The Importance of Ear Canal Microbiota and Earwax in the Prevention of Outer Ear Infections

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have submitted a narrative review on cerumen and ear microbiota in prevention of ear canal infections. Suggest authors adhere to SANRA criteria for narrative reviews when revising the manuscript.

1.the article's importance, and aims should be formulated clearly and justified. 

2. Search strategy should be described in detail.  Mention of "various databases", PubMed and 15 years in Abstract is inadequate. 

3. Are outer ear infections a result of disturbances in the composition of microbiome or the ear canal environment (humidity, pH, immunity) or both? The abstract mentions dysbiosis and amount of ear wax contributing to ear infection. Please discuss.

4.Can altering the pH help in the treatment of outer ear infections?

 

Author Response

Reviewer 1

The authors have submitted a narrative review on cerumen and ear microbiota in prevention of ear canal infections. Suggest authors adhere to SANRA criteria for narrative reviews when revising the manuscript.

To incorporate this suggestion when revising our manuscript, we considered the evaluation scale for review articles, which highlights the importance, objectives, description of the literature search, referencing of sources, scientific argumentation, and data presentation. Accordingly, we have structured our abstract and provide additional illustrations with text descriptions. However, we would like to emphasize that the way the information is presented is typical of a review article and does not reflect the typical structure of a narrative review.

1.the article's importance, and aims should be formulated clearly and justified. 

Thank you for pointing this out. It was corrected in revised version of our manuscript. Now we provide a structured abstract, and modified text

2. Search strategy should be described in detail.  Mention of "various databases", PubMed and 15 years in Abstract is inadequate. 

Thank you for pointing this out. The specific databases used have been added and corrected in the abstract of the revised manuscript.

3. Are outer ear infections a result of disturbances in the composition of microbiome or the ear canal environment (humidity, pH, immunity) or both? The abstract mentions dysbiosis and amount of ear wax contributing to ear infection. Please discuss.

We agree that pH is an important factor regulating the growth of microorganisms in the external auditory canal. Changes in pH can affect the activity and effectiveness of protective substances contained in earwax, thus modulating local defense mechanisms. We have clarified and explained this point in the revised version of the manuscript.

4.Can altering the pH help in the treatment of outer ear infections?

Thank you for this question. Indeed, altering the pH of the external auditory canal may be beneficial in the management of outer ear infections. The external ear normally maintains a slightly acidic environment, which inhibits the growth of pathogenic bacteria and fungi. Disruption of this acidic pH, for example due to excessive moisture or mechanical irritation, can promote microbial overgrowth and infection. Restoration or maintenance of an acidic pH can enhance the antimicrobial properties of cerumen and support the natural defense mechanisms of the external auditory canal. It was emphasized in the revised version of the manuscript.

Reviewer 2 Report

Comments and Suggestions for Authors

Report (Major revision)

Title: The importance of ear canal microbiota and earwax in the prevention of outer ear infections (ijms-4059636).

The outer ear microbiome and earwax in the ear canal is an interesting topic. However, there are some suggestions which authors can take in mind to improve this article.

1. Line 40. External ear infection (OE) is defined before please use the abbreviation only.
2. line 48. (2. outer ear microbiome). the number of the studies discussed in this section is very limited, i think this will restrict the generalization of the conclusions. authors should include more studies.
3. line 48. (2. outer ear microbiome). also authors can provide simple illustration for the bacterial stains commonly found in the outer ear.
4. line 150. (4. composition of earwax). it will be better to include sub-heading in this section. for example, 4.1. Cerumen composition and role. 4.2. different types of earwax. 4.3. disease susceptibility/mechanism of self-clean. 4. antimicrobial potential.
5. I recommend adding a new section about the role of bacteria in a mechanistic way, how this linked with the earwax dysbisis, through presenting some mechanisms like biofilm formation, adhesion or sometime the excretion of some substances, and others. Also providing an illustration to summarize will be very interesting
6. Please write all abbreviation used at the end of the article, under abbreviation heading
7. I recommend adding new section dealing with other diseases (that can be directly/indirectly associated) which can occur due to the inflammation such as otomycosis, eczematous otitis externa and inflammatory skin disorders, biofilm-associated ear canal infections and External auditory canal cholesteatoma. authors can include other diseases and disorders.
8. I think provide more illustrations which summarize information, will make the article interesting and easy for readers.

