Penicillin-binding proteins of Bacteroides fragilis and their role in the resistance to imipenem of clinical isolates

2005 ◽  
Vol 54 (11) ◽  
pp. 1055-1064 ◽  
Author(s):  
Juan Ayala ◽  
Alberto Quesada ◽  
Santiago Vadillo ◽  
Jerónimo Criado ◽  
Segundo Píriz
Keyword(s):  
Binding Proteins ◽  
Antimicrobial Agents ◽  
Resistance Mechanism ◽  
Bacteroides Fragilis ◽  
Resistance Mechanisms ◽  
Gene Encoding ◽  
Penicillin Binding Proteins ◽  
Mechanism Of Resistance

In this study penicillin-binding proteins (PBPs) of Bacteroides fragilis and the resistance mechanisms of this micro-organism to 11 β-lactam antibiotics were analysed. The study focused on the role of PBP2Bfr and metallo-β-lactamase in the mechanism of resistance to imipenem. The mechanism of β-lactam resistance in B. fragilis was strain dependent. The gene encoding the orthologue of Escherichia coli PBP3 gene (pbpBBfr, which encodes the protein PBP2Bfr) was sequenced in five of the eight strains studied, along with the ccrA (cfiA) gene in strain 119, and their implications for resistance were examined. Differences were found in the amino-acid sequence of PBP2Bfr in strains AK-2 and 119, and the production of β-lactamases indicated that these differences may be involved in the mechanism of resistance to imipenem. In vitro binding competition assays with membrane extracts using imipenem indicated that the PBP that bound imipenem with the highest affinity was PBP2Bfr, and that increased affinity in strain 7160 may be responsible for the moderate susceptibility of this strain to imipenem. In the same way, the importance of the chromosomal class A β-lactamase CepA in the resistance mechanism of the B. fragilis strains NCTC 9344, 7160, 2013E, AK-4, 0423 and R-212 was studied. In these strains this is the principal resistance mechanism to antimicrobial agents studied other than imipenem.

scholarly journals Struggle To Survive: the Choir of Target Alteration, Hydrolyzing Enzyme, and Plasmid Expression as a Novel Aztreonam-Avibactam Resistance Mechanism

mSystems ◽  
2020 ◽  
Vol 5 (6) ◽  
Author(s):  
Ke Ma ◽  
Yu Feng ◽  
Alan McNally ◽  
Zhiyong Zong
Keyword(s):  
Antimicrobial Resistance ◽  
Antisense Rna ◽  
Antimicrobial Agents ◽  
Binding Protein ◽  
Resistance Mechanism ◽  
Resistance Mechanisms ◽  
Penicillin Binding Protein ◽  
Plasmid Copy ◽  
Copy Numbers

ABSTRACT Aztreonam-avibactam is a promising antimicrobial combination against multidrug-resistant organisms, such as carbapenemase-producing Enterobacterales. Resistance to aztreonam-avibactam has been found, but the resistance mechanism remains poorly studied. We recovered three Escherichia coli isolates of an almost identical genome but exhibiting varied aztreonam-avibactam resistance. The isolates carried a cephalosporinase gene, blaCMY-42, on IncIγ plasmids with a single-nucleotide variation in an antisense RNA-encoding gene, inc, of the replicon. The isolates also had four extra amino acids (YRIK) in penicillin-binding protein 3 (PBP3) due to a duplication of a 12-nucleotide (TATCGAATTAAC) stretch in pbp3. By cloning and plasmid-curing experiments, we found that elevated CMY-42 cephalosporinase production or amino acid insertions in PBP3 alone mediated slightly reduced susceptibility to aztreonam-avibactam, but their combination conferred aztreonam-avibactam resistance. We show that the elevated CMY-42 production results from increased plasmid copy numbers due to mutations in inc. We also verified the findings using in vitro mutation assays, in which aztreonam-avibactam-resistant mutants also had mutations in inc and elevated CMY-42 production compared with the parental strain. This choir of target modification, hydrolyzing enzyme, and plasmid expression represents a novel, coordinated, complex antimicrobial resistance mechanism and also reflects the struggle of bacteria to survive under selection pressure imposed by antimicrobial agents. IMPORTANCE Carbapenemase-producing Enterobacterales (CPE) is a serious global challenge with limited therapeutic options. Aztreonam-avibactam is a promising antimicrobial combination with activity against CPE producing serine-based carbapenemases and metallo-β-lactamases and has the potential to be a major option for combatting CPE. Aztreonam-avibactam resistance has been found, but resistance mechanisms remain largely unknown. Understanding resistance mechanisms is essential for optimizing treatment and developing alternative therapies. Here, we found that either penicillin-binding protein 3 modification or the elevated expression of cephalosporinase CMY-42 due to increased plasmid copy numbers does not confer resistance to aztreonam-avibactam, but their combination does. We demonstrate that increased plasmid copy numbers result from mutations in antisense RNA-encoding inc of the IncIγ replicon. The findings reveal that antimicrobial resistance may be due to concerted combinatorial effects of target alteration, hydrolyzing enzyme, and plasmid expression and also highlight that resistance to any antimicrobial combination will inevitably emerge.

