Suppressing the phenotypic virulence factors of Uropathogenic Escherichia coli using marine polysaccharide

Correlation between antimicrobial resistance, biofilm formation, and virulence determinants in uropathogenic Escherichia coli from Egyptian hospital

BACKGROUND

Uropathogenic Escherichia coli (UPEC) is the main etiological agent behind community-acquired and hospital-acquired urinary tract infections (UTIs), which are among the most prevalent human infections. The management of UPEC infections is becoming increasingly difficult owing to multi-drug resistance, biofilm formation, and the possession of an extensive virulence arsenal. This study aims to characterize UPEC isolates in Tanta, Egypt, with regard to their antimicrobial resistance, phylogenetic profile, biofilm formation, and virulence, as well as the potential associations among these factors.

METHODS

One hundred UPEC isolates were obtained from UTI patients in Tanta, Egypt. Antimicrobial susceptibility was assessed using the Kirby-Bauer method. Extended-spectrum β-lactamases (ESBLs) production was screened using the double disk synergy test and confirmed with PCR. Biofilm formation was evaluated using the microtiter-plate assay and microscopy-based techniques. The phylogenetic groups of the isolates were determined. The hemolytic activity, motility, siderophore production, and serum resistance of the isolates were also evaluated. The clonal relatedness of the isolates was assessed using ERIC-PCR.

RESULTS

Isolates displayed elevated resistance to cephalosporins (90-43%), sulfamethoxazole-trimethoprim (63%), and ciprofloxacin (53%). Ninety percent of the isolates were multidrug-resistant (MDR)/ extensively drug-resistant (XDR) and 67% produced ESBLs. Notably, there was an inverse correlation between biofilm formation and antimicrobial resistance, and 31%, 29%, 32%, and 8% of the isolates were strong, moderate, weak, and non-biofilm producers, respectively. Beta-hemolysis, motility, siderophore production, and serum resistance were detected in 64%, 84%, 65%, and 11% of the isolates, respectively. Siderophore production was correlated to resistance to multiple antibiotics, while hemolysis was more prevalent in susceptible isolates and associated with stronger biofilms. Phylogroups B2 and D predominated, with lower resistance and stronger biofilms in group B2. ERIC-PCR revealed considerable diversity among the isolates.

CONCLUSION

This research highlights the dissemination of resistance in UPEC in Tanta, Egypt. The evident correlation between biofilm and resistance suggests a resistance cost on bacterial cells; and that isolates with lower resistance may rely on biofilms to enhance their survival. This emphasizes the importance of considering biofilm formation ability during the treatment of UPEC infections to avoid therapeutic failure and/or infection recurrence.

Anti-biofilm mechanism of a synthetical low molecular weight poly-d-mannose on Salmonella Typhimurium

In this study, a low molecular weight poly-d-mannose (LMWM) was separated from a mixed polysaccharide synthesized previously. Monosaccharide composition, Fourier-Transform infrared spectroscopy (FT-IR), periodate oxidation and smith degradation were determined. After safety evaluation, the inhibition of LMWM on the different biofilm formation stages of Salmonella enterica serovar Typhimurium (S. Typhimurium) was tested in vitro. Furthermore, the effect of LMWM on the adhesion of S. Typhimurium to Caco-2 cells and cell surface hydrophobicity (CSH) were observed. Results indicated that LMWM was a homopolysaccharide without cytotoxicity and hemolysis, containing both α-mannose and β-mannose. It showed obvious anti-biofilm activity on S. Typhimurium and mainly activated on the initial adhesion and formation stage, even better than the commercial S. cerevisiae mannan (CM). LMWM inhibited the adhesion of S. Typhimurium on Caco-2 cells with the inhibition rate of 61.04 % at 2 mg/ml. Meanwhile, LMWM decreased the hydrophobicity of S. Typhimurium cell surface. In conclusion, the inhibitory effect on S. Typhimurium biofilm was not caused by bacteriostatic or bactericidal activity of LMWM. The specific anti-adhesion and the decrease of bacterial CSH by LMWM may closely relate to anti-biofilm mechanism. This study provides some supports for the application of LMWM as antibiotics alternative on S. Typhimurium in the future.

