201
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Powers RA, Swanson HC, Taracila MA, Florek NW, Romagnoli C, Caselli E, Prati F, Bonomo RA, Wallar BJ. Biochemical and structural analysis of inhibitors targeting the ADC-7 cephalosporinase of Acinetobacter baumannii. Biochemistry 2014; 53:7670-9. [PMID: 25380506 PMCID: PMC4263437 DOI: 10.1021/bi500887n] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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β-Lactam
resistance in Acinetobacter baumannii presents one
of the greatest challenges to contemporary antimicrobial chemotherapy.
Much of this resistance to cephalosporins derives from the expression
of the class C β-lactamase enzymes, known as Acinetobacter-derived cephalosporinases (ADCs). Currently, β-lactamase inhibitors
are structurally similar to β-lactam substrates and are not
effective inactivators of this class C cephalosporinase. Herein, two boronic acid transition state inhibitors
(BATSIs S02030 and SM23) that are chemically distinct from β-lactams
were designed and tested for inhibition of ADC enzymes. BATSIs SM23
and S02030 bind with high affinity to ADC-7, a chromosomal cephalosporinase
from Acinetobacter baumannii (Ki = 21.1 ± 1.9 nM and 44.5 ± 2.2 nM, respectively).
The X-ray crystal structures of ADC-7 were determined in both the
apo form (1.73 Å resolution) and in complex with S02030 (2.0
Å resolution). In the complex, S02030 makes several canonical
interactions: the O1 oxygen of S02030 is bound in the oxyanion hole,
and the R1 amide group makes key interactions with conserved residues
Asn152 and Gln120. In addition, the carboxylate group of the inhibitor
is meant to mimic the C3/C4 carboxylate found
in β-lactams. The C3/C4 carboxylate recognition
site in class C enzymes is comprised of Asn346 and Arg349 (AmpC numbering),
and these residues are conserved in ADC-7. Interestingly, in the ADC-7/S02030
complex, the inhibitor carboxylate group is observed to interact with
Arg340, a residue that distinguishes ADC-7 from the related class
C enzyme AmpC. A thermodynamic analysis suggests that ΔH driven compounds may be optimized to generate
new lead agents. The ADC-7/BATSI complex provides insight into recognition
of non-β-lactam inhibitors by ADC enzymes and offers a starting
point for the structure-based optimization of this class of novel
β-lactamase inhibitors against a key resistance target.
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Affiliation(s)
- Rachel A Powers
- Department of Chemistry, Grand Valley State University , 1 Campus Drive, Allendale, Michigan 49401, United States
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202
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Temkin E, Adler A, Lerner A, Carmeli Y. Carbapenem-resistant Enterobacteriaceae: biology, epidemiology, and management. Ann N Y Acad Sci 2014; 1323:22-42. [PMID: 25195939 DOI: 10.1111/nyas.12537] [Citation(s) in RCA: 160] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Introduced in the 1980s, carbapenem antibiotics have served as the last line of defense against multidrug-resistant Gram-negative organisms. Over the last decade, carbapenem-resistant Enterobacteriaceae (CRE) have emerged as a significant public health threat. This review summarizes the molecular genetics, natural history, and epidemiology of CRE and discusses approaches to prevention and treatment.
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Affiliation(s)
- Elizabeth Temkin
- Division of Epidemiology and Preventive Medicine, Tel Aviv Sourasky Medical Center, Israel
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203
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Dzhekieva L, Adediran SA, Pratt RF. Interactions of "bora-penicilloates" with serine β-lactamases and DD-peptidases. Biochemistry 2014; 53:6530-8. [PMID: 25302576 PMCID: PMC4204886 DOI: 10.1021/bi500970f] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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Specific
boronic acids are generally powerful tetrahedral intermediate/transition
state analogue inhibitors of serine amidohydrolases. This group of
enzymes includes bacterial β-lactamases and DD-peptidases where
there has been considerable development of boronic acid inhibitors.
This paper describes the synthesis, determination of the inhibitory
activity, and analysis of the results from two α-(2-thiazolidinyl)
boronic acids that are closer analogues of particular tetrahedral
intermediates involved in β-lactamase and DD-peptidase catalysis
than those previously described. One of them, 2-[1-(dihydroxyboranyl)(2-phenylacetamido)methyl]-5,5-dimethyl-1,3-thiazolidine-4-carboxylic
acid, is a direct analogue of the deacylation tetrahedral intermediates
of these enzymes. These compounds are micromolar inhibitors of class
C β-lactamases but, very unexpectedly, not inhibitors of class
A β-lactamases. We rationalize the latter result on the basis
of a new mechanism of boronic acid inhibition of the class A enzymes.
