scholarly journals Individual bacteria in structured environments rely on phenotypic resistance to phage

PLoS Biology ◽  
2021 ◽  
Vol 19 (10) ◽  
pp. e3001406
Author(s):  
Erin L. Attrill ◽  
Rory Claydon ◽  
Urszula Łapińska ◽  
Mario Recker ◽  
Sean Meaden ◽  
...  
Keyword(s):  
Genetic Resistance ◽  
Natural Environments ◽  
Bacterial Survival ◽  
Phenotypic Resistance ◽  
Bacterial Response ◽  
Modelling Framework ◽  
Planktonic Bacteria ◽  
Phage Dna ◽  
Phage Receptor

Bacteriophages represent an avenue to overcome the current antibiotic resistance crisis, but evolution of genetic resistance to phages remains a concern. In vitro, bacteria evolve genetic resistance, preventing phage adsorption or degrading phage DNA. In natural environments, evolved resistance is lower possibly because the spatial heterogeneity within biofilms, microcolonies, or wall populations favours phenotypic survival to lytic phages. However, it is also possible that the persistence of genetically sensitive bacteria is due to less efficient phage amplification in natural environments, the existence of refuges where bacteria can hide, and a reduced spread of resistant genotypes. Here, we monitor the interactions between individual planktonic bacteria in isolation in ephemeral refuges and bacteriophage by tracking the survival of individual cells. We find that in these transient spatial refuges, phenotypic resistance due to reduced expression of the phage receptor is a key determinant of bacterial survival. This survival strategy is in contrast with the emergence of genetic resistance in the absence of ephemeral refuges in well-mixed environments. Predictions generated via a mathematical modelling framework to track bacterial response to phages reveal that the presence of spatial refuges leads to fundamentally different population dynamics that should be considered in order to predict and manipulate the evolutionary and ecological dynamics of bacteria–phage interactions in naturally structured environments.

scholarly journals Diversity of Multidrug Efflux Genes and Phenotypic Evaluation of the In vitro Resistance Dynamics of Clinical Staphylococcus Aureus Isolates Using Methicillin; a Model β-lactam

2017 ◽  
Vol 11 (1) ◽  
pp. 132-141 ◽  
Author(s):  
John F. Antiabong ◽  
Marleen M. Kock ◽  
Nontombi M. Mbelle ◽  
Marthie M. Ehlers
Keyword(s):  
Staphylococcus Aureus ◽  
Treatment Options ◽  
Hospital Setting ◽  
Growth Dynamics ◽  
Distribution Patterns ◽  
Clinical Isolates ◽  
Resistance Pattern ◽  
Bacterial Survival ◽  
Phenotypic Resistance

Objectives:Methicillin-resistantStaphylococcus aureus(MRSA) across the world often leave clinicians with little or no choice of treatment options. The multi-drug efflux (MDE) genes are bacterial survival mechanisms responsible for the pumping out of antibiotics and other biocides from the cytoplasm. Whilst effort is being made in the development of antibiotic adjuvants such as efflux pumps inhibitors, information is needed on the diversity of these MDEs in the circulatingS. aureusand on the growth dynamics of the clinical isolates in response to antibiotics is not regularly examined.Methods:Here, we evaluated the diversity of MDEs in cinicalS. aureusrecovered in a tertiary academic hospital, Pretoria, South African hospital using PCR and also employed visual minimum inhibitory concentration and quantitative analysis of spectrophometric measurements of bacterial growth in the presence of a model β lactam antibiotic (methicillin), to phenotypically elucidate the resistance pattern of these isolates in response to methicillin.Results:Three major distribution patterns of MDEs were observed in the clinical isolates evaluated. Moreover,norA,norB andtet38 were present in 98.9% of the isolates while other MDE were present in different proportions ranging from 40 to 98.6% of the isolates. In addition,S. aureusisolates, be it of MRSA or MSSA genotype did not habour the same set of MDEs despite being recovered from the same hospital setting. Finally, we showed that MSSA displayed phenotypic resistance to methicilllin despite the non-detection of themecA resistance gene.Conclusions:Our data suggest that the growth ofS. aureusmay be enhanced by β lactams (methicillin) and that MSSA may also display resistance to methicillin and perhaps other β lactam antibiotics. The high prevalence of MDEs suggestive of resistance to a broad spectrum of biocides and fluoroquinolones are particularly disturbing.

