Browsing by Author "Aishwarya Nikhil"

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Antifungal Susceptibility Profile of Aspergillus Strains Isolated From the Lower Respiratory Tract in Eastern Indian Patients: A Hospital-Based Study
(John Wiley and Sons Inc, 2025) Aishwarya Nikhil; Sradha Choudhury; Mohit Bhatia; Atul Kumar Tiwari; Ritika Srivastava; Abhirami Prasad; Ragini Tilak; Munesh Kumar Gupta; Roger Jagdish Narayan
Respiratory aspergillosis refers to a range of infections, from allergic to chronic and invasive, which can be life-threatening and are primarily caused by Aspergillus fumigatus and Aspergillus flavus. Other species, including Aspergillus terreus, Aspergillus nidulans, and Aspergillus versicolor, have also been implicated in respiratory infections. Treatment for chronic to invasive pulmonary aspergillosis typically involves azole antifungal drugs, although studies have shown varying minimum inhibitory concentrations (MIC) for these medications, with a growing concern over voriconazole resistance. During the period from August 2022 to May 2024, characteristic hyphae were detected in 7.2% of lower respiratory samples, with culture positivity in 12.8%, including early morning sputum and bronchoalveolar lavage fluid samples. A. flavus (n = 282) was the most frequently isolated species, followed by A. fumigatus (n = 86). Additionally, a seasonal trend was observed for Aspergillus infections, with peaks in April and September. The MIC of itraconazole, voriconazole, posaconazole, amphotericin B, ravuconazole, and caspofungin were assessed for the isolated Aspergillus species. A higher MIC of amphotericin B was observed against A. flavus and A. terreus, whereas azoles exhibited a relatively lower MIC. Caspofungin and posaconazole exhibited the lowest MIC against the isolated Aspergillus species. Therefore, it is crucial to identify the causative fungi and determine the antifungal MIC for Aspergillus species responsible for lower respiratory tract infections. This study emphasizes the significance of respiratory aspergillosis in TB-endemic regions of Eastern India. © 2025 The Author(s). MicrobiologyOpen published by John Wiley & Sons Ltd.
Fungal Rhinosinusitis Caused by Uncommon Scedosporium Apiospermum Fungus species: A Case Report and Review of Literature
(Springer, 2025) Ragini Tilak; Sushil Kumar Aggarwal; Abhirami Prasad; Munesh Kumar Gupta; Aishwarya Nikhil; Shradha Choudhury; Dolly Talda
We report a case of rhinosinusitis caused by Scedosporium apiospermum in a 35-year-old male who presented with nasal discharge. Diagnosis was made by demonstration of hyaline hyphae in the tissue biopsy and culture characteristics. The patient was managed by surgical debridement and oral voriconazole. The patient responded well to the treatment. This case signifies the importance of culture isolation and antifungal minimal inhibitory concentration (MIC) in each case of fungal rhinosinusitis. © Association of Otolaryngologists of India 2025.
Making vancomycin a potent broad-spectrum antimicrobial agent using polyaziridine-stabilized gold nanoparticles as a delivery vehicle
(SAGE Publications Ltd, 2025) Atul Kumar Tiwari; Aishwarya Nikhil; Avinash Kumar Chaurasia; Prem Chandra Pandey; Roger Jagdish Narayan; Munesh Kumar Gupta
The rise of antimicrobial drug resistance among microorganisms presents a global challenge to clinicians. Therefore, it is essential to investigate drug delivery systems to combat resistant bacteria and fungi. This study examined the potential and mode of action of vancomycin-conjugated gold nanoparticles (PEI-AuNP@Van) to enhance vancomycin’s biocidal activity against C. tropicalis, C. albicans, E. coli, and P. aeruginosa. Drug conjugation and nanoparticle characterization were assessed using UV-Vis spectroscopy, X-ray diffraction, TEM, ATR-FTIR, and fluorescence spectroscopy. Effective vancomycin conjugation on polyethyleneimine-stabilized gold nanoparticles was achieved via electrostatic interactions or hydrogen bonding between the COO-/OH groups of vancomycin and the NH- groups of polyethyleneimine, yielding nanoparticles with a narrow size distribution and high zeta potential. The high luminescence of the nanoparticles facilitated their detection in microbial cells. PEI-AuNP@Van was internalized in C. albicans and C. tropicalis but showed surface adsorption in E. coli and P. aeruginosa. The in vitro results indicated that the nanodelivery system exhibited superior biocidal activity against the tested strains compared to free vancomycin and unconjugated AuNPs. The mode of action of PEI-AuNP@Van was cell-type-dependent, involving intracellular reactive oxygen species accumulation, cell membrane integrity loss, and apoptosis. The development of antimicrobial nanoformulations using AuNPs and efficient conjugation systems offers a promising approach to address antimicrobial drug resistance. © The Author(s) 2025.
