scholarly journals 1230. Evaluation of the Interplay Between β-lactamases and Porin Production on β-Lactam MICs in Klebsiella pneumoniae

2021 ◽  
Vol 8 (Supplement_1) ◽  
pp. S704-S705
Author(s):  
Alyssa K Whitney ◽  
Nancy D Hanson
Keyword(s):  
Outer Membrane ◽  
Clinical Isolate ◽  
Resistance Mechanisms ◽  
Diagnostic Tools ◽  
Resistant Phenotype ◽  
Outer Membrane Porin ◽  
Low Copy Number ◽  
Outer Membrane Porins ◽  
The Impact ◽  
M 14

Abstract Background K. pneumoniae can emerge resistant to β-lactam antibiotics through the production of β-lactamase enzymes and/or loss of the outer membrane porins, OmpK35, OmpK36, and/or PhoE. While both mechanisms are hypothesized to work synergistically, β-lactamases have been the focus of previous studies. As a result, the contribution of outer membrane porin loss to the β-lactam minimum inhibitory concentration (MIC) is unknown. The objective of this study was to evaluate the contribution of specific β-lactamases and porin production to β-lactam susceptibility. We hypothesize that production of a β-lactamase in a clinical isolate deficient in 3 major porins will result in higher β-lactam MICs but not always a resistant phenotype. Methods The structural gene and promoter of CTX-M-14, CTX-M-15, and CMY-2 were cloned into a low copy number vector and transformed into Kp 23, a wild-type clinical isolate, and KPM 20, a clinical isolate deficient in OmpK35/36 and PhoE. MICs to ceftolozane/tazobactam, cefotaxime, ceftazidime, cefepime, and meropenem were determined by E-test. Kp 23 and KPM 20 were characterized by Western blot and whole genome sequencing. Results Production of CMY-2 alone led to a resistant phenotype for ceftolozane/tazobactam, cefotaxime, and ceftazidime regardless of porin production (Figure 1). CMY-2 production in KPM 20 resulted in non-susceptibility to meropenem. Both clones were susceptible to cefepime. Production of CTX-M-14 and CTX-M-15 in Kp 23 resulted in only cefotaxime resistance. Production of CTX-M-14 and CTX-M-15 in KPM 20 resulted in isolates non-susceptible to all antibiotics tested. Figure 1. MICs of K. pneumoniae clones against panel of β-lactam antibiotics. Conclusion When evaluating clinical isolates, it is impossible to determine the contribution of individual resistance mechanisms in the susceptibility pattern. This study demonstrated that resistance is not solely dependent on the β-lactamase produced and that the impact of porin deficiency varies with the antibiotic being evaluated. These data suggest that antibiotic selection may be more nuanced and that a broader range of therapeutics may be available given the appropriate diagnostic tools. Understanding the contributions of all resistance mechanisms is necessary to inform selection of the most appropriate antibiotic therapy. Disclosures Nancy D. Hanson, PhD, Merck (Grant/Research Support)

scholarly journals Detection ofβ-Lactamases and Outer Membrane Porins amongKlebsiella pneumoniaeStrains Isolated in Iran

Scientifica ◽  
2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Ali Hashemi ◽  
Fatemeh Fallah ◽  
Soroor Erfanimanesh ◽  
Parastu Hamedani ◽  
Shadi Alimehr ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Control Measures ◽  
Confirmatory Test ◽  
Disk Diffusion Test ◽  
Infection Control Measures ◽  
Outer Membrane Porin ◽  
Sds Page ◽  
Outer Membrane Porins ◽  
High Prevalence ◽  
Susceptibility Tests

