scholarly journals  Molecular mechanisms of ceftazidime resistance in Pseudomonas aeruginosa isolates from canine and human infections

2010 ◽  
Vol 55 (No. 4) ◽  
pp. 172-182 ◽  
Author(s):  
S-J Du ◽  
H-C Kuo ◽  
C-H Cheng ◽  
ACY Fei ◽  
H-W Wei ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Antimicrobial Agents ◽  
Bloodstream Infections ◽  
Beta Lactamase ◽  
Efflux System ◽  
Human Patient ◽  
Minimal Inhibitory Concentrations ◽  
Class A ◽  
Efflux Inhibition ◽  
Human Infections

Sixty-six clinical P. aeruginosa isolates, 17 obtained from canine otitis specimens and 49 received from human patients with bloodstream infections, were collected between February 2007 and January 2008. The minimal inhibitory concentrations (MICs) of the antimicrobial agents of these isolates were determined. Multidrug resistance was common, with 23 (34.8%) isolates found to be ceftazidime resistant. To explore the mechanisms of ceftazidime resistance, PCR analyses were performed to detect drug-resistance genes. The prevalence rate of Ambler class A, B, and D &beta;-lactamase genes were obtained, with bla<sub>TEM-1</sub> 100%, bla<sub>PSE-1</sub> 100%, bla<sub>OXA-2</sub> 96.2%, bla<sub>SHV-18</sub> 91.3%, bla<sub>OXA-17</sub> 78.3%, bla<sub>VIM-3</sub> 26.1%, bla<sub>OXA-10</sub> 21.7% and bla<sub>SHV-1</sub> 8.7%. An efflux inhibition assay with the PA&beta;N compound was conducted. The ceftazidime resistance isolates were also tested by RT-qPCR to determine the mRNA expression levels of the oprM and ampC genes. Five (21.7%) of the ceftazidime resistance isolates appeared to overactivate the OprM efflux system. The ampD, ampE, and ampR genes and the ampC-ampR intergenic region were subsequently amplified and sequenced. Five (21.7%) of the ceftazidime resistance isolates from humans and canines had a point mutation in AmpR (Asp135-Asn, n = 3; Als194-Ser, n = 2), which induces AmpC overproduction from 10- to 80-fold. This study first reported ceftazidime resistance in P. aeruginosa from canine otitis specimens, which are closely related to ESBLs (50%), including the overproduction of AmpC (25%) and the OprM efflux system (25%). The ESBLs (100%) played an important role in all ceftazidime resistance isolates from humans, and either AmpC (21.1%) or OprM (21.1%) might be overexpressed within the same isolate. A human patient isolate (H307B) showed simultaneous expression of ESBLs, the OprM efflux system, and AmpC overproduction.

scholarly journals Prevalence of beta-lactam drug-resistance genes in commensal Escherichia coli contaminating ready-to-eat lettuce

2019 ◽  
Author(s):  
Ningbo Liao ◽  
Julia Rubin ◽  
Yuan Hu ◽  
Hector A. Ramirez ◽  
Clarissa Araújo Borges ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Drug Resistance ◽  
Resistance Genes ◽  
Beta Lactamase ◽  
Beta Lactam ◽  
E Coli ◽  
Class A ◽  
Distinct Sequence ◽  
Human Infections ◽  
Sequence Types

ABSTRACTThe objective of this study was to evaluate the prevalence of antibiotic resistance and beta-lactam drug resistance genes in Escherichia coli isolated from ready-to-eat lettuce, obtained from local supermarkets in Northern California. Bags of lettuce were purchased from 4 chain supermarkets during three different periods—Oct 2018–Jan 2019, Feb 2019–Apr 2019 and May 2019–July 2019. From 91 packages of lettuce, we recovered 34 E. coli isolates from 22 (24%) lettuce samples. All E. coli isolates were genotyped by multilocus sequence typing (MLST), and we found 15 distinct sequence types (STs). Five of these genotypes (ST2819, ST4600, ST2432, ST1198 and ST5143) have been reported to cause infection in humans. Twenty (59%) E. coli isolates were found resistant to at least one of the antibacterial drugs. They included resistance to ampicillin (AMP, 85%) and ampicillin/sulbactam (SAM, 50%), cefoxitin (FOX, 40%) and cefuroxime (CXM, 35%). We found 8 (40%) of 20 beta-lactam resistant E. coli isolates to carry blaCTX-M; 5 (25%) tested positive for blaSHV, while only 4 (20%) tested positive for blaTEM. Additionally, we identified a class A broad-spectrum beta-lactamase SED-1 gene, blaSED, reported by others in Citrobacter sedlakii isolated from bile of a patient. This study found that a large proportion of fresh lettuce carry beta-lactam drug-resistant E. coli, which could serve as a reservoir for drug resistance genes that could potentially enter pathogens to cause human infections.

