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Antimicrobial Agents and Chemotherapy May 2003The aacA29b gene, which confers an atypical aminoglycoside resistance pattern to Escherichia coli, was identified on a class 1 integron from a multidrug-resistant...
The aacA29b gene, which confers an atypical aminoglycoside resistance pattern to Escherichia coli, was identified on a class 1 integron from a multidrug-resistant isolate of Pseudomonas aeruginosa. On the basis of amino acid sequence homology, it was proposed that the gene encoded a 6'-N-acetyltransferase. The resistance gene was cloned into the pET23a(+) vector, and overexpression conferred high-level resistance to the usual substrates of the aminoglycoside N-acetyltransferase AAC(6')-I, except netilmicin. The level of resistance conferred by aacA29b correlated perfectly with the level of expression of the gene. The corresponding C-terminal six-His-tagged AAC(6')-29b protein was purified and found to exist as a dimer in solution. With a spectrophotometric assay, an extremely feeble AAC activity was detected with acetyl coenzyme A (acetyl-CoA) as an acetyl donor. Fluorescence titrations of the protein with aminoglycosides demonstrated the very tight binding of tobramycin, dibekacin, kanamycin A, sisomicin (K(d), =1 micro M) and a weaker affinity for amikacin (K(d), approximately 60 micro M). The binding of netilmicin and acetyl-CoA could not be detected by either fluorescence spectroscopy or isothermal titration calorimetry. The inability of AAC(6')-29b to efficiently bind acetyl-CoA is supported by an alignment analysis of its amino acid sequence compared with those of other AAC(6')-I family members. AAC(6')-29b lacks a number of residues involved in acetyl-CoA binding. These results lead to the conclusion that AAC(6')-29b is able to confer aminoglycoside resistance by sequestering the drug as a result of tight binding.
Topics: Acetyltransferases; Amino Acid Sequence; Aminoglycosides; Anti-Bacterial Agents; Drug Resistance, Bacterial; Escherichia coli; Molecular Sequence Data
PubMed: 12709325
DOI: 10.1128/AAC.47.5.1577-1583.2003 -
Yakugaku Zasshi : Journal of the... Jan 2008Three types of medication, Arbekacin, Vancomycin, and Teicoplanin, are used primarily to treat MRSA infections. These medications differ in their respective...
Three types of medication, Arbekacin, Vancomycin, and Teicoplanin, are used primarily to treat MRSA infections. These medications differ in their respective anti-bacterial actions, antibacterial spectrums, and pharmacokinetics. Proper use and dosage is required, and is based on patient background and the conditions of infection, among other factors. This study was conducted for a period of over one year at St. Marianna University School of Medicine, Yokohama City Seibu Hospital. It was designed to compare the conditions as they related to why doctors ordered a certain drug, the background, and their clinical examination values. The tendency to avoid selection of Arbekacin Sulfate (ABK) for patients who had kidney dysfunction was recognized, although there were a few exceptions made. Other than that, there were not any standard criteria set in selecting which medication to prescribe. Therefore, it is necessary to examine the appropriateness of the selection since ordering anti-MRSA medication seemed to depend on each doctor's own experience. Serum concentration was measured in order to avoid any side effects. Moreover, cases of young people, normal renal function and malignant tumor patients were recognized in which serum concentration of the anti-MRSA medications was not within the therapeutic range of therapeutic drug monitoring (TDM). This was to show that there is a possibility the medications involved were not sufficiently effective. Therefore, in the future it will be necessary to ensure that proper dosing instructions are followed.
Topics: Adult; Aged; Aminoglycosides; Anti-Bacterial Agents; Dibekacin; Drug Monitoring; Humans; Methicillin Resistance; Middle Aged; Staphylococcal Infections; Staphylococcus aureus; Teicoplanin; Vancomycin
PubMed: 18176058
DOI: 10.1248/yakushi.128.81 -
Journal of Korean Medical Science Apr 2006This study was undertaken to evaluate the in vitro activities of arbekacin-based combination regimens against vancomycin hetero-intermediate Staphylococcus aureus...
