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bioRxiv · 10.64898/2026.08.03.742380

Exploration of Bacteriophages Against Vancomycin-Resistant Enterococcus faecium: A Report from India

Jaiswal, L. K.·Rathor, N.·Sonne, M.·Sahu, M.·Nehra, C.·Singh, M.·Sagar, T.·Chaudhry, R.
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Abstract

The vancomycin-resistant Enterococcus faecium (VREfm) has been declared as a high priority pathogen by World Health Organisation (WHO). It presents a major therapeutic challenge to healthcare, remaining with limited antibiotic options. Bacteriophage therapy has emerged as a promising alternative for combating antimicrobial-resistant pathogens. This study reports the isolation and characterization of bacteriophages active against VREfm and MDR E. faecium clinical isolates from India. Two bacteriophages, NIMS_EF375_N69_P9 ({Phi}1) and NIMS_EF375_N74_P12 ({Phi}2), were isolated from sewage by enrichment using MDR E. faecium strain EF375 as the propagation host. Lytic activity was confirmed by spot assay and double-layer soft agar plaque assay; both phages produced clear plaques of 1.5-2.0 mm. Transmission electron microscopy showed icosahedral heads with long non-contractile tails, presenting siphovirus-like morphotype within the class Caudoviricetes. Host range was assessed against 10 MDR E. faecium isolates (including the propagation host), 2 of which were VREfm. {Phi}1 lysed 5 of 10 isolates, including the VanA-type VREfm, whereas {Phi}2 lysed 7 of 10, including both VanA- and VanB-type VREfm. In time-kill assays against EF375 at an MOI of 1, {Phi}1 produced effective decline in optical density sustained through 24 h ([~]80% reduction relative to the untreated control), whereas {Phi}2 suppressed bacterial growth with only [~]50% reduction. To the best of our knowledge, this study represents the first report from India on the isolation and characterization of bacteriophages active against clinical VREfm isolates. The broader host range of {Phi}2 and the stronger killing kinetics of {Phi}1 suggest complementary roles in a phage cocktail, warranting genomic characterization and in vivo evaluation.

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Jaiswal, L. K., Rathor, N., Sonne, M., Sahu, M., Nehra, C., Singh, M., Sagar, T., Chaudhry, R.. 2026-08-03. Exploration of Bacteriophages Against Vancomycin-Resistant Enterococcus faecium: A Report from India. https://doi.org/10.64898/2026.08.03.742380

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