Faculty Opinions recommendation of Antibiotic resistance by high-level intrinsic suppression of a frameshift mutation in an essential gene.

A fundamental feature of life is that ribosomes read the genetic code in messenger RNA (mRNA) as triplets of nucleotides in a single reading frame. Mutations that shift the reading frame generally cause gene inactivation and in essential genes cause loss of viability. Here we report and characterize a +1-nt frameshift mutation, centrally located in rpoB, an essential gene encoding the beta-subunit of RNA polymerase. Mutant Escherichia coli carrying this mutation are viable and highly resistant to rifampicin. Genetic and proteomic experiments reveal a very high rate (5%) of spontaneous frameshift suppression occurring on a heptanucleotide sequence downstream of the mutation. Production of active protein is stimulated to 61–71% of wild-type level by a feedback mechanism increasing translation initiation. The phenomenon described here could have broad significance for predictions of phenotype from genotype. Several frameshift mutations have been reported in rpoB in rifampicin-resistant clinical isolates of Mycobacterium tuberculosis (Mtb). These mutations have never been experimentally validated, and no mechanisms of action have been proposed. This work shows that frameshift mutations in rpoB can be a mutational mechanism generating antibiotic resistance. Our analysis further suggests that genetic elements supporting productive frameshifting could rapidly evolve de novo, even in essential genes.

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Novel Soil-Derived Beta-Lactam, Chloramphenicol, Fosfomycin and Trimethoprim Resistance Genes Revealed by Functional Metagenomics

Antibiotics ◽

10.3390/antibiotics10040378 ◽

2021 ◽

Vol 10 (4) ◽

pp. 378

Author(s):

Inka Marie Willms ◽

Maja Grote ◽

Melissa Kocatürk ◽

Lukas Singhoff ◽

Alina Andrea Kraft ◽

...

Keyword(s):

Antibiotic Resistance ◽

Resistance Genes ◽

Antibiotic Resistance Genes ◽

Reference Database ◽

Functional Metagenomics ◽

Beta Lactam ◽

Public Attention ◽

Soil Ecosystems ◽

High Level ◽

Antibiotic Efflux

Antibiotic resistance genes (ARGs) in soil are considered to represent one of the largest environmental resistomes on our planet. As these genes can potentially be disseminated among microorganisms via horizontal gene transfer (HGT) and in some cases are acquired by clinical pathogens, knowledge about their diversity, mobility and encoded resistance spectra gained increasing public attention. This knowledge offers opportunities with respect to improved risk prediction and development of strategies to tackle antibiotic resistance, and might help to direct the design of novel antibiotics, before further resistances reach hospital settings or the animal sector. Here, metagenomic libraries, which comprise genes of cultivated microorganisms, but, importantly, also those carried by the uncultured microbial majority, were screened for novel ARGs from forest and grassland soils. We detected three new beta-lactam, a so far unknown chloramphenicol, a novel fosfomycin, as well as three previously undiscovered trimethoprim resistance genes. These ARGs were derived from phylogenetically diverse soil bacteria and predicted to encode antibiotic inactivation, antibiotic efflux, or alternative variants of target enzymes. Moreover, deduced gene products show a minimum identity of ~21% to reference database entries and confer high-level resistance. This highlights the vast potential of functional metagenomics for the discovery of novel ARGs from soil ecosystems.

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Analysis and forecasts of Salmonella spp. antibiotic resistance in Dnipropetrovsk region (Ukraine)

Veterinary Medicine: inter-departmental subject scientific collection ◽

10.36016/vm-2019-105-3 ◽

2019 ◽

pp. 16-19

Author(s):

H. A. Martynenko

Keyword(s):

