scholarly journals Omics Approaches for the Study of Adaptive Immunity to Staphylococcus aureus and the Selection of Vaccine Candidates

Proteomes ◽  
2016 ◽  
Vol 4 (1) ◽  
pp. 11 ◽  
Author(s):  
Silva Holtfreter ◽  
Julia Kolata ◽  
Sebastian Stentzel ◽  
Stephanie Bauerfeind ◽  
Frank Schmidt ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Adaptive Immunity ◽  
Vaccine Candidates ◽  
Selection Of

The Study of Bacillus Subtils Antimicrobial Activity on Some of the Pathological Isolates

2019 ◽  
Vol 9 (02) ◽  
Author(s):  
Hussein A Kadhum ◽  
Thualfakar H Hasan2
Keyword(s):  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Antimicrobial Activity ◽  
Bacillus Subtilis ◽  
Bacterial Growth ◽  
Broad Spectrum ◽  
Inhibitory Activity ◽  
Bacterial Pathogens ◽  
Inhibitory Ability ◽  
Selection Of

The study involved the selection of two isolates from Bacillus subtilis to investigate their inhibitory activity against some bacterial pathogens. B sub-bacteria were found to have a broad spectrum against test bacteria such as Staphylococcus aureus and Pseudomonas aeruginosa. They were about 23-30 mm and less against Klebsiella sp. The sensitivity of some antibodies was tested on the test samples. The results showed that the inhibitory ability of bacterial growth in the test samples using B. subtilis extract was more effective than the antibiotics used.

The Effects of Shock Vancomycin Concentrations on the Formation of Heteroresistance in Staphylococcus aureus

2020 ◽  
Vol 65 (9-10) ◽  
pp. 3-7
Author(s):  
V. V. Gostev ◽  
Yu. V. Sopova ◽  
O. S. Kalinogorskaya ◽  
M. E. Velizhanina ◽  
I. V. Lazareva ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
In Vitro Selection ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
High Concentration ◽  
Short Term ◽  
High Concentrations ◽  
Selection Of ◽  
Selection Of Resistance ◽  
Test Cultures

Glycopeptides are the basis of the treatment of infections caused by MRSA (Methicillin-Resistant Staphylococcus aureus). Previously, it was demonstrated that antibiotic tolerant phenotypes are formed during selection of resistance under the influence of high concentrations of antibiotics. The present study uses a similar in vitro selection model with vancomycin. Clinical isolates of MRSA belonging to genetic lines ST8 and ST239, as well as the MSSA (ATCC29213) strain, were included in the experiment. Test isolates were incubated for five hours in a medium with a high concentration of vancomycin (50 μg/ml). Test cultures were grown on the medium without antibiotic for 18 hours after each exposure. A total of ten exposure cycles were performed. Vancomycin was characterized by bacteriostatic action; the proportion of surviving cells after exposure was 70–100%. After selection, there was a slight increase in the MIC to vancomycin (MIC 2 μg/ml), teicoplanin (MIC 1.5–3 μg/ml) and daptomycin (MIC 0.25–2 μg/ml). According to the results of PAP analysis, all strains showed an increase in the area under curve depending on the concentration of vancomycin after selection, while a heteroresistant phenotype (with PAP/AUC 0.9) was detected in three isolates. All isolates showed walK mutations (T188S, D235N, E261V, V380I, and G223D). Exposure to short-term shock concentrations of vancomycin promotes the formation of heteroresistance in both MRSA and MSSA. Formation of VISA phenotypes is possible during therapy with vancomycin.

scholarly journals The identification of novel immunogenic antigens as potential Shigella vaccine components

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Ruklanthi de Alwis ◽  
Li Liang ◽  
Omid Taghavian ◽  
Emma Werner ◽  
Hao Chung The ◽  
...  
Keyword(s):  
Core Genome ◽  
Genomic Analysis ◽  
Carrier Proteins ◽  
Vaccine Candidates ◽  
Vaccine Antigens ◽  
Bactericidal Antibody ◽  
In Vivo Testing ◽  
Species Specific ◽  
Selection Of

Abstract Background Shigella is a major diarrheal pathogen for which there is presently no vaccine. Whole genome sequencing provides the ability to predict and derive novel antigens for use as vaccines. Here, we aimed to identify novel immunogenic Shigella antigens that could serve as Shigella vaccine candidates, either alone, or when conjugated to Shigella O-antigen. Methods Using a reverse vaccinology approach, where genomic analysis informed the Shigella immunome via an antigen microarray, we aimed to identify novel immunogenic Shigella antigens. A core genome analysis of Shigella species, pathogenic and non-pathogenic Escherichia coli, led to the selection of 234 predicted immunogenic Shigella antigens. These antigens were expressed and probed with acute and convalescent serum from microbiologically confirmed Shigella infections. Results Several Shigella antigens displayed IgG and IgA seroconversion, with no difference in sero-reactivity across by sex or age. IgG sero-reactivity to key Shigella antigens was observed at birth, indicating transplacental antibody transfer. Six antigens (FepA, EmrK, FhuA, MdtA, NlpB, and CjrA) were identified in in vivo testing as capable of producing binding IgG and complement-mediated bactericidal antibody. Conclusions These findings provide six novel immunogenic Shigella proteins that could serve as candidate vaccine antigens, species-specific carrier proteins, or targeted adjuvants.

