Detection Of Rifampicin Resistance Research Articles

Impact of Xpert MTB/RIF on Outcomes of Adults Hospitalized With Spinal Tuberculosis: Findings From a Comparative Cohort in Beijing, China.

BackgroundSpinal tuberculosis (TB) is one of the most common forms of extrapulmonary tuberculosis, causing increased morbidity and lifelong disabilities. Here, we conducted a retrospective study to determine the impact on patient outcomes of the Xpert MTB/RIF test vs. phenotypical drug susceptibility testing for spinal TB.MethodsIn-patients with spinal TB were enrolled in 2013 and 2017 at Beijing Chest Hospital. Data were collected from an electronic patient record system that documented demographic and clinical characteristics. All the patients were routinely followed-up at 1, 3, 6, 9, and 12 months after surgery during outpatient treatment.ResultsA total of 361 patients affected by spinal TB were enrolled in our analysis, including 178 patients in 2013 and 183 patients in 2017. In 2013, the cumulative postoperative recurrence rate of patients with spinal TB was 23% (41/178), which was significantly higher than that in 2017 (8.2%, 15/183, P < 0.001). Additionally, the patients with spinal TB diagnosed in 2013 relapsed significantly sooner than those in 2017 (P < 0.001). In the multivariate analysis, rifampicin (RIF) resistance was associated with the recurrence of spinal TB. The turnaround time of Xpert ranged from 1 to 3 days, with a median of 1 day (IQR: 1–2). For the phenotypic drug susceptibility test (pDST)-based algorithm, the median turnaround time was 67 days, considerably longer than that of the Xpert-based algorithm (P < 0.001).ConclusionThe RIF resistance is an independent risk factor for postoperative recurrence in patients with spinal TB. Early detection of RIF resistance due to the application of Xpert is an effective strategy to reduce spinal TB recurrence.

Agreement between CBNAAT, liquid culture and line probe assay for detection of Mycobacterium tuberculosis and anti-tubercular drug resistance in extrapulmonary samples

PurposeCartridge based nucleic acid amplification test (CBNAAT) has been endorsed by the WHO as the screening test for diagnosing extrapulmonary tuberculosis (EPTB). In the present study we report the agreement between CBNAAT (Xpert MTB/RIF), liquid culture (LC) and line probe assay (LPA) for diagnosis of Mycobacterium tuberculosis and detection of drug resistance among EPTB cases. MethodsThe EP samples were subjected to CBNAAT (Xpert MTB/RIF, Cepheid, USA) and wherever possible, to LC (MGIT 960, Becton Dickinson, USA) followed sequentially by first line and second line-LPA (FL-LPA, SL-LPA, Hain Lifescience, Germany) on the isolates. ResultsTotal 566/4080 (13.9%) EP samples were detected positive for M. tuberculosis on CBNAAT. Aspirates from lymph nodes were most often positive (11/30; 36.6%), followed by pus (240/873; 27.5%) and CSF samples (166/104; 15.8%). The detection of M. tuberculosis was more in adults than children except in tissue biopsy samples. Rifampicin resistance was also higher among adults except CSF in which resistance was more in children. Total 185 of 566 (32.7%) CBNAAT positive and 770 of 3510 (21.9%) CBNAAT negative samples could be cultured of which 110/185 (59.4%) and 33/770 (4.3%) respectively turned positive. FL-LPA and SL-LPA of 143 culture isolates showed that 27 isolates had drug resistance, of which 3 (2.1%) were XDR, 11 (7.7%) were Pre-XDR (FQ) and 13 (9.1%) were MDR. Of these 27 resistant isolates, 12 were negative by CBNAAT and two were mislabeled as Rifampicin sensitive or indeterminate based on the unique RpoB gene mutation patterns on LPA. The positive and negative agreements between LC and CBNAAT for detection of M. tuberculosis were 67.1% and 92.7% respectively and between LPA and CBNAAT for rifampicin resistance detection were 98.9% and 92.9% respectively. ConclusionsFor EPTB, CBNAAT should be accompanied with LC wherever possible irrespective of the CBNAAT result.