Antibiotic Resistance ◽

Age Groups ◽

Quantitative Information ◽

Graphical Form ◽

Salmonella Spp ◽

Gram Negative ◽

Trend Line ◽

E Coli ◽

Short Period ◽

High Level

The paper presents data of the research aimed at studying the species composition of major pathogens circulating in the region and the resistance to antibacterial drugs in pathogens of salmonella, one of the most common zoonoses. Within the period 2014–2018 the qualitative composition of microflora from biological and pathological materials from different groups of animals was studied in Dnipropetrovsk region. Own research results and the results of the regional veterinary statistical reporting were analyzed. Within the short period of five years, 237 cultures of Gram-negative bacteria were detected and studied. The dominant agent in the studied region was E. coli (56.7%) from the Enterobacteriaceae family. The second most frequent agent in the pathology was Salmonella spp. (10.5%). In total, 29 cultures of salmonella infection were isolated from six species of animals with a predominance of bird isolates. Thus, for different age groups of poultry the most common were S. Gallinarum-Pullorum (56%) and S. Enteritidis (32%). An antibiotic resistance increase in pathogenic salmonella was observed for β-lactam antibiotics (cefazolin, ceftriaxone), aminoglycosides (gentamicin, streptomycin, kanamycin), as well as for tetracycline and polymyxin. Taking into consideration the high level of resistance against norfloxacin in the region’s dominant pathogens of the Enterobacteriaceae family, we performed a forecast in MS Excel graphically and added a trend line. In the course of work it was proved that the Dnipropetrovsk region is a geographic zone with a stable high (86 ± 3.7%) allocation from different groups of animals of Gram-negative microorganisms. It was found that local dominant pathogens are representatives of the Enterobacteriaceae family (E. coli, Salmonella spp.). This data can be used as surrogate resistance markers. The epizootological patterns of animal salmonellosis are determined. It is shown the possibility of forecasting the distribution of antibiotic resistant strains in MS Excel in graphical form by adding a trend line, using quantitative information on the sensitivity of bacteria. Prospects for further research are the prevention and control of the emergence of resistance to antibiotics in veterinary medicine and agriculture in the region and in the country

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Association among biofilm formation, virulence gene expression, and antibiotic resistance in Proteus mirabilis isolates from diarrhetic animals in northeast China

10.21203/rs.2.16502/v2 ◽

2020 ◽

Author(s):

Yadong Sun ◽

Shanshan Wen ◽

Lili Zhao ◽

Qiqi Xia ◽

Yue Pan ◽

...

Keyword(s):

Gene Expression ◽

Antibiotic Resistance ◽

Biofilm Formation ◽

Northeast China ◽

Virulence Gene ◽

Drug Susceptibility ◽

Multidrug Resistant ◽

Virulence Gene Expression ◽

Biofilm Production ◽

High Level

Abstract Background The aim of this study was to investigate the association among biofilm formation, virulence gene expression, and antibiotic resistance in P. mirabilis isolates collected from diarrhetic animals (n = 176) in northeast China between September 2014 and October 2016. Results Approximately 92.05% of the isolates were biofilm producers, whereas 7.95% of the isolates were non-producers. The prevalence of virulence genes in biofilm producers was significantly higher than that in non-producers. Biofilm production was significantly associated with the expression of ureC , zapA , rsmA , hmpA , mrpA , atfA , and pmfA ( P < 0.05). Drug susceptibility tests revealed that approximately 76.7% of the isolates were multidrug-resistant (MDR) and extensively drug-resistant (XDR). Biofilm production was significantly associated with resistance to doxycycline, tetracycline, sulfamethoxazole, kanamycin, and cephalothin ( P < 0.05). Although the pathogenicity of the biofilm producers was stronger than that of the non-producers, the biofilm-forming ability of the isolates was not significantly associated with morbidity and mortality in mice ( P > 0.05). Conclusion Our findings suggested that a high level of multidrug resistance in diarrhetic animals infected with P. mirabilis in northeast China.The results of this study indicated that the positive rates of the genes expressed by biofilm-producing P. mirabilis isolates were significantly higher than those expressed by non-producing isolates.

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Relationship between Glycopeptide Production and Resistance in the Actinomycete Nonomuraea sp. ATCC 39727

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02626-14 ◽

2014 ◽

Vol 58 (9) ◽

pp. 5191-5201 ◽

Cited By ~ 16

Author(s):

Giorgia Letizia Marcone ◽

Elisa Binda ◽

Lucia Carrano ◽

Mervyn Bibb ◽

Flavia Marinelli

Keyword(s):

