scholarly journals Development of an Antibiotic Resistance Breaker to Resensitize Drug-Resistant Staphylococcus aureus: In Silico and In Vitro Approach

2021 ◽  
Vol 11 ◽  
Author(s):  
Gopalakrishnan Thamilselvan ◽  
Hema Bhagavathi Sarveswari ◽  
Sahana Vasudevan ◽  
Alex Stanley ◽  
Karthi Shanmugam ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Boronic Acid ◽  
Bacterial Resistance ◽  
Efflux Pump ◽  
Parent Compound ◽  
Efflux Pumps ◽  
Online Tool ◽  
Efflux Pump Inhibition ◽  
Boronic Acid Derivatives

Efflux pumps are one of the predominant microbial resistant mechanisms leading to the development of multidrug resistance. In Staphylococcus aureus, overexpression of NorA protein enables the efflux of antibiotics belonging to the class of fluoroquinolones and, thus, makes S. aureus resistant. Hence, NorA efflux pumps are being extensively exploited as the potential drug target to evade bacterial resistance and resensitize bacteria to the existing antibiotics. Although several molecules are reported to inhibit NorA efflux pump effectively, boronic acid derivatives were shown to have promising NorA efflux pump inhibition. In this regard, the current study exploits 6-(3-phenylpropoxy)pyridine-3-boronic acid to further improve the activity and reduce cytotoxicity using the bioisostere approach, a classical medicinal chemistry concept. Using the SWISS-Bioisostere online tool, from the parent compound, 42 compounds were obtained upon the replacement of the boronic acid. The 42 compounds were docked with modeled NorA protein, and key molecular interactions of the prominent compounds were assessed. The top hit compounds were further analyzed for their drug-like properties using ADMET studies. The identified potent lead, 5-nitro-2-(3-phenylpropoxy)pyridine (5-NPPP), was synthesized, and in vitro efficacy studies have been proven to show enhanced efflux inhibition, thus acting as a potent antibiotic breaker to resensitize S. aureus without elucidating any cytotoxic effect to the host Hep-G2 cell lines.

Boronic species as promising inhibitors of the Staphylococcus aureus NorA efflux pump: Study of 6-substituted pyridine-3-boronic acid derivatives

2015 ◽  
Vol 95 ◽  
pp. 185-198 ◽  
Author(s):  
Fanny Fontaine ◽  
Arnaud Héquet ◽  
Anne-Sophie Voisin-Chiret ◽  
Alexandre Bouillon ◽  
Aurélien Lesnard ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Boronic Acid ◽  
Efflux Pump ◽  
Boronic Acid Derivatives

scholarly journals NorB, an Efflux Pump in Staphylococcus aureus Strain MW2, Contributes to Bacterial Fitness in Abscesses

2008 ◽  
Vol 190 (21) ◽  
pp. 7123-7129 ◽  
Author(s):  
Yanpeng Ding ◽  
Yoshikuni Onodera ◽  
Jean C. Lee ◽  
David C. Hooper
Keyword(s):  
Gene Expression ◽  
Staphylococcus Aureus ◽  
Efflux Pump ◽  
Efflux Pumps ◽  
Single Copy ◽  
Aureus Strain ◽  
Bacterial Survival ◽  
Bacterial Fitness

ABSTRACT While remaining a major problem in hospitals, Staphylococcus aureus is now spreading in communities. Strain MW2 (USA400 lineage) and other community methicillin-resistant S. aureus strains most commonly cause skin infections with abscess formation. Multidrug resistance (MDR) efflux pumps contribute to antimicrobial resistance but may also contribute to bacterial survival by removal of environmental toxins. In S. aureus, NorA, NorB, NorC, and Tet38 are chromosomally encoded efflux pumps whose overexpression can confer MDR to quinolones and other compounds (Nor pumps) or tetracyclines alone (Tet38), but the natural substrates of these pumps are not known. To determine the role of these efflux pumps in a natural environment in the absence of antibiotics, we used strain MW2 in a mouse subcutaneous abscess model and compared pump gene expression as determined by reverse transcription-PCR in the abscesses and in vitro. norB and tet38 were selectively upregulated in vivo more than 171- and 24-fold, respectively, whereas norA and norC were downregulated. These changes were associated with an increase in expression of mgrA, which encodes a transcriptional regulator known to affect pump gene expression. In competition experiments using equal inocula of a norB or tet38 mutant and parent strain MW2, each mutant exhibited growth defects of about two- to threefold in vivo. In complementation experiments, a single-copy insertion of norB (but not a single-copy insertion of tet38) in the attB site within geh restored the growth fitness of the norB mutant in vivo. Our findings indicate that some MDR pumps, like NorB, can facilitate bacterial survival when they are overexpressed in a staphylococcal abscess and may contribute to the relative resistance of abscesses to antimicrobial therapy, thus linking bacterial fitness and resistance in vivo.

