Corynebacterium amycolatum peritonitis in a patient undergoing peritoneal dialysis: case report and literature review
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Peritoneal dialysis is a blood purification technique used in cases of end-stage chronic kidney failure, based on the filtering capabilities of the peritoneum. Infections, often caused by poor asepsis during catheter manipulation, are generally attributed to Staphylococcus epidermidis and Staphylococcus aureus. Corynebacterium , usually considered non-pathogenic, is rarely involved in these infections. We present a case of peritonitis due to Corynebacterium amycolatum in a patient undergoing peritoneal dialysis. The diagnosis was made based on cytobacteriological examination of the dialysate fluid, which on two occasions showed high levels of white blood cells with a predominance of neutrophilic polymorphonuclear and a monomorphic appearance of colonies on agar medium, whose identification by biochemical tests and antibiotic sensitivity study confirmed the presence of C. amycolatum . The patient was successfully treated with vancomycin, resulting in symptom resolution and sterilization of the dialysate fluid. Although rare, the involvement of Corynebacterium species underscores the importance of confirming its pathogenicity. Further studies are needed to better understand the epidemiology of these infections and guide future treatments. This case also highlights the need for a rigorous approach to confirming the pathogenicity of Corynebacterium despite its traditional classification as a contaminant.
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I am pleased to tell you that your article has now been accepted for publication in Access Microbiology.
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Comments to Author
My concerns were sufficiently addressed by the authors.
Please rate the quality of the presentation and structure of the manuscript
Good
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Strongly support
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No
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No
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Yes
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Comments to Author
Dear authors, in future studies, both MALDI-TOF MS and 16S rRNA sequencing should be used to confirm species identification I have no more comments
Please rate the quality of the presentation and structure of the manuscript
Good
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Strongly support
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No
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The reviewers have highlighted major concerns with the work presented. Please ensure that you address their comments.
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Comments to Author
Please ONLY put comments for the Author(s) in here Major essential revisions The following are some comments and suggestions that need major review: 1. Peritoneal dialysis-related peritonitis remains the major complication and primary challenge to the long-term success of peritoneal dialysis. It is known that the organisms causing exit-site infections with the highest risk of subsequent peritonitis are S. aureus, coagulase-negative staphylococci, streptococcal species, Pseudomonas aeruginosa, Candida and also diphtheroids (Szeto CC, Li PK, Johnson DW, et al. ISPD catheter-related infection recommendations: 2017 update. Perit Dial Int. 2017; 37:141-154). If we assume that, as the authors of the study claim, only colonies with a monomorphic type of gram-positive coryneform rods were found in the …
Comments to Author
Please ONLY put comments for the Author(s) in here Major essential revisions The following are some comments and suggestions that need major review: 1. Peritoneal dialysis-related peritonitis remains the major complication and primary challenge to the long-term success of peritoneal dialysis. It is known that the organisms causing exit-site infections with the highest risk of subsequent peritonitis are S. aureus, coagulase-negative staphylococci, streptococcal species, Pseudomonas aeruginosa, Candida and also diphtheroids (Szeto CC, Li PK, Johnson DW, et al. ISPD catheter-related infection recommendations: 2017 update. Perit Dial Int. 2017; 37:141-154). If we assume that, as the authors of the study claim, only colonies with a monomorphic type of gram-positive coryneform rods were found in the dialysis fluid, then the identification of the pathogen carried out by the authors is insufficient. C. amycolatum is a typical bacterium of the flora on human skin and mucous membranes. C. amycolatum is widely known in literature as a causative agent of diverse infections in immunocompromised patients, mainly causing endocarditis, meningitis, septic arthritis, mastitis, eye infections (Reddy B.S. et al. Isolation, speciation, and antibiogram of clinically relevant non-diphtherial Corynebacteria (Diphtheroids). Indian J Med Microbiol. 2012. 30(1):52-57). However, it is know, that the identification of this species in clinical material is often erroneous. Strains of C. amycolatum are often identified as C. xerosis, C. minutissimum, or C. striatum. Differential identification of these three species by biochemical tests remains difficult, and several misidentifications have been reported previously (Funke G. et al. Most Corynebacterium xerosis strains identified in the routine clinical laboratory correspond to Corynebacterium amycolatum. J Clin Microbiol. 1996; 34:1124-1128; Wauters G., et al. Propionic acid-producing strains previously designated as Corynebacterium xerosis, C. minutissimum, C. striatum, and CDC group I2 and group F2 coryneforms belong to the species Corynebacterium amycolatum. Int J Syst Bacteriol. 1996; 46:653-657). Modern molecular methods, such as nucleic acid amplification (polymerase chain reaction (PCR), real-time PCR), DNA sequencing, and proteome analysis allow to detect and identify microorganisms with 99.9% accuracy. For example, Santos et al. developed a multiplex PCR method based on species-distinctive genes for accurate identification at the species level of C. striatum, C. amycolatum and C. xerosis (Santos C.S., et al. Efficient differentiation of Corynebacterium striatum, Corynebacterium amycolatum and Corynebacterium xerosis clinical isolates by multiplex PCR using novel species-specific primers. J Microbiol Methods. 2017 142:33-35). Based on the above, the authors need to confirm the species identification of the pathogen using MALDI-TOF MS and 16S rRNA sequencing. 2. MICs should be provided based on zone of clearances for the antimicrobial susceptibility measurements in Table 1, rather than 'resistant, intermediate, susceptible' as these are not quantitative values.