scholarly journals ANTIBACTERIAL EFFICACY OF 6% GREEN TEA EXTRACT AND 2% CHLORHEXIDINE AGAINST ENTEROCOCCUS FAECALIS BIOFILM IN VITRO

2019 ◽  
pp. 64-66
Author(s):  
FITRI REFLAN ◽  
RATNA MEIDYAWATI ◽  
DARU INDRAWATI
Keyword(s):  
Enterococcus Faecalis ◽  
Green Tea ◽  
Brain Heart Infusion ◽  
Green Tea Extract ◽  
Bacterial Suspension ◽  
Antibacterial Efficacy ◽  
Bacterial Survival ◽  
Planktonic Bacteria ◽  
Tea Extract

Objective: This study aimed to compare the antibacterial efficacy of green tea extract to chlorhexidine 2% against Enterococcus faecalis biofilm usingreal-time polymerase chain reaction (RT-PCR).Methods: E. faecalis strain ATCC 29212 colonies were collected from overnight cultures grown on brain–heart infusion agar (BHIA) and resuspendedat 108 CFU/ml according to a 0.5 McFarland standard. Aliquots of bacterial suspension (50 μl) were then inoculated onto sterile nitrocellulose filterdiscs place on BHIA and incubated aerobically at 37°C for 72 h. After incubation, the discs were removed, transferred into 10-ml phosphate-bufferedsaline (PBS) to loosen planktonic bacteria, and then incubated for 10 min at 37°C in 10 ml of 6% green tea extract, 2% chlorhexidine, or sterile PBS(control). Surviving E. faecalis cells were then quantified by RT-PCR.Results: Green tea extract reduced bacterial survival compared to control but was not as effective as chlorhexidine 2%.Conclusion: Green tea extract may help reduce oral E. faecalis biofilm. Moreover, specific antimicrobial compounds in green tea extract such asepigallocatechin-3-gallate should be tested as non-toxic alternatives to chlorhexidine.

The In Vitro Antibiofilm Activity of Water Leaf Extract of Papaya (Carica papaya L.) against Pseudomonas aeruginosa

2017 ◽  
Vol 2 (3) ◽  
pp. 150-163
Author(s):  
Ekajayanti Kining ◽  
Syamsul Falah ◽  
Novik Nurhidayat
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Contact Time ◽  
Cell Attachment ◽  
Water Extract ◽  
Opportunistic Pathogen ◽  
Bacterial Biofilm ◽  
Antibiofilm Activity ◽  
Bacterial Survival ◽  
Optimum Conditions

Pseudomonas aeruginosa is one of opportunistic pathogen forming bacterial biofilm. The biofilm sustains the bacterial survival and infections. This study aimed to assess the activity of water extract of papaya leaves on inhibition of cells attachment, growth and degradation of the biofilm using crystal violet (CV) biofilm assay. Research results showed that water extract of papaya leaves contains alkaloids, tanins, flavonoids, and steroids/terpenoids and showed antibacterial activity and antibiofilm against P. aeruginosa. Addition of extract can inhibit the cell attachment and was able to degrade the biofilm of 40.92% and 48.058% respectively at optimum conditions: extract concentration of 25% (v/v), temperature 37.5 °C and contact time 45 minutes. With a concentration of 25% (v/v), temperature of 50 °C and the contact time of 3 days, extract of papaya leaves can inhibit the growth of biofilms of 39.837% v/v.

The Research of New Inhibitors of Bacterial Methionine Aminopeptidase by Structure Based Virtual Screening Approach of ZINC DATABASE and In Vitro Validation

2020 ◽  
Vol 16 (4) ◽  
pp. 389-401 ◽  
Author(s):  
Hanane Boucherit ◽  
Abdelouahab Chikhi ◽  
Abderrahmane Bensegueni ◽  
Amina Merzoug ◽  
Jean-Michel Bolla
Keyword(s):  
Virtual Screening ◽  
Bacterial Survival ◽  
Methionine Aminopeptidase ◽  
Bacterial Strains ◽  
Microdilution Method ◽  
Zinc Database ◽  
Promising Target ◽  
New Antibiotics ◽  
Potential Inhibitors

