scholarly journals Morphological deconvolution of beta-lactam polyspecificity inE. coli

2019 ◽  
Author(s):  
William J. Godinez ◽  
Helen Chan ◽  
Imtiaz Hossain ◽  
Cindy Li ◽  
Srijan Ranjitkar ◽  
...  
Keyword(s):  
Ex Situ ◽  
Exact Nature ◽  
Enzyme Specificity ◽  
Beta Lactam ◽  
Beta Lactams ◽  
Penicillin Binding Proteins ◽  
E Coli ◽  
Beta Lactam Antibiotics ◽  
Cell Extracts ◽  
The Family

AbstractBeta-lactam antibiotics comprise one of the earliest known classes of antibiotic therapies. These molsecules covalently inhibit enzymes from the family of penicillin-binding proteins, which are essential to the construction of the bacterial cell wall. As a result, beta-lactams have long been known to cause striking changes to cellular morphology. The exact nature of the changes tend to vary by the precise PBPs engaged in the cell since beta-lactams exhibit a range of PBP enzyme specificity. The traditional method for exploring beta-lactam polyspecificity is a gel-based binding assay which is low-throughput and typically runex situin cell extracts. Here, we describe a medium-throughput, image-based assay combined with machine learning methods to automatically profile the activity of beta-lactams inE. colicells. By testing for morphological change across a panel of strains with perturbations to individual PBP enzymes, our approach automatically and quantifiably relates different beta-lactam antibiotics according to their preferences for individual PBPs in cells. We show the potential of our approach for guiding the design of novel inhibitors towards different PBP-binding profiles by recapitulating the activity of two recently-reported PBP inhibitors.

scholarly journals 1220. Is MIC all that matters? MIC Distributions of Ceftazidime and Cefepime in Ceftriaxone-Resistant E. coli and Klebsiella spp

2021 ◽  
Vol 8 (Supplement_1) ◽  
pp. S700-S700
Author(s):  
Emily Heil ◽  
Emily Heil ◽  
Kimberly C Claeys ◽  
Paul Luethy
Keyword(s):  
Testing System ◽  
Beta Lactam ◽  
Beta Lactams ◽  
Routine Testing ◽  
Beta Lactamases ◽  
E Coli ◽  
Beta Lactam Antibiotics ◽  
Recommended Treatment ◽  
Extended Spectrum Beta Lactamases ◽  
Alternative Beta

Abstract Background The Clinical and Laboratory Standards Institute (CLSI) lowered MIC breakpoints for many beta-lactam antibiotics to enhance detection of resistance among Enterobacterales. This shift was also meant to eliminate the need for routine testing for extended-spectrum beta-lactamases (ESBLs). The recommended treatment for ESBL-producing Enterobacterales is carbapenems. The IDSA guidelines for MDR-GN organisms recommend using ceftriaxone (CRO) resistance as a proxy for ESBL production and thus carbapenem treatment. Under CLSI guidelines, alternative beta-lactams such as ceftazidime (CAZ) and cefepime (FEP) may still be reported as susceptible and thus used by clinicians even in light of IDSA recommendations. The aim of this project was to characterize the MIC distributions of CAZ and FEP stratified by CRO susceptibility. Methods Clinical E. coli, K. pneumoniae, and K. oxytoca isolates from blood cultures in adult patients from Nov 2016-Dec 2018 that had MICs tested by the Vitek-2 automated susceptibility testing system for CRO, FEP and CAZ were identified. Descriptive statistics were used to compare MIC distributions across the antibiotics of interest (SPSS). Results 573 isolates were included, of these, 17.3% were CRO resistant. Most (53%) CRO-R isolates had FEP MICs ≤2 which is considered susceptible per CLSI; 19% had FEP MICs of 4-8 which would be considered S-DD by CLSI (Figure 1A; breakpoints noted by dashed lines). Using the EUCAST breakpoint of ≤1, only 11% of CRO-R isolates would be reported as FEP-S. For CAZ, 40% of CRO-R isolates had CAZ MICs ≤4, which is considered S by CLSI. Using the EUCAST breakpoint of ≤1, only 12% of CRO-R isolates would be reported as CAZ-S (Figure 1B). Cefepime MIC Distribution for Ceftriaxone Resistant Isolates Distribution of MICs for cefepime for ceftriaxone resistant isolates with the breakpoints for EUCAST and CLSI noted with a dashed line Ceftazidime MIC Distribution for Ceftriaxone Resistant Isolates Distribution of MICs for ceftazidime for ceftriaxone resistant isolates with the breakpoints for EUCAST and CLSI noted with a dashed line Conclusion Half of CRO-R E. coli, K. pneumoniae and K. oxytoca have FEP and CAZ MICs at or below the current CLSI breakpoints. This may lead to their use for serious ESBL infections where a carbapenem is preferred. To prevent unnecessary use, laboratories should consider suppressing FEP and CAZ susceptibilities when CRO-R or adopting more the aggressive EUCAST breakpoints for these agents. Disclosures Emily Heil, PharmD, MS, BCIDP, Nothing to disclose Kimberly C. Claeys, PharmD, GenMark (Speaker’s Bureau)