scholarly journals Choice of sanitary-indicative microorganisms for the assessment of the safety of split-systems

2019 ◽  
Vol 95 (3) ◽  
pp. 296-301
Author(s):  
U. A. Rakhmanin ◽  
S. E. Shibanov ◽  
Sergey V. Kozulya
Keyword(s):  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Air Conditioning ◽  
Air Conditioning System ◽  
Split Systems ◽  
Air Conditioning Systems ◽  
Cleaning And Disinfection ◽  
Epidemiological Link ◽  
And Staphylococcus Aureus ◽  
Selection Of

Purpose of work is a compilation of data about the microflora which colonizes a split-system, with the aim of selection of sanitary-indicative microorganisms, whose presence in the sample would indicate to the need for cleaning and disinfection of split-systems. Materials and methods. In the article there were used data of five years author’s scientific inquiry, related to the prevention of respiratory diseases, associated with the usage of a local air conditioning systems. We also use the data from the literature. Results. For selection of “indicative” microorganisms, we proposed the usage of nine criteria, each of them have numeric value from 0 to 3 points (risk for health, prevalence rate of the disease, epidemiological link, speed of split system’s colonization, difficulty of cultivation, resistance in the environment, resistance to disinfectants, frequency of detection in home air conditioning systems, frequency of detection in air conditioning systems of public buildings). After the calculation Pseudomonas aeruginosa and Staphylococcus aureus received maximal score (20 points). Therefore, these two types of bacteria are indicative microorganisms. The detection of these microorganisms in split systems will indicate to the contamination of air-conditioning system. This microflora also is a criterion of cleaning and disinfection quality - presence of these microorganisms in the samples after this process will mean that the processing of air conditioning systems was performed poorly. Conclusions. Split systems are very faster colonized by conditionally pathogenic and pathogenic microflora. To prevent the possible hazard for population’s health it is necessary to develop the normative base, according to which sanitary-and-hygienic control over the split-systems working must be carried out. Proposed criteria suggest that Pseudomonas aeruginosa and Staphylococcus aureus are indicative microorganisms, and it’s identification in the air-conditioning system would mean risk for health and necessity for cleaning and disinfection.

scholarly journals Staphylococcus aureusImpairs the Function of and Kills Human Dendritic Cells via the LukAB Toxin

mBio ◽  
2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Evelien T. M. Berends ◽  
Xuhui Zheng ◽  
Erin E. Zwack ◽  
Mickaël M. Ménager ◽  
Michael Cammer ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Dendritic Cells ◽  
Adaptive Immunity ◽  
T Cell Activation ◽  
Antigen Presenting Cells ◽  
Infection Model ◽  
High Morbidity ◽  
Content Type ◽  
Human Dendritic Cells ◽  
Antigen Presenting

ABSTRACTStaphylococcus aureusis a human pathogen responsible for high morbidity and mortality worldwide. Recurrent infections with this bacterium are common, suggesting thatS. aureusthwarts the development of sterilizing immunity.S. aureusstrains that cause disease in humans produce up to five different bicomponent toxins (leukocidins) that target and lyse neutrophils, innate immune cells that represent the first line of defense againstS. aureusinfections. However, little is known about the role of leukocidins in blunting adaptive immunity. Here, we explored the effects of leukocidins on human dendritic cells (DCs), antigen-presenting cells required for the development of adaptive immunity. Using anex vivoinfection model of primary human monocyte-derived dendritic cells, we found thatS. aureus, including strains from different clonal complexes and drug resistance profiles, effectively kills DCs despite efficient phagocytosis. Although all purified leukocidins could kill DCs, infections with live bacteria revealed thatS. aureustargets and kills DCs primarily via the activity of leukocidin LukAB. Moreover, using coculture experiments performed with DCs and autologous CD4+T lymphocytes, we found that LukAB inhibits DC-mediated activation and proliferation of primary human T cells. Taken together, the data determined in the study reveal a novel immunosuppressive strategy ofS. aureuswhereby the bacterium blunts the development of adaptive immunity via LukAB-mediated injury of DCs.IMPORTANCEAntigen-presenting cells such as dendritic cells (DCs) fulfill an indispensable role in the development of adaptive immunity by producing proinflammatory cytokines and presenting microbial antigens to lymphocytes to trigger a faster, specific, and long-lasting immune response. Here, we studied the effect ofStaphylococcus aureustoxins on human DCs. We discovered that the leukocidin LukAB hinders the development of adaptive immunity by targeting human DCs. The ability ofS. aureusto blunt the function of DCs could help explain the high frequency of recurrentS. aureusinfections. Taken together, the results from this study suggest that therapeutically targeting theS. aureusleukocidins may boost effective innate and adaptive immune responses by protecting innate leukocytes, enabling proper antigen presentation and T cell activation.

scholarly journals Which Approach Is More Effective in the Selection of Plants with Antimicrobial Activity?

