Acinetobacter Infections
Infections with bacteria of the genus ACINETOBACTER.
Acinetobacter baumannii
A species of gram-negative, aerobic bacteria, commonly found in the clinical laboratory, and frequently resistant to common antibiotics.
Acinetobacter calcoaceticus
A species of gram-negative, aerobic bacteria found in soil and water. Although considered to be normally nonpathogenic, this bacterium is a causative agent of nosocomial infections, particularly in debilitated individuals.
Carbapenems
A group of beta-lactam antibiotics in which the sulfur atom in the thiazolidine ring of the penicillin molecule is replaced by a carbon atom. THIENAMYCINS are a subgroup of carbapenems which have a sulfur atom as the first constituent of the side chain.
Drug Resistance, Multiple, Bacterial
Anti-Bacterial Agents
Substances that reduce the growth or reproduction of BACTERIA.
Colistin
Cyclic polypeptide antibiotic from Bacillus colistinus. It is composed of Polymyxins E1 and E2 (or Colistins A, B, and C) which act as detergents on cell membranes. Colistin is less toxic than Polymyxin B, but otherwise similar; the methanesulfonate is used orally.
Microbial Sensitivity Tests
Any tests that demonstrate the relative efficacy of different chemotherapeutic agents against specific microorganisms (i.e., bacteria, fungi, viruses).
beta-Lactamases
Enzymes found in many bacteria which catalyze the hydrolysis of the amide bond in the beta-lactam ring. Well known antibiotics destroyed by these enzymes are penicillins and cephalosporins.
Imipenem
Semisynthetic thienamycin that has a wide spectrum of antibacterial activity against gram-negative and gram-positive aerobic and anaerobic bacteria, including many multiresistant strains. It is stable to beta-lactamases. Clinical studies have demonstrated high efficacy in the treatment of infections of various body systems. Its effectiveness is enhanced when it is administered in combination with CILASTATIN, a renal dipeptidase inhibitor.
DNA, Bacterial
Deoxyribonucleic acid that makes up the genetic material of bacteria.
beta-Lactam Resistance
Nonsusceptibility of bacteria to the action of the beta-lactam antibiotics. Mechanisms responsible for beta-lactam resistance may be degradation of antibiotics by BETA-LACTAMASES, failure of antibiotics to penetrate, or low-affinity binding of antibiotics to targets.
Drug Resistance, Bacterial
Minocycline
Gram-Negative Bacteria
Thienamycins
Beta-lactam antibiotics that differ from PENICILLINS in having the thiazolidine sulfur atom replaced by carbon, the sulfur then becoming the first atom in the side chain. They are unstable chemically, but have a very broad antibacterial spectrum. Thienamycin and its more stable derivatives are proposed for use in combinations with enzyme inhibitors.
Molecular Sequence Data
Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.
Sulbactam
A beta-lactamase inhibitor with very weak antibacterial action. The compound prevents antibiotic destruction of beta-lactam antibiotics by inhibiting beta-lactamases, thus extending their spectrum activity. Combinations of sulbactam with beta-lactam antibiotics have been used successfully for the therapy of infections caused by organisms resistant to the antibiotic alone.
Alkanes
The generic name for the group of aliphatic hydrocarbons Cn-H2n+2. They are denoted by the suffix -ane. (Grant & Hackh's Chemical Dictionary, 5th ed)
Protocatechuate-3,4-Dioxygenase
Electrophoresis, Gel, Pulsed-Field
Gel electrophoresis in which the direction of the electric field is changed periodically. This technique is similar to other electrophoretic methods normally used to separate double-stranded DNA molecules ranging in size up to tens of thousands of base-pairs. However, by alternating the electric field direction one is able to separate DNA molecules up to several million base-pairs in length.
Genes, Bacterial
The functional hereditary units of BACTERIA.
Alcaligenes
Sequence Analysis, DNA
Bacterial Typing Techniques
Procedures for identifying types and strains of bacteria. The most frequently employed typing systems are BACTERIOPHAGE TYPING and SEROTYPING as well as bacteriocin typing and biotyping.
Gram-Negative Bacterial Infections
Infections caused by bacteria that show up as pink (negative) when treated by the gram-staining method.