This study was undertaken to evaluate the in vitro activities of arbekacin-based combination regimens against vancomycin hetero-intermediate Staphylococcus aureus (hetero-VISA). Combinations of arbekacin with vancomycin, rifampin, ampicillin-sulbactam, teicoplanin, or quinupristin-dalfopristin against seven hetero-VISA strains and two methicillin-resistant S. aureus strains were evaluated by the time-kill assay. The combinations of arbekacin with vancomycin, teicoplanin, or ampicillin-sulbactam showed the synergistic interaction against hetero-VISA strains. Data suggest that these arbekacin-based combination regimens may be useful candidates for treatment options of hetero-VISA infections.
Topics: Aminoglycosides; Ampicillin; Anti-Bacterial Agents; Dibekacin; Drug Resistance, Bacterial; Drug Synergism; Humans; In Vitro Techniques; Methicillin Resistance; Microbial Sensitivity Tests; Staphylococcal Infections; Staphylococcus aureus; Sulbactam; Teicoplanin; Vancomycin; Virginiamycin
PubMed: 16614499
DOI: 10.3346/jkms.2006.21.2.188 -
Antimicrobial Agents and Chemotherapy Nov 1983The molecular basis for activity of habekacin was studied by using Escherichia coli Q-13. Electron microscopic studies revealed that numerous blebs, derived from the...
The molecular basis for activity of habekacin was studied by using Escherichia coli Q-13. Electron microscopic studies revealed that numerous blebs, derived from the outer membrane, were formed on cells treated with habekacin. Cytoplasmic contents leaked into the lumina of blebs, and the membrane of some enlarged blebs was disrupted. In a cell-free system, habekacin interfered with polypeptide synthesis, caused codon misreading, and inhibited translocation of N-acetylphenylalanyl-tRNA from the acceptor site to the donor site on ribosomes. [3H]habekacin bound to both 50S and 30S ribosomal subunits. The current experiments indicated that the mechanism of action of habekacin is similar to that of 2-deoxystreptamine-containing aminoglycoside antibiotics such as dibekacin, kanamycin, gentamicin, and related substances. The relationship of membrane damage to inhibition of ribosomal functions remains to be determined.
Topics: Aminoglycosides; Anti-Bacterial Agents; Codon; Dibekacin; Escherichia coli; Peptide Biosynthesis; RNA, Transfer, Amino Acyl; Ribosomes; Translocation, Genetic
PubMed: 6362557
DOI: 10.1128/AAC.24.5.797 -
Antimicrobial Agents and Chemotherapy Mar 2002As seen by the disk diffusion method, the clinical strain of Pseudomonas aeruginosa Pa695, resistant to all extended-spectrum cephalosporins and aminoglycosides,...
As seen by the disk diffusion method, the clinical strain of Pseudomonas aeruginosa Pa695, resistant to all extended-spectrum cephalosporins and aminoglycosides, exhibited an unusual synergistic effect between ceftazidime and imipenem. This isolate produced an extended-spectrum beta-lactamase (ESBL) with a pI of 5.8 that appeared to be chromosomally encoded. Cloning experiments revealed that this ESBL was encoded by bla(GES-1), previously described in an integron from Klebsiella pneumoniae. In P. aeruginosa Pa695, a higher level of resistance to ceftazidime than to ticarcillin was observed, and no synergy between the beta-lactamase inhibitors and extended-spectrum cephalosporins was detected, in contrast to the resistance pattern observed in K. pneumoniae. Further sequence analysis demonstrated that the bla(GES-1) gene cassette was located in a class 1 integron, which contained another sequence corresponding to the fused aac3-Ib and aac6'-Ib' gene cassettes. The fusion product was functional, as was the product of each gene cloned separately: AAC3-I, despite the deletion of the four last amino acids, and AAC6', which carried three amino acid changes compared with the most homologous sequence. The AAC3-I protein conferred an expected gentamicin and fortimicin resistance, and the AAC6', despite the Leu-119-->Ser substitution, yielded resistance to kanamycin, tobramycin, and dibekacin, but slightly affected netilmicin and amikacin, and had no apparent effect on gentamicin. The fusion product conveyed a large profile of resistance, combining the AAC6' activity with a higher level of gentamicin resistance without accompanying fortimicin resistance.