scholarly journals Early Treatment Outcomes for Bloodstream Infections Caused by Potential AmpC Beta-lactamase-producing Enterobacterales with Focus on Piperacillin/Tazobactam: A Retrospective Cohort Study

Antibiotics ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 665
Author(s):  
Lena Herrmann ◽  
Aurelia Kimmig ◽  
Jürgen Rödel ◽  
Stefan Hagel ◽  
Norman Rose ◽  
...  
Keyword(s):  
Cohort Study ◽  
Treatment Outcomes ◽  
Treatment Response ◽  
Sofa Score ◽  
Early Treatment ◽  
Primary Outcome ◽  
Bloodstream Infections ◽  
Beta Lactamase ◽  
Early Treatment Response

The Gram-negative bacilli Serratia spp., Providencia spp., Morganella morganii, Citrobacter freundii complex, Enterobacter spp. and Klebsiella aerogenes are common Enterobacterales that may harbor inducible chromosomal AmpC beta-lactamase genes. The purpose of the present study was to evaluate treatment outcomes and identify predictors of early treatment response in patients with bloodstream infection caused by potential AmpC beta-lactamase-producing Enterobacterales (SPICE-BSI). This cohort study included adult patients with SPICE-BSI hospitalized between 01/2011 and 02/2019. The primary outcome was early treatment response 72 h after the start of active treatment, defined as survival, hemodynamic stability, improved or stable SOFA score, resolution of fever and leukocytosis and microbiologic resolution. Among 295 included patients, the most common focus was the lower respiratory tract (27.8%), and Enterobacter spp. (n = 155) was the main pathogen. The early treatment response rate was significantly lower (p = 0.006) in the piperacillin/tazobactam group (17/81 patients, 21.0%) than in the carbapenem group (40/82 patients, 48.8%). Independent negative predictors of early treatment response (p < 0.02) included initial SOFA score, liver comorbidity and empiric piperacillin/tazobactam treatment. In vitro piperacillin/tazobactam resistance was detected in three patients with relapsed Enterobacter-BSI and initial treatment with piperacillin/tazobactam. In conclusion, our findings show that piperacillin/tazobactam might be associated with early treatment failure in patients with SPICE-BSI.

scholarly journals LRG1 Promotes Metastatic Dissemination of Melanoma through Regulating EGFR/STAT3 Signalling

Cancers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 3279
Author(s):  
Yuet Ping Kwan ◽  
Melissa Hui Yen Teo ◽  
Jonathan Chee Woei Lim ◽  
Michelle Siying Tan ◽  
Graciella Rosellinny ◽  
...  
Keyword(s):  
Metastatic Melanoma ◽  
Melanoma Cell ◽  
Molecular Mechanisms ◽  
Complex Disease ◽  
Treatment Options ◽  
Melanoma Metastasis ◽  
Dependent Manner ◽  
Promoting Effect ◽  
Human Patient ◽  
Cell Invasiveness

Although less common, melanoma is the deadliest form of skin cancer largely due to its highly metastatic nature. Currently, there are limited treatment options for metastatic melanoma and many of them could cause serious side effects. A better understanding of the molecular mechanisms underlying the complex disease pathophysiology of metastatic melanoma may lead to the identification of novel therapeutic targets and facilitate the development of targeted therapeutics. In this study, we investigated the role of leucine-rich α-2-glycoprotein 1 (LRG1) in melanoma development and progression. We first established the association between LRG1 and melanoma in both human patient biopsies and mouse melanoma cell lines and revealed a significant induction of LRG1 expression in metastatic melanoma cells. We then showed no change in tumour cell growth, proliferation, and angiogenesis in the absence of the host Lrg1. On the other hand, there was reduced melanoma cell metastasis to the lungs in Lrg1-deficient mice. This observation was supported by the promoting effect of LRG1 in melanoma cell migration, invasion, and adhesion. Mechanistically, LRG1 mediates melanoma cell invasiveness in an EGFR/STAT3-dependent manner. Taken together, our studies provided compelling evidence that LRG1 is required for melanoma metastasis but not growth. Targeting LRG1 may offer an alternative strategy to control malignant melanoma.

