Review Reports - Bacteriophage Therapy Against <i>Klebsiella Pneumoniae</i>

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This review presents a thorough and timely survey of bacteriophage therapy targeting Klebsiella pneumoniae, with particular attention to the pressing challenges posed by CRKP and hvKP strains. The organization is logical, beginning with the clinical problem, moving through core biology, and culminating in advanced strategies and clinical evidence. The figures and tables are well-chosen, effectively supporting the written content. The manuscript excels in its detailed synthesis of receptor biology and the evolutionary dynamics of phage-host interactions, particularly regarding capsule serotypes and the emergence of resistance. The inclusion of recent clinical cases from 2019 onward provides valuable, tangible evidence of therapeutic progress and real-world complications. The section on optimization strategies is a significant highlight, offering a well-structured overview of current research avenues from cocktails to synthetic biology.

Minor revision

Positioning: While comprehensive, the review could more explicitly articulate its unique contribution within the field. A brief statement clarifying how this synthesis differs from other recent reviews (e.g., in its focus on convergent CR-hvKP strains or its integrated discussion of depolymerases) would help frame its value.
Flow: The narrative would benefit from smoother transitions, especially between the detailed receptor mechanisms (Section 4.1) and the subsequent explorations of therapeutic practice. Some guiding sentences could better connect the "how" of phage action to the "so what" of its application.
Critical Depth: Certain sections lean toward descriptive summaries of studies. Incorporating more critical analysis—such as discussing contradictory findings, weighing the evidence for and against certain strategies, or highlighting specific, unresolved gaps in knowledge—would strengthen the manuscript's scholarly impact.
Conciseness: The review is rich with strain-specific examples, which is commendable for depth. However, in some subsections (e.g., 4.1, 6.1), consolidating similar examples or presenting them in a more summarized, comparative format might improve readability for a broader audience without sacrificing key information.
Practical Challenges: The "Challenges" section effectively covers biological and clinical hurdles. Expanding it to include a brief discussion of non-scientific barriers—such as scalable manufacturing, regulatory pathways beyond compassionate use, and cost considerations—would provide a more holistic view of the field's translation.
Language Polish: The English is clear and understandable throughout. Some minor refinements in grammar, sentence structure, and word choice would further enhance clarity and flow.

With some adjustments to enhance its narrative cohesion, critical perspective, and scope, it has the potential to be a valuable and impactful publication.

Comments on the Quality of English Language

The manuscript is generally well-written and clear in conveying its scientific content. The terminology is precise, and the overall structure supports readability.

For further polish, attention could be given to:

Sentence flow: Some sentences are lengthy or structurally dense; breaking or rephrasing a few would improve pacing.

Prepositional/Article Use: Occasional minor inconsistencies (e.g., "in the vivo" vs. "in vivo") are present but do not hinder understanding.

Word choice: In a few instances, more direct or conventional phrasing could replace slightly awkward constructions (e.g., “makes treatment particularly challenging” is preferable to “greatly complicates clinical management” in certain contexts).

These are minor refinements. With careful proofreading, the language will meet the high standard expected for publication.

Author Response

3. Point-by-point response to Comments and Suggestions for Authors

Comments 1: [A brief statement clarifying how this synthesis differs from other recent reviews (e.g., in its focus on convergent CR-hvKP strains or its integrated discussion of depolymerases) would help frame its value.]

Response 1: Thank you for pointing this out. We agree with this comment. This review's primary focus and distinct contribution are its integration of fundamental research with clinical imperatives. It connects insights into the evolutionary threat of CR-hvKP convergent strains, the molecular mechanisms of phage receptor recognition and infection, and the utility of depolymerases. Notably, unlike previous literature, which often concentrated on preclinical studies or isolated successful cases, this review systematically synthesizes and evaluates successful applications of phage therapy against Klebsiella pneumoniae infections, spanning from animal models to clinical trials. It details therapeutic strategies and efficacy outcomes, thereby providing a more comprehensive and coherent empirical foundation and translational roadmap for clinical adoption. Furthermore, the review prospectively outlines key future research directions, advocating for interdisciplinary approaches that leverage synthetic biology and artificial intelligence to advance phage therapy from empirical application toward a designable, predictable next-generation precision antimicrobial strategy. We have adequately addressed this in the revised manuscript.