Please rate the quality of the presentation and structure of the manuscript
Satisfactory
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
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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
The manuscript describes a case of Corynebacterium amycolatum peritonitis in a peritoneal dialysis patient. In general, the case is well presented and the figures are informative. The methods for the culture are described in detail while some more information would be helpful concerning the resistance testing (see also specific comments below). The treatment should also be described in more detail including dosage and route of administration as well as reason for the choice of antibiotic. How long was the time from onset of symptoms to treatment? Was the patient temporarily switched to hemodialysis - how did the kidney parameters evolve? Specific comments: line 73ff: What was your rationale for testing these specific antibiotics? Table 1: please indicate the obtained inhibition zone for each …
Comments to Author
The manuscript describes a case of Corynebacterium amycolatum peritonitis in a peritoneal dialysis patient. In general, the case is well presented and the figures are informative. The methods for the culture are described in detail while some more information would be helpful concerning the resistance testing (see also specific comments below). The treatment should also be described in more detail including dosage and route of administration as well as reason for the choice of antibiotic. How long was the time from onset of symptoms to treatment? Was the patient temporarily switched to hemodialysis - how did the kidney parameters evolve? Specific comments: line 73ff: What was your rationale for testing these specific antibiotics? Table 1: please indicate the obtained inhibition zone for each antibiotic and the breakpoint that was used Line 121 ff: Was resistance testing performed on those isolates? Corynebacterium amycolatum can acquire resistance to beta-lactams which would explain therapy failure. Prevalence of resistance might differ between regions. Maybe you could discuss these aspects. Was your isolate tested for resistance to cephalosporins?
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
-
Comments to Author
Suggestions It is suggested to strengthen the introduction by describing the genus-species of Corynebacterium amycolatum and microbiological characteristics. Microbiota is the newer and correct word for what was formerly referred to as microflora or flora. Microflora/flora indicates that the microorganisms in question would be of the Plant Kingdom, which, of course, is not the case (lines 39, 42, 109, etc.). Therefore, it is suggested to modify. Keywords are not observed. In order to give greater importance to the work done in the laboratory, it could be mentioned that the identification of species is technically demanding and has clinical importance, allowing the antibiotic treatment to be adjusted or opting to remove the PD catheter if the same strain is isolated repeatedly. Highlight the importance …
Comments to Author
Suggestions It is suggested to strengthen the introduction by describing the genus-species of Corynebacterium amycolatum and microbiological characteristics. Microbiota is the newer and correct word for what was formerly referred to as microflora or flora. Microflora/flora indicates that the microorganisms in question would be of the Plant Kingdom, which, of course, is not the case (lines 39, 42, 109, etc.). Therefore, it is suggested to modify. Keywords are not observed. In order to give greater importance to the work done in the laboratory, it could be mentioned that the identification of species is technically demanding and has clinical importance, allowing the antibiotic treatment to be adjusted or opting to remove the PD catheter if the same strain is isolated repeatedly. Highlight the importance of identifying the causal agent of the infection
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
-