scholarly journals Antifungal Azoles as Tetracycline Resistance-Modifiers in Staphylococcus aureus

2021 ◽  
Author(s):  
Nisha Mahey ◽  
Rushikesh Tambat ◽  
Dipesh Kumar Verma ◽  
Nishtha Chandal ◽  
Krishan Gopal Thakur ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
In Silico ◽  
Biofilm Formation ◽  
Efflux Pump ◽  
Efflux Pumps ◽  
Major Facilitator Superfamily ◽  
Efflux Pump Inhibitors ◽  
Approved Drugs ◽  
Major Facilitator

Staphylococcus aureus has developed resistance to antimicrobials since its first use. The S. aureus major facilitator superfamily (MFS) efflux pump Tet(K) contributes to resistance to tetracyclines. The efflux pump diminishes antibiotic accumulation, and biofilm hampers the diffusion of antibiotics. None of the currently known compounds have been approved as efflux pump inhibitors (EPIs) for clinical use. In the current study, we screened clinically approved drugs for possible Tet(K) efflux pump inhibition. In silico docking followed by in vitro checkerboard assays, we identified five azoles (the fungal ergosterol synthesis inhibitors) showing the putative EPI-like potential with a fractional inhibitory concentration index of ≤0.5, indicating synergism. The functionality of the azoles was confirmed using ethidium bromide (EtBr) accumulation and efflux inhibition assays. In time-kill kinetics, the combination treatment with butoconazole engendered a marked increase in the bactericidal capacity of tetracycline. When assessing the off-target effects of the azoles, we observed no disruption of bacterial membrane permeability and polarization. Finally, the combination of azoles with tetracycline led to a significant eradication of preformed mature biofilms. This study is the primary representation of azoles that can be repurposed as putative Tet(K) EPIs and to reduce biofilm formation at clinically relevant concentrations. IMPORTANCE Staphylococcus aureus use efflux pumps to transport antibiotics out of the cell and thus increase the dosage at which they endure antibiotics. Also, efflux pumps play a role in biofilm formation by the excretion of extracellular matrix molecules. One way to combat these pathogens may be to reduce the activity of efflux pumps and thereby increase pathogen sensitivity to existing antibiotics. We describe the in silico-based screen of clinically approved drugs that identified antifungal azoles inhibiting Tet(K); a pump belongs to the Major Facilitator Superfamily and shows that these compounds bind to and block the activity of the Tet(K) pump. Azoles enhanced the susceptibility of tetracycline against S. aureus and its methicillin-resistant strains. The combination of azoles with tetracycline led to a significant reduction in preformed biofilms. Repurposing of approved drugs may help solve the classical toxicity issues related to efflux pump inhibitors.

scholarly journals Chalcones Isolated from Arrabidaea brachypoda Flowers as Inhibitors of NorA and MepA Multidrug Efflux Pumps of Staphylococcus aureus

Antibiotics ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 351 ◽  
Author(s):  
Luís Mário Rezende-Júnior ◽  
Leila Maria de Sousa Andrade ◽  
Antonio Linkoln Alves Borges Leal ◽  
Avilnete Belem de Souza Mesquita ◽  
Ana Lurdes Portela de Araújo dos Santos ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Binding Sites ◽  
Bacterial Resistance ◽  
Efflux Pump ◽  
Efflux Pumps ◽  
Multidrug Resistant ◽  
Public Health Issue ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pumps ◽  
Efflux Pump Inhibitors

Bacterial resistance to antibiotics has become a public health issue around the world. The present study aimed to evaluate the antibacterial activity of chalcones isolated from flowers of Arrabidaea brachypoda, and their potential as efflux pump inhibitors of Staphylococcus aureus efflux pumps. Microdilution assays were performed with natural products from A. brachypoda. Chalcones 1, 3, 4, and 5 did not show intrinsic antimicrobial activity against all S. aureus strains tested, but they were able to potentiate the Norfloxacin action against the SA1199-B (norA) strain, with a better modulating action for the 4 trimethoxylated chalcone. All chalcones were also able to potentiate the action of EtBr against SA1199-B strain, suggesting a potential NorA inhibition. Moreover, chalcone 4 was able to interfere in the activity of MepA, and interfered weakly in the QacA/B activity. Molecular docking analyzes showed that tested chalcones are capable of binding in the hydrophobic cavity of NorA and MepA, in the same Norfloxacin binding site, indicating that chalcone 4 compete with the antibiotic for the same NorA and MepA binding sites. Association of chalcone 4 with Norfloxacin could be an alternative against multidrug resistant S. aureus over-productive of NorA or MepA.

