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Management of Spinal Tuberculosis in Young Children
Published in Alaaeldin (Alaa) Azmi Ahmad, Aakash Agarwal, Early-Onset Scoliosis, 2021
S. Rajasekaran, Sri Vijay Anand, Ajoy Prasad Shetty, Rishi Mugesh Kanna
GeneXpert is a cartridge-based nucleic-acid amplification (NAA) test. For osteoarticular tuberculosis, the pooled sensitivity and specificity of Xpert MTB/RIF (Mycobacterium tuberculosis/resistance to rifampin) were 96% and 85%, respectively, compared to culture tests [19]. It offers several advantages, such as shorter time for results (<2 hrs), portability and ability to use at remote locations, direct use without the need for processing, less contamination, and it poses less of a biohazard. The test also detects whether the organism is resistant to rifampicin by detection of defined mutations within the core region of the RNA polymerase b (rpoB) gene. In the era of drug-resistant tuberculosis, Xpert MTB/RIF assay is a vital tool and is recommended by the World Health Organization (WHO) for use worldwide. Commonly used diagnostic tests are summarised in Table 8g.1.
Rifampicin (Rifampin)
Published in M. Lindsay Grayson, Sara E. Cosgrove, Suzanne M. Crowe, M. Lindsay Grayson, William Hope, James S. McCarthy, John Mills, Johan W. Mouton, David L. Paterson, Kucers’ The Use of Antibiotics, 2017
C. Alan, C. Street, Tony M. Korman
Rifampicin-resistant strains of mycobacteria other than M. tuberculosis also contain the mutation in the rpoB gene, similar to resistant strains of M. tuberculosis (Williams et al., 1994), including M. avium complex (Obata et al., 2006), M. kansasii (Klein et al., 2001), M. leprae (Ji, 2002; Matsuoka et al., 2007; Cambau et al., 2012), and M. ulcerans (Marsollier et al., 2003; Beissner et al., 2010).
Tuberculosis in Childhood
Published in Peter D O Davies, Stephen B Gordon, Geraint Davies, Clinical Tuberculosis, 2014
Real-time polymerase chain reaction (RT-PCR) has increasingly become available for clinical use with the advantage of lower cross-contamination as well as the ability to identify rifampicin resistance. The rpoB gene of M. tuberculosis accounts for more than 95% of rifampicin resistance, and because rifampicin resistance is usually accompanied by isoniazid resistance (monoresistance is rare), this test is used as a marker for multidrug-resistant TB.
Use of Xpert MTB/RIF and Xpert Ultra in extrapulmonary tuberculosis
Published in Expert Review of Anti-infective Therapy, 2021
Xpert MTB/RIF is a hemi-nested PCR that uses the GeneXpert platform for specimen preparation, amplification, and detection of the rifampicin resistance-determining region (RRDR) of MTB rpoB gene [12,13]. The system consists of an instrument, personal computer, barcode scanner, preloaded software, and single-use disposable cartridges. It uses a 6-colored laser-detection device (see Picture 1) [12]. Five rpoB RRDR-specific molecular beacons (nucleic acid probes) are used to detect either the presence or absence of the normal rifampicin-susceptible wild-type sequence of the rpoB gene and mutations which are responsible for 95% of the RR-TB cases. If a beacon binds to the matching sequence, it fluoresces suggesting the presence of a gene sequence that is characteristic of rifampicin-susceptible TB. If a beacon fails to bind to a matching sequence or if binding is delayed, this suggests potential resistance to rifampicin [13].
Helicobacter pylori: molecular basis for colonization and survival in gastric environment and resistance to antibiotics. A short review
Published in Infectious Diseases, 2019
Sharmila Fagoonee, Rinaldo Pellicano
In the last decade, rifabutin-based rescue therapies have offered a promising option after multiple H. pylori eradication failures. H. pylori has been shown to be highly susceptible in vitro to rifabutin, an antimycobacterial agent and a spiropiperidyl derivative of rifamycin S. Furthermore, selection of H. pylori resistant strains has been low under experimental conditions. Rifamycin targets the DNA-directed RNA polymerase and primarily the ß-subunit encoded by rpoB. Resistance to rifabutin is due to mutations at four distinct regions of this gene [56]. Recently, Hays et al. reported the molecular characterization of H. pylori resistance to rifabutin. By using rifampicin to screen for rifabutin resistance in vitro, the authors sequenced rpoB. All 54 resistant strains carried at least one mutation in rpoB at codons 525, 530, 538, 540 in the rifampicin resistance determining region. A new mutation, L547, responsible for rifamycins resistance was also reported [57].
Tuberculosis in the 21th century: Current status of diagnostic methods
Published in Experimental Lung Research, 2018
Patrícia Poeta, Vanessa Silva, Andreia Guedes, José Eduardo Pereira, Ana Cláudia Coelho, Gilberto Igrejas
The Xpert MTB/RIF test is an automatic method based on the detection and amplification of nucleic acids known as RT-PCR. This test enhances TB diagnosis by detecting Koch's bacillus in less than 2 hours compared to classical diagnostic methods which take weeks. The Xpert MTB/RIF is a combination of a sample processing system and an automated heminested RT-PCR assay which are combined into a single disposable cartridge with the GeneXpert Instrument System. The assay can be performed with clinical sputum sample collected from the patient with suspected TB or from a decontaminated sputum pellet.27,28 Simultaneously, this test also detects resistance to RIF, which is the main drug applied in the treatment of TB, by detecting the rpoB gene in MTB and investigating mutations that are associated with RIF resistance.29,30 A study conducted with children with presumed pulmonary tuberculosis in Papua New Guinea revealed that Xpert MTB/RIF had a specificity of 92%, however, the sensitivity was low (31%) when compared Edwards TB score (90%).31,32