scholarly journals Morphological Сhanges of S. Aureus Cultivated in the Presence of Antibacterial Drugs

Medicina ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 31-49
Author(s):  
S. G. Andreevskaya ◽  
◽  
N. V. Shevlyagina ◽  
J. R. Pseunova ◽  
◽  
...  
Keyword(s):  
Biological Material ◽  
Reference Strain ◽  
Phenotypic Variability ◽  
Mechanisms Of Action ◽  
Growth Suppression ◽  
Clinical Isolates ◽  
Ultrastructural Changes ◽  
Bacterial Cells ◽  
Antibacterial Drugs ◽  
New Methods

The search for new methods for identifying the pathogen in biological material, including microscopic, remains relevant. The study of ultrastructural changes of microorganisms as a result of exposure to various groups of antibiotics is important, because the morphology of the bacterial cell varies considerably depending on the conditions of cultivation. The purpose of the study: 1. To identify the nature of changes in the ultrastructure of preserved bacterial cells of S. aureus, cultivated in the presence of antibiotics. 2. To determine the viability of that part of the population of S. aureus, which remained exposed to suppressive concentrations of antibacterial drugs. 3. To determine whether the ultrastructural changes of the reference strain S. aureus ATCC 25923 in the proposed conditions completely reflect the nature of these changes for strains isolated from clinical material. Materials and methods. Three strains of S. aureus isolated from biological material and the reference strain S. aureus ATCC 25923 were used to investigate the S. aureus ultrastructure. The analysis was carried out on the basis of data obtained using scanning electron microscopy (SEM). In the process of sample preparation, the technique of imprinting bacteria from agarized nutrient medium was applied. Results and conclusions. The most common feature for the strains of clinical isolates of S. aureus was the formation of a large number of bacterial cells of a specific disc-shaped form in zones of influence of bacteriostatic antibiotics. In terms of the use of bactericidal drugs, part of the population remained spherical, the other part had irregular contours. Changes in the size of bacterial cells in growth suppression zones were multidirectional. Cultivation of bacteria under conditions of exposure to suppressive concentrations of antibacterial drugs stimulated the production of exocellular matrix. The ultrastructural changes of phenotypic variability of the reference strain S. aureus ATCC 25923 did not fully correspond to changes in the morphology of the bacterial cells of the strains of clinical isolates. The viability of bacteria remaining in the zones of growth suppression has been confirmed in all cases of antibiotic exposure, except gentamicin. Thus, the study revealed the nature of changes in the ultrastructure of S. aureus as manifestations of phenotypic variability of microorganisms in response to the presence of antibacterial drugs with different mechanisms of action.

scholarly journals HDAC Inhibitors: Dissecting Mechanisms of Action to Counter Tumor Heterogeneity

Cancers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 3575
Author(s):  
Dimitris Karagiannis ◽  
Theodoros Rampias
Keyword(s):  
Tumor Heterogeneity ◽  
Histone Deacetylase Inhibitors ◽  
Phenotypic Variability ◽  
Hdac Inhibitors ◽  
Cancer Therapeutics ◽  
Mechanisms Of Action ◽  
Therapeutic Approaches ◽  
Cellular Processes ◽  
Environmental Selection ◽  
Stochastic Events

Intra-tumoral heterogeneity presents a major obstacle to cancer therapeutics, including conventional chemotherapy, immunotherapy, and targeted therapies. Stochastic events such as mutations, chromosomal aberrations, and epigenetic dysregulation, as well as micro-environmental selection pressures related to nutrient and oxygen availability, immune infiltration, and immunoediting processes can drive immense phenotypic variability in tumor cells. Here, we discuss how histone deacetylase inhibitors, a prominent class of epigenetic drugs, can be leveraged to counter tumor heterogeneity. We examine their effects on cellular processes that contribute to heterogeneity and provide insights on their mechanisms of action that could assist in the development of future therapeutic approaches.

Methods and markers used for human age estimation in forensics

2016 ◽  
Vol 294 ◽  
pp. 105-109
Author(s):  
Anna Woźniak ◽  
Keyword(s):  
Biological Material ◽  
Age Estimation ◽  
Prediction Error ◽  
Estimation Techniques ◽  
New Methods ◽  
Human Age Estimation

The article presents the previous and current methods and markers used for estimation of human age. The analysis of biological material recovered from the scene of the event makes it possible to estimate the age of a person who deposited traces. The new methods allow determining the depositor’s age, based on biological traces commonly found at the scene, such as blood, saliva or sperm, with an accuracy of a few years. The previously used age estimation techniques required larger quantities of biological material, whereas their prediction error amounted to even several decades.