PERFORMANCE OF XPERT MTB/RIF ULTRA AND GENOTYPE MTBDRPLUS ASSAY IN THE DIAGNOSIS OF DRUG-RESISTANT TB IN TIRANA, ALBANIA

TYPE: Late Breaking Abstract TOPIC: Chest Infections PURPOSE: In a low resource setting, the tuberculosis (TB) culture may pose a problem for case detection and initiation of second-line treatment due to both financial restraints and technical challenges. There is a need for rapid, reliable and easily accessible tools for diagnosis of drug resistant TB. This comparative analysis was performed to assess diagnostic performance characteristics of GeneXpert MTB/RIF Ultra and MTBDRplus Assay. METHODS: A systematic random sampling procedure was used to select sputum samples from a pool of samples received at the National TB Reference Laboratory for TB diagnosis between January to December 2021. Fifty-three smear positive sputum samples were subjected to testing by GeneXpert MTB/RIF Ultra, MTBDRplus Assay, BACTEC MGIT Culture and drug susceptibility testing (DST). Sensitivity, specificity and predictive values were then determined to assess the performance characteristics of the two assays compared to DST as a reference standard. RESULTS: For diagnosis of rifampicin resistance, GeneXpert MTB/RIF Ultra had a sensitivity, specificity, positive predictive value, and negative predictive value of 66.7, 100, 100 and 98.1% respectively while MTBDRplus assay had 100, 100, 100 and 100%. For diagnosis of isoniazid resistance, MTBDRplus assay had a sensitivity, specificity, positive predictive value, and negative predictive value of 87.5, 100, 100, and 97.8% compared to DST. CONCLUSIONS: MTBDRplus assay shows a slightly better performance characteristic to GeneXpert MTB/RIF Ultra, regarding detection of rifampicin resistance. CLINICAL IMPLICATIONS: MTBDRplus assay may represent an alternative to culture with regards to detection of both rifampicin and isoniazid resistance in smear positive samples. DISCLOSURE: No significant relationships. KEYWORD: drug resistant tuberculosis

The Diagnostic Performance of Fluorescent Microscopy and MTB/RIF Assay Gene Xpert in Pulmonary Tuberculosis at Tertiary Care Hospital of Lahore

Objective: To find out the diagnostic precision of GeneXpert and AFB smear by fluorescent microscope for diagnosis of pulmonary tuberculosis keeping the culture as a gold standard. Methodology: A survey performed in the Pulmonology and Pathology Department, Lahore General Hospital, Lahore. Patients of age 16-70 years, both genders presented with cough&gt;2weeks, fever &gt;99oF, and sputum, with radiographic findings constant with pulmonary T.B were included in this study. Patients previously diagnosed with PTB and on antibiotics within 2 weeks at the time of inclusion and patients having extrapulmonary TB were excluded from this study. Patients were asked to submit sputum samples in 2 containers, one having 2-3 ml and the other having 4-5 ml of sputum. The samples were proceeded according to SOPs for FM sputum microscopy, MTB/RIF assay &amp; sputum culture. The collected data was analysed statistically with the help of SPSS version 20. Results: There were 100 patients included in this study with mean age of cases 42.66 ± 15.69 years. There were 59% male and 41% female, with a higher male to female ratio. 73% cases were positive on Gene Xpert, 68% on AFB smear, and 72% cases were positive on culture. The specificity, sensitivity, NPV, PPV &amp; overall diagnostic accuracy of Gene Xpert was 71.43%, 90.28%, 74.07%, 89.04% and 85.00% and for AFB LED-FM microscopy was 86.11%, 78.57%, 91.18%, 68.75% and 84.00% respectively. Conclusion: Simple modality like fluorescent microscopy gave better results and diagnostic yield as compared to Zn microscopy. Gene Xpert MTB/RIF assay detected TB in very short time, and it is sensitive and accurate method along with detection of rifampicin resistance. However, more studies like that should be recommended as Pakistan is still at 5th number among high load diseased countries. The culture is always a gold standard method among all these sensitive and specific methods. Keywords: Pulmonary TB, Gene Xpert, Fluorescent microscopy, sensitivity, specificity.

Evaluating diagnostic performance of Truenat MTB Plus for gastrointestinal tuberculosis.

Prompt and accurate diagnosis of gastrointestinal tuberculosis (GITB) along with simultaneous detection of drug resistance is inevitable for tuberculosis elimination. Truenat MTB Plus (TruPlus), a chip-based real-time polymerase chain reaction assay, was evaluated for the first time for diagnosing GITB and detecting rifampicin resistance. Fifty ileocecal biopsy specimens (5 microbiologically confirmed GITB [culture-positive], 25 clinically confirmed GITB [culture-negative], and 20 control patients) processed in the Department of Microbiology between 2011 and 2021 were subjected to TruPlus assay, Xpert MTB RIF assay multiplex polymerase chain reaction. Their performance was evaluated against both culture and composite reference standard. The overall sensitivity and specificity of TruPlus in diagnosing GITB was 70% (21/30) and 100%, respectively. The sensitivity was 60% (3/5) for microbiologically confirmed cases and 72% (18/25) for clinically confirmed cases. Performance of TruPlus was superior to Xpert (sensitivity=30%; P=0.001) and comparable with MPCR (sensitivity=83.33%; P=0.13). Both TruPlus and MPCR had moderate agreement with reference standards, and MPCR detected additional three cases. Both TruPlus and Xpert correctly reported Rifampicin resistance in three cases. TruPlus, with its greater portability and higher sensitivity than Xpert, could serve as an important tool for diagnosing GITB and rifampicin resistance at outreach endemic areas.

