Detection of vanA genes in vancomycin susceptible Enterococcus faecium isolates; implications for additional testing
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To assess the frequency of silent vancomycin resistance, phenotypically susceptible Enterococcus faecium isolates underwent genotypic testing using Cepheid’s Xpert vanA/vanB PCR. 6% of isolates had silent vanA genes. However, the clinical relevance of silent van genes, and the lack of rapid, random-access genotypic methods poses an ongoing challenge to laboratories.
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Dear Dr. Jordan, Your manuscript has now been assessed by two reviewers, both of which provided a favourable feedback. Yet, one of the reviewers raised a concern about the repetition of the Vitek2 assay to confirm the profile of vancomycin susceptibility. Please ammend the text to include this information. If necessary, please add to the discussion that this is a limitation of your study. You will be able to resubmit your work for further consideration once you have addressed this issue. Best regards, Gustavo
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Comments to Author
In this study, the vanA gene was identified in three E. faecium isolates initially reported as susceptible to vancomycin by Vitek 2. Although the presence of the vanA gene was confirmed through two independent assays, it remains unclear whether Vitek 2 testing was repeated to verify vancomycin susceptibility. Such confirmation is crucial for classifying these isolates as false-negative VRE cases.
Please rate the manuscript for methodological rigour
Poor
Please rate the quality of the presentation and structure of the manuscript
Good
To what extent are the conclusions supported by the data?
Partially support
Do you have any concerns of possible image manipulation, plagiarism or any other unethical practices?
No
Is…
Comments to Author
In this study, the vanA gene was identified in three E. faecium isolates initially reported as susceptible to vancomycin by Vitek 2. Although the presence of the vanA gene was confirmed through two independent assays, it remains unclear whether Vitek 2 testing was repeated to verify vancomycin susceptibility. Such confirmation is crucial for classifying these isolates as false-negative VRE cases.
Please rate the manuscript for methodological rigour
Poor
Please rate the quality of the presentation and structure of the manuscript
Good
To what extent are the conclusions supported by the data?
Partially support
Do you have any concerns of possible image manipulation, plagiarism or any other unethical practices?
No
Is there a potential financial or other conflict of interest between yourself and the author(s)?
No
If this manuscript involves human and/or animal work, have the subjects been treated in an ethical manner and the authors complied with the appropriate guidelines?
Yes
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Comments to Author
Firstly, thank you for the opportunity to review this manuscript. The present study addresses the problem of detection of vancomycin-resistant genes in E. faecium isolates that may remain undetected when tested by conventional phenotypic testing. The methods were clearly described and the authors acknowledge limitations, such as the small sample size. Additionally, the explanation of how GeneXpert vanA/vanB protocol was adapted and validated for use in colonies is relevant, and the associated limitations were appropriately mentioned in the manuscript. The results are presented in an organized and logical manner, with statistical analyses were described where necessary. Table 1 summarizes most of the findings. The manuscript, overall, is well-structured, with clearly defined sections that flow …
Comments to Author
Firstly, thank you for the opportunity to review this manuscript. The present study addresses the problem of detection of vancomycin-resistant genes in E. faecium isolates that may remain undetected when tested by conventional phenotypic testing. The methods were clearly described and the authors acknowledge limitations, such as the small sample size. Additionally, the explanation of how GeneXpert vanA/vanB protocol was adapted and validated for use in colonies is relevant, and the associated limitations were appropriately mentioned in the manuscript. The results are presented in an organized and logical manner, with statistical analyses were described where necessary. Table 1 summarizes most of the findings. The manuscript, overall, is well-structured, with clearly defined sections that flow logically. It is well written in clear, concise and accessible language. The discussion section appropriately reviews the results of selected studies that are relevant to contextualize the present findings. In conclusion, while the study has acknowledged methodological limitations, the findings are relevant. The manuscript is suitable for publication.
Please rate the manuscript for methodological rigour
Good
Please rate the quality of the presentation and structure of the manuscript
Good
To what extent are the conclusions supported by the data?
Strongly support
Do you have any concerns of possible image manipulation, plagiarism or any other unethical practices?
No
Is there a potential financial or other conflict of interest between yourself and the author(s)?
No
If this manuscript involves human and/or animal work, have the subjects been treated in an ethical manner and the authors complied with the appropriate guidelines?
Yes
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Dear Victoria Jordan, The manuscript entitled "Detection of vanA genes in vancomycin susceptible E. faecium isolates; implications for additional testing" illustrates an important matter for antimicrobial treatment: the correlation between the detection of resistance genes and the existence of resistant phenotypes. Although the paper is of interest, a few amendments are necessary before the paper proceeds to peer-review. First, more details about the isolation and preservation of the isolates are necessary. How were the bacteria frozen? Were these isolates cultured before freezing? In what media? Also, it would be useful to have more details on the patient material from where the bacteria were isolated (which 'fluid' and which "tissue'?). Moreover, ideally the origin of each isolate would be described; if this is absolutely not …
Dear Victoria Jordan, The manuscript entitled "Detection of vanA genes in vancomycin susceptible E. faecium isolates; implications for additional testing" illustrates an important matter for antimicrobial treatment: the correlation between the detection of resistance genes and the existence of resistant phenotypes. Although the paper is of interest, a few amendments are necessary before the paper proceeds to peer-review. First, more details about the isolation and preservation of the isolates are necessary. How were the bacteria frozen? Were these isolates cultured before freezing? In what media? Also, it would be useful to have more details on the patient material from where the bacteria were isolated (which 'fluid' and which "tissue'?). Moreover, ideally the origin of each isolate would be described; if this is absolutely not possible, the 'health district' covered in this study should be delineated. Also, please clarify if vancomycin susceptibility was determined directly on the isolates. Regarding the results, it would be useful to have a better description of the vancomycin-resistant (vanA positive) E. faecium that was later isolated from one patient. How was resistance to vancomycin determined? Did it respond to treatment? Also, please do not abbreviate the name of the species in the title and make sure the full specific name is given when the organism is first mentioned in the text. Best regards, Gustavo
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