Adipates
Derivatives of adipic acid. Included under this heading are a broad variety of acid forms, salts, esters, and amides that contain a 1,6-carboxy terminated aliphatic structure.
Bacteremia
The presence of viable bacteria circulating in the blood. Fever, chills, tachycardia, and tachypnea are common acute manifestations of bacteremia. The majority of cases are seen in already hospitalized patients, most of whom have underlying diseases or procedures which render their bloodstreams susceptible to invasion.
DNA Fingerprinting
A technique for identifying individuals of a species that is based on the uniqueness of their DNA sequence. Uniqueness is determined by identifying which combination of allelic variations occur in the individual at a statistically relevant number of different loci. In forensic studies, RESTRICTION FRAGMENT LENGTH POLYMORPHISM of multiple, highly polymorphic VNTR LOCI or MICROSATELLITE REPEAT loci are analyzed. The number of loci used for the profile depends on the ALLELE FREQUENCY in the population.
Intensive Care Units
Moraxella
Molecular Typing
Using MOLECULAR BIOLOGY techniques, such as DNA SEQUENCE ANALYSIS; PULSED-FIELD GEL ELECTROPHORESIS; and DNA FINGERPRINTING, to identify, classify, and compare organisms and their subtypes.
Hospitals, Military
Hospitals which provide care for the military personnel and usually for their dependents.
Amikacin
Integrons
Molecular Epidemiology
Transformation, Bacterial
The heritable modification of the properties of a competent bacterium by naked DNA from another source. The uptake of naked DNA is a naturally occuring phenomenon in some bacteria. It is often used as a GENE TRANSFER TECHNIQUE.
Bacteria
One of the three domains of life (the others being Eukarya and ARCHAEA), also called Eubacteria. They are unicellular prokaryotic microorganisms which generally possess rigid cell walls, multiply by cell division, and exhibit three principal forms: round or coccal, rodlike or bacillary, and spiral or spirochetal. Bacteria can be classified by their response to OXYGEN: aerobic, anaerobic, or facultatively anaerobic; by the mode by which they obtain their energy: chemotrophy (via chemical reaction) or PHOTOTROPHY (via light reaction); for chemotrophs by their source of chemical energy: CHEMOLITHOTROPHY (from inorganic compounds) or chemoorganotrophy (from organic compounds); and by their source for CARBON; NITROGEN; etc.; HETEROTROPHY (from organic sources) or AUTOTROPHY (from CARBON DIOXIDE). They can also be classified by whether or not they stain (based on the structure of their CELL WALLS) with CRYSTAL VIOLET dye: gram-negative or gram-positive.
Drug Resistance, Microbial
Hydroxybenzoates
beta-Lactams
Four-membered cyclic AMIDES, best known for the PENICILLINS based on a bicyclo-thiazolidine, as well as the CEPHALOSPORINS based on a bicyclo-thiazine, and including monocyclic MONOBACTAMS. The BETA-LACTAMASES hydrolyze the beta lactam ring, accounting for BETA-LACTAM RESISTANCE of infective bacteria.
Polymerase Chain Reaction
In vitro method for producing large amounts of specific DNA or RNA fragments of defined length and sequence from small amounts of short oligonucleotide flanking sequences (primers). The essential steps include thermal denaturation of the double-stranded target molecules, annealing of the primers to their complementary sequences, and extension of the annealed primers by enzymatic synthesis with DNA polymerase. The reaction is efficient, specific, and extremely sensitive. Uses for the reaction include disease diagnosis, detection of difficult-to-isolate pathogens, mutation analysis, genetic testing, DNA sequencing, and analyzing evolutionary relationships.
Multilocus Sequence Typing
Disk Diffusion Antimicrobial Tests
Pseudomonas aeruginosa
A species of gram-negative, aerobic, rod-shaped bacteria commonly isolated from clinical specimens (wound, burn, and urinary tract infections). It is also found widely distributed in soil and water. P. aeruginosa is a major agent of nosocomial infection.
