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 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 Occurrence of cross-resistance and beta-lactam seesaw effect in glycopeptide, lipopeptide, and lipoglycopeptide-resistant MRSA correlates with membrane phosphatidylglycerol levels

2019 ◽  
Author(s):  
Kelly M. Hines ◽  
Tianwei Shen ◽  
Nate K. Ashford ◽  
Adam Waalkes ◽  
Kelsi Penewit ◽  
...  
Keyword(s):  
Membrane Lipids ◽  
Membrane Lipid ◽  
Cross Resistance ◽  
Membrane Composition ◽  
Beta Lactam ◽  
Beta Lactams ◽  
Penicillin Binding Proteins ◽  
Mrsa Strains ◽  
The Relationship

ABSTRACTTreatment of methicillin-resistantStaphylococcus aureus(MRSA) infections is challenging and is associated with high rates of therapeutic failure. The glycopeptide (GP) vancomycin and the lipopeptide (LP) daptomycin are still relied upon to manage invasive MRSA infections; however, resistance to these antibiotics has emerged and there is evidence of cross-resistance between them. It has been observed that the susceptibility of MRSA to beta-lactams increases as susceptibility to GPs and LPs decreases, a phenomenon termed the seesaw effect. Recent efforts to understand the mechanism underlying the seesaw effect have focused on the penicillin binding proteins (PBPs). However, while daptomycin resistance is largely mediated by remodeling of membrane lipid composition, the role of membrane lipids in producing cross-resistance and the seesaw effect has not yet been investigated. Here, we evaluate the lipid profiles, cross susceptibilities, and beta-lactam susceptibilities of a collection of isogenic MRSA strains selected against daptomycin, vancomycin or dalbavancin (a lipoglycopeptide; LGP) to assess the relationship between membrane composition, cross-resistance, and the seesaw effect. We found that modification of membrane composition occurs not only in daptomycin-selected strains, but also vancomycin- and dalbavancin-selected strains. Significantly, we observed that typically the levels of short-chain phosphatidylglycerols (PGs) negatively correlate with MICs of GP/LP/LGP and positively correlate with MIC of certain beta-lactams, the latter being dependent on the primary PBP target of the particular beta-lactam. Furthermore, changes to certain PGs with long-chain fatty acids correlate well with presence of the seesaw effect. These studies demonstrate a major association between membrane remodeling and the seesaw effect.

scholarly journals Multidrug-resistant Staphylococcus cohnii and Staphylococcus urealyticus isolates from German dairy farms exhibit resistance to beta-lactam antibiotics and divergent penicillin-binding proteins

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tobias Lienen ◽  
Arne Schnitt ◽  
Jens Andre Hammerl ◽  
Stephen F. Marino ◽  
Sven Maurischat ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Gene Prediction ◽  
Dairy Farms ◽  
Multidrug Resistant ◽  
Amino Acid Sequences ◽  
Penicillin Binding Protein ◽  
Beta Lactam ◽  
Penicillin Binding Proteins ◽  
Antimicrobial Substances ◽  
Beta Lactam Antibiotics

AbstractNon-aureus staphylococci are commonly found on dairy farms. Two rarely investigated species are Staphylococcus (S.) cohnii and S. urealyticus. Since multidrug-resistant S. cohnii and S. urealyticus are known, they may serve as an antimicrobial resistance (AMR) gene reservoir for harmful staphylococcal species. In our study, nine S. cohnii and six S. urealyticus isolates from German dairy farms were analyzed by whole-genome sequencing and AMR testing. The isolates harbored various AMR genes (aadD1, str, mecA, dfrC/K, tetK/L, ermC, lnuA, fexA, fusF, fosB6, qacG/H) and exhibited non-wildtype phenotypes (resistances) against chloramphenicol, clindamycin, erythromycin, fusidic acid, rifampicin, streptomycin, tetracycline, tiamulin and trimethoprim. Although 14/15 isolates lacked the blaZ, mecA and mecC genes, they showed reduced susceptibility to a number of beta-lactam antibiotics including cefoxitin (MIC 4–8 mg/L) and penicillin (MIC 0.25–0.5 mg/L). The specificity of cefoxitin susceptibility testing for mecA or mecC gene prediction in S. cohnii and S. urealyticus seems to be low. A comparison with penicillin-binding protein (PBP) amino acid sequences of S. aureus showed identities of only 70–80% with regard to PBP1, PBP2 and PBP3. In conclusion, S. cohnii and S. urealyticus from selected German dairy farms show multiple resistances to antimicrobial substances and may carry unknown antimicrobial resistance determinants.

scholarly journals Differential Effects of Penicillin Binding Protein Deletion on the Susceptibility of Enterococcus faecium to Cationic Peptide Antibiotics

2015 ◽  
Vol 59 (10) ◽  
pp. 6132-6139 ◽  
Author(s):  
George Sakoulas ◽  
Monika Kumaraswamy ◽  
Poochit Nonejuie ◽  
Brian J. Werth ◽  
Micahel J. Rybak ◽  
...  
Keyword(s):  
Enterococcus Faecium ◽  
Cumulative Effect ◽  
Human Neutrophils ◽  
Peptide Antibiotics ◽  
Penicillin Binding Protein ◽  
Beta Lactam ◽  
Content Type ◽  
Penicillin Binding Proteins ◽  
Beta Lactam Antibiotics ◽  
Knockout Mutants

ABSTRACTBeta-lactam antibiotics sensitizeEnterococcus faeciumto killing by endogenous antimicrobial peptides (AMPs) of the innate immune system and daptomycin through mechanisms yet to be elucidated. It has been speculated that beta-lactam inactivation of selectE. faeciumpenicillin binding proteins (PBPs) may play a pivotal role in this sensitization process. To characterize the specific PBP inactivation that may be responsible for these phenotypes, we utilized a previously characterized set ofE. faeciumPBP knockout mutants to determine the effects of such mutations on the activity of daptomycin and the AMP human cathelicidin (LL-37). Enhanced susceptibility to daptomycin was dependent more on a cumulative effect of multiple PBP deletions than on inactivation of any single specific PBP. Selective knockout of PBPZ renderedE. faeciummore vulnerable to killing by both recombinant LL-37 and human neutrophils, which produce the antimicrobial peptide in high quantities. Pharmacotherapy targeting multiple PBPs may be used as adjunctive therapy with daptomycin to treat difficultE. faeciuminfections.

scholarly journals Binding of 125I-labeled .BETA.-lactam antibiotics to the penicillin binding proteins of Escherichia coli.

1984 ◽  
Vol 37 (4) ◽  
pp. 389-393 ◽  
Author(s):  
FERNANDO ROJO ◽  
JUAN A. AYALA ◽  
ENRIQUE J. DE LA ROSA ◽  
MIGUEL A. DE PEDRO ◽  
VICENTE ARÁN ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Binding Proteins ◽  
Beta Lactam ◽  
Penicillin Binding Proteins ◽  
Beta Lactam Antibiotics
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