole-genome sequencing confirmed drug resistance mutations identified by multiplex allele specific polymerase chain reaction.ResultsDNA sequencing revealed that 68.9% of multidrug-resistant strains have point mutations at codon 315 of the katG gene, 19.8% within the mabA-inhA promoter, and 98.0% at three hotspots within rpoB. Multiplex allele specific polymerase chain reaction detected each of these five mutations, yielding 82.3% sensitivity and 100% specificity for isoniazid resistance, and 97.9% sensitivity and 100% specificity for rifampin resistance as compared to drug susceptibility testing.ConclusionsThe results show that multiplex allele specific polymerase chain reaction is an inexpensive and practical method for rapid detection of multidrug-resistant tuberculosis in developing countries.