Advances in sulfonated modification and bioactivity of polysaccharides

Polysaccharides, as biological macromolecules, are widely found in plants, animals, fungi, and bacteria and exhibit various biological activities. However, many natural polysaccharides exhibit low or non-existent biological activities because of their high molecular weights and poor water solubility, limiting their application in many fields. Sulfonation is one of the most effective chemical modification methods to improve physicochemical properties and biological activities of natural polysaccharides or even impart natural polysaccharides with new biological activities. Therefore, sulfonated polysaccharides have attracted increasing attention because of their antioxidant, anticoagulant, antiviral, and immunomodulatory properties. This paper reviews the recent advances in the sulfonation of polysaccharides, including preparation, characterization, and biological activities of sulfonated polysaccharides, and provides a theoretical basis for wide applications of sulfonated polysaccharides.

Development of an anti-infective urinary catheter composed of polyvinyl alcohol/sodium alginate/methylcellulose/polyethylene glycol by using a pressure-assisted 3D-printing technique

Catheter-associated urinary tract infections (CAUTI) are a common complication associated with catheterization, leading to urosepsis, bacteriuria, and septicaemia. The present work focuses on 3D printing a urinary catheter with anti-infective properties using various concentrations of polyvinyl alcohol (PVA, e.g., 6-8 %), sodium alginate (NaAlg, e.g. 1-4 %), methylcellulose (MC, 5 %), polyethylene glycol (PEG, 5 %) impregnated with secnidazole, an antibiotic acting against Gram-negative bacteria. To produce suitable polymer ink for Pressure Assisted Microsyringe (PAM) 3D printing, the cross-linked between NaAlg and calcium chloride is necessary to prepare the catheter. The optimised catheter was found to have an outer diameter of 5 mm, an inner diameter of 3.5 mm, and a length of the catheter of 50 mm. The analysis by various methods confirms the successful incorporation of secnidazole in the 3D-printed catheter. A drug-loaded/coated catheter showed an initial drug release of 79 % following a sustained release to reach 100 % within 5 h. Weibull model fits well with the drug release data. The release models suggest the Quasi-Fickian diffusion mechanism from the system. Moreover, the secnidazole 3D printed catheter disrupted biofilms and suppressed all the Quorum sensing mediated virulence factors of two important keystone pathogens causing urinary tract infections.

Polysaccharide-based antibacterial coating technologies

To tackle antimicrobial resistance, a global threat identified by the United Nations, is a common cause of healthcare-associated infections (HAI) and is responsible for significant costs on healthcare systems, a substantial amount of research has been devoted to developing polysaccharide-based strategies that prevent bacterial attachment and biofilm formation on surfaces. Polysaccharides are essential building blocks for life and an abundant renewable resource that have attracted much attention due to their intrinsic remarkable biological potential antibacterial activities. If converted into efficient antibacterial coatings that could be applied to a broad range of surfaces and applications, polysaccharide-based coatings could have a significant potential global impact. However, the ultimate success of polysaccharide-based antibacterial materials will be determined by their potential for use in manufacturing processes that are scalable, versatile, and affordable. Therefore, in this review we focus on recent advances in polysaccharide-based antibacterial coatings from the perspective of fabrication methods. We first provide an overview of strategies for designing polysaccharide-based antimicrobial formulations and methods to assess the antibacterial properties of coatings. Recent advances on manufacturing polysaccharide-based coatings using some of the most common polysaccharides and fabrication methods are then detailed, followed by a critical comparative overview of associated challenges and opportunities for future developments. STATEMENT OF SIGNIFICANCE: Our review presents a timely perspective by being the first review in the field to focus on advances on polysaccharide-based antibacterial coatings from the perspective of fabrication methods along with an overview of strategies for designing polysaccharide-based antimicrobial formulations, methods to assess the antibacterial properties of coatings as well as a critical comparative overview of associated challenges and opportunities for future developments. Meanwhile this work is specifically targeted at an audience focused on featuring critical information and guidelines for developing polysaccharide-based coatings. Including such a complementary work in the journal could lead to further developments on polysaccharide antibacterial applications.