Comparison of conventional diagnostic methods with molecular method for the diagnosis of pulmonary tuberculosis

BackgroundTuberculosis remains one of the deadliest communicable diseases. Prompt diagnosis of active tuberculosis cases facilitates timely therapeutic intervention and minimizes the community transmission. Although conventional microscopy has low sensitivity, still it remains the corner stone for the diagnosis of pulmonary tuberculosis in high burden countries like India. On the other hand, Nucleic acid amplification techniques due to their rapidity and sensitivity, not only help in early diagnosis and management of tuberculosis but also curtail the transmission of the disease. This study therefore was aimed at assessing the diagnostic performance of Microscopy by Ziehl Neelsen (ZN) and Auramine Staining (AO) with Gene Xpert/CBNAAT (Cartridge based nucleic acid amplification test) in the diagnosis of Pulmonary Tuberculosis. MethodsA prospective comparative study was done on the sputum samples of 1583 adult patients from November 2018 to May 2020 suspected of having pulmonary tuberculosis as per NTEP criteria visiting the Designated Microscopic Centre of SGT Medical College, Budhera, Gurugram. Each sample was subjected to ZN staining, AO staining, and was run on CBNAAT as per National Tuberculosis Elimination Program (NTEP) guidelines. The sensitivity, specificity, PPV and NPV and Area under the curve of ZN microscopy and Fluorescent Microscopy were calculated taking CBNAAT as reference in absence of culture. ResultsOut of the 1583 samples studied, 145 (9.15%) and 197 (12.44%) were positive by ZN and AO staining methods respectively. By CBNAAT 246 (15.54%) samples were positive for M. tuberculosis. AO was also able to detect more pauci-bacillary cases than ZN. While CBNAAT detected M. tuberculosis in 49 sputum samples which were missed by both methods of microscopy. On the other hand there were 9 samples which were positive for AFB by both the smear microscopy techniques but M. tuberculosis was not detected by CBNAAT, these were considered as Non-Tuberculous Mycobacteria. Seventeen samples were resistant to rifampicin. ConclusionAuramine Staining technique is more sensitive and less time consuming for the diagnosis of pulmonary tuberculosis as compared to the conventional ZN Staining. CBNAAT can be a useful tool for early diagnosis of patients with high clinical suspicion of pulmonary tuberculosis and detecting rifampicin resistance.

Clinical evaluation of the cobas® MTB-RIF/INH reagent and the cobas® 6800 for the detection of isoniazid and rifampicin resistance

We aimed to validate the performance of a newly developed real-time PCR assay using cobas® MTB-RIF/INH reagent on the cobas® 6800 system for detecting isoniazid (INH) and rifampicin (RIF) resistance, using Japanese Mycobacterium tuberculosis (MTB) isolates. In total, 119 mock sputum specimens spiked with resistant MTB were tested using the cobas® MTB-RIF/INH reagent. The whole genomes of all MTB isolates were sequenced by MiSeq and analysed for mutations/indels causing drug resistance. All isolates were tested for phenotypic drug susceptibility, then MTB negative sputa were collected and pooled to prepare mock sputum specimens for the study. The sensitivity and specificity for INH resistance at a concentration equal to 3 × the limit of detection were 77.8% and 90.0%, respectively; those for RIF resistance were 91.8% and 93.5%, respectively. The sensitivities for INH and RIF were statistically different (P = 0.014), but not the specificities (P = 0.624). Twenty-two false-susceptible and two false-resistant results were obtained in INH; meanwhile, six false-susceptible and three false-resistant results were obtained in RIF. False-resistance for INH and RIF was mainly due to disputed mutations. The cobas® MTB-RIF/INH reagent showed better performance than other rapid molecular tests.