scholarly journals 1593. Antimicrobial Activity of Ceftazidime-Avibactam and Comparator Agents Against OXA-48 β-lactamase–Producing Enterobacterales Collected in International Medical Centers, Including the United States, in 2017–2018

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S793-S793
Author(s):  
Lynn-Yao Lin ◽  
Dmitri Debabov ◽  
William Chang
Keyword(s):  
Antimicrobial Agents ◽  
The United States ◽  
Resistance Mechanisms ◽  
Clinical Isolates ◽  
Surveillance Program ◽  
Multiple Resistance ◽  
In Vitro Susceptibility ◽  
Medical Centers ◽  
Custom Made

Abstract Background OXA-48 is a carbapenemase with low-level hydrolytic activity toward cephalosporins. This study evaluated in vitro activities of ceftazidime-avibactam (CAZ-AVI), meropenem (MEM), meropenem-vaborbactam (MVB), ceftolozane-tazobactam (C/T), and other antimicrobial agents against 113 OXA-48-producing Enterobacterales with multiple resistance mechanisms collected in a 2017–2018 global surveillance program. Methods Nonduplicate clinical isolates of 113 Enterobacterales were collected from medical centers in 25 countries in 2017–2018. In vitro susceptibility tests were performed by broth microdilution with a custom-made panel consisting of CAZ-AVI, ceftazidime (CAZ), MEM, MVB, C/T, colistin (COL), gentamicin (GEN), levofloxacin (LEV), and amikacin (AMK). Whole genome sequencing or quantitative PCR data were used to analyze resistance mechanisms, such as OXA-48, extended-spectrum β-lactamase (ESBL), original-spectrum β-lactamase (OSBL), and AmpC β-lactamase. Clinical and Laboratory Standards Institute breakpoints were applied for susceptibility interpretations. Results Of 113 OXA-48–producing clinical isolates, 20 carried OXA-48 alone. The remaining 93 isolates carried additional β-lactamases, including 63 with ESBL (CTX-M-15) + OSBL (SHV, TEM), 15 with AmpC (DHA, AAC, CMY) + ESBL (CTX-M-15), and 15 with OSBL (SHV, TEM). 99.1% (all but 1) of all isolates tested were susceptible to CAZ-AVI, whereas 71.7%, 17.7%, and 14.2% were susceptible to MVB, MEM, and C/T, respectively. Among isolates harboring multiple resistance mechanisms (OXA-48 + ESBL + OSBL; n=63), 98.4%, 69.8%, 11.1%, and 7.9% were susceptible to CAZ-AVI, MVB, MEM, and C/T, respectively. Among isolates carrying OXA-48 + AmpC + ESBL + OSBL (n=15), 100%, 66.7%, 13.3%, and 13.3% were susceptible to CAZ-AVI, MVB, MEM, and C/T, respectively (Table). Aminoglycosides (AMK and GEN) and other β-lactams (eg, CAZ) were 20%–90% active against these isolates. COL was the second most effective comparator, inhibiting 83.2% of these isolates. Table Conclusion CAZ-AVI was the most effective agent in this study compared with other antibiotics, including β-lactams, β-lactam–β-lactamase inhibitor combinations, aminoglycosides, and COL, against OXA-48-producing Enterobacterales carrying multiple β-lactamases. Disclosures Lynn-Yao Lin, MS, AbbVie (Employee) Dmitri Debabov, PhD, AbbVie (Employee) William Chang, BS, AbbVie (Employee)

scholarly journals Interaction between Poly(ADP-ribose) and NuMA Contributes to Mitotic Spindle Pole Assembly

2009 ◽  
Vol 20 (21) ◽  
pp. 4575-4585 ◽  
Author(s):  
Paul Chang ◽  
Margaret Coughlin ◽  
Timothy J. Mitchison
Keyword(s):  
Binding Proteins ◽  
Magnetic Beads ◽  
Spindle Pole ◽  
Covalent Modification ◽  
Mitotic Spindles ◽  
Spindle Poles ◽  
Tankyrase 1 ◽  
Mitotic Spindle Pole

