Y229W substitution in #NDM-1/L209F variant restores the hydrolytic activity of the enzyme towards #penicillins, #cephalosporins and #carbapenems: kinetic profile and molecular dynamic studies (Antimicrob Agents Chemother., abstract)

[Source: Antimicrobial Agents and Chemotherapy, full page: (LINK). Abstract, edited.]

Y229W substitution in NDM-1/L209F variant restores the hydrolytic activity of the enzyme towards penicillins, cephalosporins and carbapenems: kinetic profile and molecular dynamic studies

Alessandra Piccirilli, Fabrizia Brisdelli, Massimiliano Aschi, Giuseppe Celenza, Gianfranco Amicosante, Mariagrazia Perilli

DOI: 10.1128/AAC.02270-18

 

ABSTRACT

NDM-1 enzyme is the most common metallo-β-lactamase identified in many Gram-negative bacteria causing severe nosocomial infections. The aim of this study was to focus the attention on non-active site residues, L209 and Y229, of NDM-1 and to investigate their role in the catalytic mechanism. Specifically, the effect of Y229W substitution in L209F variant was evaluated by antimicrobial susceptibility testing, kinetic and molecular dynamic (MD) studies. The Y229W single mutant and L209F/Y229W double mutant were generated by site-directed mutagenesis. The Km, kcat and kcat/Km kinetic constants, calculated for the two mutants, were compared with those of NDM-1 and L209F variants. Compared to L209F single mutant, L209F/Y229W mutant showed a remarkable increase of kcat values of 100-, 240-, 250- and 420-fold for imipenem, meropenem, benzylpenicillin and cefepime, respectively. In L209F/Y229W enzyme we observed a remarkable increase of kcat/Km of 370-, 140- and 80-fold for cefepime, meropenem and cefazolin, respectively. The same behavior was stated by antimicrobial susceptibility test. MD simulations were carried out on both L209F and L209F/Y229W enzymes complexed with benzylpenicillin focusing the attention on the overall mechanical features and on the differences between the two systems. With respect to L209F variant, the L209F/Y229W double mutant showed a mechanical stabilization of Loop 10 and N-terminal region but a destabilization of C-terminal and 149-154 regions. The epistatic effect of Y229W mutation jointly with stabilization of Loop 10 lead to a better catalytic efficiency of β-lactams. NDM numbering is used in order to facilitate the comparison with other NDM-1 studies.

Copyright © 2019 American Society for Microbiology. All Rights Reserved.

Keywords: Antibiotics; Drugs Resistance; Carbapenem; Beta-lactams; NDM1; Imipenem; Meropenem; Penicillins.

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Dose-dependent Synergistic Interactions of #Colistin with #Rifampicin, #Meropenem and #Tigecycline against #Carbapenem-resistant #Klebsiella pneumoniae #Biofilms (Antimicrob Agents Chemother., abstract)

[Source: Antimicrobial Agents and Chemotherapy, full page: (LINK). Abstract, edited.]

Dose-dependent Synergistic Interactions of Colistin with Rifampicin, Meropenem and Tigecycline against Carbapenem-resistant Klebsiella pneumoniae Biofilms

Anastasia Geladari, Maria Simitsopoulou, Charalampos Antachopoulos, Emmanuel Roilides

DOI: 10.1128/AAC.02357-18

 

ABSTRACT

Carbapenem-resistant Klebsiella pneumoniae (CR-Kp) can cause biofilm-related bloodstream infections associated with significant morbidity and mortality worldwide. We investigated the bactericidal activities of colistin (CST), rifampicin (RIF), meropenem (MEM), gentamicin (GEN) and tigecycline (TGC) alone and that of CST in combination with RIF, MEM, GEN or TGC against CR-Kp mature biofilms. Twenty CR-Kp blood isolates were derived from equal number of bloodstream infections in adult patients. Biofilm formation was assessed by staining with 0.4% crystal violet and measuring optical density spectrophotometrically at 545 nm. Biofilm damage was measured as % reduction of metabolic activity by XTT assay. MIC50 for biofilms was determined as the minimum concentration that caused ≥50% bacterial damage compared to that for untreated controls. Antibacterial drug interactions were analyzed by the Bliss independence model. Four of the twenty CR-Kp isolates were biofilm producers. Biofilm MIC50’s of CST, RIF, MEM, GEN and TGC for these isolates were 64, 8, >256, 128 and 8 mg/L, respectively. Synergistic interactions were observed at 32-64 mg/L of CST combined with 0.25-4 mg/L of RIF, at 32 mg/L of CST combined with 0.007-0.25 mg/L of MEM, and at 16-32 mg/L of CST combined with 16-64 mg/L of TGC. The synergy was highest for CST+RIF, with %ΔE±SE 49.87±9.22 compared to 29.52±4.97 for CST+MEM (p<0.001) and 32.44±6.49 for CST+TGC (p<0.001). Indifferent results were exhibited by CST+GEN. None of the combinations exhibited antagonism. These drug interactive findings, especially that of CST with RIF, may be of importance in the treatment of biofilm-related CR-Kp infections.

