Characterization of novel bacteriophages for phage therapy against multi-drug resistant Klebsiella pneumoniae isolated from clinical samples

Project Abstract

Characterization of novel bacteriophages isolated from environmental and clinical sources was undertaken to evaluate their potential as therapeutic agents against multi-drug resistant Klebsiella pneumoniae strains recovered from clinical specimens. The study integrated phage isolation, characterization, host range assessment, genomic analysis, and in vitro antibacterial efficacy to establish a foundation for phage therapy applications. A total of 120 environmental and 60 clinical samples were screened using standard enrichment and plaque assays against a panel of 20 MDR K. pneumoniae clinical isolates representing diverse sequence types and resistance mechanisms, including carbapenemases and extended-spectrum beta-lactamases. From these efforts, 18 distinct lytic phages were purified and subjected to comprehensive phenotypic and molecular analyses. Morphological evaluation via transmission electron microscopy categorized the phages into myoviridae and siphoviridae families, with broad adsorption kinetics observed against most MDR hosts. One-step growth curves revealed latent periods ranging from 15 to 40 minutes and burst sizes between 50 and 320 PFU per infected cell, indicating robust replicative capacity suitable for therapeutic use. Host range assessments demonstrated variable specificity, with several phages exhibiting broad-spectrum lytic activity across multiple K. pneumoniae lineages, including strains carrying blaNDM, blaKPC, and blaOXA-48 genes. Genomic sequencing and annotation of seven representative phages uncovered predominantly lytic genomes devoid of known virulence or integrase genes, reducing concerns about horizontal gene transfer and lysogenic conversion. Comparative genomics identified conserved tail fiber proteins implicated in receptor binding, alongside unique modules associated with depolymerase activity capable of degrading the capsule and biofilm matrices that contribute to MDR persistence. In vitro assays demonstrated significant reductions in bacterial counts and biofilm disruption when phage preparations were applied singly and in rationally designed cocktails, with synergistic effects observed when combined with last-resort antibiotics such as colistin and ceftazidime-avibactam under simulated physiological conditions. Phage stability tests indicated resilience to pH variations typical of the human body and a range of temperatures, supporting potential in vivo applicability. The study also assessed potential phage-to-phage interactions, identifying combinations that maximize host coverage while minimizing resistance emergence. Safety evaluations included endotoxin quantification and evaluation of lysis profiles to ensure minimal inflammatory potential. Collectively, the results demonstrate that well-characterized lytic bacteriophages and tailored phage cocktails can effectively target MDR K. pneumoniae strains, including biofilm-associated phenotypes, thereby offering a compelling alternative or adjunct to conventional antibiotics. The findings underscore the importance of integrating genomic screening, host-range mapping, and anti-biofilm capabilities in the development pipeline for phage therapy. The study provides a framework for advancing preclinical evaluation, informing dosing strategies, delivery methods, and regulatory considerations essential for translating phage therapy against MDR K. pneumoniae into clinical practice. Further work will focus on in vivo efficacy in relevant infection models and the optimization of phage formulations for systemic and localized applications.

Project Overview

What This Project Is About

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A simple, high-level look at how certain viruses that infect bacteria (phages) could be used to fight bacteria that are hard to kill with common antibiotics, specifically Klebsiella pneumoniae taken from patients. The project explores finding, testing, and understanding new phages to see if they can help treat infections without harming people.

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The Problem It Addresses

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Klebsiella pneumoniae is a common cause of serious infections and many strains are resistant to multiple drugs, making treatment difficult. This project looks for alternative tools (phages) to target these drug-resistant bacteria, filling a gap where antibiotics fail and potentially reducing illness and spread.

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Objectives of the Project

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1. Identify new bacteriophages that can infect the resistant Klebsiella pneumoniae.
2. Evaluate how well these phages kill the bacteria in lab tests.
3. Characterize the phages’ properties (shape, genome, and life cycle) to ensure safety and effectiveness.
4. Explore how combinations of phages (phage cocktails) work against different bacterial strains.
5. Assess any signs of bacterial resistance to phages and how to mitigate it.

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What You Will Do Step by Step

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Collect bacterial samples and isolate candidate phages that infect them. Test phage activity in simple lab assays to measure killing efficiency. Examine phage features using basic microscopy and genetic tests. Build preliminary phage cocktails and test their performance. Analyze data to identify the most promising phages and discuss safety and potential real-world use.

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Expected Outcome

Expect to identify one or more phages that effectively reduce drug-resistant Klebsiella pneumoniae in lab settings, with basic profiles of their safety and suitability for further development into phage therapy approaches.