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Microbiology Spectrum Jul 2018Mycoplasmas are intrinsically resistant to antimicrobials targeting the cell wall (fosfomycin, glycopeptides, or β-lactam antibiotics) and to sulfonamides,... (Review)
Review
Mycoplasmas are intrinsically resistant to antimicrobials targeting the cell wall (fosfomycin, glycopeptides, or β-lactam antibiotics) and to sulfonamides, first-generation quinolones, trimethoprim, polymixins, and rifampicin. The antibiotics most frequently used to control mycoplasmal infections in animals are macrolides and tetracyclines. Lincosamides, fluoroquinolones, pleuromutilins, phenicols, and aminoglycosides can also be active. Standardization of methods used for determination of susceptibility levels is difficult since no quality control strains are available and because of species-specific growth requirements. Reduced susceptibility levels or resistances to several families of antimicrobials have been reported in field isolates of pathogenic species of major veterinary interest: and in poultry; , , and in swine; in cattle; and in small ruminants. The highest resistances are observed for macrolides, followed by tetracyclines. Most strains remain susceptible to fluoroquinolones. Pleuromutilins are the most effective antibiotics . Resistance frequencies vary according to the species but also according to the countries or groups of animals from which the samples were taken. Point mutations in the target genes of different antimicrobials have been identified in resistant field isolates, -selected mutants, or strains reisolated after an experimental infection followed by one or several treatments: DNA-gyrase and topoisomerase IV for fluoroquinolones; 23S rRNA for macrolides, lincosamides, pleuromutilins, and amphenicols; 16S rRNAs for tetracyclines and aminoglycosides. Further work should be carried out to determine and harmonize specific breakpoints for animal mycoplasmas so that information can be used to provide advice on selection of treatments.
Topics: Animals; Anti-Bacterial Agents; Cattle; DNA Gyrase; DNA Topoisomerase IV; Drug Resistance, Bacterial; Microbial Sensitivity Tests; Mycoplasma; Mycoplasma Infections; Point Mutation; Poultry; RNA, Ribosomal, 16S; RNA, Ribosomal, 23S; Ruminants; Species Specificity; Swine
PubMed: 30003864
DOI: 10.1128/microbiolspec.ARBA-0030-2018 -
Drug Resistance Updates : Reviews and... Sep 2016The genus Burkholderia comprises metabolically diverse and adaptable Gram-negative bacteria, which thrive in often adversarial environments. A few members of the genus... (Review)
Review
The genus Burkholderia comprises metabolically diverse and adaptable Gram-negative bacteria, which thrive in often adversarial environments. A few members of the genus are prominent opportunistic pathogens. These include Burkholderia mallei and Burkholderia pseudomallei of the B. pseudomallei complex, which cause glanders and melioidosis, respectively. Burkholderia cenocepacia, Burkholderia multivorans, and Burkholderia vietnamiensis belong to the Burkholderia cepacia complex and affect mostly cystic fibrosis patients. Infections caused by these bacteria are difficult to treat because of significant antibiotic resistance. The first line of defense against antimicrobials in Burkholderia species is the outer membrane penetration barrier. Most Burkholderia contain a modified lipopolysaccharide that causes intrinsic polymyxin resistance. Contributing to reduced drug penetration are restrictive porin proteins. Efflux pumps of the resistance nodulation cell division family are major players in Burkholderia multidrug resistance. Third and fourth generation β-lactam antibiotics are seminal for treatment of Burkholderia infections, but therapeutic efficacy is compromised by expression of several β-lactamases and ceftazidime target mutations. Altered DNA gyrase and dihydrofolate reductase targets cause fluoroquinolone and trimethoprim resistance, respectively. Although antibiotic resistance hampers therapy of Burkholderia infections, the characterization of resistance mechanisms lags behind other non-enteric Gram-negative pathogens, especially ESKAPE bacteria such as Acinetobacter baumannii, Klebsiella pneumoniae and Pseudomonas aeruginosa.
