I am a holder of PhD in Microbiology and Immunology. My current area of research is targeting of virulence and quorum sensing inhibition. Address: Egypt
Biofilms facilitate the pathogenesis of life-threatening Pseudomonas aeruginosa infections by coa... more Biofilms facilitate the pathogenesis of life-threatening Pseudomonas aeruginosa infections by coating mucosal surfaces or invasive devices and offer protection from antimicrobial therapy and the host immune response, thus increasing mortality rates and financial burden. Herein, new hybrid N-acylcysteines (NAC) incorporating selected acyl groups from organic acids and their derivatives, which are capable of quenching pathogen quorum sensing (QS) systems, were designed and their antibiofilm activity and anti-QS were evaluated. N-acylcysteines (4a−h) were synthesized and characterized by 1 H NMR and 13 C NMR, and their purity was confirmed by elemental analyses. N-(4-Hydroxy-3,5-dimethoxybenzoyl)-L-cysteine (4d) and N-(4-methoxybenzoyl)-L-cysteine (4h) showed a higher antibiofilm activity against PAO1 biofilms than the rest of the targets and the standard NAC. They showed 83 and 82% inhibition of biofilms at 5 mM and eradicated mature biofilms at 20 mM concentrations (NAC biofilm inhibition = 66% at 10 mM and minimum biofilm eradication concentration = 40 mM). This was confirmed via visualizing adherent biofilm cells on catheter pieces using scanning electron microscopy. In the same vein, both 4d and 4h showed the highest docking score with the QS signal receptor protein LasR (−7.8), which was much higher than that of NAC (−5) but less than the score of the natural agonist N-(3-oxododecanoyl)-L-homoserine (OdDHL) (−8.5). Target 4h (5 mM) decreased the expression of quorum sensing encoding genes in P. aeruginosa PAO1 strain by 53% for pslA, 47% for lasI and lasR, and 29% for filC, lowered PAO1 pyocyanin production by 76.43%, completely blocked the proteolytic activity of PAO1, and did not affect PAO1 cell viability. Targets 4d and 4h may find applications for the prevention and treatment of biofilm-mediated P. aeruginosa local infections of the skin, eye, and wounds. N-(4-Methoxybenzoyl)-L-cysteine 4h is a promising dual-acting matrix disruptive and anti-QS antibiofilm agent for further investigation and optimization.
Biofilms facilitate the pathogenesis of life-threatening Pseudomonas aeruginosa infections by coa... more Biofilms facilitate the pathogenesis of life-threatening Pseudomonas aeruginosa infections by coating mucosal surfaces or invasive devices and offer protection from antimicrobial therapy and the host immune response, thus increasing mortality rates and financial burden. Herein, new hybrid N-acylcysteines (NAC) incorporating selected acyl groups from organic acids and their derivatives, which are capable of quenching pathogen quorum sensing (QS) systems, were designed and their antibiofilm activity and anti-QS were evaluated. N-acylcysteines (4a−h) were synthesized and characterized by 1 H NMR and 13 C NMR, and their purity was confirmed by elemental analyses. N-(4-Hydroxy-3,5-dimethoxybenzoyl)-L-cysteine (4d) and N-(4-methoxybenzoyl)-L-cysteine (4h) showed a higher antibiofilm activity against PAO1 biofilms than the rest of the targets and the standard NAC. They showed 83 and 82% inhibition of biofilms at 5 mM and eradicated mature biofilms at 20 mM concentrations (NAC biofilm inhibition = 66% at 10 mM and minimum biofilm eradication concentration = 40 mM). This was confirmed via visualizing adherent biofilm cells on catheter pieces using scanning electron microscopy. In the same vein, both 4d and 4h showed the highest docking score with the QS signal receptor protein LasR (−7.8), which was much higher than that of NAC (−5) but less than the score of the natural agonist N-(3-oxododecanoyl)-L-homoserine (OdDHL) (−8.5). Target 4h (5 mM) decreased the expression of quorum sensing encoding genes in P. aeruginosa PAO1 strain by 53% for pslA, 47% for lasI and lasR, and 29% for filC, lowered PAO1 pyocyanin production by 76.43%, completely blocked the proteolytic activity of PAO1, and did not affect PAO1 cell viability. Targets 4d and 4h may find applications for the prevention and treatment of biofilm-mediated P. aeruginosa local infections of the skin, eye, and wounds. N-(4-Methoxybenzoyl)-L-cysteine 4h is a promising dual-acting matrix disruptive and anti-QS antibiofilm agent for further investigation and optimization.
The repurposing of drugs is one of the most competent strategies for discovering new antimicrobia... more The repurposing of drugs is one of the most competent strategies for discovering new antimicrobial agents. Vildagliptin is a dipeptidyl peptidase-4 inhibitor (DPI-4) that is used effectively in combination with metformin to control blood glucose levels in diabetic patients. This study was designed to evaluate the anti-virulence activities of this combination against one of the most clinically important pathogens, Pseudomonas aeruginosa. The current findings show a significant ability of the vildagliptin–metformin combination to diminish biofilm formation, bacterial motility, and the production of virulent extracellular enzymes and pyocyanin pigment. Furthermore, this drug combination significantly increased the susceptibility of P. aeruginosa to oxidative stress, indicating immunity enhancement in the eradication of bacterial cells. In compliance with the in vitro findings, the histopathological photomicrographs of mice showed a considerable protective effect of the metformin–vildag...
The development of bacterial resistance to traditional antibiotics constitutes an emerging public... more The development of bacterial resistance to traditional antibiotics constitutes an emerging public health issue. Promising approaches have been innovated to conquer bacterial resistance, and targeting bacterial virulence is one of these approaches. Bacterial virulence mitigation offers several merits, as antivirulence agents do not affect the growth of bacteria and hence do not induce bacteria to develop resistance. In this direction, numerous drugs have been repurposed as antivirulence agents prior to their clinical use alone or in combination with traditional antibiotics. Quorum sensing (QS) plays a key role in controlling bacterial virulence. In the current study, dipeptidase inhibitor-4 (DPI-4) antidiabetic gliptins were screened for their antivirulence and anti-quorum sensing (anti-QS) activities against Gram-negative Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus. Upon assessing their antibiofilm activities, the ten tested gliptins significantly diminished biofi...