Background: The great emergence of multi-resistant bacterial strains and the low renewal of antibiotics molecules are leading human and veterinary medicine to certain therapeutic impasses. Therefore, there is an urgent need to find new therapeutic alternatives including new molecules in the current treatments of infectious diseases. Methionine aminopeptidase (MetAP) is a promising target for developing new antibiotics because it is essential for bacterial survival. Objective: To screen for potential MetAP inhibitors by in silico virtual screening of the ZINC database and evaluate the best potential lead molecules by in vitro studies. Methods: We have considered 200,000 compounds from the ZINC database for virtual screening with FlexX software to identify potential inhibitors against bacterial MetAP. Nine chemical compounds of the top hits predicted were purchased and evaluated in vitro. The antimicrobial activity of each inhibitor of MetAP was tested by the disc-diffusion assay against one Gram-positive (Staphylococcus aureus) and two Gram-negative (Escherichia coli & Pseudomonas aeruginosa) bacteria. Among the studied compounds, compounds ZINC04785369 and ZINC03307916 showed promising antibacterial activity. To further characterize their efficacy, the minimum inhibitory concentration was determined for each compound by the microdilution method which showed significant results. Results: These results suggest compounds ZINC04785369 and ZINC03307916 as promising molecules for developing MetAP inhibitors. Conclusion: Furthermore, they could therefore serve as lead molecules for further chemical modifications to obtain clinically useful antibacterial agents.

In vitro synthesis of enzymatically active HIV-1 protease for rapid phenotypic resistance profiling

2005 ◽  
Vol 32 (4) ◽  
pp. 294-299 ◽  
Author(s):  
Dieter Hoffmann ◽  
Bernd Buchberger ◽  
Cordula Nemetz
Keyword(s):  
In Vitro Synthesis ◽  
Phenotypic Resistance ◽  
Hiv 1

scholarly journals In vivo transcriptome analysis provides insights into host-dependent expression of virulence factors by Yersinia entomophaga MH96, during infection of Galleria mellonella

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Amber R Paulson ◽  
Maureen O’Callaghan ◽  
Xue-Xian Zhang ◽  
Paul B Rainey ◽  
Mark R H Hurst
Keyword(s):  
Galleria Mellonella ◽  
Functional Enrichment ◽  
Natural Environments ◽  
Insecticidal Toxin ◽  
Heat Stable ◽  
Expression Of Genes ◽  
Genes Encoding ◽  
Cell Densities

Abstract The function of microbes can be inferred from knowledge of genes specifically expressed in natural environments. Here, we report the in vivo transcriptome of the entomopathogenic bacterium Yersinia entomophaga MH96, captured during initial, septicemic, and pre-cadaveric stages of intrahemocoelic infection in Galleria mellonella. A total of 1285 genes were significantly upregulated by MH96 during infection; 829 genes responded to in vivo conditions during at least one stage of infection, 289 responded during two stages of infection, and 167 transcripts responded throughout all three stages of infection compared to in vitro conditions at equivalent cell densities. Genes upregulated during the earliest infection stage included components of the insecticidal toxin complex Yen-TC (chi1, chi2, and yenC1), genes for rearrangement hotspot element containing protein yenC3, cytolethal distending toxin cdtAB, and vegetative insecticidal toxin vip2. Genes more highly expressed throughout the infection cycle included the putative heat-stable enterotoxin yenT and three adhesins (usher-chaperone fimbria, filamentous hemagglutinin, and an AidA-like secreted adhesin). Clustering and functional enrichment of gene expression data also revealed expression of genes encoding type III and VI secretion system-associated effectors. Together these data provide insight into the pathobiology of MH96 and serve as an important resource supporting efforts to identify novel insecticidal agents.

scholarly journals The Role of Prophage for Genome Diversification within a Clonal Lineage of Lactobacillus johnsonii: Characterization of the Defective Prophage LJ771