Copyright © 2019 American Society for Microbiology. All Rights Reserved.

Keywords: Antibiotics; Drugs Resistance; Carbapene; Klebsiella pneumoniae; Colistin; Gentamicin; Tigecycline; Meropenem; Rifampicin.

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Activity of #nacubactam (RG6080/OP0595) combinations against #MBL-producing #Enterobacteriaceae (J Antimicrob Chemother., abstract)

[Source: Journal of Antimicrobial Chemotherapy, full page: (LINK). Abstract, edited.]

Activity of nacubactam (RG6080/OP0595) combinations against MBL-producing Enterobacteriaceae

Shazad Mushtaq, Anna Vickers, Neil Woodford, Andreas Haldimann, David M Livermore

Journal of Antimicrobial Chemotherapy, dky522, https://doi.org/10.1093/jac/dky522

Published: 24 December 2018

 

Abstract

Background

Diazabicyclooctanes (DBOs) are promising β-lactamase inhibitors. Some, including nacubactam (OP0595/RG6080), also bind PBP2 and have an enhancer effect, allowing activity against Enterobacteriaceae with MBLs, which DBOs do not inhibit. We tested the activity of nacubactam/β-lactam combinations against MBL-producing Enterobacteriaceae.

Methods

Test panels comprised (i) 210 consecutive Enterobacteriaceae with NDM or VIM MBLs, as referred by UK diagnostic laboratories, and (ii) 99 supplementary MBL-producing Enterobacteriaceae, representing less prevalent phenotypes, species and enzymes. MICs were determined by CLSI agar dilution.

Results

MICs of nacubactam alone were bimodal, clustering at 1–8 mg/L or >32 mg/L; >85% of values for Escherichia coli and Enterobacter spp. fell into the low MIC cluster, whereas Proteeae were universally resistant and the Klebsiella spp. were divided between the two groups. Depending on the prospective breakpoint (4 + 4 or 8 + 4 mg/L), and on whether all isolates were considered or solely the Consecutive Collection, meropenem/nacubactam and cefepime/nacubactam inhibited 80.3%–93.3% of MBL producers, with substantial gains over nacubactam alone. Against the most resistant isolates (comprising 57 organisms with MICs of nacubactam >32 mg/L, cefepime ≥128 mg/L and meropenem ≥128 mg/L), cefepime/nacubactam at 8 + 4 mg/L inhibited 63.2% and meropenem/nacubactam at 8 + 4 mg/L inhibited 43.9%. Aztreonam/nacubactam, incorporating an MBL-stable β-lactam partner, was almost universally active against the MBL producers and, unlike aztreonam/avibactam, had an enhancer effect.

Conclusions

Nacubactam combinations, including those using MBL-labile β-lactams, e.g. meropenem and cefepime, can overcome most MBL-mediated resistance. This behaviour reflects nacubactam’s direct antibacterial and enhancer activity.

Topic: phenotype – cefepime – agar – aztreonam – enterobacter – enterobacteriaceae – klebsiella – laboratory – lactams – diagnosis – enzymes – meropenem – anti-bacterial agents – escherichia coli – enhancer of transcription – dilution technique – dilute (action) – binding (molecular function) – malnutrition-inflammation-cachexia syndrome – avibactam

Issue Section: ORIGINAL RESEARCH

© The Author(s) 2018. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For permissions, please email: journals.permissions@oup.com.

This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Keywords: Antibiotics; Drugs Resistance; Enterobacteriaceae; Aztreonam; Meropenem; Nacubactam.

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Averting the #postantibiotic era: successful use of #meropenem/vaborbactam for #carbapenem-resistant #Serratia marcescens and #Enterobacter aerogenes bacteraemia in a haemodialysis patient (J Antimicrob Chemother., abstract)

[Source: Journal of Antimicrobial Chemotherapy, full page: (LINK). Abstract, edited.]

