scholarly journals Relationship between rifampin MICs for and rpoB mutations of Mycobacterium tuberculosis strains isolated in Japan.

1996 ◽  
Vol 40 (4) ◽  
pp. 1053-1056 ◽  
Author(s):  
H Ohno ◽  
H Koga ◽  
S Kohno ◽  
T Tashiro ◽  
K Hara
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Point Mutation ◽  
Rpob Gene ◽  
The Other ◽  
Clinical Isolates ◽  
Sequencing Analysis ◽  
The Relationship

We analyzed the relationship between rifampin MICs and rpoB mutations of 40 clinical isolates of Mycobacterium tuberculosis. A point mutation in either codon 516, 526, or 531 was found in 13 strains requiring MICs of > or = 64 micrograms/ml, while 21 strains requiring MICs of < or = 1 microgram/ml showed no alteration in these codons. However, 3 of these 21 strains contained a point mutation in either codon 515 or 533. Of the other six strains requiring MICs between 2 and 32 micrograms/ml, three contained a point mutation in codon 516 or 526, while no alteration was detected in the other three. Our results indicate that the sequencing analysis of a 69-bp fragment in the rpoB gene is useful in predicting rifampin-resistant phenotypes.

Rifampin resistance-associated mutations in the RIF resistance-determining region (RRDR) of the rpoB gene of Mycobacterium tuberculosis clinical isolates in Shanghai, China

2019 ◽  
Author(s):  
Yinjuan Guo ◽  
Xingwei Cao ◽  
Jinghui Yang ◽  
Xiaocui Wu ◽  
Yin Liu ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Mutation Frequency ◽  
Rpob Gene ◽  
Clinical Isolates ◽  
Sequencing Analysis ◽  
Mycobacterium Tuberculosis Infection ◽  
Gene Coding ◽  
Rifampin Resistance ◽  
Dna Sequencing Analysis ◽  
The Relationship

Abstract Background: Resistance to rifampin (RIF) in Mycobacterium tuberculosis infection is associated with mutations in the rpoB gene coding for the beta-subunit of RNA polymerase. The contribution of many individual rpoB mutations to the development and level of RIF resistance remains elusive. Our objective for this study was to investigate the relationship between specific rpoB mutations and the minimum inhibitory concentrations (MICs) of RIF and rifabutin (RFB) against M.tuberculosis. Methods: We collected 195 clinical isolates of M. tuberculosis including 105 RIF-resistant and 90 RIF-susceptible isolates from Shanghai Pulmonary Hospital in China. The MICs of antituberculosis drugs in 7H10 Middlebrook medium for clinical isolates of M. tuberculosis were determined. Strains were screened for rpoB mutations by DNA extraction, rpoB gene amplification, and DNA sequencing analysis. Results: Twenty different types of mutations were identified in the rpoB gene. One hundred isolates (95.24%) were found to have mutations in the RIF resistance-determining region (RRDR) of the rpoB gene. Three rpoB mutations were identified in 90 RIF-susceptible isolates. Out of 105 isolates, 86 (81.90%) were cross-resistant to both RIF and RFB. The most frequent mutation occurred at codon 531 (65.71%), followed by 526 (8.57%). We also found a novel nine-nucleotide (ATCATGCAT) deletion (between positions 1543 and 1551) in the rpoB gene among two strains (1.90%) with resistance to RIF, but susceptibility to RFB. In addition, the mutation frequency at codon 531 was significantly higher in RIF-resistant/RFB-resistant (RIFR/RFBR) strains than in RIFR/RFBS strains (75.58% versus 21.05%), whereas the mutation frequency at codon 516 was significantly lower in RIFR/RFBR strains than in RIFR/RFBS strains (1.16% versus 26.32%). The MICs of RIF against 87.62% (92/105) of the M.tuberculosis isolates were ≥ 16 µg/mL. Conclusions: Our data supported previous findings that various rpoB mutations are associated with differential levels of resistance to RIF. The specific mutations of the rpoB gene in RIFR/RFBR isolates differed from those in RIFR/RFBS isolates. A novel deletion mutation in the RRDR might be associated with resistance to RIF, but not to RFB. Further clinical studies are required to investigate the efficacy of RFB in the treatment of M. tuberculosis infections, which harbor the mutations.