scholarly journals Staphylococcus aureus Mutants Isolated via Exposure to Nonfluorinated Quinolones: Detection of Known and Unique Mutations

2001 ◽  
Vol 45 (12) ◽  
pp. 3422-3426 ◽  
Author(s):  
Siddhartha Roychoudhury ◽  
Tracy L. Twinem ◽  
Kelly M. Makin ◽  
Mark A. Nienaber ◽  
Chuiying Li ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Sequence Analysis ◽  
Efflux Pump ◽  
Serial Passage ◽  
Efflux Pump Inhibitor ◽  
In Vitro Development ◽  
Development Of Resistance ◽  
High Level ◽  
Vitro Development

ABSTRACT The in vitro development of resistance to the new nonfluorinated quinolones (NFQs; PGE 9262932, PGE 4175997, and PGE 9509924) was investigated in Staphylococcus aureus. At concentrations two times the MIC, step 1 mutants were isolated more frequently with ciprofloxacin and trovafloxacin (9.1 × 10−8 and 5.7 × 10−9, respectively) than with the NFQs, gatifloxacin, or clinafloxacin (<5.7 × 10−10). Step 2 and step 3 mutants were selected via exposure of a step 1 mutant (selected with trovafloxacin) to four times the MICs of trovafloxacin and PGE 9262932. The step 1 mutant contained the known Ser80-Phe mutation in GrlA, and the step 2 and step 3 mutants contained the known Ser80-Phe and Ser84-Leu mutations in GrlA and GyrA, respectively. Compared to ciprofloxacin, the NFQs were 8-fold more potent against the parent and 16- to 128-fold more potent against the step 3 mutants. Mutants with high-level NFQ resistance (MIC, 32 μg/ml) were isolated by the spiral plater-based serial passage technique. DNA sequence analysis of three such mutants revealed the following mutations: (i) Ser84-Leu in GyrA and Glu84-Lys and His103-Tyr in GrlA; (ii) Ser-84Leu in GyrA, Ser52-Arg in GrlA, and Glu472-Val in GrlB; and (iii) Ser84-Leu in GyrA, Glu477-Val in GyrB, and Glu84-Lys and His103-Tyr in GrlA. Addition of the efflux pump inhibitor reserpine (10 μg/ml) resulted in 4- to 16-fold increases in the potencies of the NFQs against these mutants, whereas it resulted in 2-fold increases in the potencies of the NFQs against the parent.

scholarly journals In Vitro Infection Model Characterizing the Effect of Efflux Pump Inhibition on Prevention of Resistance to Levofloxacin and Ciprofloxacin in Streptococcus pneumoniae

2007 ◽  
Vol 51 (11) ◽  
pp. 3988-4000 ◽  
Author(s):  
Arnold Louie ◽  
David L. Brown ◽  
Weiguo Liu ◽  
Robert W. Kulawy ◽  
Mark R. Deziel ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Efflux Pump ◽  
Community Acquired Pneumonia ◽  
Fluoroquinolone Resistance ◽  
Infection Model ◽  
Wild Type ◽  
Efflux Pump Inhibition ◽  
Short Term Exposure ◽  
Emergence Of Resistance

