Identification Of Mycobacterium Tuberculosis Research Articles

AI-Based Analysis of Ziehl-Neelsen-Stained Sputum Smears for Mycobacterium tuberculosis as a Screening Method for Active Tuberculosis.

Tuberculosis is the primary cause of death due to infection in the world. Identification of Mycobacterium tuberculosis in sputum is a diagnostic test, which can be used in screening programs-especially in countries with a high incidence of tuberculosis-to identify and treat those persons with the highest risk of disseminating the infection. We previously developed an algorithm which is able to automatically detect mycobacteria on tissue; in particular, our algorithm identified acid-fast bacilli on tissue with 100% specificity, 95.65% sensitivity, and 98.33% accuracy. We tested this algorithm on 1059 Ziehl-Neelsen-stained sputum smears to evaluate its results as a possible tool for screening. The results were displayed as a heat map of 32 × 32 pixel patches. Analysis of the positive patches revealed a good specificity (86.84%) and 100% sensitivity for patches with a level of confidence over 90; furthermore, the accuracy remained over 95% for all levels of confidence over 80, except the class (95-100]. The modest specificity is caused by the peculiarities of smears (uneven thickness, dust contamination, lack of coverslip). We will train the algorithm on sputum smears to increase the specificity to over 95%. However, as our algorithm showed no false negatives, it is suitable for screening.

Targeted next-generation sequencing - a promising approach in the diagnosis of Mycobacterium tuberculosis and drug resistance.

Targeted next-generation sequencing (tNGS) offers a high-throughput, culture-independent approach that delivers a comprehensive resistance profile in a significantly shorter turn-around time, making it promising in enhancing tuberculosis (TB) diagnosis and informing treatment decisions. This study aims to evaluate the performance of tNGS in the TB diagnosis and drug resistance detection of Mycobacterium tuberculosis (MTB) using MTB clinical isolates and bronchoalveolar lavage fluid (BALF) samples. A total of 143 MTB clinical isolates were assessed, tNGS, phenotypic antimicrobial susceptibility testing (AST), and AST based on whole genome sequencing (WGS) exhibited high concordance rates, averaging 95.10% and 97.05%. Among 158 BALF samples, culture, Xpert MTB/RIF, and tNGS reported 29, 70 and 111 positives, respectively. In the confirmed cases with etiological evidence (smears, cultures, or molecular test), the positive rate of tNGS (73/83, 87.95%) was higher than that of Xpert MTB (67/83, 80.72%). Additionally, 45% (27/60) of clinically diagnosed cases (with imaging or immunological evidence) were positive for tNGS. Further validation on the discrepant results between tNGS and Xpert MTB/RIF with droplet digital PCR (ddPCR) yielded 35 positives, tNGS detected all, and Xpert MTB/RIF only identified 6 positives. In conclusion, tNGS demonstrates robust and rapid performance in the identification of MTB and its associated drug resistance, and can be directly applied to clinical samples, positioning it as a promising approach for laboratory testing of tuberculosis.

Research on improved YOLOv8s model for detecting mycobacterium tuberculosis

Accurate identification of Mycobacterium tuberculosis (M. tuberculosis) is a critical step in the diagnosis of tuberculosis. Existing object detection methods struggle with the challenges posed by the varied morphology and size of M. tuberculosis in sputum smear images, which makes precise targeting difficult. To solve these problems, an improved YOLOv8s model is proposed. Specifically, an additional detection head is added to focus on small target information. Second, a multi-scale feature fusion module is introduced to adapt the model to different sizes of M. tuberculosis. In addition, a convolutional layer is added to the Coordinate Attention (CA) module to extract more advanced semantic features. Finally, a self-attention mechanism is added after the CA module to enhance the model's ability to accurately understand and localize the varied morphology of M. tuberculosis. Our model performed well with an average precision of 85.7 % when tested on a publicly available dataset. This clearly demonstrates the effectiveness of our proposed model in M. tuberculosis detection.

Detection of Mtb and NTM: preclinical validation of a new asymmetric PCR-binary deoxyribozyme sensor assay.

