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The Journal of Antibiotics Oct 2000Fourteen different aminoglycoside antibiotics (AGs) were challenged with aminoglycoside acetyltransferases (AACs) of actinomycete origin in order to examine their...
Fourteen different aminoglycoside antibiotics (AGs) were challenged with aminoglycoside acetyltransferases (AACs) of actinomycete origin in order to examine their 'double stage activity' that is arbitrarily defined as antibiotic activity retainable after enzymatic modification. In kanamycin (KM)-group AGs tested [KM, dibekacin (DKB), amikacin and arbekacin (ABK)], ABK retained activity after acetylations by AAC(3), AAC(2') and AAC(6'). DKB also retained a weak activity after acetylation by AAC(2'). In gentamicin (GM)-group AGs tested [GM, micronomicin, sisomicin (SISO), netilmicin (NTL) and isepamicin], GM, SISO and NTL retained activites after acetylation by AAC(2'). In neomycin (NM)-group AGs tested [ribostamycin, NM, paromomycin], NM retained activity after acetylation by AAC(6') and AAC(2'). None of astromicin (ASTM)-group AGs tested (ASTM and istamycin B) retained activity after acetylation by AAC(2') and AAC(6'). The activities of acetylated ABK derivatives by AAC(3) and AAC(2') were distinctively high, compared to the others. Streptomyces lividans TK21 containing the cloned aac genes were markedly sensitive to AGs that retained activities after acetylation, indicating the substantial effect of 'double stage activity'.
Topics: Acetylation; Acetyltransferases; Actinomycetales; Aminoglycosides; Anti-Bacterial Agents; Bacillus subtilis; Carbohydrate Sequence; Chromatography, Thin Layer; Drug Resistance, Microbial; Microbial Sensitivity Tests; Molecular Sequence Data; Streptomyces
PubMed: 11132963
DOI: 10.7164/antibiotics.53.1168 -
The Journal of General and Applied... 2012Gentamicin and sisomicin are two different aminoglycoside antibiotics. The comparison of their chemical structure and biosynthetic gene clusters, coupled with...
Gentamicin and sisomicin are two different aminoglycoside antibiotics. The comparison of their chemical structure and biosynthetic gene clusters, coupled with bioinformatic analysis, suggested that the gntK gene would be associated with methylation. The gntK gene fragment in M. purpurea G1008 was inactivated by genetic engineering and its mutant strain M. purpurea GK1101 (ΔgntK) was screened. The metabolites of G1008 and GK1101 was analyzed by HPLC-MS, which revealed that GK1101 no longer produced gentamicin C(1) or C(2), while mainly synthesizing gentamicin C(1a), and the production of C(1a) increased significantly. This indicated that the metabolic flow for the gentamicin C(1) and C(2) biosynthesis was blocked by disrupting the gntK gene, which substantiated that the gntK gene encoded the enzyme that catalyzes the methylation of purpurosamine C-6'. The mutant GK1101 has good prospects for industrial application. In addition, our study provides information that can be used to clarify the function of a single gene and simplify the targeted genetic breeding of important pharmaceutical microorganisms.
Topics: Catalytic Domain; Conjugation, Genetic; Escherichia coli; Fermentation; Genes, Bacterial; Gentamicins; Heptoses; Methylation; Micromonospora; Molecular Weight; Plasmids; Transcriptional Activation
PubMed: 23149679
DOI: 10.2323/jgam.58.349 -
Antimicrobial Agents and Chemotherapy Aug 2018The next-generation aminoglycoside plazomicin, in development for infections due to multidrug-resistant (MDR) , was evaluated alongside comparators for bactericidal... (Comparative Study)
Comparative Study
The next-generation aminoglycoside plazomicin, in development for infections due to multidrug-resistant (MDR) , was evaluated alongside comparators for bactericidal activity in minimum bactericidal concentration (MBC) and time-kill (TK) assays against MDR isolates with characterized aminoglycoside and β-lactam resistance mechanisms. Overall, plazomicin and colistin were the most potent, with plazomicin demonstrating an MBC of 0.5/4 μg/ml and sustained 3-log kill against MDR , , and spp.