Flucytosine resistance in Cryptococcus gattii is indirectly mediated by the FCY2-FCY1-FUR1 pathway

2018 ◽  
Vol 56 (7) ◽  
pp. 857-867 ◽  
Author(s):  
Kiem Vu ◽  
George R Thompson ◽  
Chandler C Roe ◽  
Jane E Sykes ◽  
Elizabeth M Dreibe ◽  
...  
Keyword(s):  
Point Mutation ◽  
Molecular Mechanisms ◽  
Cytosine Deaminase ◽  
Protein S ◽  
Comparative Sequence Analysis ◽  
Cryptococcus Gattii ◽  
Clinical Isolates ◽  
Sequencing Analysis ◽  
Genomic Changes ◽  
Species Complexes

Abstract Cryptococcosis is an opportunistic fungal infection caused by members of the two sibling species complexes: Cryptococcus neoformans and Cryptococcus gattii. Flucytosine (5FC) is one of the most widely used antifungals against Cryptococcus spp., yet very few studies have looked at the molecular mechanisms responsible for 5FC resistance in this pathogen. In this study, we examined 11 C. gattii clinical isolates of the major molecular type VGIII based on differential 5FC susceptibility and asked whether there were genomic changes in the key genes involved in flucytosine metabolism. Susceptibility assays and sequencing analysis revealed an association between a point mutation in the cytosine deaminase gene (FCY1) and 5FC resistance in two of the studied 5FC resistant C. gattii VGIII clinical isolates, B9322 and JS5. This mutation results in the replacement of arginine for histidine at position 29 and occurs within a variable stretch of amino acids. Heterologous expression of FCY1 and spot sensitivity assays, however, demonstrated that this point mutation did not have any effect on FCY1 activities and was not responsible for 5FC resistance. Comparative sequence analysis further showed that no changes in the amino acid sequence and no genomic alterations were observed within 1 kb of the upstream and downstream sequences of either cytosine permeases (FCY2-4) or uracil phosphoribosyltransferase (FUR1) genes in 5FC resistant and 5FC susceptible C. gattii VGIII isolates. The herein obtained results suggest that the observed 5FC resistance in the isolates B9322 and JS5 is due to changes in unknown protein(s) or pathway(s) that regulate flucytosine metabolism.

scholarly journals Resistance Levels and rpoB Gene Mutations among In Vitro-Selected Rifampin-Resistant Mycobacterium tuberculosis Mutants

2006 ◽  
Vol 50 (8) ◽  
pp. 2860-2862 ◽  
Author(s):  
Emma Huitric ◽  
Jim Werngren ◽  
Pontus Juréen ◽  
Sven Hoffner
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Point Mutations ◽  
Gene Mutations ◽  
Rpob Gene ◽  
Clinical Isolates ◽  
Large Deletions ◽  
High Level ◽  
Level Resistance

ABSTRACT The distribution and resistance levels of 189 in vitro-selected rifampin-resistant Mycobacterium tuberculosis mutants of Beijing and other genotypes were determined. Apart from a higher amount of codon 522 point mutations and large deletions, a spread of mutations similar to that reported for clinical isolates was seen. Most mutations were correlated with high-level resistance; a lower level, or a MIC of <16 mg/liter, was associated with codon 522 mutations. Multiple mutations were detected in two Beijing mutants.

Rifampin-resistance-associated mutations in the rifampin-resistance-determining region of the rpoB gene of Mycobacterium tuberculosis clinical isolates in Shanghai, PR China

2021 ◽  
Author(s):  
Yinjuan Guo ◽  
Xingwei Cao ◽  
Jinghui Yang ◽  
Xiaocui Wu ◽  
Yin Liu ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Type Species ◽  
Mutation Frequency ◽  
Rpob Gene ◽  
Clinical Isolates ◽  
Content Type ◽  
Link Type ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Rifampin Resistance

