Could the analgesic drugs, paracetamol and indomethacin, function as quorum sensing inhibitors?

Antimicrobial Proficiency of Amlodipine: Investigating its Impact on Pseudomonas spp. in Urinary Tract Infections

Antibiotic resistance in urinary tract infections (UTIs) is a growing concern due to extensive antibiotic use. The study explores a drug repurposing approach to find non-antibiotic drugs with antibacterial activity. In the present study, 8 strains of Pseudomonas spp. were used that were clinically isolated from UTI-infected patients. Amlodipine, a cardiovascular drug used in this study, has shown potential antimicrobial effect in reducing the various virulence factors, including swimming and twitching motility, biofilm, rhamnolipid, pyocyanin, and oxidative stress resistance against all the strains. Amlodipine exhibited the most potent antimicrobial activity with MIC in the range of 6.25 to 25 µg/ml. Significant inhibition in biofilm production was seen in the range of 45.75 to 76.70%. A maximum decrease of 54.66% and 59.45% in swimming and twitching motility was observed, respectively. Maximum inhibition of 65.87% of pyocyanin pigment was observed with the effect of amlodipine. Moreover, a significant decrease in rhamnolipids production observed after amlodipine treatment was between 16.5 and 0.001 mg/ml as compared to the control. All bacterial strains exhibited leakage of proteins and nucleic acids from their cell membranes when exposed to amlodipine which suggests the damage of the structural integrity. In conclusion, amlodipine exhibited good antimicrobial activity and can be used as a potential candidate to be repurposed for the treatment of urinary tract infections.

Breaking the Phalanx: Overcoming Bacterial Drug Resistance with Quorum Sensing Inhibitors that Enhance Therapeutic Activity of Antibiotics

Antibiotic-resistant bacterial infections loom over humanity as an increasing deadly threat. There exists a dire need for new treatments, especially those that synergize with our existing arsenal of antibiotic drugs to help overcome the gap in antibiotic efficacy and attenuate the development of new antibiotic-resistance in the most dangerous pathogens. Quorum sensing systems in bacteria drive the formation of biofilms, increase surface motility, and enhance other virulence factors, making these systems attractive targets for the discovery of novel antibacterials. Quorum sensing inhibitors (QSIs) are hypothesized to synergize with existing antibiotics, making bacteria more sensitive to the effects of these drugs. In this study, we aimed to find the synergistic combinations between the QSIs and known antibiotics to combat the two deadliest hospital infections - Pseudomonas aeruginosa and Acinetobacter baumannii. We mined biochemical activity databases and literature to identify known, high efficacy QSIs against these bacteria. We used these data to develop and validate a Quantitative Structure-Activity Relationship (QSAR) model for predicting QSI activity and then employed this model to identify new potential QSIs from the Inxight database of approved and investigational drugs. We then tested binary mixtures of the identified QSIs with 11 existing antibiotics using a combinatorial matrix screening approach with ten (five of each) clinical isolates of P. aeruginosa and A. baumannii. Amongst explored drug combinations, 31 exhibited a synergistic effect, including mixtures involving naldemedine and telotristat, two drugs predicted by our model with previously undescribed QSI activity. Although no mixture inhibiting all the strains was found, piperacillin combined with curcumin, ketoprofen, indomethacin, and piroxicam demonstrated the broadest antimicrobial action. We anticipate that further preclinical investigation of these combinations of novel repurposed QSIs with a known antibiotic may lead to novel clinical candidates.

Revitalizing common drugs for antibacterial, quorum quenching, and antivirulence potential against Pseudomonas aeruginosa: in vitro and in silico insights