This descriptive study was accomplished on 83K. pneumoniaestrains isolated from two hospitals in Tehran, Iran. Antibiotic susceptibility tests were performed by disc diffusion and broth microdilution methods. ESBLs, MBL, Amp-C, and KPC producing strains were detected by phenotypic confirmatory test, combination disk diffusion test (CDDT), Amp-C detection kit, and modified Hodge test, respectively. OXA-48, NDM-1, and CTX-M-15 genes were detected by PCR and sequencing methods. The outer membrane porins such as OmpK35 and OmpK36 were analysed by SDS-PAGE, PCR, and sequencing methods. From 83K. pneumoniaeisolates, 48 (57.5%), 3 (3.5%), 23 (28%), and 5 (6%) were ESBL, MBL, Amp-C, and KPC positive, respectively. The CTX-M-15 gene was detected in 30 (62.5%) and OXA-48 gene was found in 2 (4.1%) of the 48 ESBL-producing isolates. Two isolates harboured both OXA-48 and CTX-M-15; NDM-1 gene was not detected in this study. Outer membrane porin, OmpK35, was detected in 30 (62.5%) of 48 ESBL-producing isolates while OmpK36 was found in 35 (72.91%) of 48 ESBL-producing isolates. In this study, fosfomycin and tigecycline were more effective than other antibiotics. The high prevalence ofβ-lactamase-producingK. pneumoniaedetected in this study is of great concern, which requires infection control measures including antibacterial management and identification ofβ-lactamases-producing isolates.

Molecular genetic markers for thyroid FNAB

2015 ◽  
Vol 54 (03) ◽  
pp. 94-100 ◽  
Author(s):  
P. B. Musholt ◽  
T. J. Musholt
Keyword(s):  
Genetic Markers ◽  
Thyroid Nodules ◽  
Molecular Genetic ◽  
Genetic Alterations ◽  
Diagnostic Tools ◽  
Ultrasound Screening ◽  
Thyroid Malignancy ◽  
Thyroid Carcinomas ◽  
Molecular Genetic Markers ◽  
The Impact

SummaryAim: Thyroid nodules > 1 cm are observed in about 12% of unselected adult employees aged 18–65 years screened by ultrasound scan (40). While intensive ultrasound screening leads to early detection of thyroid diseases, the determination of benign or malignant behaviour remains uncertain and may trigger anxieties in many patients and their physicians. A considerable number of thyroid resections are consecutively performed due to suspicion of malignancy in the detected nodes. Fine needle aspiration biopsy (FNAB) has been recommended for the assessment of thyroid nodules to facilitate detection of thyroid carcinomas but also to rule out malignancy and thereby avoid unnecessary thyroid resections. However, cytology results are dependent on experience of the respective cytologist and unfortunately inconclusive in many cases. Methods: Molecular genetic markers are already used nowadays to enhance sensitivity and specificity of FNAB cytology in some centers in Germany. The most clinically relevant molecular genetic markers as pre-operative diagnostic tools and the clinical implications for the intraoperative and postoperative management were reviewed. Results: Molecular genetic markers predominantly focus on the preoperative detection of thyroid malignancies rather than the exclusion of thyroid carcinomas. While some centers routinely assess FNABs, other centers concentrate on FNABs with cytology results of follicular neoplasia or suspicion of thyroid carcinoma. Predominantly mutations of BRAF, RET/PTC, RAS, and PAX8/PPARγ or expression of miRNAs are analyzed. However, only the detection of BRAF mutations predicts the presence of (papillary) thyroid malignancy with almost 98% probability, indicating necessity of oncologic thyroid resections irrespective of the cytology result. Other genetic alterations are associated with thyroid malignancy with varying frequency and achieve less impact on the clinical management. Conclusion: Molecular genetic analysis of FNABs is increasingly performed in Germany. Standardization, quality controls, and validation of various methods need to be implemented in the near future to be able to compare the results. With increasing knowledge about the impact of genetic alterations on the prognosis of thyroid carcinomas, recommendations have to be defined that may lead to individually optimized treatment strategies.

scholarly journals Amikacin and bacteriophage treatment modulates outer membrane proteins composition in Proteus mirabilis biofilm

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Agnieszka Maszewska ◽  
Magdalena Moryl ◽  
Junli Wu ◽  
Bin Liu ◽  
Lu Feng ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Outer Membrane ◽  
Proteus Mirabilis ◽  
Protein Biosynthesis ◽  
Outer Membrane Proteins ◽  
Wild Strain ◽  
Elongation Factor ◽  
Resistance Mechanisms ◽  
Trna Synthetases ◽  
Cytoplasmic Proteins