Author Response

Reviewer 2

Title: The importance of ear canal microbiota and earwax in the prevention of outer ear infections (ijms-4059636).

The outer ear microbiome and earwax in the ear canal is an interesting topic. However, there are some suggestions which authors can take in mind to improve this article.

1. Line 40. External ear infection (OE) is defined before please use the abbreviation only.

Thank you for pointing this out. It was corrected as requested

2. line 48. (2. outer ear microbiome). the number of the studies discussed in this section is very limited, I think this will restrict the generalization of the conclusions. authors should include more studies.

 Thank you for pointing this out. As suggested, more studies have been discussed, and all details are included in the revised manuscript.

3. line 48. (2. outer ear microbiome). also authors can provide simple illustration for the bacterial stains commonly found in the outer ear.

Thank you for pointing this out. Illustration has been added

4. line 150. (4. composition of earwax). it will be better to include sub-heading in this section. for example, 4.1. Cerumen composition and role. 4.2. different types of earwax. 4.3. disease susceptibility/mechanism of self-clean. 4. antimicrobial potential.

It was corrected as requested.

5. I recommend adding a new section about the role of bacteria in a mechanistic way, how this linked with the earwax dysbisis, through presenting some mechanisms like biofilm formation, adhesion or sometime the excretion of some substances, and others. Also providing an illustration to summarize will be very interesting

We thank the Reviewer for this valuable and constructive suggestion. In response, we have added information to the revised manuscript focusing on the mechanistic role of bacteria in the external auditory canal. In addition, we have included a schematic illustration summarizing the proposed mechanisms and bacterial modulation and significance of epithelial cell responses.

6. Please write all abbreviation used at the end of the article, under abbreviation heading

It was corrected as requested.

7. I recommend adding new section dealing with other diseases (that can be directly/indirectly associated) which can occur due to the inflammation such as otomycosis, eczematous otitis externa and inflammatory skin disorders, biofilm-associated ear canal infections and External auditory canal cholesteatoma. authors can include other diseases and disorders.

We thank the Reviewer for this comprehensive and valuable recommendation. In response, we have added a new section to the revised manuscript addressing other diseases and disorders that may be directly or indirectly associated with inflammation of the external auditory canal. This section now includes discussion of otomycosis, eczematous otitis externa, inflammatory skin disorders affecting the ear canal and external auditory canal cholesteatoma.

8. I think provide more illustrations which summarize information, will make the article interesting and easy for readers.

The illustrations have been added as requested

Reviewer 3 Report

Comments and Suggestions for Authors

• The authors of the review did not define the purpose of the literature review, but the title of the manuscript suggests that the authors' attention was to be focused on the importance of the ear canal microbiota and the infection-preventing properties of earwax.
• The introduction lacks information on the anatomy and histology of the ear canal, the normal bacterial load, the phyla of normally predominant microorganisms, and the taxa representing these phyla. Only by identifying the location of the microbiota of interest and the normal range can we move on to the changes that occur during the development of an ear canal infection.
• When describing microorganisms, modern taxon names should be used. For example, the correct name for Turicella otitidis is Corynebacterium otitidis. The spelling of species names should also be verified; for example, the correct spelling is Achromobacter xylosoxidans.
• Fragments of text should not be repeated.
• The authors confuse the concepts of peptide or oligopeptide (up to 50 amino acid residues) and protein or polypeptide. Thus, bactericidal permeability-increasing protein (BPI), leukoprotease inhibitor (hSLPI), and lactoferrin are proteins, not peptides.
• The section "Treatment and prevention of otitis externa" is inappropriate for a manuscript devoted to the protective properties of earwax.
• Lines 363-392 also contain information that is not related to the protective properties of earwax.
• All sources should be checked for correct citation of the information contained therein.
• None of the tables presented in the manuscript are cited.

Author Response

Reviewer 3

• The authors of the review did not define the purpose of the literature review, but the title of the manuscript suggests that the authors' attention was to be on the importance of the ear canal microbiota and the infection-preventing properties of earwax.