In the post-antibiotic era, antivirulence therapies are becoming refractory to the clinical application of existing antimicrobial regimens. Moreover, in an attempt to explore alternate intervention strategies, drug repurposing is gaining attention over development of novel drugs/antimicrobials. With the prevalence of multidrug resistance and high medical burden associated with Pseudomonas aeruginosa, there is an urgent need to devise novel therapeutics to combat this bacterial pathogen. In this context, the present study was undertaken to scrutinize the anti-quorum sensing (QS) and antivirulence potential of commonly consumed drugs such as fexofenadine (FeX), ivermectin (IvM), nitrofurantoin (NiT), levocetrizine (LvC), atorvastatin (AtS), and aceclofenac (AcF), against P. aeruginosa. The methodology involved assessment of antibacterial activity against P. aeruginosa PAO1 and quorum quenching (QQ) potential using Agrobacterium tumefaciens NTL4 biosensor strain. The antivirulence prospects were investigated by estimating the production of hallmark virulence factors in P. aeruginosa accompanied by molecular docking to predict drug associations with the QS receptors. Interestingly, all the drugs harbored antibacterial, anti-QS, and antivirulence potential in vitro, which consequently disrupted QS circuits and attenuated pseudomonal virulence phenotypically by significantly lowering the production of pyocyanin, hemolysin, pyochelin, and total bacterial protease in vitro. Moreover, the findings were validated by computational studies that predicted strong molecular interactions between the test drugs and QS receptors of P. aeruginosa. Hence, this study is the first to suggest the prospect of repurposing FeX, IvM, NiT, LvC, AtS, and AcF against P. aeruginosa.

Silver nanoparticle with potential antimicrobial and antibiofilm efficiency against multiple drug resistant, extensive drug resistant Pseudomonas aeruginosa clinical isolates

BACKGROUND

The study aims to investigate the effect of combining silver nanoparticles (AGNPs) with different antibiotics on multi-drug resistant (MDR) and extensively drug resistant (XDR) isolates of Pseudomonas aeruginosa (P. aeruginosa) and to investigate the mechanism of action of AGNPs.

METHODS

AGNPs were prepared by reduction of silver nitrate using trisodium citrate and were characterized by transmission electron microscope (TEM) in addition to an assessment of cytotoxicity. Clinical isolates of P. aeruginosa were collected, and antimicrobial susceptibility was conducted. Multiple Antibiotic Resistance (MAR) index was calculated, and bacteria were categorized as MDR or XDR. Minimum inhibitory concentration (MIC) of gentamicin, ciprofloxacin, ceftazidime, and AGNPs were determined. The mechanism of action of AGNPs was researched by evaluating their effect on biofilm formation, swarming motility, protease, gelatinase, and pyocyanin production. Real-time PCR was performed to investigate the effect on the expression of genes encoding various virulence factors.

RESULTS

TEM revealed the spherical shape of AGNPs with an average particle size of 10.84 ± 4.64 nm. AGNPS were safe, as indicated by IC50 (42.5 µg /ml). The greatest incidence of resistance was shown against ciprofloxacin which accounted for 43% of the bacterial isolates. Heterogonous resistance patterns were shown in 63 isolates out of the tested 107. The MAR indices ranged from 0.077 to 0.84. Out of 63 P. aeruginosa isolates, 12 and 13 were MDR and XDR, respectively. The MIC values of AGNPs ranged from 2.65 to 21.25 µg /ml. Combination of AGNPs with antibiotics reduced their MIC by 5-9, 2-9, and 3-10Fold in the case of gentamicin, ceftazidime, and ciprofloxacin, respectively, with synergism being evident. AGNPs produced significant inhibition of biofilm formation and decreased swarming motility, protease, gelatinase and pyocyanin production. PCR confirmed the finding, as shown by decreased expression of genes encoding various virulence factors.

CONCLUSION

AGNPs augment gentamicin, ceftazidime, and ciprofloxacin against MDR and XDR Pseudomonas isolates. The efficacy of AGNPs can be attributed to their effect on the virulence factors of P. aeruginosa. The combination of AGNPs with antibiotics is a promising strategy to attack resistant isolates of P. aeruginosa.