Averting the post-antibiotic era: successful use of meropenem/vaborbactam for carbapenem-resistant Serratia marcescens and Enterobacter aerogenes bacteraemia in a haemodialysis patient

Sarah C J Jorgensen, Philip McDonald, Ryan P Mynatt, Jason M Pogue, Stephen A Lerner, Sorabh Dhar, Hossein Salimnia, Michael J Rybak

Journal of Antimicrobial Chemotherapy, dky346, https://doi.org/10.1093/jac/dky346

Published: 04 September 2018

Sir,

The prevalence of carbapenem-resistant Enterobacteriaceae (CRE) has increased dramatically over the past two decades, fuelling speculation that we are nearing the ‘post-antibiotic era’ and attesting to the critical need for novel antibiotics with activity against MDR pathogens.1 In 2015 the US FDA approved ceftazidime/avibactam for the treatment of complicated urinary tract infections (cUTIs) and complicated intra-abdominal infections caused by MDR Gram-negative bacteria.2 The introduction of ceftazidime/avibactam represented significant progress in the treatment of CRE, with accumulating real‐world data demonstrating improved efficacy and safety compared with older, more toxic antibiotics.3–5However, treatment failure rates as high as 30%–50% have been…

(…)

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Issue Section: Research letter

© The Author(s) 2018. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For permissions, please email: journals.permissions@oup.com.

This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Keywords: Antibiotics; Drugs Resistance; Carbapenem; Serratia marcescens; Enterobacter aerogenes; Bacteremia; Meropenem; Vaborbactam.

……

Various sequence types of #Enterobacteriaceae carrying #blaNDM-5 gene from commercial #chicken #farms in #China (Antimicrob Agents Chemother., abstract)

[Source: Antimicrobial Agents and Chemotherapy, full page: (LINK). Abstract, edited.]

Various sequence types of Enterobacteriaceae carrying blaNDM-5 gene from commercial chicken farms in China

Rong Xiang, An-Yun Zhang, Xiao-Lan Ye, Zhuang-Zhuang Kang, Chang-Wei Leiand Hong-Ning Wang*

Author Affiliations: Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610065, Sichuan, P.R.China

 

ABSTRACT

A total of 108 meropenem-resistant Enterobacteriaceae isolates were obtained from 1658 rectal swabs collected from 15 unrelated commercial chicken farms in China between 2014 and 2016. These samples yielded sixteen Escherichia coli and two Klebsiella pneumoniae isolates of diverse sequence types carrying a blaNDM-5-bearing IncX3 plasmid. Klebsiella pneumoniae strain sequence type 709 (ST709) has two blaNDM-5-carrying plasmids that were transferred together to E.coli.

 

FOOTNOTES

*Corresponding author. Mailing address: College of Life science, Sichuan University, NO. 29 Wangjiang Road, Chengdu, Sichuan, China, 610064., Phone: +86-28-8547-1599. Fax: +86-28-8547-1599., E-mail: whongning@163.com

Copyright © 2018 American Society for Microbiology. All Rights Reserved.

Keywords: Antibiotics; Drugs Resistance; Meropenem; Enterobacteriaceae; Poultry; China.

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In vitro activity of #ceftazidime / #avibactam against isolates of #Pseudomonas aeruginosa collected in #European countries: INFORM global surveillance 2012–15 (J Antimicrob Chemother., abstract)

[Source: Journal of Antimicrobial Chemotherapy, full page: (LINK). Abstract, edited.]

In vitro activity of ceftazidime/avibactam against isolates of Pseudomonas aeruginosa collected in European countries: INFORM global surveillance 2012–15

Krystyna M Kazmierczak, Boudewijn L M de Jonge, Gregory G Stone, Daniel F Sahm

Journal of Antimicrobial Chemotherapy, dky267, https://doi.org/10.1093/jac/dky267

Published: 11 July 2018

 

Abstract

Objectives

The activity of ceftazidime/avibactam was assessed against 5716 Pseudomonas aeruginosa isolates collected from 96 medical centres in 18 European countries as part of the International Network for Optimal Resistance Monitoring (INFORM) global surveillance programme from 2012 to 2015. Activity was analysed against subsets of isolates based on resistance phenotypes and β-lactamase content.

Methods

Antimicrobial susceptibility testing was performed by broth microdilution and β-lactamase genes were detected by PCR screening and sequencing.

