Characterization of Escherichia coli from Water and Food Sold on the Streets of Maputo: Molecular Typing, Virulence Genes, and Antibiotic Resistance
, Suse Alves 1, Lélia Chambel 3, Manuel Malfeito-Ferreira 1 and LuÃsa Brito 1
Round 1
Reviewer 1 Report
Dear Authors,
The manuscript is well written and suitable for English with a clear structure. The authors presented a fascinating study investigating virulence genes, antibiotic resistance and molecular typing of E. coli isolated from food and water samples. They showed the relationship between different profiles of antibiotic resistance, virulence factor encoding genes and PFGE genotyping patterns. Regarding the significant findings that emerged from and the methods used in this study, I highly recommend it for publication BUT not in Applied Microbiology Journal. I checked the aim and scope of the Applied Microbiology Journal, and I did not find any correspondence with any aim and scope topics of this journal, and this is my main concern. Consequently, I should reject this manuscript for publication in Applied Microbiology Journal and strongly suggest Antibiotics Journal (MDPI) for submitting this valuable manuscript and consideration for publication as the main findings of this manuscript are the molecular characterization of multi-drug resistant E. coli isolates.
Kind regards,
Author Response
Answer: Thank you very much for your kind comments about our work. We hope it will contribute to improving food safety in Maputo in particular and in Mozambique and related countries in general.
Reviewer 2 Report
The paper title “Characterization of Escherichia coli isolates from water and food sold on the streets of Maputo: Molecular typing, virulence genes and antibiotic resistance” is an interesting and valuable article that provides new and important insights about antimicrobial resistance and E. coli detected in ready to eat street food and water in Maputo. The article should be prepared according to "Instructions for Authors" and I have only minor comments which I put in the text in yellow because the article doesn’t have a line number, Abstract is too long it should be according 200 words according to “Instructions”. References [1,2] are a little confusing, because of the first author, maybe put some EFSA reports.
Comments for author File: 
Comments.pdf
Author Response
Reviewer-2
- put the space after:
Answer: Done (line 15)
- put whole name, and after that abbr.
Answer: Done (line 20)
- after whole name The Authors should put abbr.
Answer: Done (line 42)
- the references for this ISO not only for the authors article
Answer: Done (reference added, ref 20 and 21)
- The Authors should check (Figure 1 or Fig. 1), in all the text
Answer: Done
Reviewer 3 Report
This study investigated the pathogenic potential and antibiotic resistance of E. coli isolates from ready-to-eat street food and drinking water sold in the city of Maputo, Mozambique.
Why only these virulence genes (stx, lt, st, astA and eae) were screened to evaluate the pathogenic potential? Very old approached were adopted in this study.
There are many typo throughout the manuscript: the gene name should be italic; XbaI; Taq; Shiga toxin; etc.
Author Response
Reviewer-3
This study investigated the pathogenic potential and antibiotic resistance of E. coli isolates from ready-to-eat street food and drinking water sold in the city of Maputo, Mozambique.
- Why only these virulence genes (stx, lt, st,astA and eae) were screened to evaluate the pathogenic potential? Very old approached were adopted in this study.
Answer: Dear reviewer, Thanks for your observation.
The approach used in this study aimed to identify and characterize diarrheagenic E. coli originated from food and water sold on the streets. Therefore, we are concerned about food or waterborne diseases. The selection of genes investigated in this study thus considered the virulence factors associated with this type of disease, although some of these genes were also investigated in other studies, some also carried out in Mozambique, but with clinical isolates. This allowed us to try to relate the occurrence of clinical cases with the possible link with water and food safety.
- There are many typo throughout the manuscript: the gene name should be italic; XbaI; Taq; Shiga toxin; etc.
Answer: Done, all scientific names have been italicized. Although, italics convention is no longer considered essential for enzyme names (IUPAC, 2003).
Reviewer 4 Report
The detailed comments have been attached here.
Comments for author File: Comments.pdf
Author Response
Reviewer-4
Comments for the authors
The study describes the virulence and antibiotic-resistant genes from Escherichia coli isolated from water and food. The authors also reported the current antibiotic profile of the E. coli strains with the available 15 antibiotics. The manuscript needs careful check for English language and the formatting errors such as extra spacing between the words.
Title:
- The title needs to be revised as “Characterization of Escherichia coli from water and food sold on the streets of Maputo: Molecular typing, virulence genes, and antibiotic resistance.”
Answer: Done. According to suggestion
Abstract:
- The first word “The” should not be bold
Answer: Done (line 15)
- The first sentence of the abstract is not clear and should be revised. The authors mentioned pathogenicity among these genes, but nothing was mentioned before.
Answer: Done. The Abstract was rewritten also to attend the limits of the journal.
- The aim of the study should be mentioned separately from the methodology, and the sentence “The aim of this study was to investigate the pathogenic potential and antibiotic resistance” should be written correctly. The word antibiotic-resistant would be better than antibiotic resistance here.
