Acetylation of fluoroquinolone antimicrobial agents by an<i>Escherichia coli</i>strain isolated from a municipal wastewater treatment plant

Jung, Carina M.; Heinze, Thomas M.; Strakosha, R.; Elkins, Christopher A.; Sutherland, John B.

doi:10.1111/j.1365-2672.2008.04026.x

Cited by 48 publications

(36 citation statements)

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“…qnrS2 was found on a plasmid isolated from the activated sludge basin of a wastewater treatment plant in Germany at about the same time (14,99). qnrS from veterinary clinical E. coli isolates in Guangdong, China, that was deposited in GenBank as qnrS1 (GenBank accession number ABU52984) differed from qnrS1 in one codon and has thus been renamed qnrS3.…”

Section: Discovery Of Qnr Genesmentioning

confidence: 99%

Plasmid-Mediated Quinolone Resistance: a Multifaceted Threat

et al. 2009

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SUMMARY Although plasmid-mediated quinolone resistance (PMQR) was thought not to exist before its discovery in 1998, the past decade has seen an explosion of research characterizing this phenomenon. The best-described form of PMQR is determined by the qnr group of genes. These genes, likely originating in aquatic organisms, code for pentapeptide repeat proteins. These proteins reduce susceptibility to quinolones by protecting the complex of DNA and DNA gyrase or topoisomerase IV enzymes from the inhibitory effect of quinolones. Two additional PMQR mechanisms were recently described. aac(6′)-Ib-cr encodes a variant aminoglycoside acetyltransferase with two amino acid alterations allowing it to inactivate ciprofloxacin through the acetylation of its piperazinyl substituent. oqxAB and qepA encode efflux pumps that extrude quinolones. All of these genes determine relatively small increases in the MICs of quinolones, but these changes are sufficient to facilitate the selection of mutants with higher levels of resistance. The contribution of these genes to the emergence of quinolone resistance is being actively investigated. Several factors suggest their importance in this process, including their increasing ubiquity, their association with other resistance elements, and their emergence simultaneous with the expansion of clinical quinolone resistance. Of concern, these genes are not yet being taken into account in resistance screening by clinical microbiology laboratories.

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Section: Discovery Of Qnr Genesmentioning

confidence: 99%

Plasmid-Mediated Quinolone Resistance: a Multifaceted Threat

et al. 2009

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“…Pure cultures of bacteria and mixed cultures from wastewater treatment plants degrade the piperazine moieties of some fluoroquinolones (1, 12, 13). A modified aminoglycoside acetyltransferase from Escherichia coli is responsible for acetylation of fluoroquinolones (28,43).It seemed possible that bacteria capable of fluoroquinolone modification or degradation could be isolated from a wastewater treatment plant and that the metabolites produced could be identified to determine the metabolic pathways. By using HPLC, mass spectrometric (liquid chromatography-ESI-MS/MS [LC-ESI-MS/MS]), and proton nuclear magnetic resonance (NMR) analyses, it was shown that a norfloxacin-insensitive strain of Microbacterium sp.…”

mentioning

confidence: 99%

Modification of Norfloxacin by a Microbacterium sp. Strain Isolated from a Wastewater Treatment Plant

Kim

Heinze

Kim

et al. 2011

Appl Environ Microbiol

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Antimicrobial residues found in municipal wastewater may increase selective pressure on microorganisms for development of resistance, but studies with mixed microbial cultures derived from wastewater have suggested that some bacteria are able to inactivate fluoroquinolones. Medium containing N-phenylpiperazine and inoculated with wastewater was used to enrich fluoroquinolone-modifying bacteria. One bacterial strain isolated from an enrichment culture was identified by 16S rRNA gene sequence analysis as a Microbacterium sp. similar to a plant growth-promoting bacterium, Microbacterium azadirachtae (99.70%), and a nematode pathogen, "M. nematophilum" (99.02%). During growth in medium with norfloxacin, this strain produced four metabolites, which were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and nuclear magnetic resonance (NMR) analyses as 8-hydroxynorfloxacin, 6-defluoro-6-hydroxynorfloxacin, desethylene norfloxacin, and N-acetylnorfloxacin. The production of the first three metabolites was enhanced by ascorbic acid and nitrate, but it was inhibited by phosphate, amino acids, mannitol, formate, and thiourea. In contrast, N-acetylnorfloxacin was most abundant in cultures supplemented with amino acids. This is the first report of defluorination and hydroxylation of a fluoroquinolone by an isolated bacterial strain. The results suggest that some bacteria may degrade fluoroquinolones in wastewater to metabolites with less antibacterial activity that could be subject to further degradation by other microorganisms.A variety of pharmaceuticals, including several fluoroquinolone antimicrobial agents used in human and veterinary medicine, have been detected at low concentrations in wastewater treatment plants and other environmental sites in many countries (16,23,30,50,55). Understanding the degradation pathways of these drugs and the potential biological activity of the metabolites (48) is important to prevent selection for drugresistant strains. Solid-phase extraction, high-performance liquid chromatography (HPLC), and electrospray ionization-tandem mass spectrometry (ESI-MS/MS) have been used to concentrate and detect norfloxacin and other fluoroquinolones in wastewater (11,33,47). When fluoroquinolones given to livestock are excreted and the treatment of wastewater is minimal or nonexistent, as in some feed lots and slaughterhouses, fluoroquinolones may be released into river water (47). In contrast, when wastewater is treated by the activated sludge process, much of the fluoroquinolone content is sorbed and cannot be detected (11, 55). Some bacteria with resistance to antibiotics, however, may proliferate in wastewater and transfer resistance genes to other species (30).The metabolism of fluoroquinolones by environmental brown rot fungi is well understood (51-53), and some metabolic pathways for fluoroquinolones have also been determined for other fungi (40-42). Ring oxidation or hydroxylation is generally the first step in fungal degradation of fluoroquinolones (51, 53). Fluoroquinolone...

