Investigating the phenotypic alterations associated with hypermucoviscous hypervirulent Klebsiella pneumoniae during phage resistance development

Abstract Phage therapy has been explored and used compassionately in the post-antibiotic era, though phage resistance might pose a serious challenge. The advent of hypervirulent and hypermucoviscous traits in Klebsiella pneumoniae limits therapeutic choices. This study investigated the phage resista...

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Main Authors: Ramya Juliet, Ramesh Nachimuthu
Format: Article
Language:English
Published: BMC 2025-08-01
Series:BMC Microbiology
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Online Access:https://doi.org/10.1186/s12866-025-04268-x
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author Ramya Juliet
Ramesh Nachimuthu
author_facet Ramya Juliet
Ramesh Nachimuthu
author_sort Ramya Juliet
collection DOAJ
description Abstract Phage therapy has been explored and used compassionately in the post-antibiotic era, though phage resistance might pose a serious challenge. The advent of hypervirulent and hypermucoviscous traits in Klebsiella pneumoniae limits therapeutic choices. This study investigated the phage resistance in hypermucoviscous hypervirulent Klebsiella pneumoniae clinical strain Kleb_53. A Klebsiella phage Disc against the Kleb_53 strain was isolated from sewage. The phage exhibited stability between − 20 °C and 60 °C and within the pH range of 3 to 11. The phage adsorption time was 15 min, with a latent period of 30 min and a burst size of 354 virions. The phage-resistant Kleb_53 variants were screened and examined for their phenotypic variations, antibiotic susceptibility, and biofilm formation. Colony morphotype variants were observed, including smooth, rough, and small colony variants. String, aggregation, and wetness tests confirmed reduced mucoviscosity. The plaque morphology differed between the wild and variants. Additionally, resistance to meropenem and third-generation cephalosporins was reversed, whereas the biofilm-forming ability varied among the recovered variants. This study demonstrates that ongoing phage-host interactions drive phenotypic changes and the emergence of phage-resistant variants with altered antibiotic susceptibility and biofilm-forming capacity. It also underscores the need for further research on phage resistance and strategies to overcome it for the effective application of phage therapy.
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spelling doaj-art-b5fd7da3ef8b41cd84ccb7cf22b173a12025-08-24T11:10:52ZengBMCBMC Microbiology1471-21802025-08-0125111110.1186/s12866-025-04268-xInvestigating the phenotypic alterations associated with hypermucoviscous hypervirulent Klebsiella pneumoniae during phage resistance developmentRamya Juliet0Ramesh Nachimuthu1Antibiotic Resistance and Phage Therapy Laboratory, Centre for Advanced Research in Bacteriophage and Infectious Diseases, School of Bio Sciences and Technology, Vellore Institute of Technology (VIT)Antibiotic Resistance and Phage Therapy Laboratory, Centre for Advanced Research in Bacteriophage and Infectious Diseases, School of Bio Sciences and Technology, Vellore Institute of Technology (VIT)Abstract Phage therapy has been explored and used compassionately in the post-antibiotic era, though phage resistance might pose a serious challenge. The advent of hypervirulent and hypermucoviscous traits in Klebsiella pneumoniae limits therapeutic choices. This study investigated the phage resistance in hypermucoviscous hypervirulent Klebsiella pneumoniae clinical strain Kleb_53. A Klebsiella phage Disc against the Kleb_53 strain was isolated from sewage. The phage exhibited stability between − 20 °C and 60 °C and within the pH range of 3 to 11. The phage adsorption time was 15 min, with a latent period of 30 min and a burst size of 354 virions. The phage-resistant Kleb_53 variants were screened and examined for their phenotypic variations, antibiotic susceptibility, and biofilm formation. Colony morphotype variants were observed, including smooth, rough, and small colony variants. String, aggregation, and wetness tests confirmed reduced mucoviscosity. The plaque morphology differed between the wild and variants. Additionally, resistance to meropenem and third-generation cephalosporins was reversed, whereas the biofilm-forming ability varied among the recovered variants. This study demonstrates that ongoing phage-host interactions drive phenotypic changes and the emergence of phage-resistant variants with altered antibiotic susceptibility and biofilm-forming capacity. It also underscores the need for further research on phage resistance and strategies to overcome it for the effective application of phage therapy.https://doi.org/10.1186/s12866-025-04268-xAntibiotic resistancePhage resistanceKlebsiella pneumoniaeHypermucoviscousPhage TherapyBiofilms
spellingShingle Ramya Juliet
Ramesh Nachimuthu
Investigating the phenotypic alterations associated with hypermucoviscous hypervirulent Klebsiella pneumoniae during phage resistance development
BMC Microbiology
Antibiotic resistance
Phage resistance
Klebsiella pneumoniae
Hypermucoviscous
Phage Therapy
Biofilms
title Investigating the phenotypic alterations associated with hypermucoviscous hypervirulent Klebsiella pneumoniae during phage resistance development
title_full Investigating the phenotypic alterations associated with hypermucoviscous hypervirulent Klebsiella pneumoniae during phage resistance development
title_fullStr Investigating the phenotypic alterations associated with hypermucoviscous hypervirulent Klebsiella pneumoniae during phage resistance development
title_full_unstemmed Investigating the phenotypic alterations associated with hypermucoviscous hypervirulent Klebsiella pneumoniae during phage resistance development
title_short Investigating the phenotypic alterations associated with hypermucoviscous hypervirulent Klebsiella pneumoniae during phage resistance development
title_sort investigating the phenotypic alterations associated with hypermucoviscous hypervirulent klebsiella pneumoniae during phage resistance development
topic Antibiotic resistance
Phage resistance
Klebsiella pneumoniae
Hypermucoviscous
Phage Therapy
Biofilms
url https://doi.org/10.1186/s12866-025-04268-x
work_keys_str_mv AT ramyajuliet investigatingthephenotypicalterationsassociatedwithhypermucoviscoushypervirulentklebsiellapneumoniaeduringphageresistancedevelopment
AT rameshnachimuthu investigatingthephenotypicalterationsassociatedwithhypermucoviscoushypervirulentklebsiellapneumoniaeduringphageresistancedevelopment