scholarly journals Morphological characteristics of an experimental catheter-associated infection following immunosuppression and the use of a low-molecular cationic peptide of the lantibiotic family – warnerin

2021 ◽  
Vol 10 (4) ◽  
pp. 14-24
Author(s):  
V.V. Litvinov ◽  
◽  
L.M. Lemkina ◽  
G.G. Freynd ◽  
V.P. Korobov ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Morphological Characteristics ◽  
Infection Model ◽  
Cationic Peptide ◽  
Ether Anesthesia ◽  
Catheter Implantation ◽  
Outbred Mice ◽  
Intravascular Catheters ◽  
Immunohistochemical Studies ◽  
Immunosuppressed Mice

Introduction. Catheter-associated infection is caused by microorganism colonization of the surface of the implanted catheter with a biofilm formation that significantly increases their resistance to antiseptics and antibiotics, especially in immunosuppression. Low-molecular antibacterial peptides are compounds capable of combating biofilm formation. The aim of the study was to describe morphological characteristics of a catheter-associated infection model on laboratory mice secondary to immunosuppression and to assess the efficacy of the low-molecular cationic antibacterial peptide (warnerin). Materials and methods. An experiment included white outbred mice (25–30 g body weight) under ether anesthesia that received 1.0-cm fragments of intravascular catheters under the skin of the backs. The animals underwent preliminary immunosuppression with cyclophosphamide. We used Staphylococcus epidermidis 33 (in the form of suspensions or biofilms previously grown on catheter segments) and low-molecular cationic peptide warnerin. All animals were sacrificed by ether overdose on days 1, 2, and 3 after the manipulation. We took the tissues surrounding the catheter for histological and immunohistochemical studies with antibodies to CD34, vimentin, CD68, CD3, and CD20. Results. The warnerin administration at the site of the catheter implantation led to disappearance of or a significant decrease in the number of bacterial. In the infiltrate, the number of neutrophils significantly increased, whereas that of fibroblasts decreased. Immunohistochemistry confirmed the features of the cellular reactions around the catheters with bacterial contamination with warnerin administration. Conclusion. In a model of catheter-associated infection in immunosuppressed mice, the warnerin antibacterial manifests in characteristic histological alterations in the inflammatory infiltrate composition. Keywords: catheter-associated infection model, morphology of inflammation, warnerin antibacterial cationic peptide

scholarly journals Antibiofilm and antivirulence potential of silver nanoparticles against multidrug-resistant Acinetobacter baumannii

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Helal F. Hetta ◽  
Israa M. S. Al-Kadmy ◽  
Saba Saadoon Khazaal ◽  
Suhad Abbas ◽  
Ahmed Suhail ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Antibacterial Activity ◽  
Acinetobacter Baumannii ◽  
Biofilm Formation ◽  
Microtiter Plate ◽  
Diffusion Method ◽  
Resistance Pattern ◽  
Infection Model ◽  
The Impact

AbstractWe aimed to isolate Acinetobacter baumannii (A. baumannii) from wound infections, determine their resistance and virulence profile, and assess the impact of Silver nanoparticles (AgNPs) on the bacterial growth, virulence and biofilm-related gene expression. AgNPs were synthesized and characterized using TEM, XRD and FTIR spectroscopy. A. baumannii (n = 200) were isolated and identified. Resistance pattern was determined and virulence genes (afa/draBC, cnf1, cnf2, csgA, cvaC, fimH, fyuA, ibeA, iutA, kpsMT II, PAI, papC, PapG II, III, sfa/focDE and traT) were screened using PCR. Biofilm formation was evaluated using Microtiter plate method. Then, the antimicrobial activity of AgNPs was evaluated by the well-diffusion method, growth kinetics and MIC determination. Inhibition of biofilm formation and the ability to disperse biofilms in exposure to AgNPs were evaluated. The effect of AgNPs on the expression of virulence and biofilm-related genes (bap, OmpA, abaI, csuA/B, A1S_2091, A1S_1510, A1S_0690, A1S_0114) were estimated using QRT-PCR. In vitro infection model for analyzing the antibacterial activity of AgNPs was done using a co-culture infection model of A. baumannii with human fibroblast skin cell line HFF-1 or Vero cell lines. A. baumannii had high level of resistance to antibiotics. Most of the isolates harbored the fimH, afa/draBC, cnf1, csgA and cnf2, and the majority of A. baumannii produced strong biofilms. AgNPs inhibited the growth of A. baumannii efficiently with MIC ranging from 4 to 25 µg/ml. A. baumannii showed a reduced growth rate in the presence of AgNPs. The inhibitory activity and the anti-biofilm activity of AgNPs were more pronounced against the weak biofilm producers. Moreover, AgNPs decreased the expression of kpsMII , afa/draBC,bap, OmpA, and csuA/B genes. The in vitro infection model revealed a significant antibacterial activity of AgNPs against extracellular and intracellular A. baumannii. AgNPs highly interrupted bacterial multiplication and biofilm formation. AgNPs downregulated the transcription level of important virulence and biofilm-related genes. Our findings provide an additional step towards understanding the mechanisms by which sliver nanoparticles interfere with the microbial spread and persistence.