Topics: Acetyltransferases; Aminoglycosides; Anti-Bacterial Agents; Cloning, Molecular; Conjugation, Genetic; DNA, Recombinant; Drug Resistance; Escherichia coli; Genes, Bacterial; Microbial Sensitivity Tests; Plasmids; Pseudomonas aeruginosa; Reverse Transcriptase Polymerase Chain Reaction; beta-Lactam Resistance
PubMed: 11850242
DOI: 10.1128/AAC.46.3.638-645.2002 -
Antimicrobial Agents and Chemotherapy Oct 1979The in vitro susceptibilities of 242 isolates of Serratia marcescens to 17 antibacterial drugs have been determined. Oxolinic acid, nalidixic acid, cefoxitin, and...
The in vitro susceptibilities of 242 isolates of Serratia marcescens to 17 antibacterial drugs have been determined. Oxolinic acid, nalidixic acid, cefoxitin, and amikacin were the most active drugs. Ampicillin, kanamycin, and cephalothin were among the least active. A 4-year study showed that resistance of S. marcescens to dibekacin, tobramycin, sisomycin, and gentamicin has increased at least one order of magnitude in that period, whereas resistance to amikacin showed but a twofold increase.
Topics: Aminoglycosides; Anti-Bacterial Agents; Enterobacteriaceae Infections; Humans; Microbial Sensitivity Tests; Serratia marcescens
PubMed: 391150
DOI: 10.1128/AAC.16.4.523 -
The Journal of Antibiotics Aug 1982The occurrence in beta-lactam treated patients of unstable L-forms of Pseudomonas aeruginosa insensitive to various antibiotics and synergistic effect of combined action...
Synergistic effects of a macrolide and a cell wall-affecting antibiotic on Pseudomonas aeruginosa in vitro and in vivo. 3. Incorporation of [14C]midecamycin acetate (MOM) into P. aeruginosa pretreated with cell wall-affecting antibiotics.
The occurrence in beta-lactam treated patients of unstable L-forms of Pseudomonas aeruginosa insensitive to various antibiotics and synergistic effect of combined action of cell wall-affecting antibiotics and macrolide on Pseudomonas infection led us to examine the effects of macrolide on P. aeruginosa pretreated with cell wall-affecting antibiotics. The effects of macrolide antibiotics such as midecamycin acetate (MOM) on P. aeruginosa was investigated, a rapid killing effect by MOM was noted after treatment with suboptimal doses of cell wall-affecting antibiotics such as polymyxin B, carbenicillin, dibekacin or fosfomycin. Incorporation of [14C]MOM into intact P. aeruginosa cells was not significant, but was apparent into L-form cells or cells pretreated with cell wall-affecting antibiotics. The incorporated radioactivity was found in the 70 S ribosome fraction, binding with the 50 S subunits of ribosome in both cases. These results indicate that under certain conditions a macrolide antibiotic can enter the P. aeruginosa cell.
Topics: Anti-Bacterial Agents; Carbon Radioisotopes; Cell Wall; Drug Synergism; L Forms; Leucomycins; Pseudomonas aeruginosa; Ribosomes
PubMed: 6815146
DOI: 10.7164/antibiotics.35.1086 -
The Journal of Antibiotics Oct 1999From a rare actinomycete strain #8 isolated from soil as arbekacin (ABK) resistant, we cloned a gene segment (0.9 kb) conferring multiple resistance to aminoglycoside... (Comparative Study)
Comparative Study
Role of aminoglycoside 6'-acetyltransferase in a novel multiple aminoglycoside resistance of an actinomycete strain #8: inactivation of aminoglycosides with 6'-amino group except arbekacin and neomycin.
From a rare actinomycete strain #8 isolated from soil as arbekacin (ABK) resistant, we cloned a gene segment (0.9 kb) conferring multiple resistance to aminoglycoside (AG) antibiotics with 6'-NH2 including semisynthetic ones except ABK and neomycin (NM). Enzymatic modification using cell free extracts from Streptomyces lividans TK21/pANT-S2 carrying the cloned gene revealed that the gene coded for an AG 6'-acetyltransferase [AAC(6')] capable of acetylating all of the tested AGs with 6'-NH2 including semisynthetic ones and astromicin. The substrate specificity of the enzyme was thus similar to that of AAC(6')-Ie of Enterococcus faecalis. Antibiotic assay revealed a weak but clear antibiotic activity of 6'-N-acetylABK (8% of ABK activity) in contrast with substantial inactivation by the AAC(6') of the other AGs including amikacin and isepamicin. The NM acetylation by the AAC(6') also did not result in NM inactivation. It seems thus likely that AAC(6')-dependent resistance to ABK and NM, if it emerges, will remain at low level.