The Promising Effect of Ascorbic Acid and Paracetamol as Anti-Biofilm and Anti-Virulence Agents against Resistant Escherichia coli

Escherichia coli is a major cause of serious infections, with antibiotic resistance rendering many treatments ineffective. Hence, novel strategies to combat this pathogen are needed. Anti-virulence therapy is a promising new approach for the subsequent era. Recent research has examined the impact of sub-inhibitory doses of ascorbic acid and paracetamol on Escherichia coli virulence factors. This study evaluated biofilm formation, protease production, motility behavior, serum resistance, expression of virulence-regulating genes (using RT-PCR), and survival rates in a mouse model. Ascorbic acid significantly reduced biofilm formation, protease production, motility, and serum resistance from 100% in untreated isolates to 22-89%, 10-89%, 2-57%, and 31-35% in treated isolates, respectively. Paracetamol also reduced these factors from 100% in untreated isolates to 16-76%, 1-43%, 16-38%, and 31-35%, respectively. Both drugs significantly down-regulated virulence-regulating genes papC, fimH, ompT_m, stcE, fliC, and kpsMTII. Mice treated with these drugs had a 100% survival rate compared with 60% in the positive control group control inoculated with untreated bacteria. This study highlights the potential of ascorbic acid and paracetamol as anti-virulence agents, suggesting their use as adjunct therapies alongside conventional antimicrobials or as alternative treatments for resistant Escherichia coli infections.

Miconazole and phenothiazine hinder the quorum sensing regulated virulence in Pseudomonas aeruginosa

Antibiotic resistance is a major health problem worldwide. Pseudomonas aeruginosa is a Gram-negative pathogen with an arsenal of virulence factors and elevated antimicrobial resistance. It is a leading cause of nosocomial infections with high morbidity and mortality. The significant time and effort required to develop new antibiotics can be circumvented using alternative therapeutic strategies, including anti-virulence targets. This study aimed to investigate the anti-virulence activity of the FDA-approved drugs miconazole and phenothiazine against P. aeruginosa. The phenotypic effect of sub-inhibitory concentrations of miconazole and phenothiazine on biofilm, pyocyanin, protease, rhamnolipid and hemolysin activities in PAO1 strain was examined. qRT-PCR was used to assess the effect of drugs on quorum-sensing genes that regulate virulence. Further, the anti-virulence potential of miconazole and phenothiazine was evaluated in silico and in vivo. Miconazole showed significant inhibition of Pseudomonas virulence by reducing biofilm-formation approximately 45-48%, hemolytic-activity by 59%, pyocyanin-production by 47-49%, rhamnolipid-activity by approximately 42-47% and protease activity by 36-40%. While, phenothiazine showed lower anti-virulence activity, it inhibited biofilm (31-35%), pyocyanin (37-39%), protease (32-40%), rhamnolipid (35-40%) and hemolytic activity (47-56%). Similarly, there was significantly reduced expression of RhlR, PqsR, LasI and LasR following treatment with miconazole, but less so with phenothiazine. In-silico analysis revealed that miconazole had higher binding affinity than phenothiazine to LasR, RhlR, and PqsR QS-proteins. Furthermore, there was 100% survival in mice injected with PAO1 treated with miconazole. In conclusion, miconazole and phenothiazine are promising anti-virulence agents for P. aeruginosa.

Unveiling the hidden language of bacteria: anti-quorum sensing strategies for gram-negative bacteria infection control

Quorum sensing (QS) is a communication mechanism employed by many bacteria to regulate gene expression in a population density-dependent manner. It plays a crucial role in coordinating various bacterial behaviors, including biofilm formation, virulence factor production, and antibiotic resistance. However, the dysregulation of QS can lead to detrimental effects, making it an attractive target for developing novel therapeutic strategies. Anti-QS approaches aim to interfere with QS signaling pathways, inhibiting the communication between bacteria, and disrupting their coordinated activities. Various strategies have been explored to achieve this goal. Advances in understanding QS mechanisms and the discovery of new targets have paved the way for the development of innovative anti-QS approaches. Combining multiple anti-QS strategies or utilizing them in combination with traditional antibiotics holds great promise for combating bacterial infections and addressing the challenges posed by antibiotic resistance. Anti-QS approaches offer a diverse range of strategies including natural compounds, antibody-mediated quorum quenching (QQ), computer-aided drug design for QQ, repurposing of Drugs approved by FDA as anti-QS agents and modulating quorum-sensing molecules which were discussed in detail in this review. This review, comprehensively and for the first time, sheds light on the significance of diverse anti-QS strategies in solving antimicrobial resistance problem in Gram-negative microbial infection.