2021 Frank Stinchfield Award: A novel cemented hip hemiarthroplasty infection model with real-time in vivo imaging in rats

2021 ◽  
Vol 103-B (7 Supple B) ◽  
pp. 9-16
Author(s):  
William J. Hadden ◽  
Mazen Ibrahim ◽  
Mariam Taha ◽  
Kerstin Ure ◽  
Yun Liu ◽  
...  
Keyword(s):  
Real Time ◽  
In Vivo Imaging ◽  
Biofilm Formation ◽  
Joint Infection ◽  
Volumetric Analysis ◽  
In Vivo Model ◽  
Infection Model ◽  
Sprague Dawley ◽  
Hip Hemiarthroplasty

Aims The aims of this study were to develop an in vivo model of periprosthetic joint infection (PJI) in cemented hip hemiarthroplasty, and to monitor infection and biofilm formation in real-time. Methods Sprague-Dawley rats underwent cemented hip hemiarthroplasty via the posterior approach with pre- and postoperative gait assessments. Infection with Staphylococcus aureus Xen36 was monitored with in vivo photoluminescent imaging in real-time. Pre- and postoperative gait analyses were performed and compared. Postmortem micro (m) CT was used to assess implant integration; field emission scanning electron microscopy (FE-SEM) was used to assess biofilm formation on prosthetic surfaces. Results All animals tolerated surgery well, with preservation of gait mechanics and weightbearing in control individuals. Postoperative in vivo imaging demonstrated predictable evolution of infection with logarithmic signal decay coinciding with abscess formation. Postmortem mCT qualitative volumetric analysis showed high contact area and both cement-bone and cement-implant interdigitation. FE-SEM revealed biofilm formation on the prosthetic head. Conclusion This study demonstrates the utility of a new, high-fidelity model of in vivo PJI using cemented hip hemiarthroplasty in rats. Inoculation with bioluminescent bacteria allows for non-invasive, real-time monitoring of infection. Cite this article: Bone Joint J 2021;103-B(7 Supple B):9–16.

scholarly journals Effects of iron on the growth, biofilm formation and virulence of Klebsiella pneumoniae causing liver abscess

2020 ◽  
Author(s):  
Tao Chen ◽  
Guofeng Dong ◽  
Siqin Zhang ◽  
Xiucai Zhang ◽  
Yajie Zhao ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Liver Abscess ◽  
Biofilm Formation ◽  
Iron Chelator ◽  
Infection Model ◽  
Invasive Infection ◽  
Liver Abscesses ◽  
Severe Infections ◽  
Lower Expression ◽  
Additional Iron

Abstract Background: Klebsiella pneumoniae is considered the most clinically relevant species of Enterobacteriaceae, known to cause severe infections including liver abscesses. To the best of our knowledge, a large proportion of iron in the human body is accumulated and stored in the liver. We hypothesize that increased iron availability is an important factor driving liver abscess formation and we therefore aim to understand the effects of iron on K. pneumoniae causing liver abscesses. Results: All tested K. pneumoniae clinical isolates, including those isolated from liver abscesses and other abdominal invasive infection sites, grew optimally when cultured in LB broth supplemented with 50 μM iron and exhibited the strongest biofilm formation ability under those conditions. Decreased growth and biofilm formation ability were observed in all tested strains when cultured with an iron chelator (P<0.05). The infection model of G. mellonella larvae indicated the virulence of liver abscess-causing K. pneumoniae (2/3) cultured in LB broth with additional iron was significantly higher than those under iron-restricted conditions (P<0.05). The relative expression levels of the four siderophore genes (iucB, iroB, irp1, entB) in K. pneumoniae strains isolated from liver abscesses cultured with additional iron were lower than those under iron-restricted conditions (P<0.05). Conclusions: It is suggested by our research that iron in the environment can promote growth, biofilm formation and enhance virulence of K. pneumoniae causing liver abscesses. A lower expression of siderophore genes correlates with increased virulence of liver abscess-causing K. pneumoniae. Further deeper evaluation of these phenomena is warranted.

