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https://www.readbyqxmd.com/read/28413506/active-efflux-pump-adeb-is-involved-in-multidrug-resistance-of-acinetobacter-baumannii-induced-by-antibacterial-agents
#1
Tingting Zhang, Min Wang, Yixin Xie, Xianping Li, Zhihui Dong, Yanhua Liu, Ling Wang, Min Yang, Huan Song, Hong Cao, Wei Cao
The aim of the present study was to investigate the resistance of Acinetobacter baumannii, which was induced by cefepime (FEP), cefoperazone-sulbactam (SCF), tazobactam (TZP), levofloxacin (LEV), amikacin (AK), imipenem (IPM), and ciprofloxacin (CIP), in vitro. Multi-step drug resistance selection of 16 A. baumannii strains was performed using seven antibacterial agents (FEP, TZP, CIP, AK, IPM, SCF, and LEV). The minimum inhibitory concentration (MIC) was determined using the agar dilution method. Random amplified polymorphic DNA polymerase chain reaction was performed to analyze the genotypes and the carrying rates of aac(3)-I, aac(6')-I, ant(3)-I, aph(3)-Via, OXA-23, OXA-24, AmpC, TEM-1, metallo-β-lactamase gene (IMP), armA, rmtA, rmtB, parC, gyrA and adeB...
April 2017: Experimental and Therapeutic Medicine
https://www.readbyqxmd.com/read/28412384/molecular-epidemiology-of-penicillinase-producing-neisseria-gonorrhoeae-isolates-in-france
#2
Maité Micaëlo, Agathe Goubard, Guy La Ruche, Erick Denamur, Olivier Tenaillon, Emmanuelle Cambau, Hervé Jacquier, Béatrice Bercot
OBJECTIVES: Characterising the molecular epidemiology of antibiotic resistance is crucial for a better understanding of the evolution and spread of resistance in Neisseria gonorrhoeae. Here, we examine the molecular epidemiology of penicillinase-producing N. gonorrhoeae (PPNG) isolates in France. METHODS: We investigated 176 PPNG isolates collected between 2010 and 2012 by the National Reference Centre in France. Genotyping was performed using the NG-MAST technique, blaTEM genes were Sanger-sequenced, and plasmids were characterized by PCR-typing...
April 13, 2017: Clinical Microbiology and Infection
https://www.readbyqxmd.com/read/28378066/genetic-background-of-%C3%AE-lactamases-in-enterobacteriaceae-isolates-from-environmental-samples
#3
Daniele V de Oliveira, Luciana S Nunes, Afonso Luís Barth, Sueli T Van Der Sand
The prevalence of β-lactamase-producing Enterobacteriaceae has increased worldwide. Although antibiotic-resistant bacteria are usually associated with hospitals, there are a growing number of reports of resistant bacteria in other environments. Concern about resistant microorganisms outside the hospital setting highlights the need to investigate mechanisms of antibiotic resistance in isolates collected from the environment. The present study evaluated the resistance mechanism to β-lactam antibiotics in 40 isolates from hospital sewage and surface water from the Dilúvio Stream, Porto Alegre City, Southern Brazil...
April 4, 2017: Microbial Ecology
https://www.readbyqxmd.com/read/28369441/a-combination-of-mecillinam-and-amoxicillin-clavulanate-can-restore-susceptibility-of-high-level-tem-1-producing-escherichia-coli-to-mecillinam
#4
André Birgy, Marine Delecourt, Guillaume Geslain, Emilie Desselas, Marion Caseris, Mélanie Magnan, Patricia Mariani-Kurkdjian, Philippe Bidet, Stéphane Bonacorsi
Objectives: Mecillinam is recommended in France as a first-line treatment for lower urinary tract infections, due to the large increase in resistance of Escherichia coli to other oral treatments, such as co-trimoxazole or fluoroquinolones, its limited impact on faecal microbiota and its stability in the presence of numerous β-lactamases. However, we recently identified several mecillinam-resistant E. coli isolates with a high-level expression penicillinase (HEP) phenotype that merit further study...
March 27, 2017: Journal of Antimicrobial Chemotherapy
https://www.readbyqxmd.com/read/28368864/characterization-of-esbl-producing-escherichia-coli-recovered-from-companion-dogs-in-tai-an-china
#5
Song Li, Junhe Liu, Yufa Zhou, Zengmin Miao
INTRODUCTION: Animals are considered to be reservoirs of extended-spectrum beta-lactamase (ESBL)-producing bacteria, but few epidemiological data on ESBL-producing Escherichia coli urinary tract isolates in pet dogs are available in China. METHODOLOGY: This study was conducted to describe the prevalence and characterization of ESBL producers among E. coli urinary tract isolates from pet dogs in Tai'an, China. RESULTS: A total of 118 E. coli were obtained from urinary samples of 80 companion dogs suffering from acute or chronic cystitis, of which three isolates from different dogs were ESBL producers...