The development of bacterial resistance is an insistent global health care issue, especially in l... more The development of bacterial resistance is an insistent global health care issue, especially in light of the dwindled supply of new antimicrobial agents. This mandates the development of new innovative approaches to overcome the resistance development obstacle. Mitigation of bacterial virulence is an interesting approach that offers multiple advantages. Employing safe chemicals or drugs to mitigate bacterial virulence is an additive advantage. In the current study, the in vitro antivirulence activities of citrate were evaluated. Significantly, sodium citrate inhibited bacterial biofilm formation at sub-MIC concentrations. Furthermore, sodium citrate decreased the production of virulence factors protease and pyocyanin and diminished bacterial motility. Quorum sensing (QS) is the communicative system that bacterial cells utilize to communicate with each other and regulate the virulence of the host cells. In the present study, citrate in silico blocked the Pseudomonas QS receptors and ...
Journal of microbiology, biotechnology and food sciences, 2021
Respiratory tract infections caused by Klebsiella pneumoniae are frequently associated with high ... more Respiratory tract infections caused by Klebsiella pneumoniae are frequently associated with high mortality and morbidity rates. Treatment of these infections is usually difficult due to the emergence of multiple resistances to antibiotics. Multidrug efflux pumps are greatly involved in antibiotic resistance in Gram-negative bacteria including Klebsiella pneumoniae. In the current study, efflux activity was observed in 93.75% of Klebsiella pneumoniae clinical isolates by the qualitative acridine orange agar method. This finding was further confirmed genotypically by polymerase chain reaction that showed the presence of efflux genes AcrA, AcrB, TolC and mdtk in these isolates. The ability of metformin to inhibit efflux activity was compared with the reference efflux pump inhibitors verapamil and ascorbic acid. Metformin was more active than ascorbic acid and less active than verapamil. Up to our knowledge, this is the first report that shows that metformin has an efflux pump-inhibitin...
Hepatitis C virus (HCV) is one of the most epidemic viral infections in the world. Three-quarters... more Hepatitis C virus (HCV) is one of the most epidemic viral infections in the world. Three-quarters of individuals infected with HCV become chronic. As a consequence of persistent inflammation, a considerable percentage of chronic patients progress to liver fibrosis, cirrhosis, and finally hepatocellular carcinoma. Cytokines, which are particularly produced from T-helper cells, play a crucial role in immune protection against HCV and the progression of the disease as well. In this study, the role of interleukins IL-33, IL-17, and IL-25 in HCV patients and progression of disease from chronicity to hepatocellular carcinoma will be characterized in order to use them as biomarkers of disease progression. The serum levels of the tested interleukins were measured in patients suffering from chronic hepatitis C (CHC), hepatocellular carcinoma (HCC), and healthy controls (C), and their levels were correlated to the degree of liver fibrosis, liver fibrosis markers and viral load. In contrast to...
Serratia marcescens is an opportunistic pathogen that causes diverse nosocomial infections. S. ma... more Serratia marcescens is an opportunistic pathogen that causes diverse nosocomial infections. S. marcescens has developed considerable resistance to different antibiotics and is equipped with an armory of virulence factors. These virulence factors are regulated in S. marcescens by an intercellular communication system termed quorum sensing (QS). Targeting bacterial virulence and QS is an interesting approach to mitigating bacterial pathogenesis and overcoming the development of resistance to antimicrobials. In this study, we aimed to evaluate the anti-virulence activities of secnidazole on a clinical isolate of S. marcescens. The effects of secnidazole at sub-inhibitory concentrations (sub-MICs) on virulence factors, swarming motility, biofilm formation, proteases, hemolysin activity, and prodigiosin production were evaluated in vitro. Secnidazole’s protective activity against S. marcescens pathogenesis was assessed in vivo in mice. Furthermore, a molecular docking study was conducted...
The bacterial resistance development due to the incessant administration of antibiotics has led t... more The bacterial resistance development due to the incessant administration of antibiotics has led to difficulty in their treatment. Natural adjuvant compounds can be co-administered to hinder the pathogenesis of resistant bacteria. Sotolon is the prevailing aromatic compound that gives fenugreek its typical smell. In the current work, the anti-virulence activities of sotolon on Pseudomonas aeruginosa have been evaluated. P. aeruginosa has been treated with sotolon at sub-minimum inhibitory concentration (MIC), and production of biofilm and other virulence factors were assessed. Moreover, the anti-quorum sensing (QS) activity of sotolon was in-silico evaluated by evaluating the affinity of sotolon to bind to QS receptors, and the expression of QS genes was measured in the presence of sotolon sub-MIC. Furthermore, the sotolon in-vivo capability to protect mice against P. aeruginosa was assessed. Significantly, sotolon decreased the production of bacterial biofilm and virulence factors, ...
Serratia marcescens is an opportunistic nosocomial pathogen and causes wound and burn infections.... more Serratia marcescens is an opportunistic nosocomial pathogen and causes wound and burn infections. It shows high resistance to antibiotics and its pathogenicity is mediated by an arsenal of virulence factors. Another therapeutic option to such infections is targeting quorum sensing (QS), which controls the expression of different S. marcescens virulence factors. Prevention of QS can deprive S. marcescens from its bacterial virulence without applying stress on the bacterial growth and facilitates the eradication of the bacteria by immunity. The objective of the current study is to explore the antimicrobial and antivirulence activities of xylitol against S. marcescens. Xylitol could inhibit the growth of S. marcescens. Sub-inhibitory concentrations of xylitol could inhibit biofilm formation, reduce prodigiosin production, and completely block protease activity. Moreover, xylitol decreased swimming motility, swarming motility and increased the sensitivity to hydrogen peroxide. The expre...