scholarly journals Case Report: Uterine Adenosarcoma With Sarcomatous Overgrowth and Malignant Heterologous Elements

2022 ◽  
Vol 8 ◽  
Author(s):  
Yunuén I. García-Mendoza ◽  
Mario Murguia-Perez ◽  
Aldo I. Galván-Linares ◽  
Saulo Mendoza-Ramírez ◽  
Norma L. García-Salinas ◽  
...  
Keyword(s):  
Case Report ◽  
Morphological Characteristics ◽  
Endometrial Biopsy ◽  
Lower Uterine Segment ◽  
Differential Diagnoses ◽  
Pathological Examination ◽  
Surgical Specimen ◽  
Immunohistochemical Studies ◽  
Made In

A 46- year-old woman presented a uterine adenosarcoma originating in the lower uterine segment. The diagnosis was made in an endometrial biopsy and confirmed in the pathological examination of the complete surgical specimen, both identifying heterologous malignant elements. In addition, complementary immunohistochemical studies were performed. We reviewed the literature, illustrating the clinical and morphological characteristics and the differential diagnoses to be evaluated.

scholarly journals New data on the immunohistochemical and morphological characteristics of ductal pancreatic adenocarcinoma

2018 ◽  
Vol 42 (4) ◽  
pp. 47-52
Author(s):  
Y. Y. Rakina ◽  
M. V. Zav’yalova ◽  
N. V. Krakhmal ◽  
A. P. Koshel ◽  
S. G. Afanasyev ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
Pancreatic Adenocarcinoma ◽  
Malignant Tumors ◽  
Standard Procedure ◽  
Morphological Characteristics ◽  
Developed Countries ◽  
Ductal Pancreatic Adenocarcinoma ◽  
Microscopic Features ◽  
Giovanni Battista Morgagni ◽  
Immunohistochemical Studies

In recent years, especially in developed countries, there has been an increase in the incidence of pancreatic cancer. Only 20% of tumors at the time of diagnosis are evaluated as resectable, but in these cases, the prognosis of the disease is unfavorable. The overall 5-year survival rate does not exceed 5%. Pancreatic cancer was described in the 1760s by Giovanni Battista Morgagni in his classic book “De Sedibus et Causis Morborum per Anatomen Indigatis”. Over the next 200 years, pathologists significantly improved our understanding of the macro- and microscopic features of this disease. At the same time, morphological research remained the basis of diagnostics for centuries. The introduction of immunohistochemical studies into clinical practice in the late 1970s and early 1980s radically changed our approach to diagnosing this disease. Evaluation of morphological features, as well as features of expression of markers that determine the invasive potential of such neoplasms, can serve in the future as a fundamental basis in solving questions concerning possible factors of prognosis upon malignant tumors of such a localization. Aim of research — to study the morphological and immunohistochemical features of ductal pancreatic adenocarcinoma. Materials and methods. The study included 84 patients with pancreatic cancer T1-4N0-2M0-1 stage, aged from 37 to 83, who underwent surgical treatment. Morphological study of the operating material was carried out. The condition for inclusion in the study was a histotype of the tumor, namely ductal pancreatic adenocarcinoma. Posting of the material, preparation of histological preparations, coloring, immunohistochemical examination were carried out according to a standard procedure. Results and conclusion. The study made it possible to characterize the tumor morphology, as well as the features of expression of markers associated with more evident invasive characteristics of the tumor. The results of this work may be of interest in terms of their further comparison with the parameters of various forms of progression upon pancreatic cancer.

scholarly journals Conversion of Staphylococcus epidermidis Strains from Commensal to Invasive by Expression of the ica Locus Encoding Production of Biofilm Exopolysaccharide

