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Samer Kayal - One of the best experts on this subject based on the ideXlab platform.
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comparison of cefoxitin and Moxalactam 30 µg disc diffusion methods for detection of methicillin resistance in coagulase negative staphylococci
Journal of Antimicrobial Chemotherapy, 2007Co-Authors: Olivier Joinlambert, Sylvain Clauser, Christelle Guillet, Jeanphilippe Jais, Eric Abachin, Gilles Quesnes, Etienne Carbonnelle, Alban Le Monnier, Jeanralph Zahar, Samer KayalAbstract:Objectives: To compare cefoxitin and/or Moxalactam 30 μg disc diffusion (DD) methods to detect methicillin resistance in coagulase-negative staphylococci (CoNS) using both high- and low-density (HD/LD) inoculum techniques. Methods: A challenge set of 192 CoNS was tested. DD test results were compared with PBP2a detection. Results: With the LD inoculum, the sensitivity/specificity of cefoxitin and Moxalactam were 94.4%/100% and 100%/92.4%, respectively, using the DD breakpoints of the Comite de l'Antibiogramme de la Societe Francaise de Microbiologie. With the HD inoculum, the sensitivity/specificity of cefoxitin and Moxalactam were 93.7%/100% and 100%/96.9%, using the cefoxitin DD breakpoints of the CLSI and a resistant/susceptible breakpoint of <20 mm/≥20 mm for Moxalactam. Comparison of receiver operating characteristic AUCs did not show significant difference between studied assays, but the overlapping zone where both PBP2a-positive and PBP2a-negative isolates were observed concerned a lower number of strains with Moxalactam than with cefoxitin (P < 0.001). Combination of cefoxitin and Moxalactam DD methods demonstrated that all isolates with a concordant cefoxitin/Moxalactam phenotype were correctly classified. Interestingly, all isolates misclassified by each DD method used alone were cefoxitin-susceptible and Moxalactam-resistant. Conclusions: Although all DD methods studied here performed well for detecting methicillin resistance in CoNS, Moxalactam had a higher accuracy than cefoxitin to differentiate heteroresistant isolates from PBP2a-negative strains. Identification of isolates that should be submitted to a confirmatory test to conclude on methicillin resistance can be easily obtained by combining cefoxitin and Moxalactam DD methods.
Olivier Joinlambert - One of the best experts on this subject based on the ideXlab platform.
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comparison of cefoxitin and Moxalactam 30 µg disc diffusion methods for detection of methicillin resistance in coagulase negative staphylococci
Journal of Antimicrobial Chemotherapy, 2007Co-Authors: Olivier Joinlambert, Sylvain Clauser, Christelle Guillet, Jeanphilippe Jais, Eric Abachin, Gilles Quesnes, Etienne Carbonnelle, Alban Le Monnier, Jeanralph Zahar, Samer KayalAbstract:Objectives: To compare cefoxitin and/or Moxalactam 30 μg disc diffusion (DD) methods to detect methicillin resistance in coagulase-negative staphylococci (CoNS) using both high- and low-density (HD/LD) inoculum techniques. Methods: A challenge set of 192 CoNS was tested. DD test results were compared with PBP2a detection. Results: With the LD inoculum, the sensitivity/specificity of cefoxitin and Moxalactam were 94.4%/100% and 100%/92.4%, respectively, using the DD breakpoints of the Comite de l'Antibiogramme de la Societe Francaise de Microbiologie. With the HD inoculum, the sensitivity/specificity of cefoxitin and Moxalactam were 93.7%/100% and 100%/96.9%, using the cefoxitin DD breakpoints of the CLSI and a resistant/susceptible breakpoint of <20 mm/≥20 mm for Moxalactam. Comparison of receiver operating characteristic AUCs did not show significant difference between studied assays, but the overlapping zone where both PBP2a-positive and PBP2a-negative isolates were observed concerned a lower number of strains with Moxalactam than with cefoxitin (P < 0.001). Combination of cefoxitin and Moxalactam DD methods demonstrated that all isolates with a concordant cefoxitin/Moxalactam phenotype were correctly classified. Interestingly, all isolates misclassified by each DD method used alone were cefoxitin-susceptible and Moxalactam-resistant. Conclusions: Although all DD methods studied here performed well for detecting methicillin resistance in CoNS, Moxalactam had a higher accuracy than cefoxitin to differentiate heteroresistant isolates from PBP2a-negative strains. Identification of isolates that should be submitted to a confirmatory test to conclude on methicillin resistance can be easily obtained by combining cefoxitin and Moxalactam DD methods.