Results

Ceftazidime/avibactam was highly active in vitro against the overall collection of P. aeruginosa isolates and colistin-resistant isolates (92.4% and 92.9% susceptible, respectively). Although activity was slightly reduced against MBL-negative subsets of ceftazidime-non-susceptible (79.6% susceptible), meropenem-non-susceptible (85.1% susceptible) and MDR (81.6% susceptible) P. aeruginosa, ceftazidime/avibactam remained the second most active entity, after colistin, compared with all other comparator agents tested. At the country level, susceptibility to ceftazidime/avibactam ranged from 74.6% to 99.6%, with decreased susceptibilities only observed in countries where MBLs are more frequently encountered, such as the Czech Republic, Greece, Romania and Russia. Ceftazidime/avibactam was also active in vitro against 87.6% of meropenem-non-susceptible isolates in which no acquired β-lactamases were detected by molecular methods; these isolates were assumed to hyperproduce the chromosomally encoded AmpC in combination with alterations in OprD or drug efflux. As expected, ceftazidime/avibactam was not active against isolates carrying MBLs.

Conclusions

The data show that ceftazidime/avibactam is highly potent in vitro against clinical isolates of P. aeruginosa collected in European countries, including isolates that exhibit resistance to ceftazidime, meropenem and colistin and combined resistance to agents from multiple drug classes.

Issue Section: ORIGINAL RESEARCH

© The Author(s) 2018. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For permissions, please email: journals.permissions@oup.com.

This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices)

Keywords: Antibiotics; Drugs Resistance; Colistin; Meropenem; Avibactam; Ceftazidime; Pseudomonas aeruginosa; European Region.

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In vitro activity of #ceftazidime / #avibactam against isolates of #Enterobacteriaceae collected in #European countries: #INFORM global surveillance 2012–15 (J Antimicrob Chemother., abstract)

[Source: Journal of Antimicrobial Chemotherapy, full page: (LINK). Abstract, edited.]

In vitro activity of ceftazidime/avibactam against isolates of Enterobacteriaceae collected in European countries: INFORM global surveillance 2012–15

Krystyna M Kazmierczak, Boudewijn L M de Jonge, Gregory G Stone, Daniel F Sahm

Journal of Antimicrobial Chemotherapy, dky266, https://doi.org/10.1093/jac/dky266

Published: 11 July 2018

 

Abstract

Objectives

The activity of ceftazidime/avibactam was assessed against 24 750 isolates of Enterobacteriaceae collected from 96 medical centres in 18 European countries as part of the International Network for Optimal Resistance Monitoring (INFORM) global surveillance programme from 2012 to 2015. Activity was analysed against subsets of isolates based on resistant phenotypes and β-lactamase content.

Methods

Antimicrobial susceptibility testing was performed using broth microdilution and the presence of β-lactamase genes in isolates of interest was determined using PCR and sequencing.

Results

Ceftazidime/avibactam was the most active agent, compared with all other tested comparator agents, against the overall collection of Enterobacteriaceae isolates (99.4% susceptible) and against subsets of ceftazidime-non-susceptible (97.7% susceptible), colistin-resistant (98.2% susceptible), MDR (96.7% susceptible) and meropenem-non-susceptible, MBL-negative (98.5% susceptible) isolates. At the country level, susceptibility to ceftazidime/avibactam ranged from 96.3% to 100% among Enterobacteriaceae isolates, with decreased susceptibilities only observed in countries where MBLs were more frequently encountered (e.g. Greece and Romania). Ceftazidime/avibactam was active against 99.7% of Enterobacteriaceae isolates that carried serine β-lactamases, including ESBLs, AmpC cephalosporinases and carbapenemases (KPC, GES and OXA-48-like) in all combinations. As expected, ceftazidime/avibactam was not active against isolates carrying MBLs.

Conclusions

The data show that ceftazidime/avibactam is highly potent in vitro against clinical isolates of Enterobacteriaceae collected in European countries, including isolates that exhibit resistance to ceftazidime, meropenem and colistin and combined resistance to agents from multiple drug classes.

Issue Section: ORIGINAL RESEARCH

© The Author(s) 2018. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For permissions, please email: journals.permissions@oup.com.

This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices)

Keywords: Antibiotics; Drugs Resistance; Colistin; Meropenem; Ceftazidime; Avibactam; Enterobacteriaceae; European Region.

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