Tuberculosis (TB) and infectious diseases caused by non-tuberculous mycobacteria (NTM) are global concerns. The development of a rapid and accurate diagnostic method, capable of detecting and identifying different mycobacteria species, is crucial. We propose a molecular approach, the BiDz-TB/NTM, based on the use of binary deoxyribozyme (BiDz) sensors for the detection of Mycobacterium tuberculosis (Mtb) and NTM of clinical interest. A panel of DNA samples was used to evaluate Mtb-BiDz, Mycobacterium abscessus/Mycobacterium chelonae-BiDz, Mycobacterium avium-BiDz, Mycobacterium intracellulare/Mycobacterium chimaera-BiDz, and Mycobacterium kansasii-BiDz sensors in terms of specificity, sensitivity, accuracy, and limit of detection. The BiDz sensors were designed to hybridize specifically with the genetic signatures of the target species. To obtain the BiDz sensor targets, amplification of a fragment containing the hypervariable region 2 of the 16S rRNA was performed, under asymmetric PCR conditions using the reverse primer designed based on linear-after-the-exponential principles. The BiDz-TB/NTM was able to correctly identify 99.6% of the samples, with 100% sensitivity and 0.99 accuracy. The individual values of specificity, sensitivity, and accuracy, obtained for each BiDz sensor, satisfied the recommendations for new diagnostic methods, with sensitivity of 100%, specificity and accuracy ranging from 98% to 100% and from 0.98 to 1.0, respectively. The limit of detection of BiDz sensors ranged from 12 genome copies (Mtb-BiDz) to 2,110 genome copies (Mkan-BiDz). The BiDz-TB/NTM platform would be able to generate results rapidly, allowing the implementation of the appropriate therapeutic regimen and, consequently, the reduction of morbidity and mortality of patients.IMPORTANCEThis article describes the development and evaluation of a new molecular platform for accurate, sensitive, and specific detection and identification of Mycobacterium tuberculosis and other mycobacteria of clinical importance. Based on BiDz sensor technology, this assay prototype is amenable to implementation at the point of care. Our data demonstrate the feasibility of combining the species specificity of BiDz sensors with the sensitivity afforded by asymmetric PCR amplification of target sequences. Preclinical validation of this assay on a large panel of clinical samples supports the further development of this diagnostic tool for the molecular detection of pathogenic mycobacteria.

Advancements in Tuberculosis Diagnostics: A Comprehensive Review of the Critical Role and Future Prospects of Xpert MTB/RIF Ultra Technology.

Tuberculosis remains a persistent global health challenge, demanding swift and accurate diagnostic methods for effective treatment. The emergence of the Xpert MTB/RIF Ultra system marks a significant milestone in combating tuberculosis, streamlining the identification of Mycobacterium tuberculosis, and advancing our pursuit of eradicating the disease. Delving into the therapeutic landscape of tuberculosis and rifampicin resistance, this scientific narrative review offers a comprehensive exploration. It begins by delving into the historical backdrop and the hurdles encountered with traditional tuberculosis diagnostics. From there, it traces the journey of the Xpert MTB/RIF technology, underscoring its molecular underpinnings. In this narrative review, the performance of the Xpert MTB/RIF Ultra system undergoes thorough scrutiny, encompassing investigations into sensitivity, specificity, and comparisons with alternative diagnostic methods. The spotlight shines on its clinical applications across diverse scenarios, from diagnosing pulmonary and extrapulmonary tuberculosis to its pivotal role in identifying rifampicin resistance. The study also evaluates its clinical efficacy in enhancing patient outcomes and supporting global tuberculosis control initiatives. However, the review does not shy away from discussing the challenges and limitations associated with the Xpert MTB/RIF Ultra system. It meticulously addresses concerns regarding cost, infrastructure requirements, and potential diagnostic inaccuracies. Offering a panoramic view, the review assesses the system's impact in resource-constrained settings and its potential to bolster tuberculosis elimination endeavors worldwide. Peering into the future, it explores ongoing research avenues and potential enhancements in Xpert MTB/RIF Ultra technology, envisioning a landscape of improved performance, broader applications, and emerging diagnostic innovations in the realm of tuberculosis diagnostics.