New D-π-A-Based Coumarin- Derived Fluorescent Theranostic Probes With Broad-Spectrum Antimicrobial Activity
(John Wiley and Sons Inc, 2025) Himanshu Rai; Atul Kumar Tiwari; Aishwarya Nikhil; Ankit Tiwari; Prahalad Singh Bharti; Suresh Kumar Maury; Munesh Kumar Gupta; Sundaram Singh; Saroj Kumar; Gyan Prakash Modi
Understanding how multidrug-resistant (MDR) bacteria and fungi defy the existing antimicrobial agents requires innovative tools and techniques for real-time, in situ exploration of bacterial responses to antibiotics. Fluorescence-tagged antibiotics or dyes with inherent antimicrobial activity can provide a profound understanding of the molecular biology underlying antibiotic action and resistance mechanisms. Cutting-edge research highlights the pursuit of benzo-α-pyrone (coumarin) derivatives due to their excellent pharmacokinetics, diverse pharmacological activities, and innovative fluorescence molecular probes. In this study, donor-π-acceptor-based coumarin dyes were designed and evaluated for antimicrobial efficacy against fungal strains (Candida albicans), Gram-negative pathogens (Escherichia coli), and Gram-positive bacteria (Staphylococcus aureus). I-6 exhibited notable antimicrobial activity against S. aureus and C. albicans compared with E. coli. Conversely, I-9, a congener of I-6, showed a comparable affinity for S. aureus but found poor activity against the remaining tested strains. Mechanistic investigative studies unveiled that the inhibitory efficacy of I-6 can be attributed to its capacity to generate high reactive oxygen species (ROS) formation. Despite the evident antimicrobial potential of I-6 in the data, our future prospects, including real-time visualization to study physiological processes like uptake, distribution, and mechanism of action through fluorescence-based imaging modalities, could enhance the applicability of these probes. © 2025 Deutsche Pharmazeutische Gesellschaft.
Synthesis of imidazole-fused nitrogen-bridgehead heterocycles catalysed by lipase and their antifungal and antimicrobial bioactivity
(Royal Society of Chemistry, 2024) Manjit Singh; Manisha Malviya; Vijay B. Yadav; Aishwarya Nikhil; Munesh Gupta
An effective approach for selective C-N bond formation for synthesising imidazo[1,2-a] pyridine-based heterocycles using porcine pancreatic lipase (PPL) as a biocatalyst has been devised. Under moderate conditions, a series of imidazo[1,2-a]pyridine-based heterocycle derivatives were synthesised with remarkable selectivity in good-to-excellent yields (89-95%). Further, the antimicrobial and antifungal activities of derivatives 3ha, 3ka, 3fa, 3hc, and 3eb were observed, and they were found to be biologically active in antimicrobial susceptibility tests for Gram-positive bacteria (Enterococcus faecalis ATCC 29212 and Staphylococcus auris ATCC 25923), Gram-negative bacteria (Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853) and fungal strains (Candida albicans ATCC 90028 and Candida tropicalis ATCC 750). © 2024 The Royal Society of Chemistry.
Vancomycin-Conjugated Polyethyleneimine-Stabilized Gold Nanoparticles Attenuate Germination and Show Potent Antifungal Activity against Aspergillus spp.
(Multidisciplinary Digital Publishing Institute (MDPI), 2024) Aishwarya Nikhil; Atul Kumar Tiwari; Ragini Tilak; Saroj Kumar; Prahlad Singh Bharti; Prem C. Pandey; Roger J. Narayan; Munesh Kumar Gupta
Antifungal drug resistance in filamentous fungi, particularly Aspergillus species, is increasing worldwide. Therefore, new antifungal drugs or combinations of drugs are urgently required to overcome this public health situation. In the present study, we examined the antifungal activity of vancomycin-functionalized AuNPs. These functionalized AuNPs were characterized, and their antifungal activity and associated killing mechanism were investigated using conventional methodologies against the conidia of A. fumigatus and A. flavus. The differential antifungal activity of vancomycin-functionalized Au-NPs against the conidia of Aspergillus species is dependent on structural differences in the conidial cell wall. The results demonstrated potent fungicidal activity against A. fumigatus, with a MIC value of 4.68 µg/mL, 93% germination inhibition, and 38.4% killing rate within 8 h of exposure. However, the activity against A. flavus was fungistatic; a MIC value of 18.7 µg/mL and 35% conidial germination inhibition, followed by 28.4% killing rate, were noted under similar conditions. Furthermore, endogenous reactive oxygen species (ROS) accumulation was 37.4 and 23.1% in conidial populations of A. fumigatus and A. flavus, respectively. Raman spectroscopy analysis confirmed the possible (but not confirmed) binding of functionalized AuNPs with the chitin and galactomannan components of the cell wall. A potential strategy that involves the exploration of antibacterial drugs using AuNPs as efficient drug carriers may also be appropriate for countering emerging drug resistance in filamentous fungi. © 2024 by the authors.