Promising New Targets for the Treatment of Infections Caused by Acinetobacter baumannii: A Review

Acinetobacter baumannii is a globally disseminated Gram-negative bacterium that causes several types of serious nosocomial infections, the most worrisome being ventilator-associated pneumonia and bacteremia related to using venous catheters. Due to its great ability to form biofilms, combined with its survival for prolonged periods on abiotic surfaces and its potential to acquire and control the genes that determine antibiotic resistance, A. baumannii is at the top of the World Health Organization's priority list of pathogens in urgent need of new therapies. In this sense, this review aimed to present and discuss new molecular targets present in A. baumannii with potential for promising treatment approaches. This review highlights crucial molecular targets, including cell division proteins, membrane synthesis enzymes, and biofilm-associated components, offering promising targets for novel antimicrobial drug development against A. baumannii infections.

Repurposing albendazole as a potent inhibitor of quorum sensing-regulated virulence factors in Pseudomonas aeruginosa: Novel prospects of a classical drug

Pseudomonas aeruginosa has emerged as a critical superbug that poses a serious threat to public health. Owing to its virulence and multidrug resistance profiles, the pathogen demands immediate attention for devising alternate intervention strategies. In an attempt to repurpose drugs against P. aeruginosa, this preclinical study was aimed at investigating the antivirulence prospects of albendazole (AbZ), an FDA-approved anti-helminthic drug, recently predicted to disrupt quorum sensing (QS) in Chromobacterium violaceum. AbZ was scrutinized for its quorum quenching (QQ) prospects, effect on bacterial virulence, different motility phenotypes, and biofilm formation in vitro. Additionally, in silico analysis was employed to predict the molecular interactions between AbZ and QS receptors. At sub-inhibitory levels, AbZ demonstrated anti-QS activity and significantly abrogated AHL biosynthesis in P. aeruginosa. Moreover, AbZ significantly downregulated the transcript levels of QS- (lasI/lasR, rhlI/rhlR, and pqsA/pqsR) and QS-dependent virulence (aprA, lasA, lasB, plcH, and toxA) genes in P. aeruginosa. This coincided with reduced hemolysin, alginate, pyocyanin, rhamnolipids, total protease, and elastase production, thereby lowering phenotypic virulence. Molecular docking with AbZ further revealed strong associations and high binding energies with LasR (-8.8 kcal/mol), RhlR (-6.5 kcal/mol), and PqsR (-6.3 kcal/mol) receptors. AbZ also impeded bacterial motility and abolished EPS production, severely compromising pseudomonal biofilm formation. For the first time, AbZ was shown to interfere with QS circuitry and consequently disarming pseudomonal virulence. Hence, AbZ can be exploited for its antivirulence properties against P. aeruginosa.

Anti-virulence prospects of Metformin against Pseudomonas aeruginosa: A new dimension to a multifaceted drug

Metformin (MeT) is an FDA-approved drug with a myriad of health benefits. Besides being used as an anti-diabetic drug, MeT is also effective against various cancers, liver-, cardiovascular-, and renal diseases. This study was undertaken to examine its unique potential as an anti-virulence drug against an opportunistic bacterial pathogen, Pseudomonas aeruginosa. Due to the menace of multidrug resistance in pathogenic microorganisms, many novel or repurposed drugs with anti-virulence prospects are emerging as next-generation therapies with the aim to overshadow the application of existing antimicrobial regimens. The quorum sensing (QS) mechanisms of P. aeruginosa are an attractive drug target for attenuating bacterial virulence. In this context, the anti-QS potential of MeT was scrutinized using biosensor assays. MeT was comprehensively evaluated for its effects on different motility phenotypes, virulence factor production (phenotypic and genotypic expression) along with biofilm development in P. aeruginosa in vitro. At sub-lethal concentrations, MeT displayed prolific quorum quenching (QQ) ability and remarkably inhibited AHL biosynthesis in P. aeruginosa. Moreover, MeT (1/8 MIC) effectively downregulated the expression levels of various QS- and virulence genes in P. aeruginosa, which coincided with a notable reduction in the levels of alginate, hemolysin, pyocyanin, pyochelin, elastase, and protease production. In silico analysis through molecular docking also predicted strong associations between MeT and QS receptors of P. aeruginosa. MeT also compromised the motility phenotypes and successfully abrogated biofilm formation by inhibiting EPS production in P. aeruginosa. Hence, MeT may be repurposed as an anti-virulence drug against P. aeruginosa in clinical settings.