Improved MALDI-TOF MS Identification of Mycobacterium tuberculosis by Use of an Enhanced Cell Disruption Protocol.

Mycobacterium tuberculosis is the microorganism that causes tuberculosis, a disease affecting millions of people worldwide. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a fast, reliable, and cost-effective method for microorganism identification which has been used for the identification of Mycobacterium spp. isolates. However, the mycobacteria cell wall is rich in lipids, which makes it difficult to obtain proteins for MALDI-TOF MS analysis. In this study, two cell preparation protocols were compared: the MycoEx, recommended by MALDI-TOF instrument manufacturer Bruker Daltonics, and the MycoLyser protocol described herein, which used the MagNA Lyser instrument to enhance cell disruption with ethanol. Cell disruption and protein extraction steps with the two protocols were performed using the Mycobacterium tuberculosis H37Rv strain, and the MALDI-TOF MS results were compared. The MycoLyser protocol allowed for improved Biotyper identification of M. tuberculosis since the log(score) values obtained with this protocol were mostly ≥ 1.800 and significantly higher than that underwent MycoEx processing. The identification reliability was increased as well, considering the Bruker criteria. In view of these results, it is concluded that the MycoLyser protocol for mycobacterial cell disruption and protein extraction improves the MALDI-TOF MS method's efficacy for M. tuberculosis identification.

Epidemiology of Molecular Probes in Xpert MTB/RIF Assay in AJK, Pakistan

Objective: This study aimed to detect rifampicin-resistant tuberculosis cases and assess the frequency of missing probes in different study populations in Azad Jammu and Kashmir (AJK), Pakistan. Methodology: The study was conducted at the State TB Reference Laboratory, District Headquarters Teaching Hospital, Mirpur, AJK. A total of 2,790 specimens collected between March 2016 to August 2019 were analyzed. Pulmonary TB (PTB) accounted for 94% of the cases, while 6% were classified as extra-pulmonary cases. All respiratory and non-respiratory samples underwent fluorescence smear microscopy (AFB) and a real-time PCR test (Xpert MTB/RIF assay) to detect Mycobacterium tuberculosis (MTB) and rifampicin resistance. Results: Among the 2,790 suspected MTB patients, 734 (26%) were confirmed to have MTB using the Xpert MTB/RIF assay, while 564 (20%) tested positive by fluorescence microscopy. Of the MTB-positive patients, 720 (98%) were diagnosed with pulmonary TB, and 14 (2%) had extra-pulmonary TB. Rifampicin resistance (RR) was detected in 66 (9%) cases, with 97% of the resistant cases being pulmonary and 3% extra-pulmonary. The most frequently missing probe was E (Codon 529-533), accounting for 34% of the cases, followed by probe D (Codon 523-529) at 26%. The least frequently missing probe was C (Codon 523-529), observed in 3% of the cases. Probe B (Codon 512-518) was missing in 15.4% of cases, while probe A (Codon 518-523) was missing in 9.4% of cases. Conclusion: The utilization of molecular diagnostic techniques, such as the Xpert MTB/RIF assay, enables rapid identification of MTB and detection of rifampicin resistance. This study provides valuable baseline data on the prevalence of 81 bp mutations in the rpoB gene, highlighting the need for further evaluation of mutation patterns in AJK.

Ocular Tuberculosis in Pediatrics: A Case Report

A 17-year-old male was taken to the emergency department for decreased left visual acuity and floaters beginning that same day. There was a history of exposure to pulmonary tuberculosis five years before (mother as index case) followed by a four-month period of isoniazid prophylaxis. The ophthalmic examination showed posterior and intermediate uveitis in the left eye. Laboratory tests were normal; IgG for herpes simplex 1 was positive and both the varicella-zoster virus and remaining serologic tests were negative. Chest radiography was normal. Two weeks later, an epiretinal membrane with risk of tractional retinal detachment was observed. The Mantoux tuberculin skin test showed an induration of 15 mm and the IGRA test was positive. Sputum and vitreous humor samples were collected. Quadruple therapy and prednisolone were started. Ten days later, a posterior vitreous detachment with underlying vitreous hematoma was observed. Posterior vitrectomy and peripheral endolaser were performed without complications. One month later, the microbiological results became available, with the identification of Mycobacterium tuberculosis. Corticosteroids were weaned progressively. Antituberculous drugs were maintained for six months. The patient made a full recovery.