March 31, 2017: Journal of Infection in Developing Countries
https://www.readbyqxmd.com/read/28334649/binding-of-tem-1-beta-lactamase-to-beta-lactam-antibiotics-by-frontal-affinity-chromatography
#6
Xiu Chen, Yuhua Li, Yan Zhang, Jianting Yang, Liujiao Bian
TEM-1 beta-lactamases can accurately catalyze the hydrolysis of the beta-lactam rings in beta-lactam antibiotics, which make beta-lactam antibiotics lose its activity, and the prerequisite for the hydrolysis procedure in the binding interaction of TEM-1 beta-lactamases with beta-lactam antibiotics is the beta-lactam rings in beta-lactam antibiotics. Therefore, the binding of TEM-1 beta-lactamase to three beta-lactam antibiotics including penicillin G, cefalexin as well as cefoxitin was explored here by frontal affinity chromatography in combination with fluorescence spectra, adsorption and thermodynamic data in the temperature range of 278-288K under simulated physiological conditions...
April 15, 2017: Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences
https://www.readbyqxmd.com/read/28293886/creation-of-antigen-dependent-%C3%AE-lactamase-fusion-protein-tethered-by-circularly-permuted-antibody-variable-domains
#7
Hiroto Iwai, Miki Kojima-Misaizu, Jinhua Dong, Hiroshi Ueda
Antibody-based molecular switches that are able to recognize a range of exogenous antigens can be highly useful as a versatile biosensor. However, regulating the catalytic activity of enzymes by antibodies is still hard to achieve. Here, we describe a design method of unique antibody variable region Fv introduced with two circular permutations, called Clampbody. By tethering the Clampbody to a circularly permuted TEM-1 β-lactamase (BLA), we successfully constructed a genetically encoded molecular switch Cbody-cpBLA that shows antigen-dependent catalytic activity...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28281425/antibiotic-resistance-patterns-and-beta-lactamase-identification-in-escherichia-coli-isolated-from-young-children-in-rural-limpopo-province-south-africa-the-mal-ed-cohort
#8
A S DeFrancesco, N F Tanih, A Samie, R L Guerrant, P O Bessong
BACKGROUND: Antibiotic resistance is a growing problem worldwide. Mechanisms of resistance vary, and some can confer resistance to multiple classes of antibiotics. OBJECTIVE: To characterise the antibiotic resistance profiles of Escherichia coli isolates obtained from stool samples of young rural children exposed or unexposed to antibiotics. METHODOLOGY: The samples were collected from children aged 4 - 12 months who were participants in the Etiology, Risk Factors, and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health and Development (MAL-ED) project at the South Africa research site...
February 27, 2017: South African Medical Journal, Suid-Afrikaanse Tydskrif Vir Geneeskunde
https://www.readbyqxmd.com/read/28264855/structural-alteration-of-ompr-as-a-source-of-ertapenem-resistance-in-a-ctx-m-15-producing-escherichia-coli-o25b-h4-st131-clinical-isolate
#9
Hervé Dupont, Pascaline Choinier, David Roche, Sandine Adiba, Megan Sookdeb, Catherine Branger, Erick Denamur, Hedi Mammeri
In this study, an ertapenem-non-susceptible Escherichia coli isolate was investigated to determine the genetic basis for its carbapenem resistance phenotype. This clinical strain was recovered from a patient that received, one year ago, ertapenem to treat a cholangitis due to a carbapenem-susceptible extended-spectrum β-lactamase (ESBL)-producing E. coli isolate. Whole-genome sequencing of these strains was performed using Illumina and single molecule real-time sequencing technologies. It revealed that they belonged to the ST131 clonal group, had the predicted O25b:H4 serotype, and produced the CTX-M-15 and TEM-1 β-lactamases...
March 6, 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28264645/systematic-substitutions-at-blip-position-50-result-in-changes-in-binding-specificity-for-class-a-%C3%AE-lactamases
#10
Carolyn J Adamski, Timothy Palzkill
BACKGROUND: The production of β-lactamases by bacteria is the most common mechanism of resistance to the widely prescribed β-lactam antibiotics. β-lactamase inhibitory protein (BLIP) competitively inhibits class A β-lactamases via two binding loops that occlude the active site. It has been shown that BLIP Tyr50 is a specificity determinant in that substitutions at this position result in large differential changes in the relative affinity of BLIP for class A β-lactamases. RESULTS: In this study, the effect of systematic substitutions at BLIP position 50 on binding to class A β-lactamases was examined to further explore the role of BLIP Tyr50 in modulating specificity...