scholarly journals Phenotypic and Genotypic Properties of Fluoroquinolone-Resistant, qnr-Carrying Escherichia coli Isolated from the German Food Chain in 2017

2021 ◽  
Vol 9 (6) ◽  
pp. 1308
Author(s):  
Katharina Juraschek ◽  
Carlus Deneke ◽  
Silvia Schmoger ◽  
Mirjam Grobbel ◽  
Burkhard Malorny ◽  
...  
Keyword(s):  
Antimicrobial Agents ◽  
Point Mutations ◽  
Beta Lactamase ◽  
Resistance Development ◽  
Extended Spectrum Beta Lactamase ◽  
E Coli ◽  
German Food ◽  
Sequence Types ◽  
Ammonium Compounds ◽  
Additional Point

Fluoroquinolones are the highest priority, critically important antimicrobial agents. Resistance development can occur via different mechanisms, with plasmid-mediated quinolone resistance (PMQR) being prevalent in the livestock and food area. Especially, qnr genes, commonly located on mobile genetic elements, are major drivers for the spread of resistance determinants against fluoroquinolones. We investigated the prevalence and characteristics of qnr-positive Escherichia (E.) coli obtained from different monitoring programs in Germany in 2017. Furthermore, we aimed to evaluate commonalities of qnr-carrying plasmids in E. coli. We found qnr to be broadly spread over different livestock and food matrices, and to be present in various sequence types. The qnr-positive isolates were predominantly detected within selectively isolated ESBL (extended spectrum beta-lactamase)-producing E. coli, leading to a frequent association with other resistance genes, especially cephalosporin determinants. Furthermore, we found that qnr correlates with the presence of genes involved in resistance development against quaternary ammonium compounds (qac). The detection of additional point mutations in many isolates within the chromosomal QRDR region led to even higher MIC values against fluoroquinolones for the investigated E. coli. All of these attributes should be carefully taken into account in the risk assessment of qnr-carrying E. coli from livestock and food.

scholarly journals Multidrug Antimicrobial Resistance and Molecular Detection of mcr-1 Gene in Salmonella Species Isolated from Chicken

Animals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 206
Author(s):  
Md Bashir Uddin ◽  
S.M. Bayejed Hossain ◽  
Mahmudul Hasan ◽  
Mohammad Nurul Alam ◽  
Mita Debnath ◽  
...  
Keyword(s):  
Functional Analysis ◽  
Antimicrobial Resistance ◽  
In Silico ◽  
Salmonella Enterica ◽  
Molecular Mechanisms ◽  
Antimicrobial Agents ◽  
Genetic Relationships ◽  
Evolutionary Relationship ◽  
Salmonella Spp ◽  
Gram Negative

Colistin (polymyxin E) is widely used in animal and human medicine and is increasingly used as one of the last-resort antibiotics against Gram-negative bacilli. Due to the increased use of colistin in treating infections caused by multidrug-resistant Gram-negative bacteria, resistance to this antibiotic ought to be monitored. The study was undertaken to elucidate the molecular mechanisms, genetic relationships and phenotype correlations of colistin-resistant isolates. Here, we report the detection of the mcr-1 gene in chicken-associated Salmonella isolates in Bangladesh and its in-silico functional analysis. Out of 100 samples, 82 Salmonella spp. were isolated from chicken specimens (liver, intestine). Phenotypic disc diffusion and minimum inhibitory concentration (MIC) assay using different antimicrobial agents were performed. Salmonella isolates were characterized using PCR methods targeting genus-specific invA and mcr-1 genes with validation for the functional analysis. The majority of the tested Salmonella isolates were found resistant to colistin (92.68%), ciprofloxacin (73.17%), tigecycline (62.20%) and trimethoprim/sulfamethoxazole (60.98%). When screened using PCR, five out of ten Salmonella isolates were found to carry the mcr-1 gene. One isolate was confirmed for Salmonella enterica subsp. enterica serovar Enteritidis, and other four isolates were confirmed for Salmonella enterica subsp. enterica serovar Typhimurium. Sequencing and phylogenetic analysis revealed a divergent evolutionary relationship between the catalytic domain of Neisseria meningitidis lipooligosaccharide phosphoethanolamine transferase A (LptA) and MCR proteins, rendering them resistant to colistin. Three-dimensional homology structural analysis of MCR-1 proteins and molecular docking interactions suggested that MCR-1 and LptA share a similar substrate binding cavity, which could be validated for the functional analysis. The comprehensive molecular and in-silico analyses of the colistin resistance mcr-1 gene of Salmonella spp. of chicken origin in the present study highlight the importance of continued monitoring and surveillance for antimicrobial resistance among pathogens in food chain animals.