Identification of Mycobacterium tuberculosis in pulmonary and extrapulmonary specimens of Iranian hospitalized patients during 2017-2021.

Tuberculosis (TB) is one of the most serious public health problems worldwide which is a chronic infectious disease and is still one of the major challenges for developing countries. This study was undertaken to identify Mycobacterium TB (MTB) in clinical specimens in hospitalized patients. The study was carried out on specimens from pulmonary and extrapulmonary suspected TB patients that were admitted to one of the largest tertiary hospitals located in Tehran, Iran from 2017 to 2021. The GeneXpert MTB/rifampin (RIF) method was applied to detect MTB and RIF resistance. Characteristics of demography, clinical features, and lifestyle were obtained from medical case records registered in the hospital. Of 957 specimens, 92 (9.61%) were found positive for TB by GeneXpert assay. Of positive samples, 72 (78.26%) were considered pulmonary TB, and 20 (21.73%) of them are associated with extrapulmonary involvement. Four (4.3%) positive TB cases were categorized as rifampicin-resistant. This study showed a relatively high incidence rate of TB in distinct types of specimens in Iranian hospitalized patients but a low level of RIF resistance.

Identification of Mycobacterium Tuberculosis in Active Smokers with Ziehl–Neelsen Staining Method

Tuberculosis is still a health problem for the people of Indonesia, especially active smokers. There are many risk factors that can cause tuberculosis in active smokers including age at starting smoking, number of cigarettes consumed per day, and how long smoking has been done. The purpose of this study was to determine the results of identifying mycobacterium tuberculosis in active smokers with the Ziehl–Neelsen staining acid resistance test method. This type of research is a descriptive-analytic study that aims to determine the results of identifying Mycobacterium tuberculosis in active smokers. The Ziehl–Neelsen staining acid resistance test was conducted at the Tourism Hospital Laboratory of the University of East Indonesia Makassar on September 22 to October 6, 2022. The population in the study is 10 people. The sample was determined using a total sampling technique so that 10 samples were obtained. The research variables were active smokers. The data obtained are presented in the form of tables and narratives. After laboratory testing using the Ziehl–Neelsen staining method, the conclusion was that 1 out of 10 samples of active smokers was identified as Mycobacterium Tuberculosis.

Rapid identification of Mycobacterium tuberculosis in cultures by molecular and immunological methods

Objective : The study aimed to evaluate molecular and immunological methods and to propose a workflow using them for tuberculosis (TB) diagnosis routine. Methods : A cross-sectional retrospective study was performed, including 121 liquid cultures from a TB laboratory located in the extreme south of Brazil. All cultures were positive for Mycobacterium tuberculosis complex (MTBC) by in-house Polymerase Chain Reaction (PCR) using DNA extracted by the CTAB method (PCR-CTAB) for IS6110 detection. These cultures were subjected to faster tests than this one, the immunological MPT64 assay and the PCR using DNA extracted by thermal lysis method (PCR-TL), and these were evaluated for MTBC identification using PCR- CTAB as a reference method. Results :The sensitivity of MPT64 assay and PCR-TL to identify MTBC in positive cultures by PCR-CTAB were 73.6% (89/121) and 98.3% (119/121), respectively. We proposed a workflow based on the use of MPT64 assay in liquid cultures suggestive of MTBC, and in case of a negative result, we suggest the performance of PCR-TL. The PCR-CTAB is suggested only if faster tests are negative. Conclusions : Methods capable of confirming MTBC in cultures should continue to be standardized, tested, and optimized to meet the ideal requirements of simplicity, quickness, and effectiveness. The molecular and immunological methods evaluated have differences in the execution and detection of MTBC in cultures, but they are rapid tools for laboratory TB diagnosis.