scholarly journals Target for bacteriostatic and bactericidal activities of beta-lactam antibiotics against Escherichia coli resides in different penicillin-binding proteins.

1995 ◽  
Vol 39 (4) ◽  
pp. 812-818 ◽  
Author(s):  
G Satta ◽  
G Cornaglia ◽  
A Mazzariol ◽  
G Golini ◽  
S Valisena ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Penicillin Binding Protein ◽  
Beta Lactam ◽  
Beta Lactams ◽  
Killing Effect ◽  
Penicillin Binding Proteins ◽  
Beta Lactam Antibiotics ◽  
Bactericidal Activities ◽  
The Given ◽  
The Relationship

The relationship between cell-killing kinetics and penicillin-binding protein (PBP) saturation has been evaluated in the permeability mutant Escherichia coli DC2 in which the antimicrobial activity of beta-lactams has been described as being directly related to the extent of saturation of the PBP target(s). Saturation of a single PBP by cefsulodin (PBP 1s), mecillinam (PBP 2), and aztreonam (PBP 3) resulted in a slow rate of killing (2.5-, 1.5-, and 0.8-log-unit decreases in the number of CFU per milliliter, respectively, in 6 h). Saturation of two of the three essential PBPs resulted in a marked increase in the rate of killing, which reached the maximum value when PBPs 1s and 2 were simultaneously saturated by a combination of cefsulodin and mecillinam (4.7-log-unit decrease in the number of CFU per milliliter in 6 h). Inactivation of all three essential PBPs by the combination of cefsulodin, mecillinam, and aztreonam further increased the killing kinetics (5.5-log-unit decrease in the number of CFU per milliliter), and this was not significantly changed upon additional saturation of the nonessential PBPs 5 and 6 by cefoxitin. Similar relationships between PBP saturation and killing kinetics were obtained with imipenem and meropenem at concentrations which inhibited only one PBP (PBP 2), only two PBPs (PBP 1s and 2), or all three essential PBPs. Saturation of one or more PBPs also resulted in a different rate of bacteriolysis, the highest rate being obtained by the cefsulodin-mecillinam combination and by 5 micrograms of either imipenem or meropenem per ml. All of these conditions caused saturation of PBP 2 and saturation or extensive binding of PBP 1s. However, none of these conditions caused determined the fastest possible rate of killing, which occurred only when all three essential PBPs were saturated. It was concluded that the actual killing effect of beta-lactams is reflected by killing rates that approach the fastest possible rate for the given microorganism and that the targets for the bactericidal activity are precisely those PBPs whose saturation or binding occurs under conditions.

scholarly journals Analysis of the interactions of a novel cephalosporin derivative with its potential targets penicillin-binding proteins from different sources using a covalent docking approac

2016 ◽  
Author(s):  
Anna Verdino ◽  
Margherita De Rosa ◽  
Annunziata Soriente ◽  
Anna Marabotti
Keyword(s):  
Binding Proteins ◽  
Rational Approach ◽  
Beta Lactam ◽  
Penicillin Binding Proteins ◽  
E Coli ◽  
Beta Lactam Antibiotics ◽  
Linear Chains ◽  
Lactam Ring ◽  
Covalent Docking ◽  
Cross Links