A New Approach in Meat Bio-Preservation through the Incorporation of a Heteropolysaccharide Isolated from Lobularia maritima L

In this study, a new heteropolysaccharide extracted from Lobularia maritima (L.) Desv. (LmPS), a halophyte harvested in Tunisia, was evaluated as an antioxidant and antibacterial additive in the bio-preservation of raw minced meat. For antibacterial testing, Gram-positive bacteria such as Staphylococcus aureus ATCC and Listeria monocytogenes ATCC 19,117 and Gram-negative bacteria such as Salmonella enterica ATCC 43,972 and Escherichia coli ATCC 25,922 were used. The results indicate that this polymer had a significant antibacterial activity against foodborne pathogens. Additionally, the effects of LmPS at 0.15, 0.3 and 0.6% on refrigerated raw ground beef were investigated from a microbiological, chemical, and sensory perspective. Microbiological analysis of the meat showed that treatment with LmPS significantly (p < 0.05) improved its shelf life, while the biochemical analysis evidenced a significant (p < 0.05) decrease in lipid oxidation. LmPS at 0.6% significantly reduced by 61% and 48% metmyoglobin accumulation at the end of the storage period when compared to BHT and control samples, respectively. The chemometric approach highlighted the relationships among the different meat quality parameters. LmPS can be introduced in the food industry as a powerful natural additive and could be an alternative to synthetic antioxidant compounds.

Synthesis of Fully Deacetylated Quaternized Chitosan with Enhanced Antimicrobial Activity and Low Cytotoxicity

Fully deacetylated quaternary chitosan (DQCTS) was prepared by replacing the carboxyl group of chitosan with a quaternary ammonium salt. The DQCTS was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and nuclear magnetic resonance (NMR). The antimicrobial activity of DQCTS was evaluated using the minimum inhibitory concentrations (MIC) methods and time-kill assay. DQCTS exhibited strong antibacterial and antifungal activity against Staphylococcus aureus, Escherichia coli O157: H7, Candida albicans, and Aspergillus flavus. Especially, the antifungal activity against C. albicans of DQCTS was greatly improved at 15.6 µg/mL of MIC and 31.3 µg/mL of minimum fungicidal concentration (MFC). Expression levels of virulence genes of microorganisms were also significantly decreased by DQCTS treatment, and the risk of virulence of microorganisms might be decreased. The result of the cytotoxic effect of DQCTS on human skin cells (HaCaT cells) indicated that the cytotoxicity of DQCTS on HaCaT cells was nearly non-toxic at 50 μg/mL. The DQCTS, with strong antimicrobial and low toxicity, has a high potential for use in functional food packaging and biomedical applications.

Antimicrobial and anti-biofilm activities of chlorogenic acid grafted chitosan against Staphylococcus aureus