scholarly journals Ragged N-termini and other variants of class A β-lactamases analysed by chromatofocusing

1991 ◽  
Vol 273 (3) ◽  
pp. 503-510 ◽  
Author(s):  
A Matagne ◽  
B Joris ◽  
J Van Beeumen ◽  
J M Frère
Keyword(s):  
Experimental Error ◽  
Catalytic Properties ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Beta Lactamase ◽  
Beta Lactamases ◽  
Gram Positive Bacteria ◽  
Class A ◽  
Partial Inactivation ◽  
Asparagine Residue

Four beta-lactamases excreted by Gram-positive bacteria exhibited microheterogeneity when analysed by chromatofocusing or ion-exchange chromatography. Ragged N-termini were in part responsible for the charge variants, but deamidation of an asparagine residue was also involved, at least for the Bacillus licheniformis enzyme. The activity of a contaminating proteinase could also be demonstrated in the case of Actinomadura R39 beta-lactamase. With that enzyme, proteolysis resulted in partial inactivation, but the inactivated fragments were easily separated from the active forms. With these, as with the other enzymes, the kinetic parameters of the major variants were identical with those of the mixture within the limits of experimental error, so that the catalytic properties of these enzymes can be determined with the ‘heterogeneous’ preparations.

scholarly journals Activity of Debio1452, a FabI Inhibitor with Potent Activity against Staphylococcus aureus and Coagulase-Negative Staphylococcus spp., Including Multidrug-Resistant Strains

2015 ◽  
Vol 59 (5) ◽  
pp. 2583-2587 ◽  
Author(s):  
Robert K. Flamm ◽  
Paul R. Rhomberg ◽  
Nachum Kaplan ◽  
Ronald N. Jones ◽  
David J. Farrell
Keyword(s):  
Staphylococcus Aureus ◽  
Antimicrobial Agents ◽  
Fatty Acid Biosynthesis ◽  
Multidrug Resistant ◽  
Coagulase Negative Staphylococcus ◽  
Significant Activity ◽  
Coagulase Negative Staphylococci ◽  
Content Type ◽  
Mrsa Strains ◽  
Human Infections

ABSTRACTStaphylococcus aureusand coagulase-negative staphylococci (CoNS) are responsible for a wide variety of human infections. The investigational antibacterial Debio1450 (previously AFN-1720), a prodrug of Debio1452 (previously AFN-1252), specifically targets staphylococci without significant activity against other Gram-positive or Gram-negative species. Debio1452 inhibits FabI, an enzyme critical to fatty acid biosynthesis in staphylococci. The activity of Debio1452 against CoNS, methicillin-susceptibleS. aureus(MSSA), and methicillin-resistantS. aureus(MRSA), including significant clones, was determined. A globally diverse collection of 574 patient isolates from 35 countries was tested that included CoNS (6 species, 103 strains), MSSA (154 strains), MRSA (163 strains), and molecularly characterized strains (includingspa-typed MRSA clones; 154 strains). The isolates were tested for susceptibility by CLSI broth microdilution methods against Debio1452 and 10 comparators. The susceptibility rates for the comparators were determined using CLSI and EUCAST breakpoint criteria. AllS. aureusand CoNS strains were inhibited by Debio1452 concentrations of ≤0.12 and ≤0.5 μg/ml, respectively. The MIC50s for MSSA, MRSA, and molecularly characterized MRSA strains were 0.004 μg/ml, and the MIC90s ranged from 0.008 to 0.03 μg/ml. The MICs were higher for the CoNS isolates (MIC50/90, 0.015/0.12 μg/ml). AmongS. aureusstrains, resistance was common for erythromycin (61.6%), levofloxacin (49.0%), clindamycin (27.6%), tetracycline (15.7%), and trimethoprim-sulfamethoxazole (7.0%). Debio1452 demonstrated potent activity against MSSA, MRSA, and CoNS. Debio1452 showed significantly greater activity overall (MIC50, 0.004 μg/ml) than the other agents tested against these staphylococcal species, which included dominant MRSA clones and strains resistant to currently utilized antimicrobial agents.

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