scholarly journals In vitro anti-mycobacterial activity of (E)-N´-(monosubstituted-benzylidene) isonicotinohydrazide derivatives against isoniazid-resistant strains

2012 ◽  
Vol 4 (1) ◽  
pp. 13 ◽  
Author(s):  
Tatiane S. Coelho ◽  
Jessica B. Cantos ◽  
Marcelle L.F. Bispo ◽  
Raoni S.B. Gonçalves ◽  
Camilo H.S. Lima ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Resistant Strain ◽  
Mechanisms Of Action ◽  
Susceptible Strain ◽  
Clinical Isolates ◽  
Coding Region ◽  
Resistant Strains

A series of twenty-three <em>N-acylhydrazones</em> derived from isoniazid (INH 1-23) have been evaluated for their <em>in vitro</em> antibacterial activity against INH- susceptible strain of <em>M. tuberculosis</em> (RG500) and three INH-resistant clinical isolates (RG102, RG103 and RG113). In general, derivatives 4, 14, 15 and 16 (MIC=1.92, 1.96, 1.96 and 1.86 mM, respectively) showed relevant activities against RG500 strain, while the derivative 13 (MIC=0.98 mM) was more active than INH (MIC=1.14 mM). However, these derivatives were inactive against RGH102, which displays a mutation in the coding region of <em>inhA</em>. These results suggest that the activities of these compounds depend on the inhibition of this enzyme. However, the possibility of other mechanisms of action cannot be excluded, since compounds 2, 4, 6, 7, 12-17, 19, 21 and 23 showed good activities against <em>katG</em>-resistant strain RGH103, being more than 10-fold more active than INH.

scholarly journals Bordetella holmesii: Lipid A Structures and Corresponding Genomic Sequences Comparison in Three Clinical Isolates and the Reference Strain ATCC 51541

2017 ◽  
Vol 18 (5) ◽  
pp. 1080 ◽  
Author(s):  
Valérie Bouchez ◽  
Sami AlBitar-Nehmé ◽  
Alexey Novikov ◽  
Nicole Guiso ◽  
Martine Caroff
Keyword(s):  
Lipid A ◽  
Reference Strain ◽  
Clinical Isolates ◽  
Genomic Sequences ◽  
Strain Atcc

scholarly journals Early Events of Citrus Greening (Huanglongbing) Disease Development at the Ultrastructural Level

2010 ◽  
Vol 100 (9) ◽  
pp. 949-958 ◽  
Author(s):  
Svetlana Y. Folimonova ◽  
Diann S. Achor
Keyword(s):  
Middle Lamella ◽  
Ultrastructural Level ◽  
Citrus Greening ◽  
Ultrastructural Changes ◽  
Bacterial Cells ◽  
Tissue Samples ◽  
Large Numbers ◽  
Presymptomatic Stage ◽  
Candidatus Liberibacter ◽  
Advanced Stages

Citrus greening (Huanglongbing [HLB]) is one of the most destructive diseases of citrus worldwide. The causal agent of HLB in Florida is thought to be ‘Candidatus Liberibacter asiaticus’. Understanding of the early events in HLB infection is critical for the development of effective measures to control the disease. In this work, we conducted cytopathological studies by following the development of the disease in citrus trees graft inoculated with ‘Ca. L. asiaticus’-containing material under greenhouse conditions to examine the correlation between ultrastructural changes and symptom production, with the main objective of characterizing the early events of infection. Based on our observations, one of the first degenerative changes induced upon invasion of the pathogen appears to be swelling of middle lamella between cell walls surrounding sieve elements. This anatomical aberration was often observed in samples from newly growing flushes in inoculated sweet orange and grapefruit trees at the early “presymptomatic” stage of HLB infection. Development of symptoms and their progression correlated with an increasing degree of microscopic aberrations. Remarkably, the ability to observe the bacterium in the infected tissue also correlated with the degree of the disease progression. Large numbers of bacterial cells were found in phloem sieve tubes in tissue samples from presymptomatic young flushes. In contrast, we did not observe the bacteria in highly symptomatic leaf samples, suggesting a possibility that, at more advanced stages of the disease, a major proportion of ‘Ca. L. asiaticus’ is present in a nonviable state. We trust that observations reported here advance our understanding of how ‘Ca. L. asiaticus’ causes disease. Furthermore, they may be an important aid in answering a question: when and where within an infected tree the tissue serves as a better inoculum source for acquisition and transmission of the bacterium by its psyllid vector.

