Peer Review History

Original SubmissionJuly 12, 2020
Decision Letter - Iddya Karunasagar, Editor

PONE-D-20-21578

Class 1 Integron-Borne Cassettes harboring blaCARB-2 gene in Multidrug-Resistant Salmonella Typhimurium ST19 Strains recovered from clinical human stool samples, United States

PLOS ONE

Dear Dr. Thakur,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

==============================

Reviewer comments on the manuscript need to be addressed.

==============================

Please submit your revised manuscript by Oct 18 2020 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

  • A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
  • A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
  • An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols

We look forward to receiving your revised manuscript.

Kind regards,

Iddya Karunasagar

Academic Editor

PLOS ONE

Journal Requirements:

When submitting your revision, we need you to address these additional requirements.

1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at

https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and

https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf

Additional Editor Comments (if provided):

The reviewer comments available on the manuscript. These need to be addressed.

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

**********

2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: N/A

**********

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

**********

4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

**********

5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) (Limit 200 to 20000 Characters)

Could you please see my attached review, I have added all my comments to the Author in an attachment.

**********

6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

Attachments
Attachment
Submitted filename: Salmonella ST19.docx
Revision 1

Response to reviewers, Manuscript PONE-D-20-21578.R1

Line numbers in our response refer to the line numbers in the revised manuscript (marked-up).

General comments:

We sincerely appreciate the editorial board and reviewers for their careful review and constructive suggestions. It is our belief that the manuscript was substantially improved after making the suggested edits. We have responded to specific queries below.

Comments from Reviewers:

Reviewer #1:

This manuscript describes about the class 1 integron AMR cassettes harboring blaCARB-2 gene in MDR Salmonella Typhimurium ST19 isolates. These MDR isolates are also harbored several virulence encoding genes and SPIs.

Response: We sincerely thank the reviewer for the favorable comments.

Comments:

Based on the WHO’s description, some of the antimicrobial such as ticarcillin/clavulanic acid and tetracycline are not critically and highly important antimicrobials.

Response: We appreciate your suggestion. However, based on this document: Critically important antimicrobials for human medicine, 6th revision. Geneva: World Health Organization; 2019. https://apps.who.int/iris/bitstream/handle/10665/312266/9789241515528-eng.pdf?sequence=1&isAllowed=y, we could observe that ticarcillin/clavulanic acid and tetracycline are classified as critically and highly important antimicrobials.

Lines 69-70. ‘CARB-2-production’ was not tested in these S. Typhimurium isolates, but only the encoding gene was detected.

Response: We agree. This has been deleted in lines 72 and 245.

Line 75. It will be useful if the nature of clinical source (watery diarrhea, diarrhea with mucus or dysentery-like stool) of the isolates and clinical history of the patients described and included. In addition, the year/location of isolation is also important to be mentioned in the text to deduce whether the isolates are spread all over the country or restricted to a certain geographical location.

Response: We fully agree. At the beginning of this study, we tried to collect such information to conduct the paper describing the clinical history of the patients. In our understanding, such information could aid to mitigate strategies, as well as give to readers a full background, which denotes the real threat of salmonellosis and their impacts in human health. However, we did not get permission from Public Health Laboratory due to health information privacy to publish this information. Therefore, we respectfully request that the paper be published with the information provided.

Lines 100-101. What is the rational for selecting only 13 sequences for comparison? There other STs (e.g., ST39) that expresses more AMR than the ST19. It will be interesting to consider all the MDR S. Typhimurium STs from different sources.

Response: Our intention was to cover several countries (n=10) and sources (n=7) in this phylogeny by using S. enterica strains harboring blaCARB-2 gene, with exception of two strains that were used as out-groups.

Lines 114-115. It is not surprising, as these intermediate 
resistant isolates to doxycycline are also resistant to tetracycline. Doxycycline is a synthetic antibiotic derived from tetracycline.

Response: We agree. This has been modified in lines 117-119.

“Moreover, intermediate resistance to doxycycline was detected in three strains (HS5344, HS5437 and HS5478), and in a single isolate (HS5437) to ceftazidime”.