Spinal cord involvement in tuberculous meningitis: a case report and brief review of literature

Introduction: Tuberculosis (TB) continues to pose a significant public health problem worldwide. Tuberculous meningitis (TBM) is the most devastating form of extrapulmonary TB however other forms of central nervous system (CNS) disease include tuberculoma and spinal arachnoiditis. TBM carries high mortality even for a patient who is already receiving treatment. The difficulty in diagnosis often leads to a delay in treatment and subsequent mortality. The emergence of Xpert ultra has improved the rapid detection of MTB and rifampicin resistance in CSF and is the preferred diagnostic tool in TBM. Case: In this case report we present a 33years patient of concern who presented with progressive lower limb weakness associated with pain and paresthesia for 4 months, admitted via the Orthopedic unit with a diagnosis of spinal mass (meningioma, neurofibroma, or nerve sheath tumor) for which biopsy was done and revealed a chronic inflammatory process, necrotic bone lesions with no granulomas and no malignancy, he was later diagnosed with tuberculous meningitis and promptly started anti-tuberculous therapy with a dramatic recovery and improvement in neurological function. Conclusion: Tuberculous meningitis conditions have high morbidity and mortality yet diagnosis and start of treatment continue to experience an important delay. Clinicians should keep in mind the limitations of clinical presentation due to pleiotropy and current diagnostics and should employ a combination of diagnostic modalities in addition to a high index of suspicion to prevent morbidity in patients with TBM.

GENE MUTATION PATTERNS OF RIFAMPICIN IN MULTIDRUG RESISTANT MYCOBACTERIUM TUBERCULOSIS COMPLEX STRAINS

Objective: The aim of this study was to evaluate the GenoType®MTBDRplus test for detection of rifampicin (RIF) resistance in MDR Mycobacterium tuberculosis complex strains. Materials and Methods: Twenty-five multidrug-resistant (MDR) Mycobacterium tuberculosis clinical strains were used, gene mutations causing RIF resistance were investigated by GenoType®MTBDRplus and the results were compared with the results of the BACTEC 460 TB system. The strain was sequenced if there was no mutation and absence Wild Type (WT). Mycobacterium tuberculosis ATCC 35838 was used as a quality control (QC) strain. Results: There was 96% compliance between the GenoType®MTBDRplus and BACTEC 460 TB system for the finding of RIF resistance. The most frequent mutation zone in MDR strains was rpoB S531L promotor zone (13 strains, 52%). The other rpoB gene mutations were H526Y (three strains, 12%) and H526D (three strains, 12%), while five strains (20%) had Δ2-Δ5 mutations in the wild type probes. There was no mutation in only one strain (4%) by GenoType®MTBDRplus but it was found to be as resistant to rifampicin by the BACTEC 460 TB system. This strain was sequenced and detected to have triple mutations. Mutations were found on codons 489, 493, and 503. Conclusion: GenoType®MTBDRplus showed good compatibility with the BACTEC 460 TB system in detecting rifampicin resistance, and it was thought that GenoType®MTBDRplus could be an effective and reliable test for RIF susceptibility testing in MDRTB patients, providing a significant advantage in technical time.

A cost\u2013benefit algorithm for rapid diagnosis of tuberculosis and rifampicin resistance detection during mass screening campaigns

BackgroundActive tuberculosis (TB) case finding is important as it helps detect pulmonary TB cases missed by the other active screening methods. It requires periodic mass screening in risk population groups such as prisoners and refugees. Unfortunately, in these risk population groups periodic mass screening can be challenging due to lengthy turnaround time (TAT), cost and implementation constraints. The aim of this study was to evaluate a diagnostic algorithm that can reduce the TAT and cost for TB and Rifampicin resistance (RR) detection. The algorithm involves testing with TB-LAMP followed by Xpert MTB/RIF for positive TB-LAMP cases to diagnose TB during mass campaigns in prisons and refugee camps.MethodsThe National Tuberculosis Control Program (NTCP) organized routine TB mass-screening campaigns in 34 prisons and 3 villages with refugees camps in Cameroon in 2019. TB LAMP was used for initial TB diagnosis and all TB-LAMP positive cases tested with the Xpert MTB/RIF assay to determine RR. TAT and cost benefits analysis of the combined use of TB-LAMP and Xpert MTB/RIF assays was determined and compared to the Xpert MTB/RIF assay when used only.ResultsA total of 4075 sputum samples were collected from TB presumptive, 3672 cases in 34 prisons and 403 samples in 3 villages. Of the 4,075 samples screened with TB-LAMP, 135 were TB positive (3.31%) and run on the Xpert MTB/RIF. Of the 135 positives cases, Xpert MTB/RIF revealed 3 were RR (2.22%). The use of TB-LAMP followed by testing with Xpert MTB/RIF for TB and RR detection reduced the TAT by 73.23% in prisons and 74.92% in villages. In addition to a reduced TAT, the two molecular tests used in synergy is cost benefit from year 2 onwards.ConclusionThis study demonstrates the advantages of a diagnostic algorithm based on an initial testing with TB-LAMP followed by testing with Xpert MTB/RIF for TB diagnosis. This approach improved early and rapid TB detection with an added advantage of providing RR status. The proposed algorithm is effective and less costly from the second year of implementation and should be used by TB control programs.