A stable inhibitory complex is not accessible because of the instability
of an intermediate on its pathway of formation. The new boronic acids
also do not inhibit bacterial DD-peptidases (penicillin-binding proteins).
This result strongly supports a central feature of a previously proposed
mechanism of action of β-lactam antibiotics, where deacylation
of β-lactam-derived acyl-enzymes is not possible because of
unfavorable steric interactions.
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Affiliation(s)
- Liudmila Dzhekieva
- Department of Chemistry, Wesleyan University , Lawn Avenue, Middletown, Connecticut 06459, United States
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204
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Rossolini GM, Arena F, Pecile P, Pollini S. Update on the antibiotic resistance crisis. Curr Opin Pharmacol 2014; 18:56-60. [DOI: 10.1016/j.coph.2014.09.006] [Citation(s) in RCA: 313] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 09/05/2014] [Indexed: 01/03/2023]
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205
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Abstract
The continuing emergence of infections due to multidrug resistant bacteria is a serious public health problem. Klebsiella pneumoniae, which commonly acquires resistance encoded on mobile genetic elements, including ones that encode carbapenemases, is a prime example. K. pneumoniae carrying such genetic material, including both blaKPC and genes encoding metallo-β-lactamases, have spread globally. Many carbapenemase-producing K. pneumoniae are resistant to multiple antibiotic classes beyond β-lactams, including tetracyclines, aminoglycosides, and fluoroquinolones. The optimal treatment, if any, for infections due to these organisms is unclear but, paradoxically, appears to often require the inclusion of an optimally administered carbapenem.
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206
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Keepers TR, Gomez M, Celeri C, Nichols WW, Krause KM. Bactericidal activity, absence of serum effect, and time-kill kinetics of ceftazidime-avibactam against β-lactamase-producing Enterobacteriaceae and Pseudomonas aeruginosa. Antimicrob Agents Chemother 2014; 58:5297-305. [PMID: 24957838 PMCID: PMC4135815 DOI: 10.1128/aac.02894-14] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 06/17/2014] [Indexed: 01/31/2023] Open
Abstract
Avibactam, a non-β-lactam β-lactamase inhibitor with activity against extended-spectrum β-lactamases (ESBLs), KPC, AmpC, and some OXA enzymes, extends the antibacterial activity of ceftazidime against most ceftazidime-resistant organisms producing these enzymes. In this study, the bactericidal activity of ceftazidime-avibactam against 18 Pseudomonas aeruginosa isolates and 15 Enterobacteriaceae isolates, including wild-type isolates and ESBL, KPC, and/or AmpC producers, was evaluated. Ceftazidime-avibactam MICs (0.016 to 32 μg/ml) were lower than those for ceftazidime alone (0.06 to ≥256 μg/ml) against all isolates except for 2 P. aeruginosa isolates (1 blaVIM-positive isolate and 1 blaOXA-23-positive isolate). The minimum bactericidal concentration/MIC ratios of ceftazidime-avibactam were ≤4 for all isolates, indicating bactericidal activity. Human serum and human serum albumin had a minimal effect on ceftazidime-avibactam MICs. Ceftazidime-avibactam time-kill kinetics were evaluated at low MIC multiples and showed time-dependent reductions in the number of CFU/ml from 0 to 6 h for all strains tested. A ≥3-log10 decrease in the number of CFU/ml was observed at 6 h for all Enterobacteriaceae, and a 2-log10 reduction in the number of CFU/ml was observed at 6 h for 3 of the 6 P. aeruginosa isolates. Regrowth was noted at 24 h for some of the isolates tested in time-kill assays. These data demonstrate the potent bactericidal activity of ceftazidime-avibactam and support the continued clinical development of ceftazidime-avibactam as a new treatment option for infections caused by Enterobacteriaceae and P. aeruginosa, including isolates resistant to ceftazidime by mechanisms dependent on avibactam-sensitive β-lactamases.
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207
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Controlling resistant bacteria with a novel class of β-lactamase inhibitor peptides: from rational design to in vivo analyses. Sci Rep 2014; 4:6015. [PMID: 25109311 PMCID: PMC4127500 DOI: 10.1038/srep06015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 07/22/2014] [Indexed: 01/24/2023] Open
Abstract
Peptide rational design was used here to guide the creation of two novel short β-lactamase inhibitors, here named dBLIP-1 and -2, with length of five amino acid residues. Molecular modeling associated with peptide synthesis improved bactericidal efficacy in addition to amoxicillin, ampicillin and cefotaxime. Docked structures were consistent with calorimetric analyses against bacterial β-lactamases. These two compounds were further tested in mice. Whereas commercial antibiotics alone failed to cure mice infected with Staphylococcus aureus and Escherichia coli expressing β-lactamases, infection was cleared when treated with antibiotics in combination with dBLIPs, clearly suggesting that peptides were able to neutralize bacterial resistance. Moreover, immunological assays were also performed showing that dBLIPs were unable to modify mammalian immune response in both models, reducing the risks of collateral effects. In summary, the unusual peptides here described provide leads to overcome β-lactamase-based resistance, a remarkable clinical challenge.