In this work, Chitosan-grafted-chlorogenic acid (CS-g-CA) was prepared by the carbodiimide method. The purpose of this study was to investigate the antibacterial and anti-biofilm activity of CS-g-CA against Staphylococcus aureus (S. aureus). The minimum inhibitory concentration (MIC) of CS-g-CA against S. aureus was identified as 0.625 mg/mL. S. aureus treated with 1/2×MIC of CS-g-CA had a longer logarithmic growth phase than that of the CK group, while 1×MIC and 2×MIC inhibited the growth of bacteria. The damaging effect of CS-g-CA on bacterial cells was analyzed by measuring the activity of cellular antioxidant enzymes (Catalase (CAT) and Glutathione peroxidase (GSH-Px)) and intracellular enzymes (alkaline phosphatase (AKPase) and adenosine triphosphatase (ATPase)). The results of DNA gel electrophoresis illustrated that CS-g-CA disrupted the normal metabolism of bacteria. Scanning electron microscopy (SEM) results showed that S. aureus shrank and died under CS-g-CA treatment. 1×MIC of CS-g-CA can significantly inhibit the formation of biofilms, and 1/2×MIC of CS-g-CA control the swimming speed of S. aureus. In addition, 77.53% mature biofilm and 60.62% extracellular polysaccharide (EPS) in the mature biofilm of S. aureus were eradicated by CS-g-CA at 2×MIC. Confocal laser scanning microscopy (CLSM) observation further confirmed these results. Therefore, CS-g-CA was an antimicrobial and antibiofilm agent to control S. aureus, which can effectively controlling the growth of S. aureus in food, thereby preventing the occurrence of food-borne diseases.

Exopolysaccharides from Marine Microbes: Source, Structure and Application

The unique living environment of marine microorganisms endows them with the potential to produce novel chemical compounds with various biological activities. Among them, the exopolysaccharides produced by marine microbes are an important factor for them to survive in these extreme environments. Up to now, exopolysaccharides from marine microbes, especially from extremophiles, have attracted more and more attention due to their structural complexity, biodegradability, biological activities, and biocompatibility. With the development of culture and separation methods, an increasing number of novel exopolysaccharides are being found and investigated. Here, the source, structure and biological activities of exopolysaccharides, as well as their potential applications in environmental restoration fields of the last decade are summarized, indicating the commercial potential of these versatile EPS in different areas, such as food, cosmetic, and biomedical industries, and also in environmental remediation.

New tools to mitigate drug resistance in Enterobacteriaceae - Escherichia coli and Klebsiella pneumoniae

Treatment to common bacterial infections are becoming ineffective of late, owing to the emergence and dissemination of antibiotic resistance globally. Escherichia coli and Klebsiella pneumoniae are the most notorious microorganisms and are among the critical priority pathogens listed by WHO in 2017. These pathogens are the predominant cause of sepsis, urinary tract infections (UTIs), pneumonia, meningitis and pyogenic liver abscess. Concern arises due to the resistance of bacteria to most of the beta lactam antibiotics like penicillin, cephalosporin, monobactams and carbapenems, even to the last resort antibiotics like colistin. Preventing influx by modulation of porins, extruding the antibiotics by overexpression of efflux pumps, mutations of drug targets/receptors, biofilm formation, altering the drug molecules and rendering them ineffective are few resistance mechanisms that are adapted by Enterobacteriaeceae upon exposure to antibiotics. The situation is exacerbated due to the process of horizontal gene transfer (HGT), wherein the genes encoding resistance mechanisms are transferred to the neighbouring bacteria through plasmids/phages/uptake of free DNA. Carbapenemases, other beta lactamases and mcr genes coding for colistin resistance are widely disseminated leading to limited/no therapeutic options against those infections. Development of new antibiotics can be viewed as a possible solution but it involves major investment, time and labour despite which, the bacteria can easily adapt to the new antibiotic and evolve resistance in a relatively short time. Targeting the resistance mechanisms can be one feasible alternative to tackle these multidrug resistant (MDR) pathogens. Removal of plasmid (plasmid curing) causing resistance, use of bacteriophages and bacteriotherapy can be other potential approaches to combat infections caused by MDR E. coli and K. pneumoniae. The present review discusses the efficacies of these therapies in mitigating these infections, which can be potentially used as an adjuvant therapy along with existing antibiotics.