A new droplet digital PCR assay: improving detection of paucibacillary smear-negative pulmonary tuberculosis

ObjectivesSmear-negative pulmonary TB (PTB) is difficult to diagnose. Current diagnosis and treatment monitoring methods have inherent limitations. Droplet digital PCR (ddPCR) is a new technique with high sensitivity. This study presents a novel ddPCR for rapid and sensitive identification of Mycobacterium tuberculosis (MTB). MethodsMTB DNA was detected in respiratory specimens from suspected PTB cases using ddPCR assay, which was directed at two different locations within IS6110. We, for the first time, evaluated the clinical diagnostic ability of this ddPCR for paucibacillary smear-negative PTB. ResultsA total of 605 PTB suspects were recruited, including 263 patients with confirmed PTB (84.03% from smear-negative PTB) and 342 without PTB. The sensitivity and specificity of IS6110 ddPCR were 61.22% (95% confidence interval (CI) 55.00-67.10%) and 95.03% (95% CI 92.20-97.10%) for total PTB and 57.92% (95% CI 51.10-64.50%) and 94.57% (95% CI 91.20-96.90%) for smear-negative PTB. ddPCR assay outperformed Xpert MTB/RIF (53.08% vs 28.46%, P = 0.020) in smear-negative PTB detection. Furthermore, effective anti-TB treatment was linked to significantly lower IS6110 copies detected by ddPCR. ConclusionHerein, we developed and validated a highly sensitive and robust ddPCR assay for MTB quantification in respiratory specimens, which improves diagnosis and therapeutic effect evaluation of smear-negative PTB.

Innovations in Molecular Identification of Mycobacterium tuberculosis

Tuberculosis (TB) continues to be a significant public health concern on a global scale. Quick and precise identification of Mycobacterium tuberculosis (MTB) in symptomatic patients is pivotal for worldwide TB eradication initiatives. As an infectious disorder induced by MTB, it remains a critical threat to public health, particularly in poor countries, due to an inadequate diagnostic research laboratory. There is a need for a persistent incentive to reduce response time for effective diagnosis and control of TB infection, which is a benefit that molecular techniques provide over traditional methods. Although there is a tremendous overall prevalence of TB and a relatively poor probability of case identification worldwide. Common screening techniques have focused on tests that have many fundamental shortcomings. Due to the development of antibiotic-resistant Mycobacterium strains, TB is one of the leading contributors to fatalities. It is now possible to examine TB using molecular detection techniques, which are faster and more cost-effective than previous methods, such as standard culture procedures to test and verify antibiotic resistance in patients with TB. Whole genome sequencing (WGS), faster nucleic acid amplification tests, has made it easier to diagnose and treat TB more quickly. This article addresses the genetic approaches for detecting Mycobacterium tuberculosis complex (MTBC) in clinical specimens as well as antibiotic resistance in mycobacterium and discusses the practical limitations of using these methods.

Machine learning analysis of SERS fingerprinting for the rapid determination of Mycobacterium tuberculosis infection and drug resistance

Over the past decades, conventional methods and molecular assays have been developed for the detection of tuberculosis (TB). However, these techniques suffer limitations in the identification of Mycobacterium tuberculosis (Mtb), such as long turnaround time and low detection sensitivity, etc., not even mentioning the difficulty in discriminating antibiotics-resistant Mtb strains that cause great challenges in TB treatment and prevention. Thus, techniques with easy implementation for rapid diagnosis of Mtb infection are in high demand for routine TB diagnosis. Due to the label-free, low-cost and non-invasive features, surface enhanced Raman spectroscopy (SERS) has been extensively investigated for its potential in bacterial pathogen identification. However, at current stage, few studies have recruited handheld Raman spectrometer to discriminate sputum samples with or without Mtb, separate pulmonary Mtb strains from extra-pulmonary Mtb strains, or profile Mtb strains with different antibiotic resistance characteristics. In this study, we recruited a set of supervised machine learning algorithms to dissect different SERS spectra generated via a handheld Raman spectrometer with a focus on deep learning algorithms, through which sputum samples with or without Mtb strains were successfully differentiated (5-fold cross-validation accuracy = 94.32%). Meanwhile, Mtb strains isolated from pulmonary and extra-pulmonary samples were effectively separated (5-fold cross-validation accuracy = 99.86%). Moreover, Mtb strains with different drug-resistant profiles were also competently distinguished (5-fold cross-validation accuracy = 99.59%). Taken together, we concluded that, with the assistance of deep learning algorithms, handheld Raman spectrometer has a high application potential for rapid point-of-care diagnosis of Mtb infections in future.