Motivation. Cephalosporins are a class of beta-lactam antibiotics widely used in clinics for their antibacterial activity. Their mode of action, common to other beta lactam antibiotics such as penicillins, is the impairment of the synthesis of the peptidoglycan forming the bacterial cell wall. This polymer, essential for bacterium survival, is made by aminosugars connected by glycosidic bonds to form linear chains, and by short peptides forming cross-links between the linear chains. The enzymes catalyzing the creation of these cross-links are transpeptidases, also called penicillin binding proteins (PBPs) for their ability to interact with penicillins and other beta lactam antibiotics. These molecules mimic the D-Ala-D-Ala terminus of the peptides, therefore they competitively inactivate the PBPs by binding covalently to the Ser residue responsible for the catalysis and stopping the transpeptidation. This results in cell lysis and bacterial death. One of the main problems to face when using cephalosporins is the development of several mechanisms of resistance, either for the reduced affinity of PBPs to the beta lactams, or for the selection of new beta-lactam-insensitive PBPs, or for the production of beta lactamases, enzymes able to hydrolyze the beta lactam ring, thus deactivating the antibiotics. Additionally, most cephalosporins have a limited spectrum of action, against only Gram+ or Gram- bacteria. Therefore, during the time, many new beta lactam antibiotics have been synthesized with the aim of broadening the spectrum of action and/or overcoming the resistance. The prototype of a new group of cephalosporins is AMA-10, in which another beta lactam ring bound to a short alkyl chain has been linked to the aminocephalosporanic ring by means of an amidic bond. In order to develop other molecules, however, it is essential to understand how they interact with their target. Therefore, to apply a rational approach for the design of new derivatives, we have performed a computational study by simulating the binding of AMA-10 to selected PBPs of different species, whose crystallographic structures were available, using a particular approach, covalent docking, able to take into account the covalent bond formed between the antibiotic and the enzyme. Methods. The structures of PBP3 and PBP4 from both Gram+ (S. aureus, B. subtilis) and Gram- (E. coli, P. aeruginosae) organisms were downloaded from Protein Data Bank (PDB) database, as well as the structures of beta-lactamase from S. aureus and from E. coli. The representative structures were selected on the basis of their quality. Then, covalent docking was made by using a modified version of the program AutoDock 4.2, using the flexible side chain method [Bianco et al, 2016]. [Abstract truncated at 3,000 characters - the full version is available in the pdf file].

scholarly journals Analysis of the interactions of a novel cephalosporin derivative with its potential targets penicillin-binding proteins from different sources using a covalent docking approac

2016 ◽  
Author(s):  
Anna Verdino ◽  
Margherita De Rosa ◽  
Annunziata Soriente ◽  
Anna Marabotti
Keyword(s):  
Binding Proteins ◽  
Rational Approach ◽  
Beta Lactam ◽  
Penicillin Binding Proteins ◽  
E Coli ◽  
Beta Lactam Antibiotics ◽  
Linear Chains ◽  
Lactam Ring ◽  
Covalent Docking ◽  
Cross Links

Motivation. Cephalosporins are a class of beta-lactam antibiotics widely used in clinics for their antibacterial activity. Their mode of action, common to other beta lactam antibiotics such as penicillins, is the impairment of the synthesis of the peptidoglycan forming the bacterial cell wall. This polymer, essential for bacterium survival, is made by aminosugars connected by glycosidic bonds to form linear chains, and by short peptides forming cross-links between the linear chains. The enzymes catalyzing the creation of these cross-links are transpeptidases, also called penicillin binding proteins (PBPs) for their ability to interact with penicillins and other beta lactam antibiotics. These molecules mimic the D-Ala-D-Ala terminus of the peptides, therefore they competitively inactivate the PBPs by binding covalently to the Ser residue responsible for the catalysis and stopping the transpeptidation. This results in cell lysis and bacterial death. One of the main problems to face when using cephalosporins is the development of several mechanisms of resistance, either for the reduced affinity of PBPs to the beta lactams, or for the selection of new beta-lactam-insensitive PBPs, or for the production of beta lactamases, enzymes able to hydrolyze the beta lactam ring, thus deactivating the antibiotics. Additionally, most cephalosporins have a limited spectrum of action, against only Gram+ or Gram- bacteria. Therefore, during the time, many new beta lactam antibiotics have been synthesized with the aim of broadening the spectrum of action and/or overcoming the resistance. The prototype of a new group of cephalosporins is AMA-10, in which another beta lactam ring bound to a short alkyl chain has been linked to the aminocephalosporanic ring by means of an amidic bond. In order to develop other molecules, however, it is essential to understand how they interact with their target. Therefore, to apply a rational approach for the design of new derivatives, we have performed a computational study by simulating the binding of AMA-10 to selected PBPs of different species, whose crystallographic structures were available, using a particular approach, covalent docking, able to take into account the covalent bond formed between the antibiotic and the enzyme. Methods. The structures of PBP3 and PBP4 from both Gram+ (S. aureus, B. subtilis) and Gram- (E. coli, P. aeruginosae) organisms were downloaded from Protein Data Bank (PDB) database, as well as the structures of beta-lactamase from S. aureus and from E. coli. The representative structures were selected on the basis of their quality. Then, covalent docking was made by using a modified version of the program AutoDock 4.2, using the flexible side chain method [Bianco et al, 2016]. [Abstract truncated at 3,000 characters - the full version is available in the pdf file].