Antibacterial, antibiofilm, and anti-quorum sensing activities of pyocyanin against methicillin-resistant Staphylococcus aureus: in vitro and in vivo study

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) infections are considered a major public health problem, as the treatment options are restricted. Biofilm formation and the quorum sensing (QS) system play a pivotal role in S. aureus pathogenicity. Hence, this study was performed to explore the antibacterial effect of pyocyanin (PCN) on MRSA as well as its effect on MRSA biofilm and QS.

RESULTS

Data revealed that PCN exhibited strong antibacterial activity against all test MRSA isolates (n = 30) with a MIC value equal to 8 µg/ml. About 88% of MRSA biofilms were eradicated by PCN treatment using the crystal violet assay. The disruption of MRSA biofilm was confirmed using confocal laser scanning microscopy, which showed a reduction in bacterial viability (approximately equal to 82%) and biofilm thickness (approximately equal to 60%). Additionally, the disruption of the formation of microcolonies and the disturbance of the connection between bacterial cells in the MRSA biofilm after PCN treatment were examined by scanning electron microscopy. The 1/2 and 1/4 MICs of PCN exerted promising anti-QS activity without affecting bacterial viability; Agr QS-dependent virulence factors (hemolysin, protease, and motility), and the expression of agrA gene, decreased after PCN treatment. The in silico analysis confirmed the binding of PCN to the AgrA protein active site, which blocked its action. The in vivo study using the rat wound infection model confirmed the ability of PCN to modulate the biofilm and QS of MRSA isolates.

CONCLUSION

The extracted PCN seems to be a good candidate for treating MRSA infection through biofilm eradication and Agr QS inhibition.

Ketoprofen, Piroxicam and Indomethacin Suppressed Quorum Sensing and Virulence Factors in Acinetobacter baumannii

AIM

Quorum sensing (QS) inhibition is a promising strategy to suppress bacterial virulence, and control infection caused by Gram-negative and Gram-positive bacteria. This study explores the quorum sensing inhibiting activity of the non-steroidal anti-inflammatory drugs (NSAIDs) in Acinetobacter baumannii.

METHODS AND RESULTS

Ketoprofen, piroxicam, and indomethacin revealed QS inhibition via elimination of violacein production of the reporter strain Chromobacterium violaceum ATCC 12472 without affecting bacterial growth. The minimal inhibitory concentration (MIC) of ketoprofen, piroxicam, and indomethacin was determined against A. baumannii strains ATCC 17978, ATCC 19606, A1, A11, and A27 by the microbroth dilution method. The MICs of ketoprofen against tested isolates were 3.12-6.25 mg mL^-1 , piroxicam MICs were 1.25-2.5 mg mL^-1 , and indomethacin MICs were 3.12-12.5 mg mL^-1 . Those compounds significantly inhibited QS-associated virulence factors such as biofilm formation, and surface motility, as well as, significantly increased bacterial tolerance to oxidative stress without affecting bacterial growth. On the molecular level, the three compounds significantly inhibited the transcription of QS regulatory genes abaI/abaR, and biofilm regulated genes cusD, and pgaB. Molecular docking analysis revealed potent binding affinity of the three compounds with AbaI via hydrogen and/or hydrophobic bonds.

CONCLUSION

These results indicate that NSAIDs, ketoprofen, piroxicam, and indomethacin, could be potential inhibitors of the QS and could suppress the QS-related virulence factors of A. baumannii.

SIGNIFICANCE AND IMPACT

Ketoprofen, piroxicam, and indomethacin could provide promising implications and strategies for combating the virulence, and pathogenesis of A. baumannii.