Detection of Mycobacterium tuberculosis Rifampicin Resistance Conferred by Borderline rpoB Mutations: Xpert MTB/RIF is Superior to Phenotypic Drug Susceptibility Testing

ObjectiveTo compare the ability of detection of borderline rifampicin resistance in Mycobacterium tuberculosis between molecular assay and phenotypic drug susceptibility tests.MethodsFifty-seven isolates with His445Leu, Asp435Tyr, Leu452Pro, Leu430Pro, His445Asn, Ile491Phe, and His445Ser mutations in rpoB gene identified by whole-genome sequencing conferring borderline rifampicin resistance were included. Molecular-based Xpert MTB/RIF, phenotypic Löwenstein–Jensen (L-J) medium-based drug susceptibility test (DST) with a critical concentration of 40.0μg/mL and minimal inhibitory concentration (MIC) assay were performed to detect borderline rifampicin resistance.ResultsWhen using Xpert MTB/RIF, 48/57 (84.2%) isolates exhibited resistance to rifampicin. 25/57 (43.9%) and 33/57 (57.9%) isolates showed rifampicin resistance by L-J medium-based DST with 4 and 6 weeks of incubation, respectively. 30/57 (52.6%) and 40/57 (70.2%) strains were resistant to rifampicin by MIC method at cutoff values of 1.0 and 0.5μg/mL, respectively. The detection rate of rifampicin resistance of Xpert MTB/RIF was significantly higher than that of phenotypic methods (p < 0.001). Of the 57 isolates with borderline rpoB mutations, 5 (8.8%) had MICs of 0.25 or 0.12μg/mL, 22 (38.6%) had MICs of 0.5μg/mL or 1.0μg/mL, and 30 (52.6%) other isolates showed MICs ≥2.0μg/mL.ConclusionMolecular-based Xpert MTB/RIF showed superior ability to detect borderline rifampicin resistance over phenotypic DST methods. Extending the incubation time of L-J DST or lowering the cutoff value of the MIC method can improve borderline rifampicin resistance detection.

PREVALENCE OF POSITIVITY OF CBNAAT IN PULMONARY TUBERCULOSIS

Background: TB Is the ninth leading cause of death worldwide and the leading cause from a single infectious agent, ranking above HIV/AIDS. In 2016, there were an estimated 1.3 million TB deaths among HIV negative people (down from 1.7 million in 2000) and an additional 374 000 deaths among HIV-positive people.&#x0D; Methods: This is a retrospective study conducted in the department of Pulmonary medicine. Early morning sputum sample was collected from the patients in a clean sterile container.&#x0D; Results: Among the total 500 samples, 110 were detected tuberculosis positive by CBNAAT method and 390 were negative. And among 110 positive cases, 107 were Rifampicin sensitive and 3 were Rifampicin resistant&#x0D; Conclusion: CBNAAT detects pulmonary TB with greater efficacy than sputum microscopy also helping in early diagnosis in less than 2 hours. It also detects rifampicin resistance with high specificity and can be used for screening for MDR-TB so that early therapy can be started thus decreasing the incidence of MDR-TB. WHO recommends CBNAAT for early diagnosis of pulmonary tuberculosis and detection of rifampicin resistance and retreatment cases, who are at risk of MDR-TB.&#x0D; Keywords: CBNAAT, MDR, Pulmonary tuberculosis

DETECTION OF PULMONARY AND EXTRA-PULMONARY TUBERCULOSIS FROM CLINICAL SAMPLES WITH RIFAMPICIN (RIF) RESISTANCE BY GENE-XPERT MTB/RIF ASSAY AT A TERTIARY CARE TEACHING HOSPITAL, UDAIPUR, RAJASTHAN