2005 ◽  
Vol 73 (5) ◽  
pp. 3188-3191 ◽  
Author(s):  
Hualin Li ◽  
Lin Xu ◽  
Jianping Wang ◽  
Yumei Wen ◽  
Cuong Vuong ◽  
...  
Keyword(s):  
Central Venous Catheter ◽  
Staphylococcus Epidermidis ◽  
Biofilm Formation ◽  
Venous Catheter ◽  
Infection Model ◽  
Polysaccharide Intercellular Adhesin ◽  
Central Venous ◽  
Biofilm Production ◽  
Central Venous Catheter Infection

ABSTRACT To test if biofilm formation in Staphylococcus epidermidis is dependent on the polysaccharide intercellular adhesin, whose biosynthesis is driven by the ica locus, a plasmid containing the ica locus was transferred to three ica-negative strains. Using in vitro biofilm assays and a rat central venous catheter infection model, we confirmed the importance of the ica locus for biofilm production and pathogenesis of S. epidermidis.

scholarly journals Bap, a Staphylococcus aureus Surface Protein Involved in Biofilm Formation

2001 ◽  
Vol 183 (9) ◽  
pp. 2888-2896 ◽  
Author(s):  
Carme Cucarella ◽  
Cristina Solano ◽  
Jaione Valle ◽  
Beatriz Amorena ◽  
Íñigo Lasa ◽  
...  
Keyword(s):  
Amino Acids ◽  
Staphylococcus Aureus ◽  
Biofilm Formation ◽  
Bovine Mastitis ◽  
Surface Protein ◽  
Surface Proteins ◽  
Infection Model ◽  
Mouse Infection Model ◽  
New Genes ◽  
Inert Surfaces

ABSTRACT Identification of new genes involved in biofilm formation is needed to understand the molecular basis of strain variation and the pathogenic mechanisms implicated in chronic staphylococcal infections. A biofilm-producing Staphylococcus aureus isolate was used to generate biofilm-negative transposon (Tn917) insertion mutants. Two mutants were found with a significant decrease in attachment to inert surfaces (early adherence), intercellular adhesion, and biofilm formation. The transposon was inserted at the same locus in both mutants. This locus (bap [for biofilm associated protein]) encodes a novel cell wall associated protein of 2,276 amino acids (Bap), which shows global organizational similarities to surface proteins of gram-negative (Pseudomonas aeruginosa andSalmonella enterica serovar Typhi) and gram-positive (Enteroccocus faecalis) microorganisms. Bap's core region represents 52% of the protein and consists of 13 successive nearly identical repeats, each containing 86 amino acids. bap was present in a small fraction of bovine mastitis isolates (5% of the 350S. aureus isolates tested), but it was absent from the 75 clinical human S. aureus isolates analyzed. All staphylococcal isolates harboring bap were highly adherent and strong biofilm producers. In a mouse infection modelbap was involved in pathogenesis, causing a persistent infection.

Streptococcus suis small RNA rss04 contributes to the induction of meningitis by regulating capsule synthesis and by inducing biofilm formation in a mouse infection model

2017 ◽  
Vol 199 ◽  
pp. 111-119 ◽  
Author(s):  
Genhui Xiao ◽  
Huanyu Tang ◽  
Shouming Zhang ◽  
Haiyan Ren ◽  
Jiao Dai ◽  
...  
Keyword(s):  
Small Rna ◽  
Biofilm Formation ◽  
Streptococcus Suis ◽  
Infection Model ◽  
Mouse Infection Model ◽  
Mouse Infection

scholarly journals Mucoid morphotype variation of Burkholderia multivorans during chronic cystic fibrosis lung infection is correlated with changes in metabolism, motility, biofilm formation and virulence

Microbiology ◽  
2011 ◽  
Vol 157 (11) ◽  
pp. 3124-3137 ◽  
Author(s):  
Inês N. Silva ◽  
Ana S. Ferreira ◽  
Jörg D. Becker ◽  
James E. A. Zlosnik ◽  
David P. Speert ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Phenotypic Variation ◽  
Biofilm Formation ◽  
Burkholderia Cepacia ◽  
Galleria Mellonella ◽  
Acute Infection ◽  
Lung Infection ◽  
Infection Model ◽  
Burkholderia Multivorans ◽  
Expression Of Genes