Comments 2: [The narrative would benefit from smoother transitions, especially between the detailed receptor mechanisms (Section 4.1) and the subsequent explorations of therapeutic practice. Some guiding sentences could better connect the "how" of phage action to the "so what" of its application.]

Response 2: Thank you for pointing this out. We agree with this comment. To enhance the logical flow from "mechanisms of action" to "therapeutic practice," we have incorporated transitional sentences in key sections. For instance, in Section 4.1 (line 231–235), a brief note has been added to explicitly link receptor-binding mechanisms to their clinical translational potential. Similarly, in Section 4.1.3 (line 292–294), the discussion of receptor escape mechanisms naturally transitions into an explanation of their implications for clinical resistance development and the adaptation of treatment strategies. These additions strengthen the logical coherence between sections, guiding readers to better understand the continuum from fundamental scientific insights to clinical application. We have adequately addressed this in the revised manuscript.

Comments 3: [Certain sections lean toward descriptive summaries of studies. Incorporating more critical analysis—such as discussing contradictory findings, weighing the evidence for and against certain strategies, or highlighting specific, unresolved gaps in knowledge—would strengthen the manuscript's scholarly impact.]

Response 3: Thank you for pointing this out. We agree with this comment. At the methodological level (e.g., lines 352–536), we explicitly point out that the vast majority of current animal models are based on acute infection. We critically argue that efficacy and safety conclusions drawn from acute infection models cannot be simply extrapolated to chronic or recurrent infection scenarios, which involve more complex pathophysiological mechanisms. At the strategic evaluation level (e.g., lines 625–627), we weigh existing technological pathways and propose that engineered phages should be positioned as a complementary strategy to natural phages, rather than a complete replacement. Finally, at the forward-looking level (e.g., lines 477–482), we highlight a fundamental systemic gap in the field: the lack of a unified global regulatory model and evaluation framework for phage therapy. We have adequately addressed this in the revised manuscript.

Comments 4: [The review is rich with strain-specific examples, which is commendable for depth. However, in some subsections (e.g., 4.1, 6.1), consolidating similar examples or presenting them in a more summarized, comparative format might improve readability for a broader audience without sacrificing key information.]

Response 4: Thank you for pointing this out. We agree with this comment. Certain similar cases within specific subsections(e.g., 4.2.1. , 6.1.1., 6.2.-Table 2) have been consolidated or streamlined to enhance conciseness and flow. We have adequately addressed this in the revised manuscript.

Comments 5: [The "Challenges" section effectively covers biological and clinical hurdles. Expanding it to include a brief discussion of non-scientific barriers—such as scalable manufacturing, regulatory pathways beyond compassionate use, and cost considerations—would provide a more holistic view of the field's translation.]

Response 5: Thank you for pointing this out. We agree with this comment. The "Challenges" section has been enriched through the addition and adjustment of content. We have adequately addressed this in the revised manuscript.

4. Response to Comments on the Quality of English Language

Point 1:The English is clear and understandable throughout. Some minor refinements in grammar, sentence structure, and word choice would further enhance clarity and flow.Some sentences are lengthy or structurally dense; breaking or rephrasing a few would improve pacing.

Prepositional/Article Use: Occasional minor inconsistencies (e.g., "in the vivo" vs. "in vivo") are present but do not hinder understanding.

Response 1: Thank you for pointing this out. We agree with this comment. The language has been comprehensively edited and refined in the revised manuscript to enhance clarity and academic tone. We have adequately addressed this in the revised manuscript.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript entitled “Bacteriophage Therapy Against Klebsiella pneumoniae” addresses a highly relevant and timely topic in the context of antimicrobial resistance and emerging alternative therapies. The review is comprehensive in scope, well referenced, and demonstrates strong subject-matter expertise, particularly in phage biology, receptor interactions, and therapeutic strategies.

However, despite these strengths, the manuscript requires substantial revision before it can be considered for acceptance.

My suggestions:

Line 38–47 The distinction between CRKP and hvKP is well explained; however, the section title “High risk in K. pneumoniae” should be revised for clarity (e.g., “High-Risk K. pneumoniae Pathotypes”).

Line 60 – Typographical error: “Hypervirulet” should be corrected to “Hypervirulent.”

Line 69–77 The description of virulence mechanisms is informative but overly detailed for a review section; consider condensation to avoid redundancy with cited reviews.

Line 96–103 The transition into phage therapy is appropriate, but the historical overview could be shortened to improve flow.