Background: Quorum sensing inhibitionis an advanced strategy that aims to interfere with bacteria... more Background: Quorum sensing inhibitionis an advanced strategy that aims to interfere with bacterial cell-to-cell communication systems (quorum sensing), which regulate virulence factors production in Pseudomonas aeruginosa, in order to overcome the globalcrisis of antimicrobial resistance. Objectives: Study the potential quorum sensing inhibitory effect of Zinc oxide (ZnO)nanoparticlesin Pseudomonas aeruginosa and the impact on production of virulence factors. Methods: Quorum sensing inhibitory effect of ZnO was evaluated by assessing its ability to reducePseudomonas aeruginosa virulence factors production; rhamnolipids, pyocyanin, pyoverdin, hemolysins, elastase and proteases. Furthermore, qRT-PCR was performed to determine ZnO inhibitory effect onQS-regulatory geneslasI, lasR,rhlI, rhlR, pqsA and pqsR that control virulence factors secretion. Moreover, mice survival test was conducted to investigate the influence of ZnO on Pseudomonas aeruginosa-induced mortality in vivo. Results: ZnO revealed a statistically significant reduction in the production of QS-controlled virulence factors rhamnolipids, pyocyanin, pyoverdin, hemolysins, elastase and proteases. Furthermore, ZnO exhibited a significant decrease in the relative expression of QS-regulatory geneslasI, lasR,rhlI, rhlR,pqsA and pqsR. Additionally, ZnO significantly reduced the pathogenesis of Pseudomonas aeruginosa in vivo Conclusion: ZnO nanoparticles can be used as a quorum sensing inhibitor in Pseudomonas aeruginosa infections either as an adjuvant or alternative to conventional antimicrobials.
Background: Staphylococcus aureus is an important nosocomial bacterium that is responsible for a ... more Background: Staphylococcus aureus is an important nosocomial bacterium that is responsible for a number of infections that may be fatal. The treatment of such infections is limited by emergence of antibiotic resistance. Targeting virulence of Staphylococcus aureus may provide an alternative option to antibiotic that may bypass the emergence of resistant strains due to lack of stress on viability. Objectives: Investigation of the ability of glyceryl trinitrate (GTN) to inhibit staphyloxanthin, biofilm and tolerance to oxidative stress. Methods: The disk sensitivity method was used to detect the methicillin resistance of Staphylococcus aureus. The effect of sub-inhibitory concentration of GTN on biofilm formation, staphyloxanthin production and tolerance to oxidative stress was evaluated. Molecular docking study was used to investigate the ability of GTN to bind to dehydrosqualene synthase enzyme. Results: GTN showed a significant inhibition of biofilm, staphyloxanthin and tolerance to oxidative stress. In the molecular docking study, it was found that GTN could bind to dehydrosqualene synthase enzyme by hydrogen bonding,electrostatic interaction and pi-cation interaction. Conclusion: The present study revealed the ability of GTN to serve as a potential anti-virulence candidate for attenuation of S. aureus pathogenicity.
Salmonella is a causative agent of wide range of diseases varying from gastroenteritis to systemi... more Salmonella is a causative agent of wide range of diseases varying from gastroenteritis to systemic typhoid fever. It uses specialized Type III secretion system (T3SS) by its two compartments to invade and intracellularly survive inside the immune cells. T3SS is expressed in two subsequent phases by two distinct Salmonella pathogenicity islands (SP) I and II. Understanding and evaluation of components T3SS-SPI1 and T3SS-SPI2 are very important, not only to evaluate the bacterial virulence but also to develop vaccines. In this study, the effect of mutation on SsaV encoding gene (one of the essential T3SS-SPI2 components) was investigated on the virulence behavior of Salmonella enterica serovar Typhimurium. We found a significant reduction in invasion capability and intracellular replication as well.
Background: Quorum sensing is a mechanism of intercellular communication that controls the produc... more Background: Quorum sensing is a mechanism of intercellular communication that controls the production of virulence factors in Pseudomonas aeruginosa. Inhibition of quorum sensing can disarm the virulence factors without exerting stress on bacterial growth that leads to emergence of antibiotic resistance. Objectives: Finding a new quorum sensing inhibitor and determining its inhibitory activities against virulence factors of Pseudomonas aeruginosa PAO1 strain. Methods: Quorum sensing was evaluated by estimation of violacein production by Chromobacterium violaceum CV026. Molecular docking was used to investigate the possible binding of metformin to LasR and rhlR receptors. The inhibition of pyocyanin, hemolysin, protease, elastase in addition to swimming and twitching motilities, biofilm formation and resistance to oxidative stress by metformin was also assessed. Results: Metformin significantly reduced the production of violacein pigment. Significant inhibition of pyocyanin, hemolysin, protease and elastase was achieved. Metformin markedly decreased biofilm formation, swimming and twitching motilities and increased the sensitivity to oxidative stress. In the molecular docking study, metformin could bind to LasR by hydrogen bonding and electrostatic interaction and to rhlR by hydrogen bonding only. Conclusion: Metformin can act as a quorum sensing inhibitor and virulence inhibiting agent that may be useful in the treatment of Pseudomonas aeruginosa infection.
Background: Targeting quorum sensing is an alternative approach to antibiotics.Targeting quorum s... more Background: Targeting quorum sensing is an alternative approach to antibiotics.Targeting quorum sensing-regulated virulence will disarm the pathogen without exerting pressure on its growth. As a result, emergence of resistance is avoided and the immune system can easily eradicate bacteria. Objectives: Investigation of the possible inhibition of quorum sensing-regulated virulence of Pseudomonas aeruginosa by glyceryltrinitrate. Methods: The quorum sensing inhibiting activity of glyceryl trinitrate was assessed by inhibition of violacein production in Chromobacterium violaceum ATCC 12472. Its ability to inhibit pyocyanin, protease, biofilm and tolerance to oxidative stress was evaluated. Docking study was performed to study the interference of glyceryl trinitrate with the binding of autoinducers with LasR and rhlR receptors. Results: Glyceryl trinitrate exerted a significant biofilm inhibiting and eradicating activities. It decreased the production of quorum-sensing dependent violacein production. It significantly inhibited the production of pyocyanin and protease and diminished the tolerance against oxidative stress. Molecular docking study showed that glyceryl trinitrate interferes with the binding of autoinducers to their receptors. It could bind to Las Rand rhlr receptors with binding energy of-93.47 and-77.23, respectively. Conclusion: Glyceryl trinitrate can be an antivirulence agent in the treatment of Pseudomonas aeruginosa topical infections such as burn infections.