RNA, Ribosomal, 16S
Catechol 1,2-Dioxygenase
Parabens
Methyl, propyl, butyl, and ethyl esters of p-hydroxybenzoic acid. They have been approved by the FDA as antimicrobial agents for foods and pharmaceuticals. (From Hawley's Condensed Chemical Dictionary, 11th ed, p872)
Genome, Bacterial
The genetic complement of a BACTERIA as represented in its DNA.
Biodegradation, Environmental
Pneumonia, Bacterial
Inflammation of the lung parenchyma that is caused by bacterial infections.
Monobactams
Plasmids
Disease Outbreaks
Polymyxins
Enterobacteriaceae
A family of gram-negative, facultatively anaerobic, rod-shaped bacteria that do not form endospores. Its organisms are distributed worldwide with some being saprophytes and others being plant and animal parasites. Many species are of considerable economic importance due to their pathogenic effects on agriculture and livestock.
Vanillic Acid
Glucose Dehydrogenases
Pneumonia, Ventilator-Associated
Serious INFLAMMATION of the LUNG in patients who required the use of PULMONARY VENTILATOR. It is usually caused by cross bacterial infections in hospitals (NOSOCOMIAL INFECTIONS).
Base Sequence
Aminoglycosides
Culture Media
Any liquid or solid preparation made specifically for the growth, storage, or transport of microorganisms or other types of cells. The variety of media that exist allow for the culturing of specific microorganisms and cell types, such as differential media, selective media, test media, and defined media. Solid media consist of liquid media that have been solidified with an agent such as AGAR or GELATIN.
Cluster Analysis
A set of statistical methods used to group variables or observations into strongly inter-related subgroups. In epidemiology, it may be used to analyze a closely grouped series of events or cases of disease or other health-related phenomenon with well-defined distribution patterns in relation to time or place or both.
PQQ Cofactor
Waxes
A plastic substance deposited by insects or obtained from plants. Waxes are esters of various fatty acids with higher, usually monohydric alcohols. The wax of pharmacy is principally yellow wax (beeswax), the material of which honeycomb is made. It consists chiefly of cerotic acid and myricin and is used in making ointments, cerates, etc. (Dorland, 27th ed)
Chromosomes, Bacterial
DNA Transposable Elements
Discrete segments of DNA which can excise and reintegrate to another site in the genome. Most are inactive, i.e., have not been found to exist outside the integrated state. DNA transposable elements include bacterial IS (insertion sequence) elements, Tn elements, the maize controlling elements Ac and Ds, Drosophila P, gypsy, and pogo elements, the human Tigger elements and the Tc and mariner elements which are found throughout the animal kingdom.
DNA, Ribosomal
Pseudomonas
A genus of gram-negative, aerobic, rod-shaped bacteria widely distributed in nature. Some species are pathogenic for humans, animals, and plants.
Environmental Microbiology
Polymyxin B
A mixture of polymyxins B1 and B2, obtained from Bacillus polymyxa strains. They are basic polypeptides of about eight amino acids and have cationic detergent action on cell membranes. Polymyxin B is used for infections with gram-negative organisms, but may be neurotoxic and nephrotoxic.
Fuel Oils
Complex petroleum hydrocarbons consisting mainly of residues from crude oil distillation. These liquid products include heating oils, stove oils, and furnace oils and are burned to generate energy.
Kanamycin Resistance
Nonsusceptibility of bacteria to the antibiotic KANAMYCIN, which can bind to their 70S ribosomes and cause misreading of messenger RNA.
Oxygenases
Amino Acid Sequence
Amplified Fragment Length Polymorphism Analysis
Meningitis, Bacterial
Siderophores
Biofilms
Encrustations, formed from microbes (bacteria, algae, fungi, plankton, or protozoa) embedding in extracellular polymers, that adhere to surfaces such as teeth (DENTAL DEPOSITS); PROSTHESES AND IMPLANTS; and catheters. Biofilms are prevented from forming by treating surfaces with DENTIFRICES; DISINFECTANTS; ANTI-INFECTIVE AGENTS; and antifouling agents.
Bacteriological Techniques
Techniques used in studying bacteria.
Genotype
Microbial Viability
Escherichia coli
A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.