Topics: Animals; Anti-Bacterial Agents; Bacterial Proteins; Burkholderia; Burkholderia Infections; Burkholderia mallei; Burkholderia pseudomallei; DNA Gyrase; Drug Resistance, Multiple, Bacterial; Gene Expression Regulation, Bacterial; Genes, MDR; Glanders; Horses; Humans; Melioidosis; Porins; Tetrahydrofolate Dehydrogenase
PubMed: 27620956
DOI: 10.1016/j.drup.2016.07.003 -
Microbiology Spectrum Oct 2014Three mechanisms for plasmid-mediated quinolone resistance (PMQR) have been discovered since 1998. Plasmid genes qnrA, qnrB, qnrC, qnrD, qnrS, and qnrVC code for... (Review)
Review
Three mechanisms for plasmid-mediated quinolone resistance (PMQR) have been discovered since 1998. Plasmid genes qnrA, qnrB, qnrC, qnrD, qnrS, and qnrVC code for proteins of the pentapeptide repeat family that protects DNA gyrase and topoisomerase IV from quinolone inhibition. The qnr genes appear to have been acquired from chromosomal genes in aquatic bacteria, are usually associated with mobilizing or transposable elements on plasmids, and are often incorporated into sul1-type integrons. The second plasmid-mediated mechanism involves acetylation of quinolones with an appropriate amino nitrogen target by a variant of the common aminoglycoside acetyltransferase AAC(6')-Ib. The third mechanism is enhanced efflux produced by plasmid genes for pumps QepAB and OqxAB. PMQR has been found in clinical and environmental isolates around the world and appears to be spreading. The plasmid-mediated mechanisms provide only low-level resistance that by itself does not exceed the clinical breakpoint for susceptibility but nonetheless facilitates selection of higher-level resistance and makes infection by pathogens containing PMQR harder to treat.
Topics: Acetylation; Anti-Bacterial Agents; Bacteria; Bacterial Proteins; Biological Transport; DNA Gyrase; DNA Topoisomerase IV; Drug Resistance, Bacterial; Inactivation, Metabolic; Plasmids; Quinolones
PubMed: 25584197
DOI: 10.1128/microbiolspec.PLAS-0006-2013 -
The Journal of Antimicrobial... Aug 2014Loop B is important for low-level quinolone resistance conferred by Qnr proteins. The role of individual amino acids within QnrS1 loop B in quinolone resistance and...
OBJECTIVES
Loop B is important for low-level quinolone resistance conferred by Qnr proteins. The role of individual amino acids within QnrS1 loop B in quinolone resistance and gyrase protection was assessed.
METHODS
qnrS1 and 11 qnrS1 alleles with site-directed Ala mutations in loop B were expressed in Escherichia coli BL21(DE3) and proteins were purified by affinity chromatography. Ciprofloxacin MICs were determined with and without IPTG. Gyrase DNA supercoiling was measured with and without ciprofloxacin IC50 and with various concentrations of QnrS1 proteins.
RESULTS
Wild-type QnrS1 and QnrS1 with Asn-110→Ala and Arg-111→Ala substitutions increased the ciprofloxacin MIC 12-fold in BL21(DE3), although QnrS1 with Gln-107→Ala replacement increased it 2-fold more than wild-type did. However, QnrS1 with Ala substitutions at His-106, Val-108, Ser-109, Met-112, Tyr-113, Phe-114, Cys-115 and Ser-116 increased ciprofloxacin MIC 1.4- to 8-fold less than wild-type QnrS1. Induction by 10-1000 μM IPTG increased ciprofloxacin MICs for all mutants, reaching values similar to those for wild-type. Purified wild-type and mutated proteins differed in protection of gyrase from ciprofloxacin action. Wild-type QnrS1 produced complete protection of gyrase supercoiling from ciprofloxacin (1.8 μM) action at 0.05 nM and half protection at 0.5 pM, whereas QnrS1 with Ala replacements that conferred the least increase in ciprofloxacin MICs also required the highest QnrS1 concentrations for protection.
CONCLUSIONS
Key individual residues in QnrS1 loop B affect ciprofloxacin resistance and gyrase protection from ciprofloxacin action, supporting the concept that loop B is key for interaction with gyrase necessary for quinolone resistance.
Topics: Amino Acid Substitution; Anti-Bacterial Agents; Ciprofloxacin; DNA Gyrase; DNA, Superhelical; Drug Resistance, Bacterial; Escherichia coli; Escherichia coli Proteins; Isopropyl Thiogalactoside; Microbial Sensitivity Tests; Mutation; Protein Structure, Tertiary; Structure-Activity Relationship
PubMed: 24729602
DOI: 10.1093/jac/dku102 -
ChemMedChem Dec 2022Bacterial DNA gyrase, an essential enzyme, is a validated target for discovering and developing new antibiotics. Here we screened a pool of polyphenols and discovered...