Poly(ADP-ribose) (pADPr), made by PARP-5a/tankyrase-1, localizes to the poles of mitotic spindles and is required for bipolar spindle assembly, but its molecular function in the spindle is poorly understood. To investigate this, we localized pADPr at spindle poles by immuno-EM. We then developed a concentrated mitotic lysate system from HeLa cells to probe spindle pole assembly in vitro. Microtubule asters assembled in response to centrosomes and Ran-GTP in this system. Magnetic beads coated with pADPr, extended from PARP-5a, also triggered aster assembly, suggesting a functional role of the pADPr in spindle pole assembly. We found that PARP-5a is much more active in mitosis than interphase. We used mitotic PARP-5a, self-modified with pADPr chains, to capture mitosis-specific pADPr-binding proteins. Candidate binding proteins included the spindle pole protein NuMA previously shown to bind to PARP-5a directly. The rod domain of NuMA, expressed in bacteria, bound directly to pADPr. We propose that pADPr provides a dynamic cross-linking function at spindle poles by extending from covalent modification sites on PARP-5a and NuMA and binding noncovalently to NuMA and that this function helps promote assembly of exactly two poles.

β-Lactam antibiotic targets and resistance mechanisms: from covalent inhibitors to substrates

2021 ◽  
Author(s):  
Montserrat Mora-Ochomogo ◽  
Christopher T. Lohans
Keyword(s):  
Binding Proteins ◽  
Resistance Mechanisms ◽  
Penicillin Binding Proteins ◽  
Covalent Inhibitors ◽  
Lactam Antibiotic

Overview of β-lactam antibiotics and the proteins with which they covalently interact, focusing on penicillin-binding proteins and serine β-lactamases.

Activities of Tobramycin and Six Other Antibiotics against Pseudomonas aeruginosa Isolates from Patients with Cystic Fibrosis

1999 ◽  
Vol 43 (12) ◽  
pp. 2877-2880 ◽  
Author(s):  
Ribhi M. Shawar ◽  
David L. MacLeod ◽  
Richard L. Garber ◽  
Jane L. Burns ◽  
Jenny R. Stapp ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Antimicrobial Agents ◽  
Active Drug ◽  
Resistance Mechanisms ◽  
Phase Iii ◽  
In Vitro Activity ◽  
Phase Iii Clinical Trials ◽  
Multiple Antibiotics

ABSTRACT The in vitro activity of tobramycin was compared with those of six other antimicrobial agents against 1,240 Pseudomonas aeruginosa isolates collected from 508 patients with cystic fibrosis during pretreatment visits as part of the phase III clinical trials of tobramycin solution for inhalation. The tobramycin MIC at which 50% of isolates are inhibited (MIC50) and MIC90 were 1 and 8 μg/ml, respectively. Tobramycin was the most active drug tested and also showed good activity against isolates resistant to multiple antibiotics. The isolates were less frequently resistant to tobramycin (5.4%) than to ceftazidime (11.1%), aztreonam (11.9%), amikacin (13.1%), ticarcillin (16.7%), gentamicin (19.3%), or ciprofloxacin (20.7%). For all antibiotics tested, nonmucoid isolates were more resistant than mucoid isolates. Of 56 isolates for which the tobramycin MIC was ≥16 μg/ml and that were investigated for resistance mechanisms, only 7 (12.5%) were shown to possess known aminoglycoside-modifying enzymes; the remaining were presumably resistant by an incompletely understood mechanism often referred to as “impermeability.”

scholarly journals Substantiation inEnterococcus faecalisof Dose-Dependent Resistance and Cross-Resistance to Pore-Forming Antimicrobial Peptides by Use of a Polydiacetylene-Based Colorimetric Assay

2010 ◽  
Vol 77 (3) ◽  
pp. 786-793 ◽  
Author(s):  
Jitender Mehla ◽  
S. K. Sood
Keyword(s):  
Colorimetric Assay ◽  
Physiological Activity ◽  
Resistance Mechanisms ◽  
Cross Resistance ◽  
Common Mechanism ◽  
Membrane Phospholipids ◽  
Mechanism Of Resistance ◽  
Colorimetric Response ◽  
Dose Dependent