Line 119–157 The explanation of phage life cycles is accurate but reads like a textbook section; consider summarizing and focusing on clinical relevance.

Line 167–193 The advantages of phage therapy are clearly presented; however, several claims (e.g., “self-limiting,” “auto-dosing”) should be supported by additional clinical or in vivo references.

Lines 195–202: This section appropriately introduces experimental evidence; however, clearer differentiation between animal models and human data is needed.

Line 203–231 The receptor–phage interaction section is scientifically strong, though dense; schematic cross-referencing to Figure 3 could improve readability.

Line 248–268 The discussion of phage resistance mechanisms is valuable; however, the clinical implications of these resistance pathways should be more explicitly stated.

Line 270–305 Animal model studies are well summarized, but numerical outcomes (e.g., log reductions, survival rates) should be standardized for easier comparison.

Lines 306–352: Clinical case reports are informative; however, the narrative style is lengthy and should be condensed, with clearer emphasis on outcomes and limitations.

Line 353–365 The pulmonary infection case is particularly interesting; the concept of reduced virulence despite phage resistance should be highlighted more explicitly in the Discussion.

Lines 391-434: The challenges section is well-structured, but regulatory and ethical considerations could be expanded, especially in the context of global clinical deployment.

Line 436–484 Combination therapy strategies are thoroughly reviewed; however, some repetition exists between cocktail therapy and antibiotic–phage synergy subsections.

Lines 515–546: The depolymerase section is strong but may benefit from a short summary table listing depolymerases, their targets, and serotypes.

Line 594–603 The conclusion appropriately summarises the review, but should be more cautious in tone regarding clinical translation and avoid speculative language.

Author Response

3. Point-by-point response to Comments and Suggestions for Authors

Comments 1: [Line 38–47 The distinction between CRKP and hvKP is well explained; however, the section title “High risk in K. pneumoniae” should be revised for clarity (e.g., “High-Risk K. pneumoniae Pathotypes”).]

Response 1: Thank you for pointing this out. We agree with this comment. We have revised the title at the corresponding section to "High-Risk Klebsiella pneumoniae Serotypes"(Line 41) to refine the section's theme with greater precision. We have adequately addressed this in the revised manuscript.

Comments 2: [Line 60 – Typographical error: “Hypervirulet” should be corrected to “Hypervirulent.”]

Response 2: Thank you for pointing this out. We agree with this comment. We have addressed this in the revised manuscript as suggested(Line 64). We have adequately addressed this in the revised manuscript.

Comments 3: [Line 69–77 The description of virulence mechanisms is informative but overly detailed for a review section; consider condensation to avoid redundancy with cited reviews.]

Response 3: Thank you for pointing this out. We agree with this comment. The description of virulence mechanisms (Line 70-79) has been streamlined to provide a focused overview, preserving its essential elements. We have adequately addressed this in the revised manuscript.

Comments 4: [Line 96–103 The transition into phage therapy is appropriate, but the historical overview could be shortened to improve flow.]

Response 4: Thank you for pointing this out. We agree with this comment. The transitional paragraphs (Line 98-102) have been streamlined for greater conciseness and improved logical progression. We have adequately addressed this in the revised manuscript. We have adequately addressed this in the revised manuscript.

Comments 5: [Line 119–157 The explanation of phage life cycles is accurate but reads like a textbook section; consider summarizing and focusing on clinical relevance.]

Response 5: Thank you for pointing this out. We agree with this comment. In elucidating the phage life cycle (Line 119-175), we have placed particular emphasis on mechanisms with direct clinical relevance. For instance, we highlight that the pseudolysogenic state of phages may mediate the development of host bacterial resistance to other phages. Concurrently, we explore the potential of temperate phages to be repurposed through genetic engineering as targeted delivery vehicles. This focused discussion on mechanistically grounded applications provides a logical and necessary foundation for transitioning to the subsequent sections detailing clinical implementations. We have adequately addressed this in the revised manuscript.

Comments 6: [Line 167–193 The advantages of phage therapy are clearly presented; however, several claims (e.g., “self-limiting,” “auto-dosing”) should be supported by additional clinical or in vivo references.]

Response 6: Thank you for pointing this out. We agree with this comment. Regarding the discussion of key therapeutic characteristics (Line 191-214) such as "self-limiting " and "auto-dosing", we have supplemented the text with specific clinical cases or in vivo experimental data to provide direct support and strengthen the empirical foundation of our arguments. We have adequately addressed this in the revised manuscript.