Topics: Aminoglycosides; Anti-Bacterial Agents; Carbapenems; Drug Resistance, Multiple, Bacterial; Enterobacter; Escherichia coli; Fluoroquinolones; Klebsiella pneumoniae; Microbial Sensitivity Tests; Polymyxins; Sisomicin; Tetracyclines
PubMed: 29866876
DOI: 10.1128/AAC.00236-18 -
The Journal of Antibiotics Jan 1978Chemical and photochemical oxidative methods of de-N-methylation of some gentamicins and sisomicins at the 3''-position are described. Selective acetylation of...
Chemical and photochemical oxidative methods of de-N-methylation of some gentamicins and sisomicins at the 3''-position are described. Selective acetylation of gentamicins and sisomicins at the 1, 3, 2' and 6' and of gentamicin B at the 1, 3, and 6'positions are achieved by treatment of the free bases with carbon dioxide prior to acetylation. De-N-methylation of the above selectively blocked gentamicins and sisomicins followed by re-alkylation at the 3''-position and de-N-protection gives a series of 3''-N-alkyl analogues. The in vitro antibacterial properties of the new derivatives of gentamicins and sisomicins are given.
Topics: Acetylation; Alkylation; Bacteria; Drug Resistance, Microbial; Gentamicins; Methods; Methylation; Sisomicin
PubMed: 627522
DOI: 10.7164/antibiotics.31.43 -
Antimicrobial Agents and Chemotherapy Nov 2010ACHN-490 is a neoglycoside, or "next-generation" aminoglycoside (AG), that has been identified as a potentially useful agent to combat drug-resistant bacteria emerging...
ACHN-490 is a neoglycoside, or "next-generation" aminoglycoside (AG), that has been identified as a potentially useful agent to combat drug-resistant bacteria emerging in hospitals and health care facilities around the world. A focused medicinal chemistry campaign produced a collection of over 400 sisomicin analogs from which ACHN-490 was selected. We tested ACHN-490 against two panels of Gram-negative and Gram-positive pathogens, many of which harbored AG resistance mechanisms. Unlike legacy AGs, ACHN-490 was active against strains expressing known AG-modifying enzymes, including the three most common such enzymes found in Enterobacteriaceae. ACHN-490 inhibited the growth of AG-resistant Enterobacteriaceae (MIC(90), ≤4 μg/ml), with the exception of Proteus mirabilis and indole-positive Proteae (MIC(90), 8 μg/ml and 16 μg/ml, respectively). ACHN-490 was more active alone in vitro against Pseudomonas aeruginosa and Acinetobacter baumannii isolates with AG-modifying enzymes than against those with altered permeability/efflux. The MIC(90) of ACHN-490 against AG-resistant staphylococci was 2 μg/ml. Due to its promising in vitro and in vivo profiles, ACHN-490 has been advanced into clinical development as a new antibacterial agent.
Topics: Acinetobacter baumannii; Anti-Bacterial Agents; Enterobacteriaceae; Microbial Sensitivity Tests; Molecular Structure; Proteus mirabilis; Pseudomonas aeruginosa; Sisomicin
PubMed: 20805391
DOI: 10.1128/AAC.00572-10 -
BMC Genomics Jul 2014With the development of space science, it is important to analyze the relationship between the space environment and genome variations that might cause phenotypic...
BACKGROUND
With the development of space science, it is important to analyze the relationship between the space environment and genome variations that might cause phenotypic changes in microbes. Klebsiella pneumoniae is commonly found on the human body and is resistant to multiple drugs. To study space-environment-induced genome variations and drug resistance changes, K. pneumoniae was carried into outer space by the Shenzhou VIII spacecraft.
RESULTS
The K. pneumoniae strain LCT-KP289 was selected after spaceflight based on its phenotypic differences compared to the ground-control strain. Analysis of genomic structural variations revealed one inversion, 25 deletions, fifty-nine insertions, two translocations and six translocations with inversions. In addition, 155 and 400 unique genes were observed in LCT-KP214 and LCT-KP289, respectively, including the gene encoding dihydroxyacetone kinase, which generates the ATP and NADH required for microbial growth. Furthermore, a large number of mutant genes were related to transport and metabolism. Phylogenetic analysis revealed that most genes in these two strains had a dN/dS value greater than 1, indicating that the strain diversity increased after spaceflight. Analysis of drug-resistance phenotypes revealed that the K. pneumoniae strain LCT-KP289 was resistant to sulfamethoxazole, whereas the control strain, LCT-KP214, was not; both strains were resistant to benzylpenicillin, ampicillin, lincomycin, vancomycin, chloramphenicol and streptomycin. The sulfamethoxazole resistance may be associated with sequences in Scaffold7 in LCT-KP289, which were not observed in LCT-K214; this scaffold contained the gene sul1. In the strain LCT-KP289, we also observed a drug-resistance integron containing emrE (confers multidrug resistance) and ant (confers resistance to spectinomycin, streptomycin, tobramycin, kanamycin, sisomicin, dibekacin, and gentamicin). The gene ampC (confers resistance to penicillin, cephalosporin-ii and cephalosporin-i) was present near the integron. In addition, 30 and 26 drug-resistance genes were observed in LCT-KP289 and LCT-KP214, respectively.