Lines 146-151. It will be interesting to compare these putative virulence encoding genes and SPIs with the infection status of the patients (pl refer comment #3).

Response: We agree. However, as prior mentioned, we are unable to provide this information.

The title of the manuscript reflects only the MDR part, but not about the virulence.

Response: We agree. The title has been modified. “Class 1 Integron-Borne Cassettes harboring blaCARB-2 gene in Multidrug-Resistant and Virulent Salmonella Typhimurium ST19 Strains recovered from clinical human stool samples, United States”. (Lines 2-4).

There is inconsistency while using the terms isolate and strain.

Response: Thank you for this observation. Since the main target of this study was the genomic investigation and all Salmonella Typhimurium were accessed from a collection, we believe that the term strain is the most appropriate. Therefore, we have replaced these terms throughout the manuscript in lines 31, 33, 72, 76, 77, 78, 83, 114, 118, 120, 126, 163, 176, 237, and 245.

Only the blaCARB-2 
was mapped in the class 1 integron. Are the other genes (aac(6’)-Iaa, aadA2b, aph(3’)-Ia, sul1, tetG, floR,) are located in the same AMR cassettes in the integron? How they are arranged on the chromosome?

Response: This information was added to the revised version of the manuscript. Lines 137-147: “Additionally, the sul1, blaCARB-2, tetG, floR, and aadA2b resistance genes were harbored by a partial sequence of a complex class 1 integron (In104) from HS5344, HS5437, and HS5478. This sequence included duplications of parts of the integron conserved segments (CS), specifically, part of the intI1 gene from the 5’-CS and part of the 3’-CS (qacE∆1 and partial sul1 genes). Consequently, the structure had two attI1 sites, into which the aadA2b gene cassette was inserted in one and the blaCARB-2 cassette in the other. The floR and tetG genes were identified between the two integron-derived regions. In HS5302 and HS5368, only the region containing the intI1-blaCARB-2-qacE∆1-sul1-orf5-orf6 array was detected. Furthermore, while aac(6’)-Iaa was found at a site distant from the other resistance genes on the chromosome of all S. Typhimurium strains in this study, aph(3’)-Ia was identified in a partial transposon sequence from HS5478.”

Attachments
Attachment
Submitted filename: R1_Response to reviewers_PONE-D-20-21578_DM-Sid.docx
Decision Letter - Iddya Karunasagar, Editor

Class 1 Integron-Borne Cassettes harboring blaCARB-2 gene in Multidrug-Resistant and Virulent Salmonella Typhimurium ST19 Strains recovered from clinical human stool samples, United States

PONE-D-20-21578R1

Dear Dr. Thakur,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org.

If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Iddya Karunasagar

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

All reviewer comments addressed satisfactorily.

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: N/A

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: The questions above (1-5) are addressed adequately. I do not have any comments to the authors in this revised version.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Formally Accepted
Acceptance Letter - Iddya Karunasagar, Editor

PONE-D-20-21578R1

Class 1 Integron-Borne Cassettes harboring blaCARB-2 gene in Multidrug-Resistant and Virulent Salmonella Typhimurium ST19 Strains recovered from clinical human stool samples, United States

Dear Dr. Thakur:

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.

If your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org.

If we can help with anything else, please email us at plosone@plos.org.

Thank you for submitting your work to PLOS ONE and supporting open access.

Kind regards,

PLOS ONE Editorial Office Staff

on behalf of

Dr. Iddya Karunasagar

Academic Editor

PLOS ONE

Open letter on the publication of peer review reports

PLOS recognizes the benefits of transparency in the peer review process. Therefore, we enable the publication of all of the content of peer review and author responses alongside final, published articles. Reviewers remain anonymous, unless they choose to reveal their names.

We encourage other journals to join us in this initiative. We hope that our action inspires the community, including researchers, research funders, and research institutions, to recognize the benefits of published peer review reports for all parts of the research system.

Learn more at ASAPbio .