scholarly journals Uptake of cefepime by phagocytosing polymorphonuclear neutrophils and subsequent intracellular killing.

1996 ◽  
Vol 40 (8) ◽  
pp. 1870-1874 ◽  
Author(s):  
H Pruul ◽  
P J McDonald
Keyword(s):  
Polymorphonuclear Neutrophils ◽  
Beta Lactam ◽  
Beta Lactams ◽  
Phagocytic Cells ◽  
Antibiotic Concentration ◽  
E Coli ◽  
Intracellular Activity ◽  
Beta Lactam Antibiotics ◽  
Acidic Nature ◽  
And Staphylococcus Aureus

Studies of the uptake of beta-lactam antibiotics indicate that they do not accumulate in phagocytic cells. Uptake of beta-lactams is thought to occur through passive diffusion, and this is limited because of their acidic nature. Many studies of antibiotic uptake have utilized either resting phagocytic cells or cells in their postphagocytic phase. We have examined the uptake of cefepime by actively phagocytosing neutrophils under various conditions of neutrophil stimulation in order to determine cefepime intracellular activity against Escherichia coli and Staphylococcus aureus. Exposure of cefepime increased bactericidal activity against E. coli both when bacteria were added during exposure to the antibiotic and when they were added to the neutrophils in the postantibiotic phase. Antibacterial activity was only partially inhibited by phenylbutazone, and an exposure of 4 min to cefepime is sufficient for optimal intracellular activity. Under the same conditions, cefepime-associated killing of S. aureus was not as great as was observed for E. coli. Quantitation of intracellular cefepime showed that neutrophil activation in opsonizing conditions increased the antibiotic concentration by 75 (E. coli) and 55% (S. aureus). The response of neutrophils to the combination of serum, E. coli, and cefepime indicates a significant increase in the chemiluminescence response, compared with the response obtained with bacteria in the absence of cefepime. These data indicate that cefepime rapidly enters phagocytic cells under opsonizing conditions with concomitant increases in oxidative metabolism and intracellular activity against E. coli.

scholarly journals Susceptibility to beta-lactam antibiotics of Pseudomonas aeruginosa overproducing penicillin-binding protein 3.

1997 ◽  
Vol 41 (5) ◽  
pp. 1158-1161 ◽  
Author(s):  
X Liao ◽  
R E Hancock
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Binding Protein ◽  
Broad Host Range ◽  
Penicillin Binding Protein ◽  
Beta Lactam ◽  
Beta Lactams ◽  
E Coli ◽  
Beta Lactam Antibiotics ◽  
Range Vector ◽  
Cell Inhibition

By using a broad-host-range vector, pUCP27, the Pseudomonas aeruginosa and Escherichia coli pbpB genes, which encode penicillin-binding protein 3 (PBP3), were separately overexpressed in a P. aeruginosa strain, PAO4089, that is deficient in producing chromosomal beta-lactamase. Susceptibility studies indicated that overproduction of the P. aeruginosa PBP3 in PAO4089 resulted in twofold-increased resistance to aztreonam, fourfold-increased resistance to cefepime and cefsulodin, and eightfold-increased resistance to ceftazidime, whereas overproduction of the P. aeruginosa PBP3 in PAO4089 did not affect susceptibility to PBP1-targeted cephaloridine or PBP2-targeted imipenem. Similar results were obtained with PAO4089 overproducing E. coli PBP3, with the exception that there was no influence on the MICs or minimal bactericidal concentrations of cefsulodin and cefepime, which have very low affinities for E. coli PBP3. These data are consistent with the conclusion that PBP3 has to achieve a certain level of saturation, with beta-lactams targeted to this protein, to result in cell inhibition or death.