CONCLUSIONS
Comparison of a K. pneumoniae strain obtained after spaceflight with the ground-control strain revealed genome variations and phenotypic changes and elucidated the genomic basis of the acquired drug resistance. These data pave the way for future studies on the effects of spaceflight.
Topics: Anti-Bacterial Agents; Bacterial Proteins; Comparative Genomic Hybridization; Drug Resistance, Multiple, Bacterial; Genome, Bacterial; Integrons; Klebsiella pneumoniae; Mutation; Phylogeny; Sequence Analysis, DNA; Space Flight; Virulence
PubMed: 25015528
DOI: 10.1186/1471-2164-15-589 -
Antimicrobial Agents and Chemotherapy Aug 1995A novel gene encoding an aminoglycoside 3-N-acetyltransferase, which confers resistance to gentamicin, astromicin, and sisomicin, was cloned from Pseudomonas aeruginosa...
A novel gene encoding an aminoglycoside 3-N-acetyltransferase, which confers resistance to gentamicin, astromicin, and sisomicin, was cloned from Pseudomonas aeruginosa Stone 130. Its sequence was determined and found to show considerable similarity to an aac(3)-I gene previously cloned from R plasmids from Enterobacter, Pseudomonas, and Serratia spp. We have designated the genes from the R plasmids and this work aac(3)-Ia and aac(3)-Ib, respectively. The two aac(3)-I genes share 74% nucleotide identity, and their deduced protein products are 88% similar. These data suggest that the genes derive from a common ancestor. Homology between the flanking sequences of both aac(3)-I genes and other resistance determinants known to reside in integron environments was also observed. Intragenic probes specific for either aac(3)-Ia or aac(3)-Ib were used in hybridization studies with a series of gentamicin-, astromicin-, and sisomicin-resistant clinical isolates. Of 59 clinical isolates tested, no isolates hybridized with both probes, 30 (51%) hybridized with the aac(3)-Ia probe, 12 (20%) hybridized with the aac(3)-Ib probe, and 17 (29%) did not hybridize with either probe. These data suggest the existence of at least one other aac(3)-I gene.
Topics: Acetyltransferases; Amino Acid Sequence; Aminoglycosides; Anti-Bacterial Agents; Base Sequence; Cloning, Molecular; DNA, Bacterial; Escherichia coli; Genes, Bacterial; Microbial Sensitivity Tests; Molecular Sequence Data; Plasmids; Polymerase Chain Reaction; Pseudomonas aeruginosa
PubMed: 7486920
DOI: 10.1128/AAC.39.8.1790 -
Journal of Global Antimicrobial... Mar 2021Carbapenem resistance in Klebsiella pneumoniae is a major clinical challenge. Aminoglycosides remain an important asset in the current therapeutic arsenal to treat these...
Vertical and horizontal dissemination of an IncC plasmid harbouring rmtB 16S rRNA methylase gene, conferring resistance to plazomicin, among invasive ST258 and ST16 KPC-producing Klebsiella pneumoniae.
OBJECTIVES
Carbapenem resistance in Klebsiella pneumoniae is a major clinical challenge. Aminoglycosides remain an important asset in the current therapeutic arsenal to treat these infections. We examined aminoglycoside resistance phenotypes and genomics in a collection of 100 invasive KPC-producing K. pneumoniae isolates sequentially collected in a Brazilian tertiary hospital between 2014 and 2016.
METHODS
Aminoglycoside susceptibility testing was performed. We used a combined long-read (MinION) and short-read (Illumina) whole-genome sequencing strategy to provide a genomic picture of aminoglycoside resistance genes, with particular emphasis on 16S rRNA methyltransferases and related plasmids.