The aim of this study was to review the literature on differences in the composition of the outer ear microbiome and earwax in the context of the pathogenesis of outer ear infections. The introduction to this paper discusses factors contributing to the development of outer ear infections and specific conditions or situations that increase the likelihood of infection. The next section describes the properties of earwax that prevent infection.

• The introduction lacks information on the anatomy and histology of the ear canal, the normal bacterial load, the phyla of normally predominant microorganisms, and the taxa representing these phyla. Only by identifying the location of the microbiota of interest and the normal range can we move on to the changes that occur during the development of an ear canal infection.

We thank the reviewer for this insightful comment. In the revised manuscript, we have expanded the introduction with a concise illustration describing the factors that increase the risk of outer ear infection, a description of the microorganisms that make up the microbiota, and those that are potential pathogens. Further down, we have included an additional illustration describing changes in bacterial modulation and the impact of epithelial cell responses. We hope this provides a clearer context for understanding the microbiological changes that occur during the development of ear canal infection.

• When describing microorganisms, modern taxon names should be used. For example, the correct name for Turicella otitidis is Corynebacterium otitidis. The spelling of species names should also be verified; for example, the correct spelling is Achromobacter xylosoxidans.

Thank you for pointing this out. It was corrected in revised version of the manuscript.

• Fragments of text should not be repeated.

Thank you for pointing this out. It was corrected in manuscript.

• The authors confuse the concepts of peptide or oligopeptide (up to 50 amino acid residues) and protein or polypeptide. Thus, bactericidal permeability-increasing protein (BPI), leukoprotease inhibitor (hSLPI), and lactoferrin are proteins, not peptides.

We thank the Reviewer for this important clarification. This issue has already been addressed in the revised manuscript. The terms have been corrected to properly distinguish between peptides/oligopeptides and proteins/polypeptides. Specifically, bactericidal permeability-increasing protein (BPI), leukocyte protease inhibitor (hSLPI), and lactoferrin are now correctly referred to as proteins rather than peptides throughout the text

• The section "Treatment and prevention of otitis externa" is inappropriate for a manuscript devoted to the protective properties of earwax.

We thank the Reviewer for this comment. The primary aim of this manuscript is to present the protective role of earwax in maintaining external ear canal health. However, we believe that it is also important to briefly address the clinical information in which infection develops despite these natural protective mechanisms. In such cases, outlining available treatment options provides necessary clinical context.

• Lines 363-392 also contain information that is not related to the protective properties of earwax.

We thank the reviewer for this comment. We would like to clarify that the section (previous lines 363–392) was intentionally added to emphasize that earwax, in addition to its antibacterial and protective properties, and its composition can also provide valuable information in diagnostic testing. The purpose of this addition is to provide a broader perspective on the functional importance of earwax, beyond its role in preventing infections. We thank you for bringing this to our attention. A new section titled "Uses of earwax as a diagnostic material" has been added.

• All sources should be checked for correct citation of the information contained therein.

We thank the reviewer for this important comment. All sources cited in the manuscript were checked for correct citation and attribution, but no citation errors were found.

• None of the tables presented in the manuscript are cited.

Thank you for pointing this out. It was corrected in the revised version of the manuscript.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Thank you for submitting the revised manuscript

Author Response

Reviewer 1

Thank you for your positive feedback on our work.

Reviewer 2 Report

Comments and Suggestions for Authors

Report (Accept after minor revision)

Title: The importance of ear canal microbiota and earwax in the prevention of outer ear infections.

Thank you for the opportunity to evaluate this review article. The authors have really improved the article, add new paragraphs and illustrations based on the comments provided earlier, and it is now clearer and more consistent, and acceptable for publication after minor revision.

• Please add more details and descriptions to the figure captions for Figures 1, 3 and 4. This will be more easy for the readers to understand the figures without need to return to text.

 

Author Response

Reviewer 2

Please add more details and descriptions to the figure captions for Figures 1, 3 and 4. This will be more easy for the readers to understand the figures without need to return to text.

The descriptions for figures 1, 3, and 4 have been modified as requested.