Occurrence and Characteristics of Escherichia albertii in Wild Birds and Poultry Flocks in Switzerland
, Barbara Renate Vogler 2 and Roger Stephan 1,*
Round 1
Reviewer 1 Report
This is a well written and informative manuscript.
I have no comments for the authors other than please ensure that you genome sequences are readily available via you Bioproject Number.
Author Response
This is a well written and informative manuscript.
I have no comments for the authors other than please ensure that you genome sequences are readily available via you Bioproject Number.
Answer: all sequences are readily available at https://www.ncbi.nlm.nih.gov/bioproject/PRJNA879956
Reviewer 2 Report
That study reports on the occurrence of Escherichia albertii strains in wild birds in Switzerland. The topic is of marginal clinical interest for human medicine, nevertheless such study is relevant in a sense that this species can be (even through very rarely) playing a role of human opportunistic pathogen, and is definitely a bird pathogen.
The design of the study is rather clear-cut, and the reviewer appreciated the way data have been presented, with a nicely-written manuscript and accurate informations included.
I have few concerns;
- since only ca. one third of the isolates could be recovered from the positive sample, don't you think the screening procedure could be improved by performing a pre-culture in broth medium ?
- it is said that no acquired resistance gene was identified, but nothing is said about the wild-type phenotype of that species. Did WGS reveal some intrinsic resistance genes, such as an AmpC-like encoding gene like in Escherichia coli ?
- please precise if the MLST system used is that of E. coli, what I guess but does not appear clearly in the manuscript.
Author Response
The design of the study is rather clear-cut, and the reviewer appreciated the way data have been presented, with a nicely-written manuscript and accurate informations included.
I have few concerns;
- since only ca. one third of the isolates could be recovered from the positive sample, don't you think the screening procedure could be improved by performing a pre-culture in broth medium ?
Answer: this was done; we used EE-broth as a pre-culture in a first step.
- it is said that no acquired resistance gene was identified, but nothing is said about the wild-type phenotype of that species. Did WGS reveal some intrinsic resistance genes, such as an AmpC-like encoding gene like in Escherichia coli ?
Answer: E. albertii does not exhibit intrinsic resistances to clinically relevant antibiotics (added at line 54). The presence of ampC in E. albertii is known and was detected in all isolates (added at line 162).
- please precise if the MLST system used is that of E. coli, what I guess but does not appear clearly in the manuscript.
Answer: we used the Achtman scheme (added at line 112). On PubMLST, the scheme is defined as “Escherichia spp.”.
Reviewer 3 Report
The manuscript submitted by Karen et al., describes "Occurrence and characteristics of Escherichia albertii in wild birds and poultry flocks in Switzerland".
The manuscript is written well however, I have some concerns and comments which need to be addressed.
1. The authors did WGS for 12 positive E. alberti. As the authors mentioned in line 108 -109 about Antimicrobial resistance genes and virulence factors. However, I did not found any details in the introduction, Results, and Discussion section about AMR genes and other MGEs in these 12 isolates.
The authors need to add the details of AMR, virulence, and mobile elements found in these isolates
Author Response
The authors did WGS for 12 positive E. alberti. As the authors mentioned in line 108 -109 about Antimicrobial resistance genes and virulence factors. However, I did not found any details in the introduction, Results, and Discussion section about AMR genes and other MGEs in these 12 isolates.
Answer: This is now mentioned in the Introduction in lines 56/57: “Wild-type E. albertii are susceptible to clinically relevant antibiotics, but the emergence of multi-drug resistant.” Line 60: “Poultry were identified as a major source of multi-drug resistant E. albertii in China clones has been reported.” Results Line 168-170: “None of the 12 isolates harboured acquired antimicrobial resistance genes. All isolates haboured a chromosomal ampC gene encoding an intrinsic beta-lactamase.”
The authors need to add the details of AMR, virulence, and mobile elements found in these isolates
Answer: In view of resistances see answer above; the relevant virulence genes are listed in Table 2 and mentioned in lines 162ff: “All 12 isolates harboured eae genes, most of which were identical or near-identical to known variants. The ST13420 isolates possessed a novel eae variant (96.0% sequence identity with eae alpha8). Two isolates (KBV38i and KBV70i) contained stx2f. All isolates harboured the cdtB subtype II, and the two stx2f-positive isolates additionally carried cdtB-I in a second copy of the cdtABC operon.”
Round 2
Reviewer 3 Report
The authors have addressed the comments properly.