The Mycobacterium tuberculosis sRNA F6 Modifies Expression of Essential Chaperonins, GroEL2 and GroES.

ABSTRACTAlmost 140 years after the identification of Mycobacterium tuberculosis as the etiological agent of tuberculosis, important aspects of its biology remain poorly described. Little is known about the role of posttranscriptional control of gene expression and RNA biology, including the role of most of the small RNAs (sRNAs) identified to date. We have carried out a detailed investigation of the M. tuberculosis sRNA F6 and shown it to be dependent on SigF for expression and significantly induced in starvation conditions in vitro and in a mouse model of infection. Further exploration of F6 using an in vitro starvation model of infection indicates that F6 affects the expression of the essential chaperonins GroEL2 and GroES. Our results point toward a role for F6 during periods of low metabolic activity typically associated with long-term survival of M. tuberculosis in human granulomas.IMPORTANCE Control of gene expression via small regulatory RNAs (sRNAs) is poorly understood in one of the most successful pathogens, Mycobacterium tuberculosis. Here, we present an in-depth characterization of the sRNA F6, including its expression in different infection models and the differential gene expression observed upon deletion of the sRNA. Our results demonstrate that deletion of F6 leads to dysregulation of the two essential chaperonins GroEL2 and GroES and, moreover, indicate a role for F6 in the long-term survival and persistence of M. tuberculosis in the human host.

Effectiveness of inhaled hypertonic saline application for sputum induction to improve Mycobacterium tuberculosis identification in patients with pulmonary tuberculosis.

This study assessed the effectiveness and diagnostic significance of hypertonic saline sputum induction for improving Mycobacterium tuberculosis (MTB) detection. A prospective, randomized, open, two-arm, comparative study on MTB identification effectiveness when using inhaled sodium chloride hypertonic solution was performed in patients diagnosed with pulmonary tuberculosis (TB). Patients were randomly assigned into two groups: group1 (inhalation group) included patients who inhaled a7% sodium chloride solution upon admission to the hospital, and group2 (control group) coughed up their sputum as usual. For both groups, specimens were tested by bacterioscopic, bacteriological, and molecular genetic methods. Diagnostic chest radiography was performed for all participants. In this study, 644 patients (mean age 42.2years; 151 women, 23.4%) were randomly divided into two groups. Low-quality sputum samples were observed in 7.4% of patients from the inhalation group and 28.8% in the control group (p < 0.001). Acid-fast bacilli (AFB) smear was positive in 65.1% of patients from the inhalation group and 51.3% of controls (p = 0.002). Asimilar statistically significant situation was observed when culture methods (93.9% inhalation group and 81.9% control group, p < 0.001) and molecular genetic tests (92.2% inhalation group and 79.4% control group, p < 0.001) were used. Thus, active pulmonary TB was not verified microbiologically in 6.1% of patients from the inhalation group and in 18.1% of controls (p < 0.001). Hypertonic saline sputum induction improves the quality of collected samples. This method may be appropriate to increase the rate of MTB detection in sputum using microscopic, bacteriological, and molecular genetic methods for diagnosing TB on the day of specimen collection. Hypertonic saline sputum induction is suitable for middle- and low-income countries with limited resources and causes no severe adverse effects in TB patients.

