DOI: 10.4103/mgmj.mgmj_100_26 ISSN: 2347-7946
Preliminary in vitro evaluation of phage–silver nanoparticle combination against multidrug-resistant clinical isolates
Anupam Das, Nikhil Raj, Nidhi Rai, Akanksha Gupta, Aditi Singh, Prashant Kumar, Vikramjeet Singh, Manodeep Sen, Jyotsna Agarwal Abstract
Background:
Antimicrobial resistance is a growing global health challenge, underscoring the need for alternative therapeutic approaches against multidrug-resistant (MDR) bacteria. Although bacteriophages and green-synthesized silver nanoparticles (AgNPs) have been studied individually against MDR pathogens, evidence on their combined activity against clinical respiratory isolates of
Pseudomonas aeruginosa
and
Klebsiella pneumoniae
remains limited. Their combined use may therefore represent a promising antimicrobial strategy.
Aims and Objectives:
This preliminary
in vitro
study aimed to evaluate the antibacterial activity of bacteriophages and AgNPs synthesized using green methods, both individually and in combination, against MDR clinical isolates of
P. aeruginosa
and
K. pneumoniae
.
Materials and Methods:
The study included 10 MDR clinical isolates recovered from respiratory specimens, comprising 5
P. aeruginosa and
5
K. pneumoniae
isolates. We isolated bacteriophages from sewage, purified them, and characterized their lytic activity and stability. We synthesized AgNPs using
Calotropis gigantea
leaf extract via an eco-friendly green synthesis approach and characterized them using ultraviolet–visible spectroscopy and particle-size analysis. We evaluated the antibacterial activities of bacteriophages, AgNPs, and their combination by determining plaque-forming units (PFU/mL) and measuring zones of inhibition.
Results:
Both bacteriophages and AgNPs exhibited antibacterial activity against the MDR isolates. Phage titers were higher against
P. aeruginosa
(4.1 × 10
4
PFU/mL) than against
K. pneumoniae
(1.7 × 10
4
PFU/mL). AgNPs showed concentration-dependent antibacterial activity, with maximum inhibition zones of 19 mm against
P. aeruginosa
and of 22 mm against
K. pneumoniae
at 2.0 µL. The combination modestly increased inhibition zones against
P. aeruginosa
(2–4 mm); however, it showed no enhancement against
K. pneumoniae
.
Conclusion:
In this preliminary
in vitro
study, the phage–AgNP combination showed enhanced antibacterial activity, particularly against MDR
P. aeruginosa
. These findings warrant further investigation using larger, more diverse isolate collections and appropriate
in vivo
models.