Global analyses imply that Stenotrophomonas maltophilia biofilms are phenotypically highly diverse despite a common transcriptome profile

2020 ◽  
Author(s):  
Ifey Alio ◽  
Mirja Gudzuhn ◽  
Marie Schölmerich ◽  
Pablo Pérez García ◽  
Christel Vollstedt ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Stenotrophomonas Maltophilia ◽  
Phenotypic Variability ◽  
Multidrug Resistant ◽  
Clinical Isolates ◽  
Clinical Settings ◽  
Data Set ◽  
Specific Level ◽  
Key Factor ◽  
Fermentative Growth

&lt;p&gt;&lt;strong&gt;Stenotrophomonas maltophilia&lt;/strong&gt;&lt;strong&gt; is one of the most frequently isolated multidrug resistant opportunistic pathogens. It contributes to disease progression in cystic fibrosis patients and is found in wounds, other infected tissues and on catheter surfaces. Only little is known on key processes linked to biofilm formation of S. maltophilia on a broader basis. Thus the aim of this study was the identification of key processes involved in biofilm formation of S. maltophilia on a global level. Therefore, we analyzed biofilm profiles of 300 globally collected clinical and environmental isolates of the main and recently identified lineages Sgn3, Sgn4 and Sm2 - Sm18 (Groeschel et al., 2020). These data together with the 3D structural analysis of a subset of clinical 40 clinical isolates revealed an unexpectedly high phenotypic variability on a strain specific level. Further transcriptome analysis of seven clinical isolates using biofilm grown cells identified a set of 106 shared and coexpressed genes and roughly 30-35 strain-specific genes. Based on these findings S. maltophilia employs a mostly fermentative growth modus under the biofilm conditions and uptake of iron, phosphorous and other metals appears to be of high relevance. Surprisingly, the transcriptome profiles of biofilm versus planktonic cells revealed that only 8.6% of all genes were differentially regulated when both conditions were compared.&amp;#160; This implies that only relatively few genes contribute to the change from planktonic to biofilm life style. Thereby iron uptake appears to be a key factor involved in this metabolic shift. The transcriptome data generated in this study together with the phenotypic and metabolic analysis represent so far the largest data set on S. maltophilia biofilm versus planktonic grown cells. This study now lays the foundation for the identification of new strategies in fighting S. maltophilia infections in clinical settings.&lt;/strong&gt;&lt;/p&gt; &lt;p&gt;Ref: &amp;#160;Gr&amp;#246;schel et al., 2020 ,The phylogenetic landscape and nosocomial spread of the multidrug-resistant opportunist Stenotrophomonas maltophilia. Nature Commun. 2020 Apr 27;11(1):2044. doi: 10.1038/s41467-020-15123-0.&lt;/p&gt;

scholarly journals Use of Ultrasounds to Reduce the Count of Campylobacter coli in Water

2021 ◽  
Vol 70 (3) ◽  
pp. 339-343
Author(s):  
MAREK SELWET
Keyword(s):  
Reference Strain ◽  
Low Frequency ◽  
Bacterial Count ◽  
Deionized Water ◽  
Continuous Operation ◽  
Campylobacter Coli ◽  
Bacterial Cells ◽  
Death Rates ◽  
Cell Death Rate ◽  
Campylobacter Spp

The present study aimed to evaluate the effectiveness of low-frequency ultrasounds applied to eliminate Campylobacter spp. from water. The strains used in this research were isolated from water contaminated with sewage. Campylobacter coli alone was detected in the samples and used for further research. The reference strain C. coli ATCC 33559 was simultaneously tested. The isolate was exposed to ultrasounds at frequencies of 37 kHz and 80 kHz in a continuous operation device with ultrapure deionized water. After 5 min of sonication, the count of C. coli decreased by 5.78% (37 kHz) and 6.27% (80 kHz), whereas the temperature increased by 3°C (37 kHz), and 6°C (80 kHz). After 30 min of sonication, the death rates of bacterial cells were 40.15% (37 kHz) and 55.10% (80 kHz), whereas the temperature reached the maximum values of 36°C (37 kHz), and 39°C (80 kHz). Sonication at the frequency of 80 kHz reduced the bacterial count from 6.86 log CFU/ml to 3.08 log CFU/ml, whereas the frequency of 37 kHz reduced the bacterial count from 6.75 log CFU/ml to 4.04 log CFU/ml. Despite significant differences (p < 0.05) in the number of C. coli cells, the cell death rate remained at the same level.

scholarly journals Resistance of nosocomial strains to antibacterial drugs and its link to biofilm formation

2017 ◽  
Vol 8 (4) ◽  
pp. 540-546
Author(s):  
T. V. Sklyar ◽  
K. V. Lavrentievа ◽  
Y. A. Alyonkina ◽  
A. M. Kolomoets ◽  
А. І. Vinnikov
Keyword(s):  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Clinical Practice ◽  
Biofilm Formation ◽  
Direct Relationship ◽  
Wide Distribution ◽  
Clinical Isolates ◽  
Diffusion Test ◽  
Antibacterial Drugs ◽  
Agar Diffusion Test