AbstractModification of outer membrane proteins (OMPs) is the first line of Gram-negative bacteria defence against antimicrobials. Here we point to Proteus mirabilis OMPs and their role in antibiotic and phage resistance. Protein profiles of amikacin (AMKrsv), phage (Brsv) and amikacin/phage (AMK/Brsv) resistant variants of P. mirabilis were compared to that obtained for a wild strain. In resistant variants there were identified 14, 1, 5 overexpressed and 13, 5, 1 downregulated proteins for AMKrsv, Brsv and AMK/Brsv, respectively. Application of phages with amikacin led to reducing the number of up- and downregulated proteins compared to single antibiotic treatment. Proteins isolated in AMKrsv are involved in protein biosynthesis, transcription and signal transduction, which correspond to well-known mechanisms of bacteria resistance to aminoglycosides. In isolated OMPs several cytoplasmic proteins, important in antibiotic resistance, were identified, probably as a result of environmental stress, e.g. elongation factor Tu, asparaginyl-tRNA and aspartyl-tRNA synthetases. In Brsv there were identified: NusA and dynamin superfamily protein which could play a role in bacteriophage resistance. In the resistant variants proteins associated with resistance mechanisms occurring in biofilm, e.g. polyphosphate kinase, flagella basal body rod protein were detected. These results indicate proteins important in the development of P. mirabilis antibiofilm therapies.

scholarly journals Sialylation of Outer Membrane Porin Protein D: A Mechanistic Basis of Antibiotic Uptake inPseudomonas aeruginosa

2014 ◽  
Vol 13 (6) ◽  
pp. 1412-1428 ◽  
Author(s):  
Biswajit Khatua ◽  
Jeremy Van Vleet ◽  
Biswa Pronab Choudhury ◽  
Rama Chaudhry ◽  
Chitra Mandal
Keyword(s):  
Outer Membrane ◽  
Porin Protein ◽  
Outer Membrane Porin ◽  
Mechanistic Basis

scholarly journals Electroosmosis Dominates Electrophoresis of Antibiotic Transport Across the Outer Membrane Porin F

2020 ◽  
Vol 118 (11) ◽  
pp. 2844-2852 ◽  
Author(s):  
Jayesh A. Bafna ◽  
Sushil Pangeni ◽  
Mathias Winterhalter ◽  
M. Alphan Aksoyoglu
Keyword(s):  
Outer Membrane ◽  
Outer Membrane Porin

scholarly journals MicroRNA-Regulated Signaling Pathways: Potential Biomarkers for Pancreatic Ductal Adenocarcinoma

Stresses ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 30-47
Author(s):  
Maria Mortoglou ◽  
David Wallace ◽  
Aleksandra Buha Buha Djordjevic ◽  
Vladimir Djordjevic ◽  
E. Damla Arisan ◽  
...  
Keyword(s):  
Pancreatic Ductal Adenocarcinoma ◽  
Metabolic Stress ◽  
Resistance Mechanisms ◽  
Current Data ◽  
Cellular Damage ◽  
Ductal Adenocarcinoma ◽  
Aberrant Expression ◽  
Metabolic Alterations ◽  
Limited Effectiveness ◽  
The Impact

Pancreatic ductal adenocarcinoma (PDAC) is the most aggressive and invasive type of pancreatic cancer (PCa) and is expected to be the second most common cause of cancer-associated deaths. The high mortality rate is due to the asymptomatic progression of the clinical features until the advanced stages of the disease and the limited effectiveness of the current therapeutics. Aberrant expression of several microRNAs (miRs/miRNAs) has been related to PDAC progression and thus they could be potential early diagnostic, prognostic, and/or therapeutic predictors for PDAC. miRs are small (18 to 24 nucleotides long) non-coding RNAs, which regulate the expression of key genes by targeting their 3′-untranslated mRNA region. Increased evidence has also suggested that the chemoresistance of PDAC cells is associated with metabolic alterations. Metabolic stress and the dysfunctionality of systems to compensate for the altered metabolic status of PDAC cells is the foundation for cellular damage. Current data have implicated multiple systems as hallmarks of PDAC development, such as glutamine redox imbalance, oxidative stress, and mitochondrial dysfunction. Hence, both the aberrant expression of miRs and dysregulation in metabolism can have unfavorable effects in several biological processes, such as apoptosis, cell proliferation, growth, survival, stress response, angiogenesis, chemoresistance, invasion, and migration. Therefore, due to these dismal statistics, it is crucial to develop beneficial therapeutic strategies based on an improved understanding of the biology of both miRs and metabolic mediators. This review focuses on miR-mediated pathways and therapeutic resistance mechanisms in PDAC and evaluates the impact of metabolic alterations in the progression of PDAC.