Answer: Done
- Change the word antibiotic resistance to antibiotic-resistant in the sentence “and three groups of antibiotic resistance genes, ß-lactamases”
Answer: Done. (Line 19-20)
- ESBL should be mentioned in full for the first time in the abstract as well as in the introduction ampC should be written as AmpC throughout the manuscript.
Answer: Done (line 20)
- All the bla variants (Bla SHV, Bla TEM etc.) should be mentioned as blaSHV, bla bla should be italicized and the variant as a subscript.
Answer: Done.
Keywords:
- Better to delete Maputo-Mozambique from the keywords
Answer: Done partially. Maputo was deleted from the keywords. Bearing in mind that there are currently very few works like this in Mozambique, it will be important to keep at least the name of the country in the keywords. When we started working, it was one of the key words we used together with food safety, antibiotic resistance and others to assess the state of the art.
Material and methods:
- The first section should mention the study design, ethics approval, inclusion, and exclusion criteria.
Answer: done (line: 80-88). Thank for your observation. However, as the isolates in this work are from a previous study, as mentioned in section 2.1, we have added a brief summary of the methodology for obtaining the isolates, so as not to repeat information contained in an already published article.
- Section 2.1. heading better to be coli isolation instead of E. coli isolates. The collection and processing of food samples should be mentioned before isolating bacterial strains. ISO abbreviation should be mentioned in full for the first time as “International Organization for Standardization.” Reference no. 1 refers to a study conducted by Salamandane et al. in 2021 and is not a correct reference for ISO.
Answer: As mentioned before, we avoid repeating information from previous papers. Nevertheless, the information presented now is more complete (lines 80-88) and references added (ref. 20 and 21).
- Section 2.1 should also be written in detail, describing how coli were recovered and identified. Some details of the identifications and characterization of E. coli and enzymes can be cited from:
Answer: Done. Thank you for reference suggestion.
- Section 2.3. The first sentence regarding the boiling bath for 15 minutes must include a reference as https://doi.org/10.7754/clin.lab.2019.190727
Answer: Done. Thank you for suggestion. Reference added
- Methodology section on page 4: ESBL complete form was abbreviated on page 3, so it is recommended to delete the complete form “extended-spectrum β-lactamases” in the first line of the first paragraph on page 4.
Answer: Done (line 142)
- On page 5: The CLSI reference (No. 28) is of CLSI 2017, which should be replaced with the CLSI 2021 reference. The antibiotic concentrations on this page are incorrectly written in mg instead of μg, which should be collected.
Answer: Thanks for your attention. The refence and antibiotic concentrations units was changed.
Results:
- Table 3: The antibiotic concentrations in the table footnote are wrongly written in mg instead of μg. There is no need to write the concentration in the table footnote as they have mentioned within the table.
Answer: Done. The concentration was deleted in the table footnote.
- Table 4: There is no need to write the concentrations in the table footnote. It is also recommended to unbold some of the bold abbreviations.
Answer: Done. The concentration was deleted in the table footnote. Bolded abbreviations were unbolded
- Page 8, section 3.3: “From the 38 β-lactam genes, 22 (57.9%) were ESBL genes and 16 (42.1%) were β-lactams ampC. From the 21 non- β -lactam genes, 16 (76.2%) were tet genes and 5 (23.8%) were SUL genes.” It should be replaced with the following sentence “From the 38 β-lactamase genes, 22 (57.9%) were ESBL genes, and 16 (42.1%) were potential AmpC producers. From the 21 non- β-lactamase genes, 16 (76.2%) were tet genes and 5 (23.8%) were sul genes.”
Answer: Done (line 272-275)
Discussion:
- The reference of figures and tables should be removed.
Answer: Done.
- Page 10: The font size of the sentence “The prevalence of multi resistance reported here is lower than those observed in isolates from hospital isolates” is larger than the other text, and there are several extra spaces before the in-text references. Also, the words multi resistance should be replaced with multidrug
Answer: Done.
- Page 10, last paragraph: Change the word ESBL to ESBLs in the first line.
Answer: Done.
- Page 11, first paragraph: Add the word “genes” in the last line after ESBL.
Answer: Done (line 366)
- Discussion lacks the data of antibiotics. A paragraph describing antibiotic resistance should be included in the discussion section. Some antibiotic data for clinical studies must also be included. A few suggestions are:
https://doi.org/10.3390/antibiotics10040454
https://doi.org/10.3390/antibiotics10040467
https://dx.doi.org/10.12669%2Fpjms.36.2.928
Answer: Discussion has been improved. Text for antimicrobial resistance has been added (lines 343-347, 378-383)
- Study limitations should be included at the end of the discussion (such as no new antibiotics were examined etc.).
Answer: Study limitations has been added (line 410-420)
Conclusion:
- The conclusion should be comprehensive based on the study’s results. The first two sentences of the conclusion can be moved in the discussion section or removed from the study.
Answer: The reviewer is correct. Consequently, the “conclusion” section was rewritten.
Round 2
Reviewer 1 Report
The manuscript can now be accepted for publication. However, it would be better to be published in another journal such as Antibiotics (MDPI).
Reviewer 3 Report
No further comments.