The problem of nosocomial infections is considered in connection with more frequent formation and wide distribution in clinical practice of new strains of hospital bacteria that have a cross-resistence to antibacterial drugs. The nosocomial agents were isolated from wounds and identified as Staphylococcus aureus and Pseudomonas aeruginosa. 72.0% of S. aureus strains and 61.5% of P. aeruginosa clinical isolates had the capability of forming biofilms. The sensitivity to antibiotics of all isolated strains was investigated with tne agar diffusion test. This method showed that all strains of S. aureus with the capability to form biofilms had resistence to erythromycin, gentamycin, ciprofloxacin and levofloxacin. The had the greatest sensitivity to klindamycin (90.3%), vancomycin (80.6%) and gatifloxacin (80.6% cultures). The strains of S. aureus with the capability to form biofilms were more resistent to antibiotics than strains of S. aureus without such properties. Only cefotaxim suppressed the growth of 75.0% of strains of staphylococci. All isolated strains of S. aureus without the capability to form biofilms were sensitive to doxycyclin, gentamycin, ciprofloxacin, levofloxacin and klindamycin. All clinical isolates of P. aeruginosa with capability to form biofilms had resistence to ampicillin, gentamycin, imipenem, cefotaxime and ceftriaxone. They were most sensitive (75.0%) to piperacillin and cefoperazone/sulbactam. The strains of P. aeruginosa without the capability to form biofilms kept the resistence to gentamycin, imipenem and ceftriaxone. They showed the greatest sensitivity (75.0%) to ciprofloxacin (80.0% isolates) and also to amikacin, ampicillin, meropenem, norfloxacin and cefotaxime (60.0% cultures). We investigated the minimum inhibitory concentrations of gentamycin and ciprofloxacin, which appeared higher for P. aeruginosa than for S. aureus. The most effective disinfectant against all isolated nosocomial agents without the capacity for biofilm formation was “Desactin” in a concentration 0.1% or 0.2%. For strains of staphylococci with this capability, the efficiency of “Desactin” went down by 9.7%. The best biocide effect against the strains of P. aeruginosa with the capability of forming biofilms was shown by 0.1% solution of “Neochlorine tabs”, which suppressed the growth of 75.0% of tested cultures. As a result, we detected a direct relationship between resistance to antibiotics and disinfectants and the capacities for biofilm formation among the nosocomial agents S. aureus and P. aeruginosa. 

scholarly journals Resolving antagonistic interactions among clinical isolates of Acinetobacter baumannii with phylogenetic analysis

2014 ◽  
Author(s):  
Rae Heitkamp ◽  
Jason Sahl ◽  
Amy Summers ◽  
Amanda L. Roth ◽  
Benjamin C Kirkup
Keyword(s):  
Acinetobacter Baumannii ◽  
Genetic Basis ◽  
Reference Strain ◽  
Nearest Neighbor ◽  
Antagonistic Activity ◽  
Clinical Isolates ◽  
Healthcare Facilities ◽  
Genome Phylogeny ◽  
New Treatments ◽  
Antagonistic Interactions

Acinetobacter baumannii is a nosocomial species frequently isolated from the traumatic wounds of injured military personnel and increasingly detected in civilian healthcare facilities. Many clinical isolates of A. baumannii are drug resistant, so new treatments are needed for infections. Recently, the ability of strains of conspecific bacteria to inhibit the growth of other strains has been observed in increasing numbers of species. We previously reported on intraspecific semisolid-phase growth inhibition (antagonism) among 94 clinical isolates of A. baumannii. These antagonistic interactions may be the result of genetically-encoded molecules, so more closely related isolates would be expected to produce similar patterns of interactions caused by identically active gene products. However, the phylogeny of clinical A. baumannii below the species level has not been established for this set of isolates.In this study, we used Phylomark to identify three genetic loci that recapitulated a whole-genome phylogeny of published A. baumannii genomes and we created a parsimony-based phylogeny from the 1.2 kilobase concatenated sequences. One clade appeared to exhibit the highest incidence of antagonistic interactions against all other isolates screened, except for itself and one relatively distant clade. This clade's nearest neighbor was susceptible to the most consistent antagonistic activity by the first clade; both of these clades appear to belong to MLST ST1 with reference strain AYE. Other isolates with high rates of antagonistic activity fall outside of ST1. Future studies aim to elucidate the genetic basis of the antagonism phenotype in clinical Acinetobacter, particularly in the most antagonistic isolates. The next step will be to mine these interactions to identify expressed antimicrobial molecules with potential for drug therapy.

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