The effect of xylitol and sorbitol on the biofilm susceptibility to antibiotics was investigated ... more The effect of xylitol and sorbitol on the biofilm susceptibility to antibiotics was investigated by determination of their minimum biofilm regrowth concentrations in the presence of 50, 100 and 200 mg/ml of the sugar alcohols (Figures 1 and 2). Xylitol and sorbitol potentiated the antibiotic activity against pre-formed biofilms. The susceptibility of biofilm cells to the tested antibiotics increased by up to 2-8 folds with xylitol and by up to 2-32 folds with sorbitol. Sorbitol exerted higher synergistic effect than xylitol. The interaction of sorbitol with antibiotics was synergistic in all isolates with amikacin, in 3 isolates with ciprofloxacin and tobramycin, in 2 isolates with imipenem and with cefoperazone in one isolate. On the other hand, combining xylitol with antibiotics was synergistic with ciprofloxacin, amikacin and tobramycin in two isolates and with cefoperazone and imipenem in one isolate. Amikacin, ciprofloxacin and tobramycin were more potentiated than cefoperazone and imipenem when combined with xylitol and sorbitol. Comparing the synergy of antibiotics when combined with sorbitol, amikacin was the most potentiated, followed by ciprofloxacin and tobramycin, while imipenem and cefoperazone were the least potentiated. In the presence of xylitol, amikacin, ciprofloxacin and imipenem were more augmented than cefoperazone and imipenem. The synergistic effect of sorbitol was concentration-dependent in all isolates with the aminoglycosides amikacin and tobramycin and in two isolates with ciprofloxacin, cefoperazone and imipenem. Xylitol synergistic effect, on the other hand, was dose-dependent in all isolates with imipenem, in 3 isolates with cefoperazone, in 2 isolates with ciprofloxacin and amikacin and in one isolate with tobramycin. These results are in accordance with the study of Dowd
The aim of this study was to investigate the ability of ambroxol to block the swarming and swimmi... more The aim of this study was to investigate the ability of ambroxol to block the swarming and swimming motilities and biofilm formation of Proteus mirabilis isolated from diabetic foot ulcers as a new agent for the treatment of diabetic foot infections. Assays of swarming and swimming motilities on LB agar in the presence and absence of sub-inhibitory concentrations of ambroxol were performed by measuring the distance of swarming and swimming in addition to microscopical examination of vegetative and swarmer cells. Moreover, biofilm formation and removal by ambroxol was investigated in polystyrene microtiter plates. Ambroxol in sub-inhibitory concentrations significantly blocked swarming and swimming motilities in a dose-dependent manner. Ambroxol decreased swarming and swimming at concentrations of 0.6, 0.7, 0.8 and 0.9 mg/ml. At a concentration of 0.9 mg/ml, ambroxol completely inhibited swarming and swimming. Ambroxol also could significantly inhibit biofilm formation and remove pre...
Diabetic foot infection is a serious complication of diabetes that can lead to amputation of lowe... more Diabetic foot infection is a serious complication of diabetes that can lead to amputation of lower extremities. Proteus mirabilis is common in diabetic foot infections. These infections are problematic in treatment due to high resistance to antibiotics and biofilm formation. This study investigated the antimicrobial, anti-swarming and antibiofilm activities of local Egyptian clover honey against a clinical Proteus mirabilis isolate from diabetic foot ulcer. Honey is one of the oldest remedies for wound infections. Honey at a concentration of 40% was bactericidal to the planktonic cells of Proteus mirabilis. Swarming and biofilm formation are correlated. At 1/2 MIC of honey, it completely blocked swarming of Proteus mirabilis on 1.5% Luria-Bertani (LB) agar and inhibited biofilm formation by a percentage of 85.86±3.41. This study suggests the use of clover honey as an alternative therapy for treatment of diabetic foot infections caused by Proteus mirabilis due to combined antibacteri...
Pseudomonas aeruginosa can cause a variety of healthcare-associated infections by its arsenal of ... more Pseudomonas aeruginosa can cause a variety of healthcare-associated infections by its arsenal of virulence factors. Virulence factor production is largely controlled by the cell-to-cell communication system termed quorum sensing (QS). Targeting QS may be a good approach to inhibit the production of virulence factors and attenuate pathogenicity without exerting selective stress on bacterial growth. This will greatly reduce the emergence of resistant mutants. In this work, we investigated the anti-virulence and anti-QS activities of the FDA-approved drug allopurinol against the P. aeruginosa PAO1 strain. Allopurinol at 200 µg/mL (1/10 MIC) significantly decreased the production of the QS-controlled Chromobacterium violaceum CV026 violet pigment violacein and other P. aeruginosa QS-controlled virulence factors phenotypically. Furthermore, allopurinol reduced the infiltration of P. aeruginosa and leucocytes and diminished the congestion in the liver and kidney tissues of infected mice. ...
Diabetic foot ulcers are recognized to be a severe complication of diabetes, increasing the risk ... more Diabetic foot ulcers are recognized to be a severe complication of diabetes, increasing the risk of amputation and death. The bacterial infection of Diabetic foot ulcers with virulent and resistant bacteria as Proteus mirabilis greatly worsens the wound and may not be treated with conventional therapeutics. Developing new approaches to target bacterial virulence can be helpful to conquer such infections. In the current work, we evaluated the anti-virulence activities of the widely used antibacterial metronidazole. The minimum inhibitory concentrations (MIC) and minimum biofilm eradication concentrations (MEBC) were determined for selected antibiotics which P. mirabilis was resistant to them in the presence and absence of metronidazole in sub-MIC. The effect of metronidazole in sub-MIC on P. mirabilis virulence factors as production of exoenzymes, motilities, adhesion and biofilm formation, were evaluated. Furthermore, molecular docking of metronidazole into P. mirabilis adhesion and...