ABSTRACTA better understanding of the antimicrobial peptide (AMP) resistance mechanisms of bacteria will facilitate the design of effective and potent AMPs. Therefore, to understand resistance mechanisms and forin vitroassessment, variants ofEnterococcus faecalisthat are resistant to different doses of the fungal AMP alamethicin (Almr) were selected and characterized. The resistance developed was dose dependent, as both doses of alamethicin and degrees of resistance were colinear. The formation of bacterial cell aggregates observed in resistant cells may be the prime mechanism of resistance because overall, a smaller cell surface in aggregated cells is exposed to AMPs. Increased rigidity of the membranes of Almrvariants, because of their altered fatty acids, was correlated with limited membrane penetration by alamethicin. Thus, resistance developed against alamethicin was an adaptation of the bacterial cells through changes in their morphological features and physiological activity and the composition of membrane phospholipids. The Almrvariants showed cross-resistance to pediocin, which indicated that resistance developed against both AMPs may share a mechanism, i.e., an alteration in the cell membrane. High percentages of colorimetric response by both AMPs against polydiacetylene/lipid biomimetic membranes of Almrvariants confirmed that altered phospholipid and fatty acid compositions were responsible for acquisition of resistance. So far, this is the only report of quantification of resistance and cross-resistance using anin vitrocolorimetric approach. Our results imply that a single AMP or AMP analog may be effective against bacterial strains having a common mechanism of resistance. Therefore, an understanding of resistance would contribute to the development of a single efficient, potent AMP against resistant strains that share a mechanism of resistance.

scholarly journals Role of Penicillin-Binding Proteins in the Initiation of the AmpC β-Lactamase Expression inEnterobacter cloacae

2000 ◽  
Vol 44 (1) ◽  
pp. 169-172 ◽  
Author(s):  
Dieter Pfeifle ◽  
Eva Janas ◽  
Bernd Wiedemann
Keyword(s):  
Escherichia Coli ◽  
Binding Proteins ◽  
Penicillin Binding Proteins

ABSTRACT Penicillin-binding proteins (PBPs) are involved in the regulation of β-lactamase expression by determining the level of anhydromuramylpeptides in the periplasmatic space. It was hypothesized that one or more PBPs act as a sensor in the β-lactamase induction pathway. We have performed induction studies with Escherichia coli mutants lacking one to four PBPs withdd-carboxypeptidase activity. Therefore, we conclude that a strong β-lactamase inducer must inhibit alldd-carboxypeptidases as well as the essential PBPs 1a, 1b, and/or 2.

scholarly journals Susceptibility of Methicillin-Resistant Staphylococcus aureus to Five Quinazolinone Antibacterials

2019 ◽  
Vol 64 (1) ◽  
Author(s):  
Sara Ceballos ◽  
Choon Kim ◽  
Yuanyuan Qian ◽  
Shahriar Mobashery ◽  
Mayland Chang ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Amino Acid ◽  
Binding Proteins ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Methicillin Resistant ◽  
Content Type ◽  
Penicillin Binding Proteins

ABSTRACT The in vitro activities of five quinazolinone antibacterials, compounds Q1 to Q5, were tested against 210 strains of methicillin-resistant Staphylococcus aureus (MRSA). The MIC50/MIC90 values (in μg/ml) were as follows: Q1, 0.5/2; Q2, 1/4; Q3, 2/4; Q4, 0.06/0.25; and Q5, 0.125/0.5. Several strains with high MIC values (from 8 to >32 μg/ml) for some of these compounds exhibited amino acid changes in the penicillin-binding proteins, which are targeted by these antibacterials.

scholarly journals Corneal Infection Models: Tools to Investigate the Role of Biofilms in Bacterial Keratitis

Cells ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 2450
Author(s):  
Lucy Urwin ◽  
Katarzyna Okurowska ◽  
Grace Crowther ◽  
Sanhita Roy ◽  
Prashant Garg ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Bacterial Species ◽  
Resistance Mechanisms ◽  
Bacterial Keratitis ◽  
Corneal Surface ◽  
Corneal Infection ◽  
Infection Models

Bacterial keratitis is a corneal infection which may cause visual impairment or even loss of the infected eye. It remains a major cause of blindness in the developing world. Staphylococcus aureus and Pseudomonas aeruginosa are common causative agents and these bacterial species are known to colonise the corneal surface as biofilm populations. Biofilms are complex bacterial communities encased in an extracellular polymeric matrix and are notoriously difficult to eradicate once established. Biofilm bacteria exhibit different phenotypic characteristics from their planktonic counterparts, including an increased resistance to antibiotics and the host immune response. Therefore, understanding the role of biofilms will be essential in the development of new ophthalmic antimicrobials. A brief overview of biofilm-specific resistance mechanisms is provided, but this is a highly multifactorial and rapidly expanding field that warrants further research. Progression in this field is dependent on the development of suitable biofilm models that acknowledge the complexity of the ocular environment. Abiotic models of biofilm formation (where biofilms are studied on non-living surfaces) currently dominate the literature, but co-culture infection models are beginning to emerge. In vitro, ex vivo and in vivo corneal infection models have now been reported which use a variety of different experimental techniques and animal models. In this review, we will discuss existing corneal infection models and their application in the study of biofilms and host-pathogen interactions at the corneal surface.

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