Hospitals, University
Rhizosphere
Gene Expression Regulation, Bacterial
Any of the processes by which cytoplasmic or intercellular factors influence the differential control of gene action in bacteria.
Gram-Negative Aerobic Bacteria
A large group of aerobic bacteria which show up as pink (negative) when treated by the gram-staining method. This is because the cell walls of gram-negative bacteria are low in peptidoglycan and thus have low affinity for violet stain and high affinity for the pink dye safranine.
Pseudomonas Infections
4-Hydroxybenzoate-3-Monooxygenase
Species Specificity
The restriction of a characteristic behavior, anatomical structure or physical system, such as immune response; metabolic response, or gene or gene variant to the members of one species. It refers to that property which differentiates one species from another but it is also used for phylogenetic levels higher or lower than the species.
Polyphosphates
Drug Resistance, Multiple
Colony Count, Microbial
Enumeration by direct count of viable, isolated bacterial, archaeal, or fungal CELLS or SPORES capable of growth on solid CULTURE MEDIA. The method is used routinely by environmental microbiologists for quantifying organisms in AIR; FOOD; and WATER; by clinicians for measuring patients' microbial load; and in antimicrobial drug testing.
Phosphotransferases (Phosphate Group Acceptor)
Glucose 1-Dehydrogenase
Cephalosporinase
Cephalosporinase is an enzyme produced by certain bacteria that can hydrolyze and confer resistance to cephalosporin antibiotics.
Iraq
Pediculus
Tetracyclines
Ceftazidime
Semisynthetic, broad-spectrum antibacterial derived from CEPHALORIDINE and used especially for Pseudomonas and other gram-negative infections in debilitated patients.
Mutation
Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.
Infection Control
Water Microbiology
The presence of bacteria, viruses, and fungi in water. This term is not restricted to pathogenic organisms.
Hydrocarbons
Hydrocarbons are organic compounds consisting entirely of hydrogen and carbon atoms, forming the basis of classes such as alkanes, alkenes, alkynes, and aromatic hydrocarbons, which play a vital role in energy production and chemical synthesis.
Tertiary Care Centers
Cloning, Molecular
Klebsiella pneumoniae
Cilastatin
A renal dehydropeptidase-I and leukotriene D4 dipeptidase inhibitor. Since the antibiotic, IMIPENEM, is hydrolyzed by dehydropeptidase-I, which resides in the brush border of the renal tubule, cilastatin is administered with imipenem to increase its effectiveness. The drug also inhibits the metabolism of leukotriene D4 to leukotriene E4.
Benzoates
Derivatives of BENZOIC ACID. Included under this heading are a broad variety of acid forms, salts, esters, and amides that contain the carboxybenzene structure.
Soil Microbiology
The presence of bacteria, viruses, and fungi in the soil. This term is not restricted to pathogenic organisms.
Alcohol Oxidoreductases
A subclass of enzymes which includes all dehydrogenases acting on primary and secondary alcohols as well as hemiacetals. They are further classified according to the acceptor which can be NAD+ or NADP+ (subclass 1.1.1), cytochrome (1.1.2), oxygen (1.1.3), quinone (1.1.5), or another acceptor (1.1.99).
Conjugation, Genetic
A parasexual process in BACTERIA; ALGAE; FUNGI; and ciliate EUKARYOTA for achieving exchange of chromosome material during fusion of two cells. In bacteria, this is a uni-directional transfer of genetic material; in protozoa it is a bi-directional exchange. In algae and fungi, it is a form of sexual reproduction, with the union of male and female gametes.
Bacterial Infections
Infections by bacteria, general or unspecified.
Bacterial Outer Membrane Proteins
Proteins isolated from the outer membrane of Gram-negative bacteria.
Anti-Infective Agents
Czech Republic
Created 1 January 1993 as a result of the division of Czechoslovakia into the Czech Republic and Slovakia.
Clavulanic Acid
Clavulanic acid and its salts and esters. The acid is a suicide inhibitor of bacterial beta-lactamase enzymes from Streptomyces clavuligerus. Administered alone, it has only weak antibacterial activity against most organisms, but given in combination with other beta-lactam antibiotics it prevents antibiotic inactivation by microbial lactamase.