Biofilms facilitate the pathogenesis of life-threatening Pseudomonas aeruginosa infections by coa... more Biofilms facilitate the pathogenesis of life-threatening Pseudomonas aeruginosa infections by coating mucosal surfaces or invasive devices and offer protection from antimicrobial therapy and the host immune response, thus increasing mortality rates and financial burden. Herein, new hybrid N-acylcysteines (NAC) incorporating selected acyl groups from organic acids and their derivatives, which are capable of quenching pathogen quorum sensing (QS) systems, were designed and their antibiofilm activity and anti-QS were evaluated. N-acylcysteines (4a−h) were synthesized and characterized by 1 H NMR and 13 C NMR, and their purity was confirmed by elemental analyses. N-(4-Hydroxy-3,5-dimethoxybenzoyl)-L-cysteine (4d) and N-(4-methoxybenzoyl)-L-cysteine (4h) showed a higher antibiofilm activity against PAO1 biofilms than the rest of the targets and the standard NAC. They showed 83 and 82% inhibition of biofilms at 5 mM and eradicated mature biofilms at 20 mM concentrations (NAC biofilm inhibition = 66% at 10 mM and minimum biofilm eradication concentration = 40 mM). This was confirmed via visualizing adherent biofilm cells on catheter pieces using scanning electron microscopy. In the same vein, both 4d and 4h showed the highest docking score with the QS signal receptor protein LasR (−7.8), which was much higher than that of NAC (−5) but less than the score of the natural agonist N-(3-oxododecanoyl)-L-homoserine (OdDHL) (−8.5). Target 4h (5 mM) decreased the expression of quorum sensing encoding genes in P. aeruginosa PAO1 strain by 53% for pslA, 47% for lasI and lasR, and 29% for filC, lowered PAO1 pyocyanin production by 76.43%, completely blocked the proteolytic activity of PAO1, and did not affect PAO1 cell viability. Targets 4d and 4h may find applications for the prevention and treatment of biofilm-mediated P. aeruginosa local infections of the skin, eye, and wounds. N-(4-Methoxybenzoyl)-L-cysteine 4h is a promising dual-acting matrix disruptive and anti-QS antibiofilm agent for further investigation and optimization.
Biofilms facilitate the pathogenesis of life-threatening Pseudomonas aeruginosa infections by coa... more Biofilms facilitate the pathogenesis of life-threatening Pseudomonas aeruginosa infections by coating mucosal surfaces or invasive devices and offer protection from antimicrobial therapy and the host immune response, thus increasing mortality rates and financial burden. Herein, new hybrid N-acylcysteines (NAC) incorporating selected acyl groups from organic acids and their derivatives, which are capable of quenching pathogen quorum sensing (QS) systems, were designed and their antibiofilm activity and anti-QS were evaluated. N-acylcysteines (4a−h) were synthesized and characterized by 1 H NMR and 13 C NMR, and their purity was confirmed by elemental analyses. N-(4-Hydroxy-3,5-dimethoxybenzoyl)-L-cysteine (4d) and N-(4-methoxybenzoyl)-L-cysteine (4h) showed a higher antibiofilm activity against PAO1 biofilms than the rest of the targets and the standard NAC. They showed 83 and 82% inhibition of biofilms at 5 mM and eradicated mature biofilms at 20 mM concentrations (NAC biofilm inhibition = 66% at 10 mM and minimum biofilm eradication concentration = 40 mM). This was confirmed via visualizing adherent biofilm cells on catheter pieces using scanning electron microscopy. In the same vein, both 4d and 4h showed the highest docking score with the QS signal receptor protein LasR (−7.8), which was much higher than that of NAC (−5) but less than the score of the natural agonist N-(3-oxododecanoyl)-L-homoserine (OdDHL) (−8.5). Target 4h (5 mM) decreased the expression of quorum sensing encoding genes in P. aeruginosa PAO1 strain by 53% for pslA, 47% for lasI and lasR, and 29% for filC, lowered PAO1 pyocyanin production by 76.43%, completely blocked the proteolytic activity of PAO1, and did not affect PAO1 cell viability. Targets 4d and 4h may find applications for the prevention and treatment of biofilm-mediated P. aeruginosa local infections of the skin, eye, and wounds. N-(4-Methoxybenzoyl)-L-cysteine 4h is a promising dual-acting matrix disruptive and anti-QS antibiofilm agent for further investigation and optimization.
The repurposing of drugs is one of the most competent strategies for discovering new antimicrobia... more The repurposing of drugs is one of the most competent strategies for discovering new antimicrobial agents. Vildagliptin is a dipeptidyl peptidase-4 inhibitor (DPI-4) that is used effectively in combination with metformin to control blood glucose levels in diabetic patients. This study was designed to evaluate the anti-virulence activities of this combination against one of the most clinically important pathogens, Pseudomonas aeruginosa. The current findings show a significant ability of the vildagliptin–metformin combination to diminish biofilm formation, bacterial motility, and the production of virulent extracellular enzymes and pyocyanin pigment. Furthermore, this drug combination significantly increased the susceptibility of P. aeruginosa to oxidative stress, indicating immunity enhancement in the eradication of bacterial cells. In compliance with the in vitro findings, the histopathological photomicrographs of mice showed a considerable protective effect of the metformin–vildag...
The development of bacterial resistance to traditional antibiotics constitutes an emerging public... more The development of bacterial resistance to traditional antibiotics constitutes an emerging public health issue. Promising approaches have been innovated to conquer bacterial resistance, and targeting bacterial virulence is one of these approaches. Bacterial virulence mitigation offers several merits, as antivirulence agents do not affect the growth of bacteria and hence do not induce bacteria to develop resistance. In this direction, numerous drugs have been repurposed as antivirulence agents prior to their clinical use alone or in combination with traditional antibiotics. Quorum sensing (QS) plays a key role in controlling bacterial virulence. In the current study, dipeptidase inhibitor-4 (DPI-4) antidiabetic gliptins were screened for their antivirulence and anti-quorum sensing (anti-QS) activities against Gram-negative Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus. Upon assessing their antibiofilm activities, the ten tested gliptins significantly diminished biofi...