RESULTS
68% of the strains were resistant to gentamicin and 42% to amikacin, with 35% resistant to both of these commonly used aminoglycosides. We identified the 16S rRNA methyltransferase gene rmtB in 30% of these isolates: 97% (29/30) belonged to sequence type 258 (ST258) and a single isolate to the emergent ST16 clone. In ST258 and ST16 the rmtB gene was located on large IncC plasmids of 177 kb and 174 kb, respectively, highly similar to a plasmid previously identified in Proteus mirabilis in the same hospital. Moreover, 99% of the isolates remained susceptible to the veterinary-approved drug apramycin, currently under clinical development for human medicine.
CONCLUSION
Such findings in geographically and temporally related isolates suggest a combination of vertical clonal spread as well as horizontal interspecies and intraspecies plasmid transfer. This broad rmtB dissemination in an endemic setting for KPC-producing clones is worrisome since it provides resistance to most clinically available aminoglycosides, including the novel aminoglycoside-modifying enzyme-resistant plazomicin.
Topics: Bacterial Proteins; Brazil; Humans; Interleukins; Klebsiella pneumoniae; Methyltransferases; Microbial Sensitivity Tests; Plasmids; RNA, Ribosomal, 16S; Sisomicin; beta-Lactamases
PubMed: 33373732
DOI: 10.1016/j.jgar.2020.12.006 -
Pharmaceuticals (Basel, Switzerland) Feb 2023Plazomicin is a recent U.S. Food and Drug Administration (FDA)-approved semisynthetic aminoglycoside. Its structure consists of a sisomicin scaffold modified by adding a...
Plazomicin is a recent U.S. Food and Drug Administration (FDA)-approved semisynthetic aminoglycoside. Its structure consists of a sisomicin scaffold modified by adding a 2(S)-hydroxy aminobutyryl group at the N1 position and a hydroxyethyl substituent at the 6' position. These substitutions produced a molecule refractory to most aminoglycoside-modifying enzymes. The main enzyme within this group that recognizes plazomicin as substrate is the aminoglycoside 2'--acetyltransferase type Ia [AAC(2')-Ia], which reduces the antibiotic's potency. Designing formulations that combine an antimicrobial with an inhibitor of resistance is a recognized strategy to extend the useful life of existing antibiotics. We have recently found that several metal ions inhibit the enzymatic inactivation of numerous aminoglycosides mediated by the aminoglycoside 6'--acetyltransferase type Ib [AAC(6')-Ib]. In particular, Ag, which also enhances the effect of aminoglycosides by other mechanisms, is very effective in interfering with AAC(6')-Ib-mediated resistance to amikacin. Here we report that silver acetate is a potent inhibitor of AAC(2')-Ia-mediated acetylation of plazomicin in vitro, and it reduces resistance levels of carrying . The resistance reversion assays produced equivalent results when the structural gene was expressed under the control of the natural or the promoters. The antibiotic effect of plazomicin in combination with silver was bactericidal, and the mix did not show significant toxicity to human embryonic kidney 293 (HEK293) cells.
PubMed: 37259383
DOI: 10.3390/ph16020236 -
The Journal of Antibiotics Aug 1976A radioimmunoassay (RIA) has been developed using 125I-amikacin. Amikacin was iodinated by a modified BOLTON and HUNTER method. Dextran-charcoal was used to separate... (Comparative Study)
Comparative Study
A radioimmunoassay (RIA) has been developed using 125I-amikacin. Amikacin was iodinated by a modified BOLTON and HUNTER method. Dextran-charcoal was used to separate bound from free drug. The standard curve was linear on a logit-log plot in the range of 0.5 ng to 4 ng amikacin per tube. There was no cross-reactivity of amikacin antisera to the amino-glycosides gentamicin, tobramycin, netilmicin, and sisomicin but a 70% cross-reaction was observed with kanamycin, the compound from which amikacin is synthetically derived. Correlation of the RIA with a microbioassay for the determination of serum amikacin levels in 18 patient samples was excellent (r = 0.94). This new RIA technique is more sensitive, rapid, versatile, and less costly than the RIA using 3H-amikacin, and is far more sensitive and faster than microbioassay.
Topics: Amikacin; Animals; Antibody Specificity; Biological Assay; Immunization; Iodine Radioisotopes; Kanamycin; Methods; Rabbits; Radioimmunoassay
PubMed: 1033175
DOI: 10.7164/antibiotics.29.829