scholarly journals Inherent protection of bacteria from beta-lactam antibiotics by wet-dry cycles with microscopic surface wetness

2020 ◽  
Author(s):  
Yana Beizman-Magen ◽  
Maor Grinberg ◽  
Tomer Orevi ◽  
Nadav Kashtan
Keyword(s):  
Model Organism ◽  
Liquid Films ◽  
Interspecies Interactions ◽  
Beta Lactam ◽  
Beta Lactams ◽  
Surface Wetness ◽  
Beta Lactam Antibiotics ◽  
Hygroscopic Salts ◽  
Antibiotic Response ◽  
Microscopic Surface

AbstractA large portion of bacterial life occurs on surfaces that are not constantly saturated with water and experience recurrent wet-dry cycles. While soil, plant leaves and roots, and many indoor surfaces may appear dry when not saturated with water, they are in fact often covered by thin liquid films and microdroplets, invisible to the naked eye, known as microscopic surface wetness (MSW). Such MSW, resulting from the condensation of water vapor to hygroscopic salts, is ubiquitous yet largely underexplored. A wide variety of antibiotics are abundant in environments where MSW occurs, yet little is known about bacterial response to antibiotics in wet-dry cycles and under MSW conditions. Using E. coli as a model organism, we show, through a combination of experiments and computational modeling, that bacteria are considerably more protected from beta-lactams under wet-dry cycles with MSW phases, than they are under constantly wet conditions. This is due to the combined effect of several mechanisms, including tolerance triggered by inherent properties of MSW, i.e., high salt concentrations and slow cell growth, and the deactivation of antibiotics due to physicochemical properties of MSW. Remarkably, we also find evidence for a cross-protection effect, where addition of lethal doses of antibiotic before drying significantly increases cells’ survival under MSW. As wet-dry cycles with MSW and beta-lactams, as well as other antibiotics, are common in vast terrestrial microbial habitats, our findings are expected to have significant implications for how we understand antibiotic response, population dynamics, and interspecies interactions in these globally important microbial ecosystems.

Comparison of Sensitivity Enterobacteriaceae of Extended Spectrum BetaLactamase (ESBL) against Antibiotics of Quinolone and Carbapenem Group in Clinical Microbiology Laboratory, Faculty of Medicine, Universitas Indonesia

2020 ◽  
Vol 4 (2) ◽  
pp. 71-76
Author(s):  
Conny Riana Tjampakasari ◽  
Alya Iranti ◽  
Tjahjani Mirawati Sudiro
Keyword(s):  
Clinical Microbiology ◽  
Antibiotic Sensitivity ◽  
Female Gender ◽  
Clinical Microbiology Laboratory ◽  
Microbiology Laboratory ◽  
Beta Lactam ◽  
Medical Problems ◽  
E Coli ◽  
Beta Lactam Antibiotics ◽  
Age Range

Antibiotic resistance is a challenge in medical problems. One prevalence of resistance that tends to expand globally is against ESBL-producing Enterobacteriaceae, a group of bacteria capable of destroying beta-lactam antibiotics. The known ESBL producing bacteria are E. coli and K. pneumoniae. This study aims to compare the sensitivity of quinolone and carbapenem antibiotics to ESBL-producing bacteria based on data obtained from Clinical Microbiology Laboratory, Faculty of Medicine, Universitas Indonesia through 2018-2019. Using the Vitek 2® Compact identification method, the results showed that the prevalence of E. coli and K. pneumoniae ESBL was positive less than 5%. All of the ESBL–producing E. coli came from urine specimens, while ESBLproducing K. pneumoniae came from different types of specimens which are sputum and blood. Most prevalence comes in the age range >50 years with female gender. In general, antibiotic sensitivity to the quinolones was less than 50% against ESBL-producing E. coli. Meanwhile, the sensitivity of carbapenem antibiotics reached 100% both against ESBL-producing E.coli and K.pneumoniae.