The development of bacterial resistance is an insistent global health care issue, especially in l... more The development of bacterial resistance is an insistent global health care issue, especially in light of the dwindled supply of new antimicrobial agents. This mandates the development of new innovative approaches to overcome the resistance development obstacle. Mitigation of bacterial virulence is an interesting approach that offers multiple advantages. Employing safe chemicals or drugs to mitigate bacterial virulence is an additive advantage. In the current study, the in vitro antivirulence activities of citrate were evaluated. Significantly, sodium citrate inhibited bacterial biofilm formation at sub-MIC concentrations. Furthermore, sodium citrate decreased the production of virulence factors protease and pyocyanin and diminished bacterial motility. Quorum sensing (QS) is the communicative system that bacterial cells utilize to communicate with each other and regulate the virulence of the host cells. In the present study, citrate in silico blocked the Pseudomonas QS receptors and ...
Journal of microbiology, biotechnology and food sciences, 2021
Respiratory tract infections caused by Klebsiella pneumoniae are frequently associated with high ... more Respiratory tract infections caused by Klebsiella pneumoniae are frequently associated with high mortality and morbidity rates. Treatment of these infections is usually difficult due to the emergence of multiple resistances to antibiotics. Multidrug efflux pumps are greatly involved in antibiotic resistance in Gram-negative bacteria including Klebsiella pneumoniae. In the current study, efflux activity was observed in 93.75% of Klebsiella pneumoniae clinical isolates by the qualitative acridine orange agar method. This finding was further confirmed genotypically by polymerase chain reaction that showed the presence of efflux genes AcrA, AcrB, TolC and mdtk in these isolates. The ability of metformin to inhibit efflux activity was compared with the reference efflux pump inhibitors verapamil and ascorbic acid. Metformin was more active than ascorbic acid and less active than verapamil. Up to our knowledge, this is the first report that shows that metformin has an efflux pump-inhibitin...
Hepatitis C virus (HCV) is one of the most epidemic viral infections in the world. Three-quarters... more Hepatitis C virus (HCV) is one of the most epidemic viral infections in the world. Three-quarters of individuals infected with HCV become chronic. As a consequence of persistent inflammation, a considerable percentage of chronic patients progress to liver fibrosis, cirrhosis, and finally hepatocellular carcinoma. Cytokines, which are particularly produced from T-helper cells, play a crucial role in immune protection against HCV and the progression of the disease as well. In this study, the role of interleukins IL-33, IL-17, and IL-25 in HCV patients and progression of disease from chronicity to hepatocellular carcinoma will be characterized in order to use them as biomarkers of disease progression. The serum levels of the tested interleukins were measured in patients suffering from chronic hepatitis C (CHC), hepatocellular carcinoma (HCC), and healthy controls (C), and their levels were correlated to the degree of liver fibrosis, liver fibrosis markers and viral load. In contrast to...
Serratia marcescens is an opportunistic pathogen that causes diverse nosocomial infections. S. ma... more Serratia marcescens is an opportunistic pathogen that causes diverse nosocomial infections. S. marcescens has developed considerable resistance to different antibiotics and is equipped with an armory of virulence factors. These virulence factors are regulated in S. marcescens by an intercellular communication system termed quorum sensing (QS). Targeting bacterial virulence and QS is an interesting approach to mitigating bacterial pathogenesis and overcoming the development of resistance to antimicrobials. In this study, we aimed to evaluate the anti-virulence activities of secnidazole on a clinical isolate of S. marcescens. The effects of secnidazole at sub-inhibitory concentrations (sub-MICs) on virulence factors, swarming motility, biofilm formation, proteases, hemolysin activity, and prodigiosin production were evaluated in vitro. Secnidazole’s protective activity against S. marcescens pathogenesis was assessed in vivo in mice. Furthermore, a molecular docking study was conducted...
The bacterial resistance development due to the incessant administration of antibiotics has led t... more The bacterial resistance development due to the incessant administration of antibiotics has led to difficulty in their treatment. Natural adjuvant compounds can be co-administered to hinder the pathogenesis of resistant bacteria. Sotolon is the prevailing aromatic compound that gives fenugreek its typical smell. In the current work, the anti-virulence activities of sotolon on Pseudomonas aeruginosa have been evaluated. P. aeruginosa has been treated with sotolon at sub-minimum inhibitory concentration (MIC), and production of biofilm and other virulence factors were assessed. Moreover, the anti-quorum sensing (QS) activity of sotolon was in-silico evaluated by evaluating the affinity of sotolon to bind to QS receptors, and the expression of QS genes was measured in the presence of sotolon sub-MIC. Furthermore, the sotolon in-vivo capability to protect mice against P. aeruginosa was assessed. Significantly, sotolon decreased the production of bacterial biofilm and virulence factors, ...
Serratia marcescens is an opportunistic nosocomial pathogen and causes wound and burn infections.... more Serratia marcescens is an opportunistic nosocomial pathogen and causes wound and burn infections. It shows high resistance to antibiotics and its pathogenicity is mediated by an arsenal of virulence factors. Another therapeutic option to such infections is targeting quorum sensing (QS), which controls the expression of different S. marcescens virulence factors. Prevention of QS can deprive S. marcescens from its bacterial virulence without applying stress on the bacterial growth and facilitates the eradication of the bacteria by immunity. The objective of the current study is to explore the antimicrobial and antivirulence activities of xylitol against S. marcescens. Xylitol could inhibit the growth of S. marcescens. Sub-inhibitory concentrations of xylitol could inhibit biofilm formation, reduce prodigiosin production, and completely block protease activity. Moreover, xylitol decreased swimming motility, swarming motility and increased the sensitivity to hydrogen peroxide. The expre...
