-
Journal of Clinical Microbiology Jul 2017
Topics: Anti-Bacterial Agents; Bacterial Proteins; Carbapenem-Resistant Enterobacteriaceae; Humans; Microbial Sensitivity Tests; Moxalactam; beta-Lactamases
PubMed: 28468855
DOI: 10.1128/JCM.00606-17 -
Antimicrobial Agents and Chemotherapy Dec 2016BEL-1 is an acquired class A extended-spectrum β-lactamase (ESBL) found in Pseudomonas aeruginosa clinical isolates from Belgium which is divergent from other ESBLs...
BEL-1 is an acquired class A extended-spectrum β-lactamase (ESBL) found in Pseudomonas aeruginosa clinical isolates from Belgium which is divergent from other ESBLs (maximum identity of 54% with GES-type enzymes). This enzyme is efficiently inhibited by clavulanate, imipenem, and moxalactam. Crystals of BEL-1 were obtained at pH 5.6, and the structure of native BEL-1 was determined from orthorhombic and monoclinic crystal forms at 1.60-Å and 1.48-Å resolution, respectively. By soaking native BEL-1 crystals, complexes with imipenem (monoclinic form, 1.79-Å resolution) and moxalactam (orthorhombic form, 1.85-Å resolution) were also obtained. In the acyl-enzyme complexes, imipenem and moxalactam differ by the position of the α-substituent and of the carbonyl oxygen (in or out of the oxyanion hole). More surprisingly, the Ω-loop, which includes the catalytically relevant residue Glu166, was found in different conformations in the various subunits, resulting in the Glu166 side chain being rotated out of the active site or even in displacement of its Cα atom up to approximately 10 Å. A BEL-1 variant showing the single Leu162Phe substitution (BEL-2) confers a higher level of resistance to CAZ, CTX, and FEP and shows significantly lower K values than BEL-1, especially with oxyiminocephalosporins. BEL-1 Leu162 is located at the beginning of the Ω-loop and is surrounded by Phe72, Leu139, and Leu148 (contact distances, 3.5 to 3.9 Å). This small hydrophobic cavity could not reasonably accommodate the bulkier Phe162 found in BEL-2 without altering neighboring residues or the Ω-loop itself, thus likely causing an important alteration of the enzyme kinetic properties.
Topics: Anti-Bacterial Agents; Catalytic Domain; Citric Acid; Crystallography, X-Ray; Disulfides; Imipenem; Moxalactam; beta-Lactamases
PubMed: 27671060
DOI: 10.1128/AAC.00936-16 -
Journal of Clinical Microbiology Dec 2016Disk diffusion testing is widely used to detect methicillin resistance in staphylococci, and cefoxitin is currently considered the best marker for mecA-mediated...
Disk diffusion testing is widely used to detect methicillin resistance in staphylococci, and cefoxitin is currently considered the best marker for mecA-mediated methicillin resistance. In low-inoculum diffusion testing (colony suspension at 10 CFU/ml), the addition of moxalactam in combination with cefoxitin has been reported to improve on cefoxitin alone for the detection of methicillin-heteroresistant staphylococci. However, moxalactam is absent from EUCAST and CLSI guidelines, which use high-inoculum diffusion testing (colony suspension at 10 CFU/ml), calling into question the potential interest of including moxalactam in their recommendations. The inhibition zone diameters of cefoxitin and moxalactam, alone and in combination, were evaluated for concordance with mecA and mecC positivity in a large collection of clinical Staphylococcus isolates (611 Staphylococcus aureus, Staphylococcus lugdunensis, and Staphylococcus saprophyticus isolates and 307 coagulase-negative staphylococci other than S. lugdunensis and S. saprophyticus isolates, of which 22% and 53% were mecA-positive, respectively) and in 25 mecC-positive S. aureus isolates using high-inoculum diffusion testing. Receiver operating characteristic, sensitivity, and specificity analyses indicated that the detection of mecA- and mecC-positive and negative isolates did not improve with moxalactam, either alone or in combination with cefoxitin, compared to cefoxitin alone. These findings were similar in both the S. aureus/S. lugdunensis/S. saprophyticus group and in the coagulase-negative staphylococci group. Our results do not support the use of moxalactam as an additional marker of methicillin resistance when testing with high-inoculum disk diffusion.