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Ana Carolina Oliveira Silva ◽  
Elidiane Fonseca Santana ◽  
Antonio Marcos Saraiva ◽  
Felipe Neves Coutinho ◽  
Ricardo Henrique Acre Castro ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Antimicrobial Activity ◽  
Minimum Inhibitory Concentration ◽  
Crude Extract ◽  
Inhibitory Concentration ◽  
Antimicrobial Activities ◽  
Semiarid Region ◽  
Northeast Brazil ◽  
Plant Drugs ◽  
Selection Of

The development of the present study was based on selections using random, direct ethnopharmacological, and indirect ethnopharmacological approaches, aiming to evaluate which method is the best for bioprospecting new antimicrobial plant drugs. A crude extract of 53 species of herbaceous plants collected in the semiarid region of Northeast Brazil was tested against 11 microorganisms. Well-agar diffusion and minimum inhibitory concentration (MIC) techniques were used. Ten extracts from direct, six from random, and three from indirect ethnopharmacological selections exhibited activities that ranged from weak to very active against the organisms tested. The strain most susceptible to the evaluated extracts wasStaphylococcus aureus. The MIC analysis revealed the best result for the direct ethnopharmacological approach, considering that some species yielded extracts classified as active or moderately active (MICs between 250 and 1000 µg/mL). Furthermore, one species from this approach inhibited the growth of the threeCandidastrains. Thus, it was concluded that the direct ethnopharmacological approach is the most effective when selecting species for bioprospecting new plant drugs with antimicrobial activities.

scholarly journals Small-Colony Mutants of Staphylococcus aureus Allow Selection of Gyrase-Mediated Resistance to Dual-Target Fluoroquinolones

2002 ◽  
Vol 46 (8) ◽  
pp. 2498-2506 ◽  
Author(s):  
Xiao-Su Pan ◽  
Penelope J. Hamlyn ◽  
Raquel Talens-Visconti ◽  
Fabiana L. Alovero ◽  
Ruben H. Manzo ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Drug Target ◽  
Quinolone Resistance ◽  
Second Step ◽  
Resistant Bacteria ◽  
Topoisomerase Iv ◽  
Small Colony ◽  
Dual Target ◽  
Selection Of

ABSTRACT Fluoroquinolones acting equally through DNA gyrase and topoisomerase IV in vivo are considered desirable in requiring two target mutations for emergence of resistant bacteria. To investigate this idea, we have studied the response of Staphylococcus aureus RN4220 to stepwise challenge with sparfloxacin, a known dual-target agent, and with NSFQ-105, a more potent sulfanilyl fluoroquinolone that behaves similarly. First-step mutants were obtained with both drugs but only at the MIC. These mutants exhibited distinctive small-colony phenotypes and two- to fourfold increases in MICs of NSFQ-105, sparfloxacin, and ciprofloxacin. No changes were detected in the quinolone resistance-determining regions of the gyrA, gyrB, grlA, or grlB gene. Quinolone-induced small-colony mutants shared the delayed coagulase response but not the requirement for menadione, hemin, or thymidine characteristic of small-colony variants, a subpopulation of S. aureus that is often defective in electron transport. Second-step mutants selected with NSFQ-105 had gyrA(S84L) alterations; those obtained with sparfloxacin carried a gyrA(D83A) mutation or a novel gyrB deletion (ΔRKSAL, residues 405 to 409) affecting a trypsin-sensitive region linking functional domains of S. aureus GyrB. Each mutation was associated with four- to eightfold increases in MICs of NSFQ-105 and sparfloxacin, but not of ciprofloxacin, which we confirm targets topoisomerase IV. The presence of wild-type grlB-grlA gene sequences in second-step mutants excluded involvement of topoisomerase IV in the small-colony phenotype. Growth revertants retaining mutant gyrA or gyrB alleles were quinolone susceptible, indicating that resistance to NSFQ-105 and sparfloxacin was contingent on the small-colony mutation. We propose that small-colony mutations unbalance target sensitivities, perhaps through altered ATP or topoisomerase levels, such that gyrase becomes the primary drug target. Breaking of target parity by genetic or physiological means eliminates the need for two target mutations and provides a novel mechanism for stepwise selection of quinolone resistance.

scholarly journals Differences in Potential for Selection of Clindamycin-Resistant Mutants Between Inducible erm(A) and erm(C) Staphylococcus aureus Genes

2007 ◽  
Vol 46 (2) ◽  
pp. 546-550 ◽  
Author(s):  
C. Daurel ◽  
C. Huet ◽  
A. Dhalluin ◽  
M. Bes ◽  
J. Etienne ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Resistant Mutants ◽  
Selection Of
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