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208
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Avibactam and class C β-lactamases: mechanism of inhibition, conservation of the binding pocket, and implications for resistance. Antimicrob Agents Chemother 2014; 58:5704-13. [PMID: 25022578 DOI: 10.1128/aac.03057-14] [Citation(s) in RCA: 140] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Avibactam is a novel non-β-lactam β-lactamase inhibitor that inhibits a wide range of β-lactamases. These include class A, class C, and some class D enzymes, which erode the activity of β-lactam drugs in multidrug-resistant pathogens like Pseudomonas aeruginosa and Enterobacteriaceae spp. Avibactam is currently in clinical development in combination with the β-lactam antibiotics ceftazidime, ceftaroline fosamil, and aztreonam. Avibactam has the potential to be the first β-lactamase inhibitor that might provide activity against class C-mediated resistance, which represents a growing concern in both hospital- and community-acquired infections. Avibactam has an unusual mechanism of action: it is a covalent inhibitor that acts via ring opening, but in contrast to other currently used β-lactamase inhibitors, this reaction is reversible. Here, we present a high-resolution structure of avibactam bound to a class C β-lactamase, AmpC, from P. aeruginosa that provided insight into the mechanism of both acylation and recyclization in this enzyme class and highlighted the differences observed between class A and class C inhibition. Furthermore, variants resistant to avibactam that identified the residues important for inhibition were isolated. Finally, the structural information was used to predict effective inhibition by sequence analysis and functional studies of class C β-lactamases from a large and diverse set of contemporary clinical isolates (P. aeruginosa and several Enterobacteriaceae spp.) obtained from recent infections to understand any preexisting variability in the binding pocket that might affect inhibition by avibactam.
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209
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Tzouvelekis LS, Markogiannakis A, Piperaki E, Souli M, Daikos GL. Treating infections caused by carbapenemase-producing Enterobacteriaceae. Clin Microbiol Infect 2014; 20:862-72. [PMID: 24890393 DOI: 10.1111/1469-0691.12697] [Citation(s) in RCA: 247] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Carbapenemase-producing Enterobacteriaceae (CPE) have spread worldwide, causing serious infections with increasing frequency. CPE are resistant to almost all available antibiotics, complicating therapy and limiting treatment options. Mortality rates associated with CPE infections are unacceptably high, indicating that the current therapeutic approaches are inadequate and must be revised. Here, we review 20 clinical studies (including those describing the largest cohorts of CPE-infected patients) that provided the necessary information regarding isolate and patient characteristics and treatment schemes, as well as a clear assessment of outcome. The data summarized here indicate that treatment with a single in vitro active agent resulted in mortality rates not significantly different from that observed in patients treated with no active therapy, whereas combination therapy with two or more in vitro active agents was superior to monotherapy, providing a clear survival benefit (mortality rate, 27.4% vs. 38.7%; p <0.001). The lowest mortality rate (18.8%) was observed in patients treated with carbapenem-containing combinations.
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Affiliation(s)
- L S Tzouvelekis
- Department of Microbiology, School of Medicine, University of Athens, Athens, Greece
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210
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Singh SB. Confronting the challenges of discovery of novel antibacterial agents. Bioorg Med Chem Lett 2014; 24:3683-9. [PMID: 25017034 DOI: 10.1016/j.bmcl.2014.06.053] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 06/16/2014] [Accepted: 06/18/2014] [Indexed: 10/25/2022]
Abstract
Bacterial resistance is inevitable and is a growing concern. It can be addressed only by discovery and development of new agents. However the discovery and development of new antibacterial agents are at an all time low. This article broadly examines the historical as well as current status of antibacterial discovery and provides some perspective as how to address some of the challenges.
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Affiliation(s)
- Sheo B Singh
- SBS Pharma Consulting LLC, Edison, NJ 08820, United States.