ABSTRACT The prevalence of fluoroquinolone-resistant Streptococcus pneumoniae is slowly rising as a consequence of the increased use of fluoroquinolone antibiotics to treat community-acquired pneumonia. We tested the hypothesis that increased efflux pump (EP) expression by S. pneumoniae may facilitate the emergence of fluoroquinolone resistance. By using an in vitro pharmacodynamic infection system, a wild-type S. pneumoniae strain (Spn-058) and an isogenic strain with EP overexpression (Spn-RC2) were treated for 10 days with ciprofloxacin or levofloxacin in the presence or absence of the EP inhibitor reserpine to evaluate the effect of EP inhibition on the emergence of resistance. Cultures of Spn-058 and Spn-RC2 were exposed to concentration-time profiles simulating those in humans treated with a regimen of ciprofloxacin at 750 mg orally once every 12 h and with regimens of levofloxacin at 500 and 750 mg orally once daily (QD; with or without continuous infusions of 20 μg of reserpine/ml). The MICs of ciprofloxacin and levofloxacin for Spn-058 were both 1 μg/ml when susceptibility testing was conducted with each antibiotic alone and with each antibiotic in the presence of reserpine. For Spn-RC2, the MIC of levofloxacin alone and with reserpine was also 1 μg/ml; the MICs of ciprofloxacin were 2 and 1 μg/ml, respectively, when determined with ciprofloxacin alone and in combination with reserpine. Reserpine, alone, had no effect on the growth of Spn-058 and Spn-RC2. For Spn-058, simulated regimens of ciprofloxacin at 750 mg every 12 h or levofloxacin at 500 mg QD were associated with the emergence of fluoroquinolone resistance. However, the use of ciprofloxacin at 750 mg every 12 h and levofloxacin at 500 mg QD in combination with reserpine rapidly killed Spn-058 and prevented the emergence of resistance. For Spn-RC2, levofloxacin at 500 mg QD was associated with the emergence of resistance, but again, the resistance was prevented when this levofloxacin regimen was combined with reserpine. Ciprofloxacin at 750 mg every 12 h also rapidly selected for ciprofloxacin-resistant mutants of Spn-RC2. However, the addition of reserpine to ciprofloxacin therapy only delayed the emergence of resistance. Levofloxacin at 750 mg QD, with and without reserpine, effectively eradicated Spn-058 and Spn-RC2 without selecting for fluoroquinolone resistance. Ethidium bromide uptake and efflux studies demonstrated that, at the baseline, Spn-RC2 had greater EP expression than Spn-058. These studies also showed that ciprofloxacin was a better inducer of EP expression than levofloxacin in both Spn-058 and Spn-RC2. However, in these isolates, the increase in EP expression by short-term exposure to ciprofloxacin and levofloxacin was transient. Mutants of Spn-058 and Spn-RC2 that emerged under suboptimal antibiotic regimens had a stable increase in EP expression. Levofloxacin at 500 mg QD in combination with reserpine, an EP inhibitor, or at 750 mg QD alone killed wild-type S. pneumoniae and strains that overexpressed reserpine-inhibitable EPs and was highly effective in preventing the emergence of fluoroquinolone resistance in S. pneumoniae during therapy. Ciprofloxacin at 750 mg every 12 h, as monotherapy, was ineffective for the treatment of Spn-058 and Spn-RC2. Ciprofloxacin in combination with reserpine prevented the emergence of resistance in Spn-058 but not in Spn-RC2, the EP-overexpressing strain.

QSAR Studies on Bacterial Efflux Pump Inhibitors

2015 ◽  
pp. 238-268 ◽  
Author(s):  
Khac-Minh Thai ◽  
Trong-Nhat Do ◽  
Thuy-Viet-Phuong Nguyen ◽  
Duc-Khanh-Tho. Nguyen ◽  
Thanh-Dao Tran
Keyword(s):  
Bacterial Resistance ◽  
Efflux Pump ◽  
Current Knowledge ◽  
Efflux Pumps ◽  
Quantitative Structure Activity Relationship ◽  
Antimicrobial Drug Resistance ◽  
Qsar Studies ◽  
Hospital Stays ◽  
Efflux Pump Inhibitors

Antimicrobial drug resistance occurs when bacteria undergo certain modifications to eliminate the effectiveness of drugs, chemicals, or other agents designed to cure infections. To date, the burden of resistance has remained one of the major clinical concerns as it renders prolonged and complicated treatments, thereby increasing the medical costs with lengthier hospital stays. Of complex causes for bacterial resistance, there has been increasing evidence that proved the significant role of efflux pumps in antibiotic resistance. Coadministration of Efflux Pump Inhibitors (EPIs) with antibiotics has been considered one of the promising ways not only to improve the efficacy but also to extend the clinical utility of existing antibiotics. This chapter begins with outlining current knowledge about bacterial efflux pumps and drug designs applied in identification of their modulating compounds. Following, the chapter addresses and provides a discussion on Quantitative Structure-Activity Relationship (QSAR) analyses in search of novel and potent efflux pump inhibitors.

scholarly journals Systematic Analysis of Efflux Pump-Mediated Antiseptic Resistance in Staphylococcus aureus Suggests a Need for Greater Antiseptic Stewardship

mSphere ◽  
2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Patrick T. LaBreck ◽  
Audrey C. Bochi-Layec ◽  
Joshua Stanbro ◽  
Gina Dabbah-Krancher ◽  
Mark P. Simons ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Efflux Pump ◽  
Efflux Pumps ◽  
Transcriptional Analysis ◽  
Systematic Analysis ◽  
Daily Lives ◽  
Single Strain ◽  
Content Type ◽  
Subinhibitory Concentrations ◽  
Different Strains