Background: Quorum sensing inhibitionis an advanced strategy that aims to interfere with bacteria... more Background: Quorum sensing inhibitionis an advanced strategy that aims to interfere with bacterial cell-to-cell communication systems (quorum sensing), which regulate virulence factors production in Pseudomonas aeruginosa, in order to overcome the globalcrisis of antimicrobial resistance. Objectives: Study the potential quorum sensing inhibitory effect of Zinc oxide (ZnO)nanoparticlesin Pseudomonas aeruginosa and the impact on production of virulence factors. Methods: Quorum sensing inhibitory effect of ZnO was evaluated by assessing its ability to reducePseudomonas aeruginosa virulence factors production; rhamnolipids, pyocyanin, pyoverdin, hemolysins, elastase and proteases. Furthermore, qRT-PCR was performed to determine ZnO inhibitory effect onQS-regulatory geneslasI, lasR,rhlI, rhlR, pqsA and pqsR that control virulence factors secretion. Moreover, mice survival test was conducted to investigate the influence of ZnO on Pseudomonas aeruginosa-induced mortality in vivo. Results: ZnO revealed a statistically significant reduction in the production of QS-controlled virulence factors rhamnolipids, pyocyanin, pyoverdin, hemolysins, elastase and proteases. Furthermore, ZnO exhibited a significant decrease in the relative expression of QS-regulatory geneslasI, lasR,rhlI, rhlR,pqsA and pqsR. Additionally, ZnO significantly reduced the pathogenesis of Pseudomonas aeruginosa in vivo Conclusion: ZnO nanoparticles can be used as a quorum sensing inhibitor in Pseudomonas aeruginosa infections either as an adjuvant or alternative to conventional antimicrobials.
Background: Staphylococcus aureus is an important nosocomial bacterium that is responsible for a ... more Background: Staphylococcus aureus is an important nosocomial bacterium that is responsible for a number of infections that may be fatal. The treatment of such infections is limited by emergence of antibiotic resistance. Targeting virulence of Staphylococcus aureus may provide an alternative option to antibiotic that may bypass the emergence of resistant strains due to lack of stress on viability. Objectives: Investigation of the ability of glyceryl trinitrate (GTN) to inhibit staphyloxanthin, biofilm and tolerance to oxidative stress. Methods: The disk sensitivity method was used to detect the methicillin resistance of Staphylococcus aureus. The effect of sub-inhibitory concentration of GTN on biofilm formation, staphyloxanthin production and tolerance to oxidative stress was evaluated. Molecular docking study was used to investigate the ability of GTN to bind to dehydrosqualene synthase enzyme. Results: GTN showed a significant inhibition of biofilm, staphyloxanthin and tolerance to oxidative stress. In the molecular docking study, it was found that GTN could bind to dehydrosqualene synthase enzyme by hydrogen bonding,electrostatic interaction and pi-cation interaction. Conclusion: The present study revealed the ability of GTN to serve as a potential anti-virulence candidate for attenuation of S. aureus pathogenicity.
Salmonella is a causative agent of wide range of diseases varying from gastroenteritis to systemi... more Salmonella is a causative agent of wide range of diseases varying from gastroenteritis to systemic typhoid fever. It uses specialized Type III secretion system (T3SS) by its two compartments to invade and intracellularly survive inside the immune cells. T3SS is expressed in two subsequent phases by two distinct Salmonella pathogenicity islands (SP) I and II. Understanding and evaluation of components T3SS-SPI1 and T3SS-SPI2 are very important, not only to evaluate the bacterial virulence but also to develop vaccines. In this study, the effect of mutation on SsaV encoding gene (one of the essential T3SS-SPI2 components) was investigated on the virulence behavior of Salmonella enterica serovar Typhimurium. We found a significant reduction in invasion capability and intracellular replication as well.
Background: Quorum sensing is a mechanism of intercellular communication that controls the produc... more Background: Quorum sensing is a mechanism of intercellular communication that controls the production of virulence factors in Pseudomonas aeruginosa. Inhibition of quorum sensing can disarm the virulence factors without exerting stress on bacterial growth that leads to emergence of antibiotic resistance. Objectives: Finding a new quorum sensing inhibitor and determining its inhibitory activities against virulence factors of Pseudomonas aeruginosa PAO1 strain. Methods: Quorum sensing was evaluated by estimation of violacein production by Chromobacterium violaceum CV026. Molecular docking was used to investigate the possible binding of metformin to LasR and rhlR receptors. The inhibition of pyocyanin, hemolysin, protease, elastase in addition to swimming and twitching motilities, biofilm formation and resistance to oxidative stress by metformin was also assessed. Results: Metformin significantly reduced the production of violacein pigment. Significant inhibition of pyocyanin, hemolysin, protease and elastase was achieved. Metformin markedly decreased biofilm formation, swimming and twitching motilities and increased the sensitivity to oxidative stress. In the molecular docking study, metformin could bind to LasR by hydrogen bonding and electrostatic interaction and to rhlR by hydrogen bonding only. Conclusion: Metformin can act as a quorum sensing inhibitor and virulence inhibiting agent that may be useful in the treatment of Pseudomonas aeruginosa infection.
Background: Targeting quorum sensing is an alternative approach to antibiotics.Targeting quorum s... more Background: Targeting quorum sensing is an alternative approach to antibiotics.Targeting quorum sensing-regulated virulence will disarm the pathogen without exerting pressure on its growth. As a result, emergence of resistance is avoided and the immune system can easily eradicate bacteria. Objectives: Investigation of the possible inhibition of quorum sensing-regulated virulence of Pseudomonas aeruginosa by glyceryltrinitrate. Methods: The quorum sensing inhibiting activity of glyceryl trinitrate was assessed by inhibition of violacein production in Chromobacterium violaceum ATCC 12472. Its ability to inhibit pyocyanin, protease, biofilm and tolerance to oxidative stress was evaluated. Docking study was performed to study the interference of glyceryl trinitrate with the binding of autoinducers with LasR and rhlR receptors. Results: Glyceryl trinitrate exerted a significant biofilm inhibiting and eradicating activities. It decreased the production of quorum-sensing dependent violacein production. It significantly inhibited the production of pyocyanin and protease and diminished the tolerance against oxidative stress. Molecular docking study showed that glyceryl trinitrate interferes with the binding of autoinducers to their receptors. It could bind to Las Rand rhlr receptors with binding energy of-93.47 and-77.23, respectively. Conclusion: Glyceryl trinitrate can be an antivirulence agent in the treatment of Pseudomonas aeruginosa topical infections such as burn infections.