O Antigens
The lipopolysaccharide-protein somatic antigens, usually from gram-negative bacteria, important in the serological classification of enteric bacilli. The O-specific chains determine the specificity of the O antigens of a given serotype. O antigens are the immunodominant part of the lipopolysaccharide molecule in the intact bacterial cell. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)
Ampicillin
Housekeeping, Hospital
Lice Infestations
Parasitic attack or subsistence on the skin by members of the order Phthiraptera, especially on humans by Pediculus humanus of the family Pediculidae. The hair of the head, eyelashes, and pubis is a frequent site of infestation. (From Dorland, 28th ed; Stedman, 26th ed)
Gene Transfer, Horizontal
The naturally occurring transmission of genetic information between organisms, related or unrelated, circumventing parent-to-offspring transmission. Horizontal gene transfer may occur via a variety of naturally occurring processes such as GENETIC CONJUGATION; GENETIC TRANSDUCTION; and TRANSFECTION. It may result in a change of the recipient organism's genetic composition (TRANSFORMATION, GENETIC).
Oxidoreductases, O-Demethylating
Random Amplified Polymorphic DNA Technique
Technique that utilizes low-stringency polymerase chain reaction (PCR) amplification with single primers of arbitrary sequence to generate strain-specific arrays of anonymous DNA fragments. RAPD technique may be used to determine taxonomic identity, assess kinship relationships, analyze mixed genome samples, and create specific probes.
Fomites
Rifampin
A semisynthetic antibiotic produced from Streptomyces mediterranei. It has a broad antibacterial spectrum, including activity against several forms of Mycobacterium. In susceptible organisms it inhibits DNA-dependent RNA polymerase activity by forming a stable complex with the enzyme. It thus suppresses the initiation of RNA synthesis. Rifampin is bactericidal, and acts on both intracellular and extracellular organisms. (From Gilman et al., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 9th ed, p1160)
Phenotype
The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.
Taiwan
Ketoses
Quinolones
Mutagenesis, Insertional
Mutagenesis where the mutation is caused by the introduction of foreign DNA sequences into a gene or extragenic sequence. This may occur spontaneously in vivo or be experimentally induced in vivo or in vitro. Proviral DNA insertions into or adjacent to a cellular proto-oncogene can interrupt GENETIC TRANSLATION of the coding sequences or interfere with recognition of regulatory elements and cause unregulated expression of the proto-oncogene resulting in tumor formation.
Fluoroquinolones
A group of QUINOLONES with at least one fluorine atom and a piperazinyl group.
Republic of Korea
The capital is Seoul. The country, established September 9, 1948, is located on the southern part of the Korean Peninsula. Its northern border is shared with the Democratic People's Republic of Korea.
Benzyl Alcohols
Sugar Acids
'Sugar acids' are organic compounds derived from sugars through various processes, characterized by the presence of both a carboxyl group (-COOH) and a hydroxyl group (-OH) in their molecular structure, often found in food sources like fruits and used in industries such as food, pharmaceutical, and cosmetic.
Esterases
Esterases are hydrolase enzymes that catalyze the hydrolysis of ester bonds, converting esters into alcohols and acids, playing crucial roles in various biological processes including metabolism and detoxification.
Tertiary Healthcare
Kingella
A genus of gram-negative, aerobic, rod-shaped bacteria whose organisms are part of the normal flora of the mucous membranes of the upper respiratory tract. Some species are pathogenic for man.
Hospitals, Teaching
Benzyl Alcohol
Transformation, Genetic
Change brought about to an organisms genetic composition by unidirectional transfer (TRANSFECTION; TRANSDUCTION, GENETIC; CONJUGATION, GENETIC, etc.) and incorporation of foreign DNA into prokaryotic or eukaryotic cells by recombination of part or all of that DNA into the cell's genome.
Korea
Former kingdom, located on Korea Peninsula between Sea of Japan and Yellow Sea on east coast of Asia. In 1948, the kingdom ceased and two independent countries were formed, divided by the 38th parallel.
Cephalosporins
Esters
Polysaccharides, Bacterial
Polysaccharides found in bacteria and in capsules thereof.