Topics: Acetylation; Acetyltransferases; Actinomycetales; Aminoglycosides; Anti-Bacterial Agents; Cloning, Molecular; Dibekacin; Drug Resistance, Multiple; Neomycin; Streptomyces; Structure-Activity Relationship
PubMed: 10604758
DOI: 10.7164/antibiotics.52.889 -
FEBS Letters Jul 2003We have clinically isolated a methicillin-resistant Staphylococcus aureus (MRSA) K-1 which exhibits enhanced arbekacin (Abk) resistance. In this study, we investigated a...
We have clinically isolated a methicillin-resistant Staphylococcus aureus (MRSA) K-1 which exhibits enhanced arbekacin (Abk) resistance. In this study, we investigated a molecular mechanism for the overproduction of a bifunctional enzyme catalyzing both 2"-O-phosphorylation and 6'-N-acetylation of aminoglycoside antibiotics that is encoded by aacA-aphD and designated [AAC(6')/APH(2")] and is expressed in MRSA K-1. The sequence analysis of the 5'-adjacent region of the aacA-aphD structural gene in MRSA K-1 showed that 12 bp are deleted from the aacA-aphD promoter region when compared with that in MRSA B-26, which exhibits lower resistance to Abk than K-1. By artificially deleting the 12 bp from the corresponding region in MRSA B-26, we confirmed that the strain increases Abk resistance to the same level as seen in MRSA K-1, which suggests that the 12 bp deletion from the 5'-adjacent region of the aacA-aphD structural gene created a strong promoter to overexpress the bifunctional enzyme.
Topics: Acetylation; Aminoglycosides; Anti-Bacterial Agents; Base Sequence; Blotting, Northern; Catalysis; DNA Primers; DNA, Bacterial; Dibekacin; Genes, Bacterial; Methicillin Resistance; Microbial Sensitivity Tests; Molecular Sequence Data; Phosphorylation; Promoter Regions, Genetic; Sequence Homology, Nucleic Acid; Staphylococcus aureus
PubMed: 12832077
DOI: 10.1016/s0014-5793(03)00644-6 -
Biochemical Pharmacology Feb 1984Previous studies [Laurent et al., Biochem. Pharmac. 31, 3861 (1982)] have demonstrated that aminoglycoside antibiotics bind to negatively charged phospholipid bilayers...
Previous studies [Laurent et al., Biochem. Pharmac. 31, 3861 (1982)] have demonstrated that aminoglycoside antibiotics bind to negatively charged phospholipid bilayers and inhibit the activity of lysosomal phospholipases. This inhibition also occurs in vivo in animal and man. It is considered to be an early and significant step in the development of aminoglycoside-induced nephrotoxicity. The binding of 6 aminoglycosides in current clinical use (dibekacin, gentamicin, tobramycin, kanamycin A, amikacin and streptomycin) to phosphatidylinositol has been studied by gel filtration technique and by conformational analysis. Variation of the phosphatidylinositol content from 0 to 27% of total phospholipids causes a cooperative increase in aminoglycoside binding. At fixed phosphatidylinositol concentration, the binding of the different aminoglycosides is related to the number of aminogroups carried by the drug (viz., gentamicin greater than kanamycin A greater than streptomycin) and is largely, but not entirely dependent upon electrostatic interactions. Conformational analysis of the interaction of aminoglycosides with phosphatidylinositol monolayers was made by a step-wise computation approach. We first have taken into account the Vander Waals, torsional and electrostatic energies and we have calculated the hydrophobic and hydrophilic centers of each molecule. Assembly was then computed by successive association of one molecule of drug and up to 4 molecules of phosphatidylinositol. The calculated interaction energies varied from -8.5 kcal/mol (gentamicin) to -4.9 kcal/mol (amikacin) and -3.9 kcal/mol (streptomycin).(ABSTRACT TRUNCATED AT 250 WORDS)
Topics: Aminoglycosides; Anti-Bacterial Agents; Liposomes; Molecular Conformation; Phosphatidylinositols; Phospholipids
PubMed: 6704179
DOI: 10.1016/0006-2952(84)90319-8