Bacterial DNA gyrase, an essential enzyme, is a validated target for discovering and developing new antibiotics. Here we screened a pool of polyphenols and discovered that digallic acid is a potent DNA gyrase inhibitor. We also found that several food additives based on gallate, such as dodecyl gallate, potently inhibit bacterial DNA gyrase. Interestingly, the IC of these gallate derivatives against DNA gyrase is correlated with the length of hydrocarbon chain connecting to the gallate. These new bacterial DNA gyrase inhibitors are ATP competitive inhibitors of DNA gyrase. Our results also show that digallic acid and certain gallate derivatives potently inhibit E. coli DNA topoisomerase IV. Several gallate derivatives have strong antimicrobial activities against Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA). This study provides a solid foundation for the design and synthesis of gallate-based DNA gyrase inhibitors that may be used to combat antibacterial resistance.
Topics: DNA Gyrase; DNA, Bacterial; Topoisomerase II Inhibitors; Methicillin-Resistant Staphylococcus aureus; Escherichia coli
PubMed: 36161274
DOI: 10.1002/cmdc.202200301 -
ELife Jun 2024DNA gyrase, a ubiquitous bacterial enzyme, is a type IIA topoisomerase formed by heterotetramerisation of 2 GyrA subunits and 2 GyrB subunits, to form the active...
DNA gyrase, a ubiquitous bacterial enzyme, is a type IIA topoisomerase formed by heterotetramerisation of 2 GyrA subunits and 2 GyrB subunits, to form the active complex. DNA gyrase can loop DNA around the C-terminal domains (CTDs) of GyrA and pass one DNA duplex through a transient double-strand break (DSB) established in another duplex. This results in the conversion from a positive (+1) to a negative (-1) supercoil, thereby introducing negative supercoiling into the bacterial genome by steps of 2, an activity essential for DNA replication and transcription. The strong protein interface in the GyrA dimer must be broken to allow passage of the transported DNA segment and it is generally assumed that the interface is usually stable and only opens when DNA is transported, to prevent the introduction of deleterious DSBs in the genome. In this paper, we show that DNA gyrase can exchange its DNA-cleaving interfaces between two active heterotetramers. This so-called interface 'swapping' (IS) can occur within a few minutes in solution. We also show that bending of DNA by gyrase is essential for cleavage but not for DNA binding per se and favors IS. Interface swapping is also favored by DNA wrapping and an excess of GyrB. We suggest that proximity, promoted by GyrB oligomerization and binding and wrapping along a length of DNA, between two heterotetramers favors rapid interface swapping. This swapping does not require ATP, occurs in the presence of fluoroquinolones, and raises the possibility of non-homologous recombination solely through gyrase activity. The ability of gyrase to undergo interface swapping explains how gyrase heterodimers, containing a single active-site tyrosine, can carry out double-strand passage reactions and therefore suggests an alternative explanation to the recently proposed 'swivelling' mechanism for DNA gyrase (Gubaev et al., 2016).
Topics: DNA Gyrase; Protein Multimerization; DNA, Bacterial; Escherichia coli; DNA
PubMed: 38856655
DOI: 10.7554/eLife.86722 -
Drug Discovery Today Mar 2017Tuberculosis (TB) is the deadliest bacterial disease in the world. New therapeutic agents are urgently needed to replace existing drugs for which resistance is a... (Review)
Review
Tuberculosis (TB) is the deadliest bacterial disease in the world. New therapeutic agents are urgently needed to replace existing drugs for which resistance is a significant problem. DNA topoisomerases are well-validated targets for antimicrobial and anticancer chemotherapies. Although bacterial topoisomerase I has yet to be exploited as a target for clinical antibiotics, DNA gyrase has been extensively targeted, including the highly clinically successful fluoroquinolones, which have been utilized in TB therapy. Here, we review the exploitation of topoisomerases as antibacterial targets and summarize progress in developing new agents to target DNA topoisomerase I and DNA gyrase from Mycobacterium tuberculosis.