Uropathogenic Escherichia coli in India-an Overview on Recent Research Advancements and Trends

Urinary tract infection (UTI), a prevalent disease in India, also ranks among the most common infections in developing countries. The rapid emergence of antibiotic-resistant uropathogenic Escherichia coli (UPECs), the leading etiologic agent of UTI, in the last few years, led to an upsurge in the health care cost. This caused a considerable economic burden, especially in low-middle income country, India. This review aimed to provide an explicit overview of the recent advancements in E. coli-mediated UTI in India by incorporation of valuable information from the works published in PubMed and Google Scholar in the last six years (2015 to August, 2020). The literature survey demonstrated UPECs as the most predominant uropathogen in India, especially among females, causing both asymptomatic bacteriuria (ABU) and symptomatic UTI. An overall increasing national trend in resistance to penicillins, cephalosporins, aminoglycosides, fluoroquinolones, and sulfonamides was perceived irrespective of ABU and symptomatic UPECs during the aforementioned study period. High incidences of multidrug resistance, extended-spectrum β-lactamases, metallo β-lactamases, and AmpCs in UPECs were reported. Notable information on the pathogenic profiles, phylogroups, pathogenicity islands, and evidence of pathoadaptive FimH mutations was described. Alternative therapeutics and potential drug targets against UPECs were also reconnoitered. Therefore, the nationwide widespread occurrences of highly virulent MDR UPEC together with the limited availability of therapeutics highlighted the urgent need for promotion and invention of alternative therapeutics, search for which had already been started. Moreover, investigation of several mechanisms of UPEC infection and the search for potential drug targets might help to design newer therapeutics.

Effect of sub-minimal inhibitory concentration ceftazidime on the pathogenicity of uropathogenic Escherichia coli

Uropathogenic Escherichia coli (UPEC) is the most prevalent causative agent of urinary tract infections (UTIs). The pathogenicity of UPEC relies on the expression of virulence factors which could be regulated by intercellular signal molecules. Our previous study found that sub-minimal inhibitory concentration ceftazidime (sub-MIC CAZ) could inhibit the biofilm formation of E. coli by luxS/AI-2 or indole. Therefore, we speculated that sub-MIC CAZ might affect the pathogenic capacity of UPEC. In this study, the results showed that sub-MIC CAZ could significantly inhibit the adhesion ability, biofilm formation and swimming and swarming motilities of UPEC isolated from recurrent UTI patient. Meanwhile, obvious decreased hemolytic activity and cytotoxicity were observed in CAZ-pretreated UPEC. Furthermore, qRT-PCR results confirmed the downregulating ability of CAZ on the expression of adhesion genes, motility genes, toxin gene and signal molecule synthesis genes, which are important for virulence and biofilm formation of UPEC. Pre-treatment of UPEC with sub-MIC CAZ resulted in the reduced adhesion to human bladder epithelial cell 5637 and the decreased numbers of intracellular bacterial communities in cells. Consistent with the results in vitro, the pretreatment of CAZ resulted in the reduction of UPEC load in the bladder and the less severity of UPEC-induced inflammation compared with control group. The present study results indicated that sub-MIC CAZ could decrease the pathogenicity of UPEC and might be served as an effective antimicrobial agent to combat recurrent UTI caused by UPEC.

Chitosan coated catheters alleviates mixed species biofilms of Staphylococcus epidermidis and Candida albicans

Microorganisms which adhere to the surfaces of indwelling medical implants develop into a sessile microbial community to form monomicrobial or polymicrobial biofilms. Staphylococcus epidermidis and Candida albicans are the most common pathogens co-isolated from device mediated infections. Hence development of catheters coated with anti-fouling substances is of great interest. In this current study, chitosan, extracted from the shells of marine crab Portunus sanguinolentus was coated over the surface of the urinary catheters and checked for its efficacy to inhibit the adherence of both mono and mixed species biofilms. The Extracted Chitosan (EC) coated catheters showed profound activity in reducing the preformed biofilms and the other virulence factors of the pathogens like slime production in S. epidermidis and yeast to hyphal swtich in C. albicans. Furthermore, qPCR analysis showed that EC could downregulate the virulence genes in both the pathogens when grown as monospecies and mixed species biofilms.