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“…Production of N-acetylnorfloxacin and N-nitrosonorfloxacin by environmental Mycobacterium sp. strains has also been found, but the enzymes responsible for modifications are unknown (15) and the aac(6=)-Ib-cr variant gene has not been detected in these strains (12).…”

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confidence: 99%

“…In some strains of Escherichia coli, a mutated aminoglycoside acetyltransferase, AAC(6=)-Ib-cr, acetylates fluoroquinolones at the N-terminal of the piperazine ring (12)(13)(14) and enhances bacterial resistance to these drugs (14). Production of N-acetylnorfloxacin and N-nitrosonorfloxacin by environmental Mycobacterium sp.…”

mentioning

confidence: 99%

“…Because their persistence in the environment (2) may act as a selective pressure for naïve strains to acquire resistance (3), an understanding of the fate of these drugs should help to prevent drug resistance. The principal resistance mechanisms for fluoroquinolones include the following: (i) mutation of genes for the drug targets (GyrA, GyrB, and ParC) (4-6), (ii) mimicking the drug targets (QnrA, QnrB, and QnrS) (7)(8)(9), (iii) reduction of drug accumulation in the cells (AcrAB-TolC and QepA) (4,10,11), and (iv) enzymatic modification of the drug [N-acetylation by AAC(6=)-Ib-cr] (12)(13)(14).…”

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confidence: 99%

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Identification of the Enzyme Responsible forN-Acetylation of Norfloxacin by Microbacterium sp. Strain 4N2-2

Kim

Feng

Chen

et al. 2013

Appl Environ Microbiol

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bMicrobacterium sp. 4N2-2, isolated from a wastewater treatment plant, converts the antibacterial fluoroquinolone norfloxacin to N-acetylnorfloxacin and three other metabolites. Because N-acetylation results in loss of antibacterial activity, identification of the enzyme responsible is important for understanding fluoroquinolone resistance. The enzyme was identified as glutamine synthetase (GS); N-acetylnorfloxacin was produced only under conditions associated with GS expression. The GS gene (glnA) was cloned, and the protein (53 kDa) was heterologously expressed and isolated. Optimal conditions and biochemical properties (K m and V max ) of purified GS were characterized; the purified enzyme was inhibited by Mn 2؉ , Mg 2؉ , ATP, and ADP. The contribution of GS to norfloxacin resistance was shown by using a norfloxacin-sensitive Escherichia coli strain carrying glnA derived from Microbacterium sp. 4N2-2. The GS of Microbacterium sp. 4N2-2 was shown to act as an N-acetyltransferase for norfloxacin, which produced low-level norfloxacin resistance. Structural and docking analysis identified potential binding sites for norfloxacin at the ADP binding site and for acetyl coenzyme A (acetyl-CoA) at a cleft in GS. The results suggest that environmental bacteria whose enzymes modify fluoroquinolones may be able to survive in the presence of low fluoroquinolone concentrations. Fluoroquinolones are widely used as human and veterinary antimicrobial agents (1). Because their persistence in the environment (2) may act as a selective pressure for naïve strains to acquire resistance (3), an understanding of the fate of these drugs should help to prevent drug resistance. The principal resistance mechanisms for fluoroquinolones include the following: (i) mutation of genes for the drug targets (GyrA, GyrB, and ParC) (4-6), (ii) mimicking the drug targets (QnrA, QnrB, and QnrS) (7-9), (iii) reduction of drug accumulation in the cells (AcrAB-TolC and QepA) (4, 10, 11), and (iv) enzymatic modification of the drug [N-acetylation by AAC(6=)-Ib-cr] (12-14).In some strains of Escherichia coli, a mutated aminoglycoside acetyltransferase, AAC(6=)-Ib-cr, acetylates fluoroquinolones at the N-terminal of the piperazine ring (12-14) and enhances bacterial resistance to these drugs (14). Production of N-acetylnorfloxacin and N-nitrosonorfloxacin by environmental Mycobacterium sp. strains has also been found, but the enzymes responsible for modifications are unknown (15) and the aac(6=)-Ib-cr variant gene has not been detected in these strains (12).A norfloxacin-modifying bacterium, Microbacterium sp. strain 4N2-2, was isolated from wastewater (16). Some strains of this genus have been isolated from human clinical specimens, and the majority of them have shown fluoroquinolone resistance (17). Microbacterium sp. 4N2-2 transforms norfloxacin into four different metabolites, including N-acetylnorfloxacin, and cell extracts of this strain catalyze the N-acetylation of norfloxacin (16). NAcetylation is enhanced by Casamino Acids and inhibited by ammo...

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Acetylation of fluoroquinolone antimicrobial agents by anEscherichia colistrain isolated from a municipal wastewater treatment plant

Cited by 48 publications

References 61 publications

Plasmid-Mediated Quinolone Resistance: a Multifaceted Threat

Plasmid-Mediated Quinolone Resistance: a Multifaceted Threat

Modification of Norfloxacin by a Microbacterium sp. Strain Isolated from a Wastewater Treatment Plant

Identification of the Enzyme Responsible forN-Acetylation of Norfloxacin by Microbacterium sp. Strain 4N2-2

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