scholarly journals In Vivo Activity of QPX7728, an Ultrabroad-Spectrum Beta-Lactamase Inhibitor, in Combination with Beta-Lactams against Carbapenem-Resistant Klebsiella pneumoniae

2020 ◽  
Vol 64 (11) ◽  
Author(s):  
Mojgan Sabet ◽  
Ziad Tarazi ◽  
David C. Griffith
Keyword(s):  
Klebsiella Pneumoniae ◽  
Beta Lactamase ◽  
Beta Lactam ◽  
Beta Lactams ◽  
Bacterial Killing ◽  
Clinical Issue ◽  
Content Type ◽  
Beta Lactam Antibiotics ◽  
Carbapenem Resistant ◽  
Lactamase Inhibitor

ABSTRACT Resistance to beta-lactams has created a major clinical issue. QPX7728 is a novel ultrabroad-spectrum cyclic boronic acid beta-lactamase inhibitor with activity against both serine and metallo-beta-lactamases developed to address this resistance for use in combination with beta-lactam antibiotics. The objective of these studies was to evaluate the activity of QPX7728 in combination with multiple beta-lactams against carbapenem-resistant Klebsiella pneumoniae isolates in a neutropenic mouse thigh infection model. Neutropenic mice were infected with strains with potentiated beta-lactam MICs of ≤2 mg/liter in the presence of 8 mg/liter QPX7728. Two strains of carbapenem-resistant K. pneumoniae were tested with aztreonam, biapenem, cefepime, ceftazidime, ceftolozane, and meropenem alone or in combination with 12.5, 25, or 50 mg/kg of body weight of QPX7728 every 2 hours for 24 hours. Treatment with all beta-lactams alone either was bacteriostatic or allowed for bacterial growth. The combination of QPX7728 plus each of these beta-lactams produced bacterial killing at all QPX7728 doses tested. Overall, these data suggest that QPX7728 administered in combination with different partner beta-lactam antibiotics may have utility in the treatment of bacterial infections due to carbapenem-resistant K. pneumoniae.

scholarly journals Oral beta-lactam step down in bacteremic E. coli urinary tract infections

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Stephan Saad ◽  
Neil Mina ◽  
Colin Lee ◽  
Kevin Afra
Keyword(s):  
Urinary Tract ◽  
Propensity Score ◽  
Urinary Tract Infections ◽  
Clinical Cure ◽  
Beta Lactam ◽  
Beta Lactams ◽  
E Coli ◽  
Secondary Outcomes ◽  
Step Down ◽  
Tract Infections

Abstract Background Literature is scarce regarding oral step down to beta-lactams in bacteremic urinary tract infections. Oral fluoroquinolones are an accepted and common step down for bacteremic urinary tract infections; however, their use is associated with mounting safety concerns. We compared clinical cure in patients with E. coli bacteremic urinary tract infections who were stepped down to oral beta-lactams compared to oral fluoroquinolones. Methods This multicentre retrospective cohort study included patients with first positive concurrent urine and blood cultures from January 2016 to December 2016. Patients were included if they received empiric intravenous beta-lactam therapy with step down to either oral beta-lactam or fluoroquinolone for treatment completion. The primary outcome was clinical cure. Secondary outcomes were length of hospitalization, all-cause mortality and C. difficile infection. Multivariate analysis and propensity score were used to control for confounding. Results A total of 207 patients were identified with bacteremic E.coli urinary tract infections. Clinical cure was achieved in 72/77 (94%) in the oral beta-lactam group versus 127/130 (98%) in the oral fluoroquinolone group (absolute difference − 4.2, 95% confidence interval [CI] -10.3 to 1.9%, p = 0.13). The adjusted odds ratio (OR) for clinical cure with oral beta-lactams was 0.31 (95% CI 0.05–1.90, p = 0.21); propensity score adjusted analysis showed a similar result. There was no statistically significant difference in secondary outcomes. Conclusions Oral beta-lactams appear to be a safe and effective step down option in bacteremic E. coli urinary tract infections compared to oral fluoroquinolones.

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