Prevalence of Virulence Genes and Their Association with Antimicrobial Resistance Among Pathogenic E. coli Isolated from Egyptian Patients with Different Clinical Infections

Introduction

Escherichia (E.) coli can cause intestinal and extra-intestinal infections which ranged from mild to life-threatening infections. The severity of infection is a product of many factors including virulence properties and antimicrobial resistance.

Objectives

To determine the antibiotic resistance pattern, the distribution of virulence factors and their association with one another and with some selected resistance genes.

Methods

Virulence properties were analyzed phenotypically while antimicrobial susceptibility was tested by Kirby-Bauer agar disc diffusion method. In addition, 64 E. coli isolates were tested for 6 colicin genes, fimH, hlyA, traT, csgA, crl virulence genes and bla_−CTX-M-15, bla_−oxa-2, and bla_−oxa-10 resistance genes by polymerase chain reaction (PCR).

Results

Extra-intestinal pathogenic E. coli isolated from urine and blood samples represented a battery of virulence factors and resistance genes with a great ability to produce biofilm. Also, a significant association (P<0.05) among most of the tested colicin, virulence and resistance genes was observed. The observed associations indicate the importance and contribution of the tested factors in the establishment and the progress of infection especially with Extra-intestinal E. coli (ExPEC) which is considered a great challenging health problem.

Conclusion

There is a need for studying how to control these factors to decrease the rate and the severity of infections. The relationship between virulence factors and resistance genes is complex and needs more studies that should be specific for each area.

Novel thiazolinyl-picolinamide based palladium(II) complex-impregnated urinary catheters quench the virulence and disintegrate the biofilms of uropathogens

Pseudomonas aeruginosa and Serratia marcescens are prominent members belonging to the group of ESKAPE pathogens responsible for Urinary Tract Infections (UTI) and nosocomial infections. Both the pathogens regulate several virulence factors, including biofilm formation through quorum sensing (QS), an intercellular communication mechanism. The present study describes the anti-biofilm and QS quenching effect of thiazolinyl-picolinamide based palladium(II) complexes against P. aeruginosa and S. marcescens. Palladium(II) complexes showed quorum sensing inhibitory potential in inhibiting swarming motility behaviour, pyocyanin production and other QS mediated virulence factors in both P. aeruginosa and S. marcescens. In addition, the establishment of biofilms was prevented on palladium (II) coated catheters. Overall, the present study demonstrates that thiazolinyl-picolinamide based palladium (II) complexes will be a promising strategy to combat device-mediated UTI infections.

Antimicrobial potential of the food-grade additive carvacrol against uropathogenic E. coli based on membrane depolarization, reactive oxygen species generation, and molecular docking analysis

The antibiotic resistance of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli has increased drastically in recent years. In our study, we determined the principle mechanisms of action for the food-grade additive carvacrol against ESBL E. coli isolated from the blood of patients with a urinary tract infection. Carvacrol, which has a minimum inhibitory concentration of 150 μg/ml and a minimum bactericidal concentration of 300 μg/ml, reduced E. coli cell counts in a time-dependent manner. After treatment with carvacrol, the E. coli killing time was found to be 120 min. Fluorescent staining confirmed an increase in bacterial cell death, greater membrane depolarization, and an elevated oxidative burst in carvacrol-treated E. coli. Carvacrol also induced the release of cellular DNA, proteins, and potassium ions from bacterial cells and reduced both the number of E. coli in invasion assays against macrophages and the levels of the inflammatory proteins TNF-α and COX-2. In addition, carvacrol was found to inhibit β-lactamase enzyme activity (in vitro), which was supported by in silico results. Moreover, carvacrol inhibited motility, and protected against bacterial invasion. Overall, the findings suggest that carvacrol has significant antimicrobial potential against ESBL E. coli.