The effect of xylitol and sorbitol on the biofilm susceptibility to antibiotics was investigated ... more The effect of xylitol and sorbitol on the biofilm susceptibility to antibiotics was investigated by determination of their minimum biofilm regrowth concentrations in the presence of 50, 100 and 200 mg/ml of the sugar alcohols (Figures 1 and 2). Xylitol and sorbitol potentiated the antibiotic activity against pre-formed biofilms. The susceptibility of biofilm cells to the tested antibiotics increased by up to 2-8 folds with xylitol and by up to 2-32 folds with sorbitol. Sorbitol exerted higher synergistic effect than xylitol. The interaction of sorbitol with antibiotics was synergistic in all isolates with amikacin, in 3 isolates with ciprofloxacin and tobramycin, in 2 isolates with imipenem and with cefoperazone in one isolate. On the other hand, combining xylitol with antibiotics was synergistic with ciprofloxacin, amikacin and tobramycin in two isolates and with cefoperazone and imipenem in one isolate. Amikacin, ciprofloxacin and tobramycin were more potentiated than cefoperazone and imipenem when combined with xylitol and sorbitol. Comparing the synergy of antibiotics when combined with sorbitol, amikacin was the most potentiated, followed by ciprofloxacin and tobramycin, while imipenem and cefoperazone were the least potentiated. In the presence of xylitol, amikacin, ciprofloxacin and imipenem were more augmented than cefoperazone and imipenem. The synergistic effect of sorbitol was concentration-dependent in all isolates with the aminoglycosides amikacin and tobramycin and in two isolates with ciprofloxacin, cefoperazone and imipenem. Xylitol synergistic effect, on the other hand, was dose-dependent in all isolates with imipenem, in 3 isolates with cefoperazone, in 2 isolates with ciprofloxacin and amikacin and in one isolate with tobramycin. These results are in accordance with the study of Dowd
The aim of this study was to investigate the ability of ambroxol to block the swarming and swimmi... more The aim of this study was to investigate the ability of ambroxol to block the swarming and swimming motilities and biofilm formation of Proteus mirabilis isolated from diabetic foot ulcers as a new agent for the treatment of diabetic foot infections. Assays of swarming and swimming motilities on LB agar in the presence and absence of sub-inhibitory concentrations of ambroxol were performed by measuring the distance of swarming and swimming in addition to microscopical examination of vegetative and swarmer cells. Moreover, biofilm formation and removal by ambroxol was investigated in polystyrene microtiter plates. Ambroxol in sub-inhibitory concentrations significantly blocked swarming and swimming motilities in a dose-dependent manner. Ambroxol decreased swarming and swimming at concentrations of 0.6, 0.7, 0.8 and 0.9 mg/ml. At a concentration of 0.9 mg/ml, ambroxol completely inhibited swarming and swimming. Ambroxol also could significantly inhibit biofilm formation and remove pre...
Diabetic foot infection is a serious complication of diabetes that can lead to amputation of lowe... more Diabetic foot infection is a serious complication of diabetes that can lead to amputation of lower extremities. Proteus mirabilis is common in diabetic foot infections. These infections are problematic in treatment due to high resistance to antibiotics and biofilm formation. This study investigated the antimicrobial, anti-swarming and antibiofilm activities of local Egyptian clover honey against a clinical Proteus mirabilis isolate from diabetic foot ulcer. Honey is one of the oldest remedies for wound infections. Honey at a concentration of 40% was bactericidal to the planktonic cells of Proteus mirabilis. Swarming and biofilm formation are correlated. At 1/2 MIC of honey, it completely blocked swarming of Proteus mirabilis on 1.5% Luria-Bertani (LB) agar and inhibited biofilm formation by a percentage of 85.86±3.41. This study suggests the use of clover honey as an alternative therapy for treatment of diabetic foot infections caused by Proteus mirabilis due to combined antibacteri...
Pseudomonas aeruginosa can cause a variety of healthcare-associated infections by its arsenal of ... more Pseudomonas aeruginosa can cause a variety of healthcare-associated infections by its arsenal of virulence factors. Virulence factor production is largely controlled by the cell-to-cell communication system termed quorum sensing (QS). Targeting QS may be a good approach to inhibit the production of virulence factors and attenuate pathogenicity without exerting selective stress on bacterial growth. This will greatly reduce the emergence of resistant mutants. In this work, we investigated the anti-virulence and anti-QS activities of the FDA-approved drug allopurinol against the P. aeruginosa PAO1 strain. Allopurinol at 200 µg/mL (1/10 MIC) significantly decreased the production of the QS-controlled Chromobacterium violaceum CV026 violet pigment violacein and other P. aeruginosa QS-controlled virulence factors phenotypically. Furthermore, allopurinol reduced the infiltration of P. aeruginosa and leucocytes and diminished the congestion in the liver and kidney tissues of infected mice. ...
Diabetic foot ulcers are recognized to be a severe complication of diabetes, increasing the risk ... more Diabetic foot ulcers are recognized to be a severe complication of diabetes, increasing the risk of amputation and death. The bacterial infection of Diabetic foot ulcers with virulent and resistant bacteria as Proteus mirabilis greatly worsens the wound and may not be treated with conventional therapeutics. Developing new approaches to target bacterial virulence can be helpful to conquer such infections. In the current work, we evaluated the anti-virulence activities of the widely used antibacterial metronidazole. The minimum inhibitory concentrations (MIC) and minimum biofilm eradication concentrations (MEBC) were determined for selected antibiotics which P. mirabilis was resistant to them in the presence and absence of metronidazole in sub-MIC. The effect of metronidazole in sub-MIC on P. mirabilis virulence factors as production of exoenzymes, motilities, adhesion and biofilm formation, were evaluated. Furthermore, molecular docking of metronidazole into P. mirabilis adhesion and...
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Papers by Hisham Abbas