Topics: Antitubercular Agents; Bacterial Proteins; DNA Cleavage; DNA Gyrase; DNA Topoisomerases, Type I; Humans; Mycobacterium tuberculosis; Topoisomerase I Inhibitors; Topoisomerase II Inhibitors; Tuberculosis
PubMed: 27856347
DOI: 10.1016/j.drudis.2016.11.006 -
Annals of the New York Academy of... Sep 2015Quinolone antimicrobials are synthetic and widely used in clinical medicine. Resistance emerged with clinical use and became common in some bacterial pathogens.... (Review)
Review
Quinolone antimicrobials are synthetic and widely used in clinical medicine. Resistance emerged with clinical use and became common in some bacterial pathogens. Mechanisms of resistance include two categories of mutation and acquisition of resistance-conferring genes. Resistance mutations in one or both of the two drug target enzymes, DNA gyrase and DNA topoisomerase IV, are commonly in a localized domain of the GyrA and ParE subunits of the respective enzymes and reduce drug binding to the enzyme-DNA complex. Other resistance mutations occur in regulatory genes that control the expression of native efflux pumps localized in the bacterial membrane(s). These pumps have broad substrate profiles that include quinolones as well as other antimicrobials, disinfectants, and dyes. Mutations of both types can accumulate with selection pressure and produce highly resistant strains. Resistance genes acquired on plasmids can confer low-level resistance that promotes the selection of mutational high-level resistance. Plasmid-encoded resistance is due to Qnr proteins that protect the target enzymes from quinolone action, one mutant aminoglycoside-modifying enzyme that also modifies certain quinolones, and mobile efflux pumps. Plasmids with these mechanisms often encode additional antimicrobial resistances and can transfer multidrug resistance that includes quinolones. Thus, the bacterial quinolone resistance armamentarium is large.
Topics: Anti-Bacterial Agents; Bacteria; Bacterial Infections; Bacterial Proteins; DNA Gyrase; DNA Topoisomerase IV; Drug Resistance, Bacterial; Humans; Mutation; Quinolones
PubMed: 26190223
DOI: 10.1111/nyas.12830 -
Nucleic Acids Research Jun 2021Type IIA topoisomerases catalyze a variety of different reactions: eukaryotic topoisomerase II relaxes DNA in an ATP-dependent reaction, whereas the bacterial... (Review)
Review
Type IIA topoisomerases catalyze a variety of different reactions: eukaryotic topoisomerase II relaxes DNA in an ATP-dependent reaction, whereas the bacterial representatives gyrase and topoisomerase IV (Topo IV) preferentially introduce negative supercoils into DNA (gyrase) or decatenate DNA (Topo IV). Gyrase and Topo IV perform separate, dedicated tasks during replication: gyrase removes positive supercoils in front, Topo IV removes pre-catenanes behind the replication fork. Despite their well-separated cellular functions, gyrase and Topo IV have an overlapping activity spectrum: gyrase is also able to catalyze DNA decatenation, although less efficiently than Topo IV. The balance between supercoiling and decatenation activities is different for gyrases from different organisms. Both enzymes consist of a conserved topoisomerase core and structurally divergent C-terminal domains (CTDs). Deletion of the entire CTD, mutation of a conserved motif and even by just a single point mutation within the CTD converts gyrase into a Topo IV-like enzyme, implicating the CTDs as the major determinant for function. Here, we summarize the structural and mechanistic features that make a type IIA topoisomerase a gyrase or a Topo IV, and discuss the implications for type IIA topoisomerase evolution.
Topics: Bacteria; DNA; DNA Gyrase; DNA Topoisomerase IV; DNA Topoisomerases, Type II; Evolution, Molecular; Protein Conformation; Protein Domains
PubMed: 33905522
DOI: 10.1093/nar/gkab270 -
Future Medicinal Chemistry Mar 2022Bacterial resistance to antibiotics threatens our progress in healthcare, modern medicine, food production and ultimately life expectancy. Antibiotic resistance is a... (Review)
Review
Bacterial resistance to antibiotics threatens our progress in healthcare, modern medicine, food production and ultimately life expectancy. Antibiotic resistance is a global concern, which spreads rapidly across borders and continents due to rapid travel of people, animals and goods. Derivatives of metabolically stable pyrazole nucleus are known for their wide range of pharmacological properties, including antibacterial activities. This review highlights recent reports of pyrazole derivatives targeting different bacterial strains focusing on the drug-resistant variants. Pyrazole derivatives target different metabolic pathways of both Gram-positive and Gram-negative bacteria.
Topics: Alkyl and Aryl Transferases; Anti-Bacterial Agents; Cell Wall; DNA Gyrase; Drug Resistance, Multiple, Bacterial; Gram-Negative Bacteria; Gram-Positive Bacteria; Pyrazoles; Tetrahydrofolate Dehydrogenase
PubMed: 35050719
DOI: 10.4155/fmc-2021-0275