March 6, 2017: BMC Biochemistry
https://www.readbyqxmd.com/read/28249582/characteristics-of-extended-spectrum-%C3%AE-lactamase-producing-escherichia-coli-isolated-from-fecal-samples-of-piglets-with-diarrhea-in-central-and-southern-taiwan-in-2015
#11
Wan-Chen Lee, Kuang-Sheng Yeh
BACKGROUND: The production of extended-spectrum β-lactamases (ESBLs) confer resistance to the commonly used beta-lactam antimicrobials and ESBL-producing bacteria render treatment difficulty in human and veterinary medicine. ESBL-producing bacteria have emerged in livestock in recent years, which may raise concerns regarding possible transfer of such bacteria through the food chain. The swine industry is important in Taiwan, but investigations regarding the status of ESBL in swine are limited...
March 1, 2017: BMC Veterinary Research
https://www.readbyqxmd.com/read/28196882/trade-offs-between-enzyme-fitness-and-solubility-illuminated-by-deep-mutational-scanning
#12
Justin R Klesmith, John-Paul Bacik, Emily E Wrenbeck, Ryszard Michalczyk, Timothy A Whitehead
Proteins are marginally stable, and an understanding of the sequence determinants for improved protein solubility is highly desired. For enzymes, it is well known that many mutations that increase protein solubility decrease catalytic activity. These competing effects frustrate efforts to design and engineer stable, active enzymes without laborious high-throughput activity screens. To address the trade-off between enzyme solubility and activity, we performed deep mutational scanning using two different screens/selections that purport to gauge protein solubility for two full-length enzymes...
February 28, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28182405/blip-ii-employs-differential-hotspot-residues-to-bind-structurally-similar-staphylococcus-aureus-pbp2a-and-class-a-%C3%AE-lactamases
#13
Carolyn J Adamski, Timothy Palzkill
The interaction of β-lactamase inhibitory protein II (BLIP-II) with β-lactamases serves as a model system to investigate the principles underlying protein-protein interactions. Previous studies have focused on identifying the determinants of binding affinity and specificity between BLIP-II and class A β-lactamases. However, interactions between BLIP-II and other bacterial proteins have yet to be explored. Here, we provide evidence that BLIP-II binds penicillin binding protein 2a (PBP2a) from methicillin-resistant Staphylococcus aureus (MRSA) with a KD in the low micromolar range...
February 16, 2017: Biochemistry
https://www.readbyqxmd.com/read/28182026/prevalence-of-tem-shv-and-ctx-m-beta-lactamase-genes-in-the-urinary-isolates-of-a-tertiary-care-hospital
#14
Trupti Bajpai, M Pandey, M Varma, G S Bhatambare
INTRODUCTION: Extended-spectrum beta-lactamases (ESBLs) are the major cause of resistance to beta-lactam antibiotics such as penicillins, cephalosporins, and monobactams. They are derived from the narrow-spectrum beta-lactamases (TEM-1, TEM-2, or SHV-1) by mutations that alter the amino acid configuration around the enzyme active site. AIM: To determine the prevalence of ESBL (blaTEM, blaCTX-M, and blaSHV) genes among the members of Enterobacteriaceae. METHODOLOGY: The present prospective study was carried out from January 2015 to June 2015 in the Department of Microbiology and Molecular Medicine of a Teaching Tertiary Care Hospital...
January 2017: Avicenna Journal of Medicine
https://www.readbyqxmd.com/read/28145856/class-i-integron-and-%C3%AE-lactamase-encoding-genes-of-multidrug-resistance-salmonella-isolated-from-pigeons-and-their-environments
#15
S Yousef, R Mamdouh
Seroprevalence of Salmonella spp. was investigated in pigeon and its surrounding environment of Sharkia province, Egypt. Samples were randomly collected from fifty freshly dead squabs, forty freshly dead adults pigeons, sixty diseased adult pigeons and 100 apparently healthy adult pigeons. Bacterial isolates were tested for their susceptibility to 17 different antimicrobial discs, by using the disc diffusion method. The bacterial isolates were tested for Class I and β-lactamase encoding genes by using PCR...