Antibiotic Resistance ◽

Gene Dosage ◽

Antibiotic Production ◽

Resistance Mechanism ◽

Biosynthetic Gene Cluster ◽

Penicillin G ◽

Glycopeptide Resistance ◽

Content Type ◽

High Level

ABSTRACTGlycopeptides and β-lactams inhibit bacterial peptidoglycan synthesis in Gram-positive bacteria; resistance to these antibiotics is studied intensively in enterococci and staphylococci because of their relevance to infectious disease. Much less is known about antibiotic resistance in glycopeptide-producing actinomycetes that are likely to represent the evolutionary source of resistance determinants found in bacterial pathogens.Nonomuraeasp. ATCC 39727, the producer of A40926 (the precursor for the semisynthetic dalbavancin), does not harbor the canonicalvanHAXgenes. Consequently, we investigated the role of the β-lactam-sensitived,d-peptidase/d,d-carboxypeptidase encoded byvanYn, the onlyvan-like gene found in the A40926 biosynthetic gene cluster, in conferring immunity to the antibiotic inNonomuraeasp. ATCC 39727. Taking advantage of the tools developed recently to genetically manipulate this uncommon actinomycete, we variedvanYngene dosage and expressedvanHatAatXatfrom the teicoplanin producerActinoplanes teichomyceticusinNonomuraeasp. ATCC 39727. Knocking outvanYn, complementing avanYnmutant, or duplicatingvanYnhad no effect on growth but influenced antibiotic resistance and, in the cases of complementation and duplication, antibiotic production.Nonomuraeasp. ATCC 39727 was found to be resistant to penicillins, but its glycopeptide resistance was diminished in the presence of penicillin G, which inhibits VanYnactivity. The heterologous expression ofvanHatAatXatincreased A40926 resistance inNonomuraeasp. ATCC 39727 but did not increase antibiotic production, indicating that the level of antibiotic production is not directly determined by the level of resistance. ThevanYn-based self-resistance inNonomuraeasp. ATCC 39727 resembles the glycopeptide resistance mechanism described recently in mutants ofEnterococcus faeciumselectedin vitrofor high-level resistance to glycopeptides and penicillins.

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Improved Electrotransformation and Decreased Antibiotic Resistance of the Cystic Fibrosis Pathogen Burkholderia cenocepacia Strain J2315

Applied and Environmental Microbiology ◽

10.1128/aem.02123-09 ◽

2009 ◽

Vol 76 (4) ◽

pp. 1095-1102 ◽

Cited By ~ 15

Author(s):

Nelly Dubarry ◽

Wenli Du ◽

David Lane ◽

Franck Pasta

Keyword(s):

Cystic Fibrosis ◽

Antibiotic Resistance ◽

Resistance Genes ◽

Efflux Pump ◽

Antibiotic Resistance Genes ◽

Burkholderia Cenocepacia ◽

The Poor ◽

High Level

ABSTRACT The bacterium Burkholderia cenocepacia is pathogenic for sufferers from cystic fibrosis (CF) and certain immunocompromised conditions. The B. cenocepacia strain most frequently isolated from CF patients, and which serves as the reference for CF epidemiology, is J2315. The J2315 genome is split into three chromosomes and one plasmid. The strain was sequenced several years ago, and its annotation has been released recently. This information should allow genetic experimentation with J2315, but two major impediments appear: the poor potential of J2315 to act as a recipient in transformation and conjugation and the high level of resistance it mounts to nearly all antibiotics. Here, we describe modifications to the standard electroporation procedure that allow routine transformation of J2315 by DNA. In addition, we show that deletion of an efflux pump gene and addition of spermine to the medium enhance the sensitivity of J2315 to certain commonly used antibiotics and so allow a wider range of antibiotic resistance genes to be used for selection.

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Developmental decisions in Aspergillus nidulans are modulated by Ras activity.

Molecular and Cellular Biology ◽

10.1128/mcb.14.8.5333 ◽

1994 ◽

Vol 14 (8) ◽

pp. 5333-5348 ◽

Cited By ~ 87

Author(s):

T Som ◽

V S Kolaparthi

Keyword(s):

Aspergillus Nidulans ◽

Essential Gene ◽

Cell Types ◽

Tube Formation ◽

Stage Of Development ◽

Initial Stage ◽

Concentration Threshold ◽

High Level ◽

Multicellular Organisms ◽

Further Development

To better understand how Ras controls development of multicellular organisms, we have chosen Aspergillus nidulans as a model system. When grown on solid medium, this fungus follows a well-defined program of development, sequentially giving rise to several cell types which produce three distinct structures: vegetative hyphae, aerial hyphae, and the conidiophore structure. Here we describe a ras homolog found in this fungus (Aras) and demonstrate that it is an essential gene that regulates the ordered program of development. We created dominant alleles of this gene and expressed them to different levels in order to vary the ratio of GTP-bound (active) to GDP-bound (inactive) A-Ras protein. When the amount of active Ras is large, nuclear division proceeds, but further development is inhibited at the early step of germ tube formation. At an intermediate level of active Ras, aerial hypha formation is inhibited, while at a low level, conidiophore formation is inhibited. Maintenance of an even lower level of the active Ras is essential for initiation and progression of conidiophore formation, the final stage of development. When the level of active Ras is artificially lowered, each stage of development is initiated prematurely except germination, the initial stage of development. Therefore, the progression of the ordered developmental pathway of A. nidulans is dependent upon an initial high level of active Ras followed by its gradual decrease. We propose that several concentration threshold exist, each of which allows development to proceed to a certain point, producing the proper cell type while inhibiting further development.

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