Topics: Anti-Bacterial Agents; Bacterial Proteins; Cefoxitin; Disk Diffusion Antimicrobial Tests; Humans; Methicillin-Resistant Staphylococcus aureus; Moxalactam; Penicillin-Binding Proteins; Staphylococcus lugdunensis; Staphylococcus saprophyticus
PubMed: 27629897
DOI: 10.1128/JCM.01195-16 -
Zhonghua Yi Xue Za Zhi May 2016To observe the antibacterial activity of moxalactam against Enterobacteriaceae bacteria and anaerobic bacteria in vitro, and to compare with other antibacterial drugs,...
OBJECTIVE
To observe the antibacterial activity of moxalactam against Enterobacteriaceae bacteria and anaerobic bacteria in vitro, and to compare with other antibacterial drugs, for providing experimental basis for the clinical application of moxalactam.
METHODS
Minimum inhibitory concentrations (MICs) of moxalactam and other antibacterial agents against 491 Enterobacteriaceae spp. and anaerobic spp.collecting from clinical settings were determined by agar dilution methods and E-test strips according to the Clinical and Laboratory Standards Institute (CLSI)(2014).
RESULTS
Moxalactam showed great antibacterial activity to Enterobacteriaceae spp., including ESBLs-producing Escherichia coli, Klebsiella pneumoniae, and Proteus spp., with the MIC(50), MIC(90), and susceptibility rates of 0.25-4 mg/L, 0.5-8 mg/L, and >90%, respectively. The susceptibility rates of Enterobacteriaceae with ESBLs-producing or non-ESBLs-producing to imipenem and meropenem were both higher than 90%. The susceptibility rates of ESBLs-producing Escherichia coli, Klebsiella pneumoniae, and Proteus spp.to piperacillin/tazobactam and cefoperazone/sulbactam were 90%, 68%, 53% and 76%, 66%, 76.6%, respectively, while the susceptibility rates of non-ESBLs-producing Escherichia coli, Klebsiella pneumoniae, and Proteus spp.were all more than 95%. The susceptibility rates of Enterobacter spp. and other Enterobacter to piperacillin/tazobactam were 80%, 80%and that to cefoperazone/sulbactam were 80%, 76.7%, respectively.The MICs range of moxalactam on anaerobic spp.was from ≤0.064 to >256 mg/L, while MIC(50) was 2 mg/L and MIC(90) was 64 mg/L.
CONCLUSIONS
Moxalactam showed well activity against ESBLs-producing and non-ESBLs-producing Enterobacteriaceae and anaerobia.
Topics: Anti-Bacterial Agents; Bacteria, Anaerobic; Cefoperazone; Enterobacteriaceae; Escherichia coli; Imipenem; Klebsiella pneumoniae; Meropenem; Microbial Sensitivity Tests; Moxalactam; Penicillanic Acid; Piperacillin; Piperacillin, Tazobactam Drug Combination; Proteus; Thienamycins
PubMed: 27266357
DOI: 10.3760/cma.j.issn.0376-2491.2016.18.015 -
Journal of Medical Microbiology Jun 2016
Topics: Anti-Bacterial Agents; Bacteriological Techniques; Cefoxitin; Coagulase; Methicillin Resistance; Microbial Sensitivity Tests; Moxalactam; Sensitivity and Specificity; Staphylococcus
PubMed: 26953118
DOI: 10.1099/jmm.0.000243 -
Antimicrobial Agents and Chemotherapy Feb 2016Class C β-lactamases poorly hydrolyze cephamycins (e.g., cefoxitin, cefotetan, and moxalactam). In the past 2 decades, a new family of plasmid-based AmpC β-lactamases...