Age and sex distribution of Mycobacterium tuberculosis infection and rifampicin resistance in Myanmar as detected by Xpert MTB/RIF

BackgroundDetection of tuberculosis disease (TB) and timely identification of Mycobacterium tuberculosis (Mtb) strains that are resistant to treatment are key to halting tuberculosis transmission, improving treatment outcomes, and reducing mortality.MethodsWe used 332,657 Xpert MTB/RIF assay results, captured as part of the Myanmar Data Utilization Project, to characterize Mtb test positivity and rifampicin resistance by both age and sex, and to evaluate risk factors associated with rifampicin resistance.ResultsOverall, 70% of individuals diagnosed with TB were males. Test positivity was higher among males (47%) compared to females (39%). The highest positivity by age occurred among individuals aged 16–20, with test positivity for females (65%) higher than for males (57%). Although a greater absolute number of males were rifampicin resistant, a greater proportion of females (11.4%) were rifampicin resistant as compared to males (9.3%). In the multivariate model, history of previous treatment, age less than 30, testing in the Yangon region, and female sex were significantly positively associated with rifampicin resistance after adjusting for HIV status and year test was performed.ConclusionsOur results indicate that young adults were more likely to test positive for TB and be identified as rifampicin resistant compared to older adults.

Tuberculous otitis media in Vietnam: Clinical features and diagnostic difficulties

ObjectivesThe purpose of this article is to draw the attention of otorhinolaryngologists to tuberculous otitis media in the light of two cases illustrating the diagnostic difficulties of this rare form of extrapulmonary tuberculosis, which often presents as subacute otomastoiditis or apparently benign chronic otitis media. It is characterized by symptoms such as atonic tympanic membrane perforation with granulation tissue, absence of any history of otitis media, facial paralysis or severe otosclerosis, and failure to respond to the usual treatments. Case reportsThe first case was a 24-year-old man referred for right chronic otitis media present for 18 months despite topical treatment and tympanoplasty. The second case was a 21-year-old woman referred for right facial paralysis present for 8 days in a context of chronic otitis media, also treated medically for two years and by two tympanoplasties without success. ConclusionThe diagnosis of tuberculous otitis media is not based on histopathological examination, but bacteriological identification of Mycobacterium tuberculosis on an otorrhoea fluid sample collected according to the technique described here. A rigorous clinical approach should ensure early diagnosis and initiation of treatment to prevent complications and severe sequelae.

Identification of Mycobacterium tuberculosis and Rifampin Resistance in Pulmonary and Extra-pulmonary Clinical Specimens Using the Gene Xpert MTB/RIF Assay

Identification of Mycobacterium tuberculosis and Rifampin Resistance in Pulmonary and Extra-pulmonary Clinical Specimens Using the Gene Xpert MTB/RIF Assay

The diagnostic impact of implementing a molecular-based algorithm to standard mycobacterial screening at a reference laboratory with an intermediate prevalence for non-respiratory samples.

Rapid, reliable results can be given by molecular, direct detection and identification of the Mycobacterium tuberculosis (MTB/Mtb) complex from clinical samples. The Xpert MTB/RIF assay is an assay that has been availablefor more than a decade for identification of Mycobacterium tuberculosis and resistance to rifampicin. However, there is minimal evidence on its clinical usefulness in paucibacillary, non-respiratory samples. The Xpert MTB/RIF assay clinical utility index, its diagnostic characteristics and the number required to diagnose 2935 non-respiratory specimens submitted for routine mycobacterial work-up in a reference laboratory in an intermediate prevalence setting per specimen form were evaluated. The Xpert MTB/RIF assay showed a variable clinical utility index and number required to diagnose (NND) depending on the type of specimen, which was moderate in tissue biopsies (NND = 1.8) and excellent in pus and urine samples, compared to acid-fast microscopy and culture as a gold standard technique (NND = 1.1 and 1.2). Microscopy, on the other hand, consistently showed a weak to fair index of clinical usefulness in all specimen forms, with in NND of 2.3–12.5. The NND for detecting tuberculous infection in the cerebrospinal fluid by the Xpert MTB/RIF assay was noted to be 1.2, with a moderate clinical utility index of 0.8. The evidence presented indicates that the overall appropriate diagnostic utility of the Xpert MTB/RIF assay is clinically successful in most non-respiratory samples. To check the cost-effectiveness and prognostic effect of integrating this completely automated molecular-based assay into the routine testing algorithm for non-respiratory mycobacterial specimens, further data must be collected.