Tuberculosis (TB) is one of the major concerns of health policy and rapid detection of M. tuberculosis and detection of rifampicin (RIF) resistance in infected patients are essential for disease management. Multi-drug resistance (MDR) TB is dened as tuberculosis (TB) disease caused by a strain of Mycobacterium tuberculosis (MTB) that was resistant to at least isoniazid and rifampicin (RIF). The aim of this study was to evaluate the importance of GeneXpert MTB/RIF for detection of Mycobacterium tuberculosis (MTB) with detection of rifampicin (RIF) resistance. In this study 967suspected cases of pulmonary and extra-pulmonary TB were included. Their sputum and other (Pus, CSF, tissue, etc.,) samples were collected and subjected to smear microscopy test followed by GeneXpert MTB/RIF assay. Of total 967 samples, 470 (48.60%) were positive for Mycobacteria by GeneXpert MTB/RIF and 118 (12.20%) samples were positive by ZN smear. Among 967 positive cases, 818 (84.59%) were pulmonary, 149 (15.41%) were extra-pulmonary (EP). Two ZN smear positive cases were negative by GeneXpertMTB/RIF. Of the 470 GeneXpert positive samples for MTB, 29(6.17%) cases showed RIF resistance and diagnosed as MDR-TB. GeneXpert MTB/RIF assay is efcient and reliable technique for the rapid diagnostic of TB. The GeneXpert MTB/RIF assay is a simple, high sensitivity and specicity for RIF resistance detection implies for diagnosis of MTB and RIF resistance in MDR cases as well as suspected smear negative and extra-pulmonary cases.

Detection of Mycobacterium tuberculosis and rifampicin resistance by Xpert® MTB/RIF assay among presumptive tuberculosis cases at Jimma University Medical Center, Southwest Ethiopia.

BackgroundRapid diagnosis of tuberculosis (TB) and detection of drug resistance are very important for timely and appropriate management of patients. Xpert MTB/RIF assay is approved for use in TB and rifampicin-resistance diagnosis. However, data are limited on the impact of Xpert MTB/RIF assay under routine clinical settings with a heterogeneous group of patients and sample types in Ethiopia.MethodsA retrospective study was carried out in 2220 presumptive TB cases at Jimma University Medical Center. Data were gathered from the registration logbook using formatted data extraction tools and double entered to epidata version 3.1 and further transported to SPSS version 20 for analysis. Associations were determined using the Chi-square test and P-value <0.05 was considered statistically significant.ResultsOf 2220 cases enrolled, 1665 (75%) were adults and the remaining 555 (25%) were children aged less than 14 years. The majority, 1964 (88.46%), had pulmonary manifestation and 256 (11.54%) had extrapulmonary involvements. The overall, frequency of Mycobacterium tuberculosis (MTB) was 9.3% (206/2220), among this 10.27% (171/1665) and 6.3% (35/555) were adults and children, respectively. M. tuberculosis was detected from 171 (8.75%) of pulmonary patients and 35 (13.28%) of extrapulmonary manifested patients. Out of 206 M. tuberculosis positive cases, 7(3.4%) were rifampicin-resistant: four from pulmonary tuberculosis (PTB) patients and three from EPTB patients. In the Chi-square test, the age group of 15–24 years, previous history of TB, pus/lymph node sample, and being HIV positive were significantly associated with TB positivity by Xpert MTB/RIF (P-value <0.001).ConclusionThese data suggest that the overall frequency of M. tuberculosis and rifampicin resistance was found to be relatively low compared to the previous reports in Ethiopia. Nevertheless, better diagnostic tools and approaches are still vital to halt the burden of TB and drug-resistant TB in the country.

Primary drug resistance among Mycobacterium tuberculosis isolates from treatment naïve and new pulmonary tuberculosis patients in relation to their socio-economic status

BACKGROUND: Multidrug-resistant Tuberculosis (TB) has become an area of growing concern throughout the World, despite the global efforts in eliminating TB. Detection of primary drug resistance in treatment naïve patients, either due to spontaneous mutation or due to transmission of drug-resistant strains is an important indicator of the presence of drug-resistant strains in the community.OBJECTIVES: The objective is to estimate the prevalence of primary drug resistance in treatment naïve pulmonary TB patients and to identify the socio-economic class of the resistant population.MATERIALS AND METHODS: A total of 272 treatment naïve presumptive TB patients were enrolled in the study from September 2018 to December 2020. The samples were subjected to GeneXpert, for detecting the presence of Mycobacterium TB (MTB) along with Rifampicin (RIF) resistance detection. Phenotypic drug susceptibility testing (DST) was performed on all positive mycobacterial cultures using the 1% proportion method against first-line anti-tuberculous drugs. Socioeconomic status of the patients was also assessed based on updated Kuppuswamy Socioeconomic scale (2018).RESULTS: Of the 272 samples subjected to GeneXpert MTB/RIF assay, MTB was detected in 193 (71%) samples and RIF resistance (rpoB gene) was detected in 25 (9%) samples. Phenotypic DST detected multidrug-resistant (MDR) in 22 (8%) samples. Majority of the MDR patients (55%) were belonging to the upper lower (IV) class of Kuppuswamy socio-economic scale.CONCLUSION: High prevalence of MDR-TB among treatment naïve pulmonary TB patients was noted in patients belonging to Class IV of Kuppuswamy socio-economic scale.