Class C β-lactamases poorly hydrolyze cephamycins (e.g., cefoxitin, cefotetan, and moxalactam). In the past 2 decades, a new family of plasmid-based AmpC β-lactamases conferring resistance to cefoxitin, the FOX family, has grown to include nine unique members descended from the Aeromonas caviae chromosomal AmpC. To understand the basis for the unique cephamycinase activity in the FOX family, we determined the first X-ray crystal structures of FOX-4, apo enzyme and the acyl-enzyme with its namesake compound, cefoxitin, using the Y150F deacylation-deficient variant. Notably, recombinant expression of N-terminally tagged FOX-4 also yielded an inactive adenylylated enzyme form not previously observed in β-lactamases. The posttranslational modification (PTM), which occurs on the active site Ser64, would not seem to provide a selective advantage, yet might present an opportunity for the design of novel antibacterial drugs. Substantial ligand-induced changes in the enzyme are seen in the acyl-enzyme complex, particularly the R2 loop and helix H10 (P289 to N297), with movement of F293 by 10.3 Å. Taken together, this study provides the first picture of this highly proficient class C cephamycinase, uncovers a novel PTM, and suggests a possible cephamycin resistance mechanism involving repositioning of the substrate due to the presence of S153P, N289P, and N346I substitutions in the ligand binding pocket.
Topics: Aeromonas caviae; Amino Acid Sequence; Anti-Bacterial Agents; Bacterial Proteins; Cefoxitin; Crystallography, X-Ray; Drug Resistance, Multiple, Bacterial; Escherichia coli Proteins; Microbial Sensitivity Tests; Models, Molecular; Molecular Sequence Data; Protein Isoforms; Protein Processing, Post-Translational; Sequence Alignment; Tandem Mass Spectrometry; beta-Lactamases
PubMed: 26525784
DOI: 10.1128/AAC.01887-15 -
Antimicrobial Agents and Chemotherapy Nov 2015A meropenem-resistant Pseudomonas aeruginosa isolate was obtained from a patient in a medical setting in Hanoi, Vietnam. The isolate was found to have a novel IMP-type...
IMP-51, a novel IMP-type metallo-β-lactamase with increased doripenem- and meropenem-hydrolyzing activities, in a carbapenem-resistant Pseudomonas aeruginosa clinical isolate.
A meropenem-resistant Pseudomonas aeruginosa isolate was obtained from a patient in a medical setting in Hanoi, Vietnam. The isolate was found to have a novel IMP-type metallo-β-lactamase, IMP-51, which differed from IMP-7 by an amino acid substitution (Ser262Gly). Escherichia coli expressing blaIMP-51 showed greater resistance to cefoxitin, meropenem, and moxalactam than E. coli expressing blaIMP-7. The amino acid residue at position 262 was located near the active site, proximal to the H263 Zn(II) ligand.
Topics: Carbapenems; Cefoxitin; Doripenem; Escherichia coli; Meropenem; Microbial Sensitivity Tests; Moxalactam; Pseudomonas aeruginosa; Thienamycins; beta-Lactamases
PubMed: 26282421
DOI: 10.1128/AAC.01611-15 -
The Japanese Journal of Antibiotics Apr 2015The prevalence of extended-spectrum β-lactamase (ESBL) in Enterobacteriaceae has been increasing worldwide. The aims of this study were to determine the prevalence of...
The prevalence of extended-spectrum β-lactamase (ESBL) in Enterobacteriaceae has been increasing worldwide. The aims of this study were to determine the prevalence of ESBLs among clinical isolates of Escherichia coli obtained from 2000 to 2010 in Japan, and to characterize the sequence type (ST) and antimicrobial susceptibility of the bla(CTX-M)-carrying strains. The genes for β-lactamases were determined by conventional PCR and sequencing, and the antimicrobial susceptibility test was performed by the broth microdilution method. Among the 948 strains, 35 were judged as ESBL-positive strains. The positive rates ranged from 0.6% to 3.9% until 2008, but surged to 10.3% in 2010. Thirty-three of them carried bla(CTX-M), but all were negative for ESBL-type bla(TEM) and bla(SHV). bla(CTX-M-14) was the most prevalent (18/33) among bla(CTX-M)-carrying strains, followed by bla(CTX-M-15) (7/33) of which five were isolated in 2008 and 2010. Additionally, bla(CTX-M-27) appeared in 2010 for the first time in this study and accounted for more than a third of the bla(CTX-M)-carrying strains. From the MLST analysis, ST131 known as a world pandemic clone, has been predominantly isolated since 2006. The major types of ESBLs carried by ST131 strains clearly shifted from bla(CTX-M-14) to bla(CTX-M-15) and/or bla(CTX-M-27) between 2006 and 2010. Most of these isolates were still susceptible to doripenem, latamoxef (moxalactam), flomoxef and cefmetazole. Our results suggest that a change of the dominant type of ESBL among Enterobacteriaceae is currently in progress in Japan, and therefore further periodic surveillance is needed.
