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Chandal N, Tambat R, Kalia R, Kumar G, Mahey N, Jachak S, Nandanwar H. Efflux pump inhibitory potential of indole derivatives as an arsenal against norA over-expressing Staphylococcus aureus. Microbiol Spectr 2023; 11:e0487622. [PMID: 37754560 PMCID: PMC10581058 DOI: 10.1128/spectrum.04876-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 07/11/2023] [Indexed: 09/28/2023] Open
Abstract
NorA, an extensively studied efflux pump in Staphylococcus aureus, has been connected to fluoroquinolone, antiseptic, and disinfection resistance. Several studies have also emphasized how efflux pumps, including NorA, function as the first line of defense of S. aureus against antibiotics. In this study, we have screened some chemically synthesized indole derivatives for their activity as efflux pump inhibitors (EPIs). The derivative SMJ-5 was found to be a potent NorA efflux pump inhibitor among the screened indole derivatives, owing to increased ethidium bromide and norfloxacin accumulation in norA over-expressing S. aureus. The combination of SMJ-5 and ciprofloxacin demonstrated the eradication of S. aureus biofilm and prolonged the post-antibiotic effect more than ciprofloxacin alone. SMJ-5 was able to inhibit staphyloxanthin virulence. In in vitro time-kill trials and in vivo efficacy investigations, the combination enhanced the bactericidal activity of ciprofloxacin against S. aureus. Additionally, reverse transcription PCR results revealed that SMJ-5 also inhibits the NorA efflux pump indirectly at the transcriptional level. IMPORTANCE The NorA efflux pump is the most effective resistance mechanism in S. aureus. The clinical importance of NorA efflux pumps is demonstrated by the expression of pump genes in S. aureus strains in response to fluoroquinolones and biocides. Along with the repercussions of decreased fluoroquinolone sensitivity, increasing expression of efflux pump genes by their substrate necessitates the importance of efflux pump inhibitors. Reserpine and verapamil are clinically used to treat ailments and have proven NorA inhibitors, but, unfortunately, the concentration needed for these drugs to inhibit the pump is not safe in clinical settings. In the current study, we have screened some indole derivatives, and among them, SMJ-5 was reported to potentiate norfloxacin and ciprofloxacin at their sub-inhibitory concentration by inhibiting the norA gene transcriptionally. Here we highlight the promising points of this study, which could serve as a model to design a therapeutic EPI candidate against norA over-expressing S. aureus.
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Affiliation(s)
- Nishtha Chandal
- Clinical Microbiology and Antimicrobial Research Laboratory, CSIR-Institute of Microbial Technology, Chandigarh, India
- Academy of Scientific & Innovative Research (AcSIR), Ghaziabad, Uttar Pradesh, India
| | - Rushikesh Tambat
- Clinical Microbiology and Antimicrobial Research Laboratory, CSIR-Institute of Microbial Technology, Chandigarh, India
| | - Ritu Kalia
- Department of Natural Products, National Institute of Pharmaceutical Education and Research, Mohali, Punjab, India
| | - Gautam Kumar
- Department of Natural Products, Chemical Sciences, National Institute of Pharmaceutical Education and Research- Hyderabad, Balanagar, Telangana, India
| | - Nisha Mahey
- Clinical Microbiology and Antimicrobial Research Laboratory, CSIR-Institute of Microbial Technology, Chandigarh, India
- Academy of Scientific & Innovative Research (AcSIR), Ghaziabad, Uttar Pradesh, India
| | - Sanjay Jachak
- Department of Natural Products, National Institute of Pharmaceutical Education and Research, Mohali, Punjab, India
| | - Hemraj Nandanwar
- Clinical Microbiology and Antimicrobial Research Laboratory, CSIR-Institute of Microbial Technology, Chandigarh, India
- Academy of Scientific & Innovative Research (AcSIR), Ghaziabad, Uttar Pradesh, India