Burkholderia cepacia complex (Bcc) bacteria are opportunistic pathogens infecting hosts such as cystic fibrosis (CF) patients. Long-term Bcc infection of CF patients’ airways has been associated with emergence of phenotypic variation. Here we studied two Burkholderia multivorans clonal isolates displaying different morphotypes from a chronically infected CF patient to evaluate trait development during lung infection. Expression profiling of mucoid D2095 and non-mucoid D2214 isolates revealed decreased expression of genes encoding products related to virulence-associated traits and metabolism in D2214. Furthermore, D2214 showed no exopolysaccharide production, lower motility and chemotaxis, and more biofilm formation, particularly under microaerophilic conditions, than the clonal mucoid isolate D2095. When Galleria mellonella was used as acute infection model, D2214 at a cell number of approximately 7×106 c.f.u. caused a higher survival rate than D2095, although 6 days post-infection most of the larvae were dead. Infection with the same number of cells by mucoid D2095 caused larval death by day 4. The decreased expression of genes involved in carbon and nitrogen metabolism may reflect lower metabolic needs of D2214 caused by lack of exopolysaccharide, but also by the attenuation of pathways not required for survival. As a result, D2214 showed higher survival than D2095 in minimal medium for 28 days under aerobic conditions. Overall, adaptation during Bcc chronic lung infections gave rise to genotypic and phenotypic variation among isolates, contributing to their fitness while maintaining their capacity for survival in this opportunistic human niche.

scholarly journals Development of in Vitro Resistance to Daptomycin in Enterococcus Faecium and Estimation of Its Fitness Cost

2020 ◽  
Author(s):  
Weiliang Zeng ◽  
Tao Chen ◽  
Qing Wu ◽  
Ye Xu ◽  
Kaihang Yu ◽  
...  
Keyword(s):  
Enterococcus Faecium ◽  
Biofilm Formation ◽  
Galleria Mellonella ◽  
Resistance Mechanisms ◽  
Fitness Cost ◽  
Resistant Bacteria ◽  
Infection Model ◽  
Dynamic Resistance ◽  
Vancomycin Resistant

Abstract BackgroundDaptomycin has broad-spectrum antibacterial activity against Gram-positive pathogens, but recent studies have revealed cases where daptomycin has failed to treat multidrug-resistant bacteria, such as vancomycin-resistant Enterococcus faecium. However, the resistance evolution of E. faecium to daptomycin in vitro and fitness cost remain unclear. In this study, we sought to analyze the resistance development and mechanism of E. faecium to datomycin, and futher to investigate the relationship between daptomycin resistance and fitness cost.MethodsTo investigate the development of daptomycin resistance in E. faecium, 6 daptomycin-susceptible (DAP-S) clinical isolates, including 3 vancomycin-resistant E. faecium (VRE) and 3 vancomycin-susceptible E. faecium (VSE), were exposured to daptomycin in vitro by serial passage experiment. Then the different resistance mechanisms of daptomycin-resistant (DAP-R) mutants were analyzed by polymerase chain reaction (PCR), cytochrome C binding assay and transmission electron microscopy. Furthermore, we also estimated the changes of fitness cost among each highly DAP-R mutants by bacterial growth curve measurement, in vitro competition experiments, infection model of Galleria mellonella larvae and biofilm formation assays.ResultsIn vitro, a total of 21 DAP-R mutants with minimal inhibitory concentration (MIC) of 4 to 512 μg/mL were obtained, and these mutants carried more than one mutation of LiaFSR and YycFG system encoding genes. More positive charges were detected among highly DAP-R mutants than parent isolates, and the cell walls of SC1174-D and SC1762-D mutants were remarkly thicker than those of the parent isolates. In comparison with parent isolates, besides, the growth, competition ability and virulence were significantly reduced, while the biofilm formation capacity was markedly elevated among each highly DAP-R mutants.ConclusionsOur findings suggest that E. faecium isolates are able to rapidly acquire DAP resistance in vitro through different dynamic resistance mechanisms, which often accompany by significant fitness cost. Intriguingly, DAP and glycopeptide antibiotics may present collateral-sensitivity during E. faecium acquired DAP resistance in vitro.

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