Comments 7: [Lines 195–202: This section appropriately introduces experimental evidence; however, clearer differentiation between animal models and human data is needed.]

Response 7: Thank you for pointing this out. We agree with this comment. In this chapter (section 4.), a clearer differentiation is made between data derived from animal models and that obtained from human studies. We have adequately addressed this in the revised manuscript.

Comments 8: [Line 203–231 The receptor–phage interaction section is scientifically strong, though dense; schematic cross-referencing to Figure 3 could improve readability.]

Response 8: Thank you for pointing this out. We agree with this comment. The section on receptor-phage interactions (Line 227-275) has been condensed to enhance logical clarity.

All figures and tables in the manuscript have been cross-referenced to improve readability. We have adequately addressed this in the revised manuscript.

Comments 9: [Line 248–268 The discussion of phage resistance mechanisms is valuable; however, the clinical implications of these resistance pathways should be more explicitly stated.]

Response 9: Thank you for pointing this out. We agree with this comment. The clinical implications of phage resistance (Line 284-304) have been elaborated to create a tighter connection with the subsequent discussion on clinical applications. We have adequately addressed this in the revised manuscript.

Comments 10: [Line 270–305 Animal model studies are well summarized, but numerical outcomes (e.g., log reductions, survival rates) should be standardized for easier comparison.]

Response 10: Thank you for pointing this out. We agree with this comment. In the analysis of animal models (Line 309-356), key quantitative outcomes from the phage treatment groups—such as log reduction in bacterial load, animal survival rate, and histopathological damage scores have been listed to enhance intuitive comparison and quantitative assessment of therapeutic efficacy across different studies. We have adequately addressed this in the revised manuscript.

Comments 11: [Lines 306–352: Clinical case reports are informative; however, the narrative style is lengthy and should be condensed, with clearer emphasis on outcomes and limitations.]

Response 11: Thank you for pointing this out. We agree with this comment. The content of the clinical case reports (Line 361-431) has been streamlined, and their findings and limitations are now more explicitly highlighted. We have adequately addressed this in the revised manuscript.

Comments 12: [Line 353–365 The pulmonary infection case is particularly interesting; the concept of reduced virulence despite phage resistance should be highlighted more explicitly in the Discussion.]

Response 12: Thank you for pointing this out. We agree with this comment. The research finding that phage resistance can lead to attenuated bacterial virulence has been specifically discussed in the conclusion section for its clinical implications(Line 669-676). We have adequately addressed this in the revised manuscript.

Comments 13: [Lines 391-434: The challenges section is well-structured, but regulatory and ethical considerations could be expanded, especially in the context of global clinical deployment]

Response 13: Thank you for pointing this out. We agree with this comment. The "Challenges" section(Line 471-494) has been enriched through the addition and adjustment of content. We have adequately addressed this in the revised manuscript.

Comments 14: [Line 436–484 Combination therapy strategies are thoroughly reviewed; however, some repetition exists between cocktail therapy and antibiotic–phage synergy subsections.]

Response 14: Thank you for pointing this out. We agree with this comment. Redundant sections (section 6.1.1) have been amplified to enhance textual conciseness. We have adequately addressed this in the revised manuscript.

Comments 15: [Lines 515–546: The depolymerase section is strong but may benefit from a short summary table listing depolymerases, their targets, and serotypes.]

Response 15: Thank you for pointing this out. We agree with this comment. We have systematically consolidated information on depolymerases, their known targets, and associated serotypes into a concise summary table (Table 2). This presents the key informational network in a clear and visual format, facilitating quick reference and comparison for readers. We have adequately addressed this in the revised manuscript.

Comments 16: [Line 594–603 The conclusion appropriately summarises the review, but should be more cautious in tone regarding clinical translation and avoid speculative languag]

Response 16: Thank you for pointing this out. We agree with this comment. We have revised the conclusion (Lines 660–682) to adopt a more cautious and precise tone regarding clinical translation. Speculative language has been removed, and the text now focuses on summarizing the current evidence while clearly outlining the existing challenges and necessary future research directions to advance the field. We have adequately addressed this in the revised manuscript.

4. Response to Comments on the Quality of English Language

Point 1:The English could be improved to more clearly express the research..