Coumaric Acids
Equipment Contamination
Benzaldehydes
Penicillanic Acid
Myoviridae
Mixed Function Oxygenases
Widely distributed enzymes that carry out oxidation-reduction reactions in which one atom of the oxygen molecule is incorporated into the organic substrate; the other oxygen atom is reduced and combined with hydrogen ions to form water. They are also known as monooxygenases or hydroxylases. These reactions require two substrates as reductants for each of the two oxygen atoms. There are different classes of monooxygenases depending on the type of hydrogen-providing cosubstrate (COENZYMES) required in the mixed-function oxidation.
Malaysia
A parliamentary democracy with a constitutional monarch in southeast Asia, consisting of 11 states (West Malaysia) on the Malay Peninsula and two states (East Malaysia) on the island of BORNEO. It is also called the Federation of Malaysia. Its capital is Kuala Lumpur. Before 1963 it was the Union of Malaya. It reorganized in 1948 as the Federation of Malaya, becoming independent from British Malaya in 1957 and becoming Malaysia in 1963 as a federation of Malaya, Sabah, Sarawak, and Singapore (which seceded in 1965). The form Malay- probably derives from the Tamil malay, mountain, with reference to its geography. (From Webster's New Geographical Dictionary, 1988, p715 & Room, Brewer's Dictionary of Names, 1992, p329)
Chenopodiaceae
Benzoic Acid
Pseudomonas putida
A species of gram-negative, aerobic bacteria isolated from soil and water as well as clinical specimens. Occasionally it is an opportunistic pathogen.
Genomic Islands
Distinct units in some bacterial, bacteriophage or plasmid GENOMES that are types of MOBILE GENETIC ELEMENTS. Encoded in them are a variety of fitness conferring genes, such as VIRULENCE FACTORS (in "pathogenicity islands or islets"), ANTIBIOTIC RESISTANCE genes, or genes required for SYMBIOSIS (in "symbiosis islands or islets"). They range in size from 10 - 500 kilobases, and their GC CONTENT and CODON usage differ from the rest of the genome. They typically contain an INTEGRASE gene, although in some cases this gene has been deleted resulting in "anchored genomic islands".
Argentina
I'm sorry for any confusion, but the term "Argentina" is not a medical concept or condition that has a defined meaning within the medical field. Argentina is actually the second largest country in South America, and is known for its rich cultural history, diverse landscapes, and significant contributions to fields such as science, arts, and sports. If you have any questions related to healthcare, medicine, or biology, I would be happy to try to help answer those!
Bacterial Adhesion
Physicochemical property of fimbriated (FIMBRIAE, BACTERIAL) and non-fimbriated bacteria of attaching to cells, tissue, and nonbiological surfaces. It is a factor in bacterial colonization and pathogenicity.
Restriction Mapping
Dioxygenases
Non-heme iron-containing enzymes that incorporate two atoms of OXYGEN into the substrate. They are important in biosynthesis of FLAVONOIDS; GIBBERELLINS; and HYOSCYAMINE; and for degradation of AROMATIC HYDROCARBONS.
Aztreonam
A monocyclic beta-lactam antibiotic originally isolated from Chromobacterium violaceum. It is resistant to beta-lactamases and is used in gram-negative infections, especially of the meninges, bladder, and kidneys. It may cause a superinfection with gram-positive organisms.
Bacterial Load
Measurable quantity of bacteria in an object, organism, or organism compartment.
RNA, Bacterial
Ribonucleic acid in bacteria having regulatory and catalytic roles as well as involvement in protein synthesis.
Acyl-Butyrolactones
Cyclic esters of acylated BUTYRIC ACID containing four carbons in the ring.
Substrate Specificity
DNA Gyrase
A bacterial DNA topoisomerase II that catalyzes ATP-dependent breakage of both strands of DNA, passage of the unbroken strands through the breaks, and rejoining of the broken strands. Gyrase binds to DNA as a heterotetramer consisting of two A and two B subunits. In the presence of ATP, gyrase is able to convert the relaxed circular DNA duplex into a superhelix. In the absence of ATP, supercoiled DNA is relaxed by DNA gyrase.