scholarly journals Sialic Acid Transport in E. coli: Role of Outer Membrane Porin NanC

2011 ◽  
Vol 100 (3) ◽  
pp. 577a
Author(s):  
Janhavi Giri ◽  
John M. Tang ◽  
Christophe Wirth ◽  
Caroline M. Peneff ◽  
Tilman Schirmer ◽  
...  
Keyword(s):  
Sialic Acid ◽  
Outer Membrane ◽  
Acid Transport ◽  
E Coli ◽  
Outer Membrane Porin

Selection of AmpC β-lactamase variants and metallo-β-lactamases leading to ceftolozane/tazobactam and ceftazidime/avibactam-resistance during treatment of MDR/XDR Pseudomonas aeruginosa infections

2021 ◽  
Author(s):  
Alba Ruedas-López ◽  
Isaac Alonso García ◽  
Cristina Lasarte-Monterrubio ◽  
Paula Guijarro-Sánchez ◽  
Eva Gato ◽  
...  
Keyword(s):  
3D Models ◽  
Resistance Mechanisms ◽  
Class 1 ◽  
Long Read ◽  
Cephalosporin Resistance ◽  
One Year ◽  
Clinical Conditions ◽  
Hybrid Assemblies ◽  
Chromosomal Mutations ◽  
The Impact

Infections caused by ceftolozane/tazobactam and ceftazidime/avibactam-resistant P. aeruginosa infections are an emerging concern. We aimed to analyze the underlying ceftolozane/tazobactam and ceftazidime/avibactam resistance mechanisms in all MDR/XDR P. aeruginosa isolates recovered during one year (2020) from patients with a documented P. aeruginosa infection. Fifteen isolates showing ceftolozane/tazobactam and ceftazidime/avibactam resistance were evaluated. Clinical conditions, previous positive cultures and β-lactams received in the previous month were reviewed for each patient. MICs were determined by broth microdilution. MLSTs and resistance mechanisms were determined using short- and long-read WGS. The impact of PDCs on β-lactam resistance was demonstrated by cloning into an ampC -deficient PAO1 derivative (PAOΔC) and construction of 3D models. Genetic support of acquired β-lactamases was determined in silico from high-quality hybrid assemblies. In most cases, the isolates were recovered after treatment with ceftolozane/tazobactam or ceftazidime/avibactam. Seven isolates from different STs owed their β-lactam resistance to chromosomal mutations and all displayed specific substitutions in PDC: Phe121Leu and Gly222Ser, Pro154Leu, Ala201Thr, Gly214Arg, ΔGly203-Glu219 and Glu219Lys. In the other eight isolates, the ST175 clone was overrepresented (6 isolates) and associated with IMP-28 and IMP-13, whereas two ST1284 isolates produced VIM-2. The cloned PDCs conferred enhanced cephalosporin resistance. 3D PDC models revealed rearrangements affecting residues involved in cephalosporin hydrolysis. Carbapenemases were chromosomal (VIM-2) or plasmid-borne (IMP-28, IMP-13), and associated with class-1 integrons located in Tn402-like transposition modules. Our findings highlight that cephalosporin/ß-lactamase inhibitors are potential selectors of MDR/XDR P. aeruginosa strains producing PDC variants or metallo-ß-lactamases. Judicious use of these agents is encouraged.

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