2008 ◽  
Vol 190 (17) ◽  
pp. 5806-5813 ◽  
Author(s):  
Emmanuel Denou ◽  
Raymond David Pridmore ◽  
Marco Ventura ◽  
Anne-Cécile Pittet ◽  
Marie-Camille Zwahlen ◽  
...  
Keyword(s):  
Methionine Sulfoxide ◽  
Gene Cassette ◽  
Methionine Sulfoxide Reductase ◽  
Toxin Gene ◽  
Clonal Lineage ◽  
Lactobacillus Johnsonii ◽  
Reductase Gene ◽  
Phage Dna

ABSTRACT Two independent isolates of the gut commensal Lactobacillus johnsonii were sequenced. These isolates belonged to the same clonal lineage and differed mainly by a 40.8-kb prophage, LJ771, belonging to the Sfi11 phage lineage. LJ771 shares close DNA sequence identity with Lactobacillus gasseri prophages. LJ771 coexists as an integrated prophage and excised circular phage DNA, but phage DNA packaged into extracellular phage particles was not detected. Between the phage lysin gene and attR a likely mazE (“antitoxin”)/pemK (“toxin”) gene cassette was detected in LJ771 but not in the L. gasseri prophages. Expressed pemK could be cloned in Escherichia coli only together with the mazE gene. LJ771 was shown to be highly stable and could be cured only by coexpression of mazE from a plasmid. The prophage was integrated into the methionine sulfoxide reductase gene (msrA) and complemented the 5′ end of this gene, creating a protein with a slightly altered N-terminal sequence. The two L. johnsonii strains had identical in vitro growth and in vivo gut persistence phenotypes. Also, in an isogenic background, the presence of the prophage resulted in no growth disadvantage.

Differential stimulation by polyamines of phage DNA-directed in vitro synthesis of proteins

1983 ◽  
Vol 740 (4) ◽  
pp. 362-368 ◽  
Author(s):  
Yasuhiro Watanabe ◽  
Kazuei Igarashi ◽  
Kazuhiro Mitsui ◽  
Seiyu Hirose
Keyword(s):  
In Vitro Synthesis ◽  
Phage Dna

scholarly journals Characterization of Resistance to the Nonnucleoside NS5B Inhibitor Filibuvir in Hepatitis C Virus-Infected Patients

2011 ◽  
Vol 56 (3) ◽  
pp. 1331-1341 ◽  
Author(s):  
Philip J. F. Troke ◽  
Marilyn Lewis ◽  
Paul Simpson ◽  
Katrina Gore ◽  
Jennifer Hammond ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Amino Acid ◽  
Site Directed Mutagenesis ◽  
Phenotypic Resistance ◽  
Number Of Patients ◽  
Chronic Hcv ◽  
Selection Of

ABSTRACTFilibuvir (PF-00868554) is an investigational nonnucleoside inhibitor of the hepatitis C virus (HCV) nonstructural 5B (NS5B) RNA-dependent RNA polymerase currently in development for treating chronic HCV infection. The aim of this study was to characterize the selection of filibuvir-resistant variants in HCV-infected individuals receiving filibuvir as short (3- to 10-day) monotherapy. We identified amino acid M423 as the primary site of mutation arising upon filibuvir dosing. Through bulk cloning of clinical NS5B sequences into a transient-replicon system, and supported by site-directed mutagenesis of the Con1 replicon, we confirmed that mutations M423I/T/V mediate phenotypic resistance. Selection in patients of an NS5B mutation at M423 was associated with a reduced replicative capacityin vitrorelative to the pretherapy sequence; consistent with this, reversion to wild-type M423 was observed in the majority of patients following therapy cessation. Mutations at NS5B residues R422 and M426 were detected in a small number of patients at baseline or the end of therapy and also mediate reductions in filibuvir susceptibility, suggesting these are rare but clinically relevant alternative resistance pathways. Amino acid variants at position M423 in HCV NS5B polymerase are the preferred pathway for selection of viral resistance to filibuvirin vivo.

Phage DNA Directed Enzyme Synthesis in in vitro System from Yeast Mitochondria

1972 ◽  
Vol 238 (81) ◽  
pp. 74-76 ◽  
Author(s):  
DIETMAR RICHTER ◽  
PETER HERRLICH ◽  
MANFRED SCHWEIGER
Keyword(s):  
Enzyme Synthesis ◽  
Yeast Mitochondria ◽  
In Vitro System ◽  
Phage Dna
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