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https://www.readbyqxmd.com/read/28293886/creation-of-antigen-dependent-%C3%AE-lactamase-fusion-protein-tethered-by-circularly-permuted-antibody-variable-domains
#1
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
#2
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
#3
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
#4
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
#5
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
#6
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
#7
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
#8
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
#9
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
#10
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
#11
Jennifer 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...
January 12, 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
#12
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
#13
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
#14
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
https://www.readbyqxmd.com/read/27984780/high-rates-of-ctx-m-15-producing-escherichia-coli-and-klebsiella-pneumoniae-in-wild-boars-and-barbary-macaques-in-algeria
#15
Taous Bachiri, Sofiane Bakour, Rabia Ladjouzi, Leangapichart Thongpan, Jean Marc Rolain, Abdelaziz Touati
OBJECTIVES: The present study aimed to screen for the presence of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae in wild boars and Barbary macaques in Béjaïa and Jijel, Algeria. METHODS: A total of 216 faecal samples collected between September 2014 and August 2015 were cultured on MacConkey agar supplemented with 1μg/mL ceftazidime. Isolates were identified by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF/MS)...
December 10, 2016: Journal of Global Antimicrobial Resistance
https://www.readbyqxmd.com/read/27956418/chromosome-encoded-broad-spectrum-ambler-class-a-%C3%AE-lactamase-rub-1-from-serratia-rubidaea
#16
Rémy A Bonnin, Jennifer Didi, Ayla Ergani, Sandra Lima, Thierry Naas
Whole-genome sequencing of Serratia rubidaea CIP 103234(T) revealed a chromosomally located Ambler class A β-lactamase gene. The gene was cloned, and the β-lactamase, RUB-1, was characterized. RUB-1 displayed 74% and 73% amino acid sequence identity with the GIL-1 and TEM-1 penicillinases, respectively, and its substrate profile was similar to that of the latter β-lactamases. Analysis by 5' rapid amplification of cDNA ends revealed promoter sequences highly divergent from the Escherichia coli σ(70) consensus sequence...
February 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/27809768/comparison-of-antibiotic-resistant-escherichia-coli-obtained-from-drinking-water-sources-in-northern-tanzania-a-cross-sectional-study
#17
Beatus Lyimo, Joram Buza, Murugan Subbiah, Woutrina Smith, Douglas R Call
BACKGROUND: Antimicrobial resistance (AMR) is a growing and significant threat to public health on a global scale. Escherichia coli comprises Gram-negative, fecal-borne pathogenic and commensal bacteria that are frequently associated with antibiotic resistance. AMR E. coli can be ingested via food, water and direct contact with fecal contamination. METHODS: We estimated the prevalence of AMR Escherichia coli from select drinking water sources in northern Tanzania...
November 3, 2016: BMC Microbiology
https://www.readbyqxmd.com/read/27795467/bloodstream-infection-due-to-ctx-m-15-and-tem-1-extended-spectrum-%C3%AE-lactamase-producing-salmonella-enterica-serovar-virchow-st16
#18
Jeong-Hwan Hwang, Gee-Wook Shin, Joo-Hee Hwang, Chang-Seop Lee
A 57-year-old man presented with a high fever and diarrhea. A blood culture showed the presence of a Group C nontyphoidal Salmonella isolate. On Salmonella serotyping, the isolate was Salmonella enterica serovar Virchow. Its sequence type was determined to be ST16 by sequence analysis of seven different housekeeping genes. The blaCTX-M group 1 and blaTEM genes were amplified by multiplex PCR assays for detecting ESBL genes. Sequences of both amplicons were respectively identical to CTX-M-15- and TEM-1-encoding genes...
October 31, 2016: Japanese Journal of Infectious Diseases
https://www.readbyqxmd.com/read/27756125/engineering-specificity-from-broad-to-narrow-design-of-a-%C3%AE-lactamase-inhibitory-protein-blip-variant-that-exclusively-binds-and-detects-kpc-%C3%AE-lactamase
#19
Dar-Chone Chow, Kacie Rice, Wanzhi Huang, Robert L Atmar, Timothy Palzkill
The β-lactamase inhibitory protein (BLIP) binds and inhibits a wide range of class A β-lactamases including the TEM-1 β-lactamase (Ki = 0.5 nM), which is widely present in Gram-negative bacteria, and the KPC-2 β-lactamase (Ki = 1.2 nM), which hydrolyzes virtually all clinically useful β-lactam antibiotics. The extent to which the specificity of a protein that binds a broad range of targets can be modified to display narrow specificity was explored in this study by engineering BLIP to bind selectively to KPC-2 β-lactamase...
December 9, 2016: ACS Infectious Diseases
https://www.readbyqxmd.com/read/27736780/the-type-iii-secretion-system-effector-seoc-of-salmonella-enterica-subsp-salamae-and-s-enterica-subsp-arizonae-adp-ribosylates-src-and-inhibits-opsonophagocytosis
#20
Dominic J Pollard, Joanna C Young, Valentina Covarelli, Silvia Herrera-León, Thomas R Connor, Maria Fookes, Danielle Walker, Aurora Echeita, Nicholas R Thomson, Cedric N Berger, Gad Frankel
Salmonella species utilize type III secretion systems (T3SSs) to translocate effectors into the cytosol of mammalian host cells, subverting cell signaling and facilitating the onset of gastroenteritis. In this study, we compared a draft genome assembly of Salmonella enterica subsp. salamae strain 3588/07 against the genomes of S. enterica subsp. enterica serovar Typhimurium strain LT2 and Salmonella bongori strain 12419. S. enterica subsp. salamae encodes the Salmonella pathogenicity island 1 (SPI-1), SPI-2, and the locus of enterocyte effacement (LEE) T3SSs...
December 2016: Infection and Immunity
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