Immunological role of cluster of differentiation 56 and cluster of differentiation 19 in patients infected with mycobacterium tuberculosis in Iraq

Tuberculosis (TB) is one of the most dangerous infection mainly caused by gram positive bacteria Mycobacterium tuberculosis (Mtb) and cause many deaths every year worldwide especially in developing countries and activate the humoral and cellular immune response. The aim of this study was to investigate the role of CD56 and CD19 as diagnostic and immune markers in patients infected with Mtb. A total number of 26 patients infected Mtb and 27 patients infected with Multi-Drug resistance Mtb (MDR-Mtb) and 30 healthy individuals were included in this study. Mtb has been diagnosed by acid fast stain and MDR-Mtb were diagnosed by GeneXpert® heminested real time PCR for simultaneous detection of Mtb and rifampicin (RIF) resistance as MDR-Mtb. Serum concentration of CD56 and CD19 has been measurement by Enzyme-Linked Immune-sorbent Assay (ELISA) method. Results of this study showed a significant increase in the serum concentration of CD56 (P value = 0.0001) in Mtb-patients (1.95 ± 0.08 ng/ml) as compared with healthy individuals (1.17 ± 0.09 ng/ml). The same significant increases in the serum concentration of CD56 (2.24 ± 0.12 ng/ml) was reported in MDR-Mtb patients as compared to the healthy individuals. On the other hand, there was significant increase (P value 0.003) in serum concentration of CD19 in Mtb-patients as compared with MDR-Mtb-patients. Results of the study can be concluded that Mtb and MDR-Mtb infection stimulates the cellular and humoral immune response which resulted in the increased production of CD56 and CD19.

Detection of Mycobacterium tuberculosis and Rifampicin Resistance Using GeneXpert MTB/RIF Assay at Enat Hospital, Central Ethiopia.

Background Tuberculosis remains to be a public health threat in Ethiopia. However, the use of ill diagnostic methods and the lack of enough epidemiological information in the country contributed to the diagnostic delay and development of anti-TB drug resistance. Therefore, the present study is aimed at assessing the prevalence of pulmonary TB (PTB) and the development of drug resistance using GeneXpert MTB/RIF assay in Merhabete district, Central Ethiopia. Methods A cross-sectional, health facility-based study was conducted from December 2019 to June 2020. Bacteriological examination and GeneXpert molecular diagnostic methods were used for the detection of M. tuberculosis and rifampicin resistance (RR). Descriptive statistics and logistic regression analysis were used to determine the possible association of risk factors with the occurrence of PTB and RR. P values of <0.05 were considered statistically significant. Results The overall prevalence rates of PTB and RR M. tuberculosis were 11.2% and 15.8%, respectively. The logistic regression analysis revealed that being in the age group of 49-64 years was significantly associated with the occurrence of TB (P = 0.01). The odds of HIV-positive and retreatment study participants to be infected by M. tuberculosis were much more than those of HIV-negative and newly treated cases, respectively (P < 0.05). However, none of the sociodemographic and clinical patient characteristics was significantly associated with the development of RR-TB (P > 0.05). Conclusion In the present study, high prevalence rates of PTB and RR M. tuberculosis were observed. The findings, which were attributed to different risk factors, suggested an urgent need for appropriate intervention measures to reduce the transmission of PTB and the development of anti-TB drug resistance in the study area.

Comparative Diagnostic Accuracy of Mean and Lowest Cycle Threshold Levels in Xpert MTB/RIF Assay and Molecular Epidemiology of Missing Probes In Rifampicin Resistant Tubercular Cases From A Tertiary Care Hospital

Abstract Background: The comparative diagnostic accuracy of mean and lowest Ct values needs to be evaluated for the assessment of mycobacterial burden in tubercular cases. Mutation in any codon of 81 base-pair core regions prevents the hybridization of one or more of five overlapping Probes A-Ein Xpert MTB/RIF assay indicated by “missing probe. Molecular epidemiology of missing probes may prove useful in tracing the source of infection and selection of a more suitable drug regimen for treatment. Methods: This study included 65 rifampicin resistant cases and an equal number of rifampicin sensitive cases detected by Xpert MTB/RIF assay. Only samples tested positive for tubercular bacilli were included. The information regarding the tubercular load, Ct values of five probes targeting the rpoB gene, lowest Ct value among the five probes, missing probe in rifampicin resistant cases and time taken for the entire cycle were recorded in each case. Results: Lowest Ct is a stronger indicator of tubercular load than the mean Ct value. E probe was found to be missing in majority (64.6%) of the cases, followed by A (6.2%), B and D (4.6%), C (1.5%) probes. In 7.6% cases, more than one probe was missing. None of the probe was missing in 10.6% of rifampicin resistant cases. Conclusions: Lowest Ct value was found to be a better tool than mean Ct value for the determination of mycobacterium burden. Molecular epidemiology of missing probes could be useful in the development of new probes for the detection of rifampicin resistance.