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211
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Kumar VP, Basavannacharya C, de Sousa SM. A microplate assay for the coupled transglycosylase-transpeptidase activity of the penicillin binding proteins; a vancomycin-neutralizing tripeptide combination prevents penicillin inhibition of peptidoglycan synthesis. Biochem Biophys Res Commun 2014; 450:347-52. [PMID: 24944023 DOI: 10.1016/j.bbrc.2014.05.119] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 05/25/2014] [Indexed: 12/11/2022]
Abstract
A microplate, scintillation proximity assay to measure the coupled transglycosylase-transpeptidase activity of the penicillin binding proteins in Escherichia coli membranes was developed. Membranes were incubated with the two peptidoglycan sugar precursors UDP-N-acetyl muramylpentapeptide (UDP-MurNAc(pp)) and UDP-[(3)H]N-acetylglucosamine in the presence of 40 μM vancomycin to allow in situ accumulation of lipid II. In a second step, vancomycin inhibition was relieved by addition of a tripeptide (Lys-D-ala-D-ala) or UDP-MurNAc(pp), resulting in conversion of lipid II to cross-linked peptidoglycan. Inhibitors of the transglycosylase or transpeptidase were added at step 2. Moenomycin, a transglycosylase inhibitor, had an IC50 of 8 nM. Vancomycin and nisin also inhibited the assay. Surprisingly, the transpeptidase inhibitors penicillin and ampicillin showed no inhibition. In a pathway assay of peptidoglycan synthesis, starting from the UDP linked sugar precursors, inhibition by penicillin was reversed by a 'neutral' combination of vancomycin plus tripeptide, suggesting an interaction thus far unreported.
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212
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Qin W, Panunzio M, Biondi S. β-Lactam Antibiotics Renaissance. Antibiotics (Basel) 2014; 3:193-215. [PMID: 27025744 PMCID: PMC4790388 DOI: 10.3390/antibiotics3020193] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Revised: 04/30/2014] [Accepted: 05/04/2014] [Indexed: 11/16/2022] Open
Abstract
Since the 1940s β-lactam antibiotics have been used to treat bacterial infections. However, emergence and dissemination of β-lactam resistance has reached the point where many marketed β-lactams no longer are clinically effective. The increasing prevalence of multidrug-resistant bacteria and the progressive withdrawal of pharmaceutical companies from antibiotic research have evoked a strong reaction from health authorities, who have implemented initiatives to encourage the discovery of new antibacterials. Despite this gloomy scenario, several novel β-lactam antibiotics and β-lactamase inhibitors have recently progressed into clinical trials, and many more such compounds are being investigated. Here we seek to provide highlights of recent developments relating to the discovery of novel β-lactam antibiotics and β-lactamase inhibitors.
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Affiliation(s)
- Wenling Qin
- ISOF-CNR Department of Chemistry "G. Ciamician", Via Selmi, 2 I-40126 Bologna, Italy.
| | - Mauro Panunzio
- ISOF-CNR Department of Chemistry "G. Ciamician", Via Selmi, 2 I-40126 Bologna, Italy.
| | - Stefano Biondi
- Allecra Therapeutics SAS, 13, rue de Village-Neuf, F-68300 St-Louis, France.
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213
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Ah YM, Kim AJ, Lee JY. Colistin resistance in Klebsiella pneumoniae. Int J Antimicrob Agents 2014; 44:8-15. [PMID: 24794735 DOI: 10.1016/j.ijantimicag.2014.02.016] [Citation(s) in RCA: 123] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 02/18/2014] [Accepted: 02/27/2014] [Indexed: 11/18/2022]
Abstract
Increasing use of colistin for multidrug-resistant Gram-negative bacterial infections has led to the emergence of colistin resistance in Klebsiella pneumoniae in several countries worldwide, including Europe (especially Greece), and colistin resistance rates are continually increasing. Heteroresistance rates, which were significantly higher than resistance rates, were found to be important. Although the mechanism underlying resistance is unclear, it has been suggested that it is related to lipopolysaccharide modification via diverse routes. Several factors have been reported as being associated with colistin resistance, with improper use and patient-to-patient transmission being most often cited. Total infections and infection-related mortality from colistin-resistant K. pneumoniae are high, but currently there are no established treatment regimens. However, several combination regimens that are mainly colistin-based have been found to be successful for treating such infections.
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Affiliation(s)
- Young-Mi Ah
- College of Pharmacy, Institute of Pharmaceutical Science and Technology, Hanyang University, 55 Hanyangdaehak-no, Sangnok-gu, Ansan, Gyeonggi-do 462-791, South Korea
| | - Ah-Jung Kim
- Department of Pharmacy, Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul 110-744, South Korea
| | - Ju-Yeun Lee
- College of Pharmacy, Institute of Pharmaceutical Science and Technology, Hanyang University, 55 Hanyangdaehak-no, Sangnok-gu, Ansan, Gyeonggi-do 462-791, South Korea.
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