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Palazzotti D, Bissaro M, Bolcato G, Astolfi A, Felicetti T, Sabatini S, Sturlese M, Cecchetti V, Barreca ML, Moro S. Deciphering the Molecular Recognition Mechanism of Multidrug Resistance Staphylococcus aureus NorA Efflux Pump Using a Supervised Molecular Dynamics Approach. Int J Mol Sci 2019; 20:E4041. [PMID: 31430864 PMCID: PMC6719125 DOI: 10.3390/ijms20164041] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 08/09/2019] [Accepted: 08/15/2019] [Indexed: 12/01/2022] Open
Abstract
The use and misuse of antibiotics has resulted in critical conditions for drug-resistant bacteria emergency, accelerating the development of antimicrobial resistance (AMR). In this context, the co-administration of an antibiotic with a compound able to restore sufficient antibacterial activity may be a successful strategy. In particular, the identification of efflux pump inhibitors (EPIs) holds promise for new antibiotic resistance breakers (ARBs). Indeed, bacterial efflux pumps have a key role in AMR development; for instance, NorA efflux pump contributes to Staphylococcus aureus (S. aureus) resistance against fluoroquinolone antibiotics (e.g., ciprofloxacin) by promoting their active extrusion from the cells. Even though NorA efflux pump is known to be a potential target for EPIs development, the absence of structural information about this protein and the little knowledge available on its mechanism of action have strongly hampered rational drug discovery efforts in this area. In the present work, we investigated at the molecular level the substrate recognition pathway of NorA through a Supervised Molecular Dynamics (SuMD) approach, using a NorA homology model. Specific amino acids were identified as playing a key role in the efflux pump-mediated extrusion of its substrate, paving the way for a deeper understanding of both the mechanisms of action and the inhibition of such efflux pumps.
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Affiliation(s)
- Deborah Palazzotti
- Molecular Modeling Section (MMS), Department of Pharmaceutical and Pharmacological Sciences, University of Padova, via Marzolo 5, 35131 Padova, Italy
- Department of Pharmaceutical Sciences, “Department of excellence 2018-2022”, University of Perugia, Via del Liceo 1, 06123 Perugia, Italy
| | - Maicol Bissaro
- Molecular Modeling Section (MMS), Department of Pharmaceutical and Pharmacological Sciences, University of Padova, via Marzolo 5, 35131 Padova, Italy
| | - Giovanni Bolcato
- Molecular Modeling Section (MMS), Department of Pharmaceutical and Pharmacological Sciences, University of Padova, via Marzolo 5, 35131 Padova, Italy
| | - Andrea Astolfi
- Department of Pharmaceutical Sciences, “Department of excellence 2018-2022”, University of Perugia, Via del Liceo 1, 06123 Perugia, Italy
| | - Tommaso Felicetti
- Department of Pharmaceutical Sciences, “Department of excellence 2018-2022”, University of Perugia, Via del Liceo 1, 06123 Perugia, Italy
| | - Stefano Sabatini
- Department of Pharmaceutical Sciences, “Department of excellence 2018-2022”, University of Perugia, Via del Liceo 1, 06123 Perugia, Italy
| | - Mattia Sturlese
- Molecular Modeling Section (MMS), Department of Pharmaceutical and Pharmacological Sciences, University of Padova, via Marzolo 5, 35131 Padova, Italy
| | - Violetta Cecchetti
- Department of Pharmaceutical Sciences, “Department of excellence 2018-2022”, University of Perugia, Via del Liceo 1, 06123 Perugia, Italy
| | - Maria Letizia Barreca
- Department of Pharmaceutical Sciences, “Department of excellence 2018-2022”, University of Perugia, Via del Liceo 1, 06123 Perugia, Italy
| | - Stefano Moro
- Molecular Modeling Section (MMS), Department of Pharmaceutical and Pharmacological Sciences, University of Padova, via Marzolo 5, 35131 Padova, Italy
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