Topics: Escherichia coli; Escherichia coli Proteins; Japan; Microbial Sensitivity Tests; Multilocus Sequence Typing; Time Factors; beta-Lactamases
PubMed: 26182812
DOI: No ID Found -
Antimicrobial Agents and Chemotherapy Aug 2015We solved the crystal structure of the class C β-lactamase MOX-1 complexed with the inhibitor aztreonam at 1.9Å resolution. The main-chain oxygen of Ser315 interacts...
We solved the crystal structure of the class C β-lactamase MOX-1 complexed with the inhibitor aztreonam at 1.9Å resolution. The main-chain oxygen of Ser315 interacts with the amide nitrogen of aztreonam. Surprisingly, compared to that in the structure of free MOX-1, this main-chain carboxyl changes its position significantly upon binding to aztreonam. This result indicates that the interaction between MOX-1 and β-lactams can be accompanied by conformational changes in the B3 β-strand main chain.
Topics: Amino Acid Sequence; Anti-Bacterial Agents; Aztreonam; Bacterial Proteins; Binding Sites; Carbon Dioxide; Catalytic Domain; Crystallography, X-Ray; Drug Resistance, Multiple, Bacterial; Klebsiella pneumoniae; Microbial Sensitivity Tests; Models, Molecular; Moxalactam; Protein Conformation; Substrate Specificity; beta-Lactamases
PubMed: 26055361
DOI: 10.1128/AAC.04428-14 -
Journal of Medical Microbiology May 2015Clinical isolates of Klebsiella pneumoniae and Klebsiella oxytoca collected from 20 Japanese medical facilities between 2000 and 2010 were analysed to evaluate the...
Mechanism of resistance and antibacterial susceptibility in extended-spectrum β-lactamase phenotype Klebsiella pneumoniae and Klebsiella oxytoca isolated between 2000 and 2010 in Japan.
Clinical isolates of Klebsiella pneumoniae and Klebsiella oxytoca collected from 20 Japanese medical facilities between 2000 and 2010 were analysed to evaluate the mechanisms of resistance and antibacterial susceptibilities to 14 antimicrobials. Overall, eight of 484 (1.6%) K. pneumoniae and 19 of 359 (5.3%) K. oxytoca were determined to be extended-spectrum β-lactamase (ESBL) phenotype isolates, and the identified ESBLs amongst the K. pneumoniae isolates were CTX-M-2, -3, -14 and -15, and SHV-12. In contrast, overproduction of chromosomal β-lactamase OXY-2, which was due to a distinct mutation at the - 10 promoter region of this gene, conferred the ESBL phenotype to all the K. oxytoca isolates except one. Based on the Clinical and Laboratory Standards Institute breakpoints, all the ESBL phenotype K. pneumoniae were susceptible to doripenem, flomoxef, moxalactam (latamoxef), cefmetazole and tazobactam/piperacillin, whereas the ESBL phenotype K. oxytoca were susceptible to ceftazidime and ceftibuten in addition to the above, with the exception of tazobactam/piperacillin. Amongst the oral antimicrobials, ceftibuten was relatively effective against both ESBL phenotype Klebsiella species compared with levofloxacin and amoxicillin/clavulanic acid.
Topics: Anti-Bacterial Agents; Cross Infection; DNA, Bacterial; Humans; Japan; Klebsiella Infections; Klebsiella oxytoca; Klebsiella pneumoniae; Microbial Sensitivity Tests; Polymerase Chain Reaction; beta-Lactam Resistance; beta-Lactamases; beta-Lactams
PubMed: 25813819
DOI: 10.1099/jmm.0.000057