ABSTRACT Staphylococcus aureus-associated infections can be difficult to treat due to multidrug resistance. Thus, infection prevention is critical. Cationic antiseptics, such as chlorhexidine (CHX) and benzalkonium chloride (BKC), are liberally used in health care and community settings to prevent infection. However, increased administration of antiseptics has selected for S. aureus strains that show reduced susceptibilities to cationic antiseptics. This increased resistance has been associated with carriage of specific efflux pumps (QacA, QacC, and NorA). Since prior published studies focused on different strains and on strains carrying only a single efflux gene, the relative importance of these various systems to antiseptic resistance is difficult to ascertain. To overcome this, we engineered a collection of isogenic S. aureus strains that harbored norA, qacA, and qacC, individually or in combination. MIC assays showed that qacA was associated with increased resistance to CHX, cetrimide (CT), and BKC, qacC was associated with resistance to CT and BKC, and norA was necessary for basal-level resistance to the majority of tested antiseptics. When all three pumps were present in a single strain, an additive effect was observed in the MIC for CT. Transcriptional analysis revealed that expression of qacA and norA was significantly induced following exposure to BKC. Alarmingly, in a strain carrying qacA and norA, preexposure to BKC increased CHX tolerance. Overall, our results reveal increased antiseptic resistance in strains carrying multiple efflux pumps and indicate that preexposure to BKC, which is found in numerous daily-use products, can increase CHX tolerance. IMPORTANCE S. aureus remains a significant cause of disease within hospitals and communities. To reduce the burden of S. aureus infections, antiseptics are ubiquitously used in our daily lives. Furthermore, many antiseptic compounds are dual purpose and are found in household products. The increased abundance of antiseptic compounds has selected for S. aureus strains that carry efflux pumps that increase resistance to antiseptic compounds; however, the effect of carrying multiple pumps within S. aureus is unclear. We demonstrated that an isogenic strain carrying multiple efflux pumps had an additive resistance phenotype to cetrimide. Moreover, in a strain carrying qacA and norA, increased chlorhexidine tolerance was observed after the strain was preexposed to subinhibitory concentrations of a different common-use antiseptic. Taken together, our findings demonstrate cooperation between antiseptic resistance efflux pumps and suggest that their protective phenotype may be exacerbated by priming with subinhibitory concentrations of household antiseptics.

scholarly journals Ketone- and Cyano-Selenoesters to Overcome Efflux Pump, Quorum-Sensing, and Biofilm-Mediated Resistance

Antibiotics ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 896
Author(s):  
Nikoletta Szemerédi ◽  
Annamária Kincses ◽  
Katerina Rehorova ◽  
Lan Hoang ◽  
Noemi Salardón-Jiménez ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Quorum Sensing ◽  
Efflux Pump ◽  
Resistant Bacteria ◽  
Gram Negative Bacteria ◽  
Experimental Systems ◽  
Efflux Pump Inhibition ◽  
Target Molecules ◽  
Vibrio Campbellii

The emergence of drug-resistant pathogens leads to a gradual decline in the efficacy of many antibacterial agents, which poses a serious problem for proper therapy. Multidrug resistance (MDR) mechanisms allow resistant bacteria to have limited uptake of drugs, modification of their target molecules, drug inactivation, or release of the drug into the extracellular space by efflux pumps (EPs). In previous studies, selenoesters have proved to be promising derivatives with a noteworthy antimicrobial activity. On the basis of these results, two series of novel selenoesters were synthesized to achieve more potent antibacterial activity on Gram-positive and Gram-negative bacteria. Fifteen selenoesters (eight ketone-selenoesters and seven cyano-selenoesters) were investigated with regards to their efflux pump-inhibiting, anti-quorum-sensing (QS), and anti-biofilm effects in vitro. According to the results of the antibacterial activity, the ketone-selenoesters proved to be more potent antibacterial compounds than the cyano-selenoesters. With regard to efflux pump inhibition, one cyano-selenoester on methicillin-resistant S. aureus and one ketone-selenoester on Salmonella Typhimurium were potent inhibitors. The biofilm inhibitory capacity and the ability of the derivatives to disrupt mature biofilms were noteworthy in all the experimental systems applied. Regarding QS inhibition, four ketone-selenoesters and three cyano-selenoesters exerted a noteworthy effect on Vibrio campbellii strains.

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