December 30, 2016: Cellular and Molecular Biology
https://www.readbyqxmd.com/read/28105330/genetic-markers-associated-with-resistance-to-beta-lactam-and-quinolone-antimicrobials-in-non-typhoidal-salmonella-isolates-from-humans-and-animals-in-central-ethiopia
#16
Tadesse Eguale, Josephine Birungi, Daniel Asrat, Moses N Njahira, Joyce Njuguna, Wondwossen A Gebreyes, John S Gunn, Appolinaire Djikeng, Ephrem Engidawork
BACKGROUND: Beta-lactam and quinolone antimicrobials are commonly used for treatment of infections caused by non-typhoidal Salmonella (NTS) and other pathogens. Resistance to these classes of antimicrobials has increased significantly in the recent years. However, little is known on the genetic basis of resistance to these drugs in Salmonella isolates from Ethiopia. METHODS: Salmonella isolates with reduced susceptibility to beta-lactams (n = 43) were tested for genes encoding for beta-lactamase enzymes, and those resistant to quinolones (n = 29) for mutations in the quinolone resistance determining region (QRDR) as well as plasmid mediated quinolone resistance (PMQR) genes using PCR and sequencing...
2017: Antimicrobial Resistance and Infection Control
https://www.readbyqxmd.com/read/28087769/enzyme-efficiency-but-not-thermostability-drives-cefotaxime-resistance-evolution-in-tem-1-%C3%AE-lactamase
#17
Jennifer L Knies, Fei Cai, Daniel M Weinreich
A leading intellectual challenge in evolutionary genetics is to identify the specific phenotypes that drive adaptation. Enzymes offer a particularly promising opportunity to pursue this question, because many enzymes' contributions to organismal fitness depend on a comparatively small number of experimentally accessible properties. Moreover, on first principles the demands of enzyme thermostability stand in opposition to the demands of catalytic activity. This observation, coupled with the fact that enzymes are only marginally thermostable, motivates the widely held hypothesis that mutations conferring functional improvement require compensatory mutations to restore thermostability...
May 1, 2017: Molecular Biology and Evolution
https://www.readbyqxmd.com/read/28039104/rectal-carriage-of-extended-spectrum-%C3%AE-lactamase-and-carbapenemase-producing-enterobacteriaceae-among-hospitalised-neonates-in-a-neonatal-intensive-care-unit-in-fez-morocco
#18
Btissam Arhoune, Bouchra Oumokhtar, Fouzia Hmami, Abouddihaj Barguigua, Mohammed Timinouni, Samira El Fakir, Fouzia Chami, Abdelhak Bouharrou
OBJECTIVES: The aim of this study was to investigate the faecal carriage and molecular epidemiology of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae (ESBLE) isolated from rectal samples of neonates hospitalised in a neonatal intensive care unit (NICU) of a university hospital in Fez, Morocco. METHODS: From February-July 2013, all neonates hospitalised in the NICU were screened for ESBLE carriage at discharge. ESBLs were identified by double-disk synergy test, PCR and DNA sequencing analysis...
December 27, 2016: Journal of Global Antimicrobial Resistance
https://www.readbyqxmd.com/read/28005382/unexpected-huge-dimerization-ratio-in-one-dimensional-carbon-atomic-chains
#19
Yung-Chang Lin, Shigeyuki Morishita, Masanori Koshino, Chao-Hui Yeh, Po-Yuan Teng, Po-Wen Chiu, Hidetaka Sawada, Kazutomo Suenaga
Peierls theory predicted atomic distortion in one-dimensional (1D) crystal due to its intrinsic instability in 1930. Free-standing carbon atomic chains created in situ in transmission electron microscope (TEM)1-3 are an ideal example to experimentally observe the dimerization behavior of carbon atomic chain within a finite length. We report here a surprisingly huge distortion found in the free-standing carbon atomic chains at 773 K, which is 10 times larger than the value expected in the system. Such an abnormally distorted phase only dominates at the elevated temperatures, while two distinct phases, distorted and undistorted, coexist at lower or ambient temperatures...
December 27, 2016: Nano Letters
https://www.readbyqxmd.com/read/27988068/in-vivo-pharmacodynamics-of-piperacillin-tazobactam-implications-for-antimicrobial-efficacy-and-resistance-suppression-with-innovator-and-generic-products
#20
COMPARATIVE STUDY
Carlos A Rodriguez, Maria Agudelo, Andres F Zuluaga, Omar Vesga
Recent studies have shown that the pharmacodynamic (PD) index driving the efficacy of β-lactam/β-lactamase inhibitor combinations such as ceftazidime/avibactam and ceftolozane/tazobactam is the percentage of time the free inhibitor concentration is above a threshold (fT>threshold). However, data with piperacillin/tazobactam (TZP) are scarce. Here we aimed to assess the relationship between fT>threshold and TZP antibacterial efficacy by a population pharmacokinetic study in mice and dose-effect experiments in a neutropenic murine thigh infection model with two isogenic strains of Escherichia coli differentially expressing TEM-1 β-lactamase...
February 2017: International Journal of Antimicrobial Agents
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