Introduction. Resistance to rifampin (RIF) in Mycobacterium tuberculosis infection is associated with mutations in the rpoB gene coding for the β-subunit of RNA polymerase. The contribution of various rpoB mutations to the development and level of RIF resistance remains elusive. Hypothesis/Gap Statement. Various rpoB mutations may be associated with differential levels of RIF resistance. Aim. This study aimed to investigate the relationship between specific rpoB mutations and the MICs of RIF and rifabutin (RFB) against M. tuberculosis . Methodology. Of the 195 clinical isolates, 105 and 90 isolates were randomly selected from isolates resistant to RIF and sensitive to RIF, respectively. The MICs of 12 agents for M. tuberculosis isolates were determined using commercial Sensititre M. tuberculosis MIC plates and the broth microdilution method. Strains were screened for rpoB mutations by DNA extraction, rpoB gene amplification and DNA sequence analysis. Results. One hundred isolates (95.24 %) were found to have mutations in the RIF-resistance-determining region (RRDR) of the rpoB gene. Three rpoB mutations were identified in 90 RIF-susceptible isolates. Out of 105 isolates, 86 (81.90 %) were cross-resistant to both RIF and RFB. The most frequent mutation occurred at codons 450 and 445. We also found a novel nine-nucleotide (ATCATGCAT) deletion (between positions 1543 and 1551) in the rpoB gene in two strains (1.90 %) with resistance to RIF, but susceptibility to RFB. In addition, the mutation frequency at codon 450 was significantly higher in RIF-resistant/RFB-resistant (RIFR/RFBR) strains than in RIFR/RFBS strains (75.58 % versus 21.05 %, P<0.01), whereas the mutation frequency at codon 435 was significantly lower in RIFR/RFBR strains than in RIFR/RFBS strains (1.16 % versus 26.32 %, P<0.01). Conclusion. Our data support previous findings, which reported that various rpoB mutations are associated with differential levels of RIF resistance. The specific mutations in the rpoB gene in RIFR/RFBR isolates differed from those in the RIFR/RFBS isolates. A novel deletion mutation in the RRDR might be associated with resistance to RIF, but not to RFB. Further clinical studies are required to investigate the efficacy of RFB in the treatment of infections caused by M. tuberculosis strains harbouring these mutations.

scholarly journals Genomic epidemiology of a Cryptococcus neoformans case cluster in Glasgow, Scotland, 2018

2021 ◽  
Author(s):  
Rhys A. Farrer ◽  
Andrew M. Borman ◽  
Teresa Inkster ◽  
Matthew C. Fisher ◽  
Elizabeth M. Johnson ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
The Other ◽  
Clinical Isolates ◽  
University Hospital ◽  
Hospital Environment ◽  
Genomic Epidemiology ◽  
Pigeon Droppings ◽  
Sporadic Cases ◽  
Relationship Of ◽  
The Relationship

In 2018, a cluster of two cases of cryptococcosis occurred at the Queen Elizabeth University Hospital (QEUH) in Glasgow, Scotland (UK). It was postulated that these cases may have been linked to pigeon droppings found on the hospital site, given there have been previous reports of Cryptococcus neoformans associated with pigeon guano. Although some samples of pigeon guano taken from the site yielded culturable yeast from genera related to Cryptococcus, they have since been classified as Naganishia or Papiliotrema spp., and no isolates of C. neoformans were recovered from either the guano or subsequent widespread air sampling. In an attempt to further elucidate any possible shared source of the clinical isolates, we used whole-genome sequencing and phylogenetic analysis to examine the relationship of the two Cryptococcus isolates from the QEUH cases, along with two isolates from sporadic cases treated at a different Glasgow hospital earlier in 2018. Our work demonstrated that these four clinical isolates were not clonally related; while all isolates were from the VNI global lineage and of the same mating type (MATα), the genotypes of the two QEUH isolates were separated by 1885 base changes and belonged to different sub-lineages, recently described as the intercontinental sub-clades VNIa-93 and VNIa-5. In contrast, one of the two sporadic 2018 clinical isolates was determined to belong to the VNIb sub-lineage and the other classified as a VNIV/VNI hybrid. Our work demonstrated that the two 2018 QEUH isolates and the two prior C. neoformans clinical isolates were all genetically distinct. It was not possible to determine whether the QEUH genotypes stemmed from independent sources or from the same source, i.e. pigeons carrying different genotypes, but it should be noted that whilst members of allied genera within the Tremellomycetes were isolated from the hospital environment, there were no environmental isolations of C. neoformans.

scholarly journals Frequency of mutations in the rpoB gene of multidrug-resistant Mycobacterium tuberculosis clinical isolates from Sudan

2014 ◽  
Vol 8 (06) ◽  
pp. 796-798 ◽  
Author(s):  
Haitham Elbir ◽  
Nuha Yousif Ibrahim
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Full Text ◽  
Rpob Gene ◽  
Multidrug Resistant ◽  
Clinical Isolates

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