Hedi Mammeri - One of the best experts on this subject based on the ideXlab platform.
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Laurence DRIEUX, 7
2016Co-Authors: Emilie Pluquet, Guillaume Arlet, E Bingen, Hedi Mammeri, Amiens FranceAbstract:ow nloaded from 2 27 Abstract 28 29 Moxalactam is highly hydrolyzed by plasmid-mediated metallo-!-30 lactamases (MBLs) whereas it is poorly inactivated by serine-active 31 carbapenemases. This study demonstrated that Moxalactam resistance 32 constituted an effective screen for MBL expression in enterobacteria, 33 which could be confirm, even in low-MBL-producing isolates, by a disk 34 potentiation test using Moxalactam and EDTA. 3
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sensitive and specific phenotypic assay for metallo beta lactamase detection in enterobacteria by use of a Moxalactam disk supplemented with edta
Journal of Clinical Microbiology, 2011Co-Authors: Emilie Pluquet, Guillaume Arlet, E Bingen, Laurence Drieux, Hedi MammeriAbstract:Moxalactam is highly hydrolyzed by plasmid-mediated metallo-β-lactamases (MBLs), whereas it is poorly inactivated by serine-active carbapenemases. This study demonstrated that Moxalactam resistance constituted an effective screen for MBL expression in enterobacteria, which could be confirmed, even in low-MBL-producing isolates, by a disk potentiation test using Moxalactam and EDTA.
Jozef Van Beeumen - One of the best experts on this subject based on the ideXlab platform.
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inactivation of aeromonas hydrophila metallo beta lactamase by cephamycins and Moxalactam
FEBS Journal, 2001Co-Authors: Astrid Zervosen, Maria Hernandez Valladares, Bart Devreese, Christelle Prosperimeys, Hanswerner Adolph, Paola Sandra Mercuri, Marc Vanhove, Gianfranco Amicosante, Jozef Van BeeumenAbstract:Incubation of Moxalactam and cefoxitin with the Aeromonas hydrophila metallo-b-lactamase CphA leads to enzyme-catalyzed hydrolysis of both compounds and to irreversible inactivation of the enzyme by the reaction products. As shown by electrospray mass spectrometry, the inactivation of CphA by cefoxitin and Moxalactam is accompanied by the formation of stable adducts with mass increases of 445 and 111 Da, respectively. The single thiol group of the inactivated enzyme is no longer titrable, and dithiothreitol treatment of the complexes partially restores the catalytic activity. The mechanism of inactivation by Moxalactam was studied in detail. Hydrolysis of Moxalactam is followed by elimination of the 3 0 leaving group (5-mercapto-1-methyltetrazole), which forms a disulfide bond with the cysteine residue of CphA located in the active site. Interestingly, this reaction is catalyzed by cacodylate.
Hubert Chardon - One of the best experts on this subject based on the ideXlab platform.
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Disk Diffusion Testing for Detection of Methicillin-Resistant Staphylococci: Does Moxalactam Improve upon Cefoxitin?
Journal of Clinical Microbiology, 2016Co-Authors: Marie Bonjean, Elisabeth Hodille, Oana Dumitrescu, Céline Dupieux, Christina Nkoud Mongo, Camille Allam, Mathilde Beghin, Mickael Paris, Ophelie Borrel, Hubert ChardonAbstract: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 106 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 108 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.