Rifampicin Resistance by Xpert MTB/RIF Assay in Pulmonary Tuberculosis- Is there a Need for Confirmation by Retesting?

Introduction: Xpert Mycobacterium tuberculosis/ resistance to Rifampicin (MTB/RIF) assay detects MTB complex (MTBC) and rifampicin resistance simultaneously. In high prevalence countries like India, detection of rifampicin resistance in sputum specimen of a newly diagnosed case of pulmonary TB with a low pretest probability needs to be confirmed by retesting. Aim: To evaluate the results of retesting of rifampicin resistant specimens in newly diagnosed pulmonary TB cases. Materials and Methods: A retrospective analysis of the data of Xpert assay was performed on specimens received in Department of Microbiology, Seth G.S. Medical College and KEM Hospital, Mumbai, Maharashtra, India. If rifampicin resistance was detected in a newly diagnosed case of Tuberculosis (TB), a second specimen was retested by Xpert assay for confirmation. Concordance of retesting was seen with results of Line Probe Assay (LPA). Results: Total 27,429 specimens were processed by Xpert assay of which 803 specimens showed rifampicin resistance, 157 sputum specimens fulfilling criteria of Programmatic Management of Drug resistant Tuberculosis (PMDT) guidelines were retested. High, medium, low and very low bacterial load was observed in 30, 51, 34 and 42 specimens’ respectively. All specimens having high or medium bacillary load showed rifampicin resistant result on retesting. On retesting 34 sputum specimens with low bacterial load, rifampicin resistance was confirmed in 30 specimens. LPA done after growing them by liquid culture confirmed rifampicin resistance in remaining four specimens. Conclusion: Xpert assay is recommended when the bacterial load identified by Xpert assay is very low and when there is discordance between Xpert results of rifampicin resistance and the reflex LPA testing.

Evaluation of a Molecular Test for Detection of Mycobacterium tuberculosis Isolates Resistant to Rifampicin and Isoniazid.

Multidrug-resistant tuberculosis (MDR-TB) is increasing worldwide and is a major cause of death in many countries. It has become a major challenge for national tuberculosis control programs. Therefore, rapid identification of MDR strains of Mycobacterium tuberculosis and monitoring of their transmission could contribute significantly to the fight against tuberculosis. The GenoType MTBDRplus assay has been recommended by the World Health Organization to identify rifampicin (RIF)- and isoniazid (INH)-resistant M. Tuberculosis isolates. The objectives of this study were to evaluate the performance of the GenoType MTBDRplus test in the detection of rifampicin and isoniazid resistance of M. tuberculosis isolates in a Moroccan hospital and then to determine the frequency of mutations associated with resistance to these two major anti-tuberculosis drugs. This is a retrospective study conducted at the bacteriology department of the Mohammed V military hospital over a period of one year from 01/01/2018 to 12/31/2019. A total of 92 isolates of M. tuberculosis from pulmonary and extra-pulmonary specimens were evaluated for drug susceptibility by MGIT™ 960 AST system and compared to the GenoType MTBDRplus assay. The MGIT™ 960 AST system was used as the gold standard for the evaluation of the GenoType MTBDRplus assay. Sensitivity and specificity of the GenoType MTBDRplus assay for the detection of RIF-resistant M. tuberculosis isolates were 83.33% and 100%, respectively. Its sensitivity and specificity for the detection of INH-resistant M. tuberculosis were 88.23% and 100% respectively. The concordances of the GenoType MTBDRplus assay and the MGIT™ 960 AST system for the detection of sensitivity to RIF and INH were 99% (1/92) and 98% (2/92), respectively. Among the five RIF-resistant isolates, the MUT3 mutation in the rpoB gene (codon S531L mutation) was present in 80% of isolates, whereas mutations in the rpoB MUT1 gene were present in only one (20%) RIF-resistant isolate. INH resistance was detected in 15 isolates, of which nine isolates (60%) had specific mutations of the katG gene (codon S315T1) and conferred a high level of resistance to INH. The results of this study have shown that the GenoType MTBDRplus test has a high sensitivity and specificity for the detection of resistance to RIF and INH.