Case report: a missed case of chronic Q fever infective endocarditis demonstrating the ongoing diagnostic challenges
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Diagnosis of chronic Q fever is often difficult for clinicians, particularly in the presence of a second pathology. In addition to the chronic constitutional symptoms, the most common manifestations of chronic Q fever include infective endocarditis and endovascular infection. We describe a case of prosthetic valve infective endocarditis caused by both Streptococcus sanguinis and Coxiella burnetti on a background of a previous aortic graft and bioprosthetic aortic valve replacement 2 years earlier. The diagnosis of chronic Q fever infective endocarditis was delayed because the significance of the abnormal valve histology from the patient’s previous surgery was initially overlooked. It was only after the patient had relapsed on appropriate therapy for the S. sanguinis prosthetic valve endocarditis that a subsequent review of the operative valve histology, along with the patient’s epidemiological risk factors, led to consideration of an additional culture-negative cause for infective endocarditis. Histological examination of the valve tissue had shown exophytic fibrin vegetations and acute inflammation. Further clinical assessment revealed previous exposure to Q fever and C. burnetti DNA was detected via polymerase chain reaction on the valve tissue. Q fever infective endocarditis must be considered if valves are inflamed or have vegetations with a subsequent negative culture. It should also still be considered in the presence of an alternative bacteraemia if the patient has risk factors for exposure.
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Comments to Author
- Description of the case Presented is a complex case of prosthetic valve endocarditis with Coxiella burnetii and Strep. sanguinis in a patient implanted with bioprosthetic aortic valve. This is an interesting case as it highlights a need to consider the range of epidemiological and exposure history in patients presenting with cardiac complaints warranting surgical intervention and valve replacement, to ensure there are no missed opportunities to diagnose cryptic causes of endocarditis. In this case it the culture positive results guided the clinical team in one direction and Coxiella burnetii as the cause of cardiac injury wasn't considered. This was later considered with knowledge of the exposure history and fortunately the tissue from the original cardiac surgery at implantation had been retained …
Comments to Author
- Description of the case Presented is a complex case of prosthetic valve endocarditis with Coxiella burnetii and Strep. sanguinis in a patient implanted with bioprosthetic aortic valve. This is an interesting case as it highlights a need to consider the range of epidemiological and exposure history in patients presenting with cardiac complaints warranting surgical intervention and valve replacement, to ensure there are no missed opportunities to diagnose cryptic causes of endocarditis. In this case it the culture positive results guided the clinical team in one direction and Coxiella burnetii as the cause of cardiac injury wasn't considered. This was later considered with knowledge of the exposure history and fortunately the tissue from the original cardiac surgery at implantation had been retained and could be tested to definitively diagnose Q fever. Some important lessons for clinical teams who may face other similar cases. - How the style and organization of the paper communicates and represents key findings Generally a good narrative of the case, which is clearly described. It would benefit from inclusion of further technical detail of some of the testing performed and an explanation of some jargon which would be unfamiliar with those not from clinical backgrounds to make the piece clearer. The lessons learnt are spelled out well. -Any other relevant comments The piece is generally well written and structured. It would benefit from some figures/visual aspects to illustrate aspects such as some of the diagnostic testing performed, TOE images for example, which would be more engaging for the reader. The editor should satisfy themselves that the authors have indeed discussed this with the patient and obtained consent, either in confirmation, however they explicitly indicate they have obtained written consent, so the editor should see this. Line 30-36 discusses the zoonosis of Coxiella burnetii but omits discussion of the over 40 species of hard ticks implicated as transmission vectors. Its critical to appreciate all the routes of transmission to understand the risk to patients and for clinicians reading the paper to apply consider Coxiella appropriately in patients with relevant exposure, even where culture positive endocarditis is found. Line 72: Whats the logic of this given Strep sanguinis is predominantly oral flora. Line 124: Describe briefly what Phase 1 and Phase 2 IgGs represent, are reacting to, and why they help stage Q-fever based on mechanism, this should probably be added to the introduction. Line 141: It would be useful to comment further or even illustrate the timeline of events from possible exposure, to original cardiac surgery, to current presenting illness and the obtained results and comment on whether this is expected in the literature given what is known about disease progression in Q fever endocarditis. Were there any historical serology samples predating cardiac surgery available for serology testing? Line 150: How does this compare with features commonly present in Strep sanguinis endocarditis, it isn't clear whether there was any doubt regarding this diagnosis early in the course of case investigation based on the lack of aortic valve vegetation. Related to the Strep sanguinis endoarditis were surveillance blood cultures collected a few days into therapy to demonstrate effect of therapy and clearance of bacteraemia? Given the wide readership of the journal consider including some brief discussion of epidemiology worldwide and ensure all the risk factors for exposure are made clear. Line 20: Be precise here with language, rather than other causes of culture negative infective endocarditis you already had a culture positive probable cause, what you went looking for was alternative causes which would not have been picked up in routine culture. Line 30, Change threating to threatening. Line 64: Describe in more detail some of the peripheral stigmata of endocarditis, the journal has a wide readership and would benefit from further explanation of terminology throughout. Line 67: Describe the antibiotic therapy and ideally describe what guidelines were followed to decide on this. Line 68: Change Shown to showed Line 68: Spell this out a bit clearer for unfamiliar audiences, i.e important to note not severe abnormality with the valve warranting surgery, surprising/not surprising that there was no evidence of vegetation but mitral regurgitation was seen. Line 72: What was the penicillin MIC for the strep sanguinis, an expectation would be that this is appropriate as long as the organism is exquisitely sensitive, otherwise single agent would probably not be appropriate here. Line 80: phase one IgG of 40,925 Whats? and Phase 2 IgG of 10240 whats? Express the unitage of this, or express it clearly as a titre, specifying it as a titre/dilution factor ( i.e. IgG titre of 1:40,925), how was the titration performed, was this by IFU or ELISA, was this done in house in your local laboratory or at the national reference laboratory? Line 89: this is interesting ,not every laboratory would retain material like this, and for this length of time, important to make this more obvious as its an important point for people to consider in their own laboratories. Good thinking. Line 72: Also how long was the patients intended treatment duration for possible Strep sanguinis endocarditis Line 75: OPAT ceftriaxone, describe the dosage and interval for this.
Please rate the quality of the presentation and structure of the manuscript
Very 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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The reviewers have highlighted minor concerns with the work presented. Please ensure that you address their comments.
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Comments to Author
I would like to compliment the authors on this excellent case-report. It is very well-written and very clinically relevant. It reads like a novel! Thank you for sharing this case. Although your patient recovered fully, this might not be the case for other patients with chronic Q fever endocarditis and a second pathogen. I hope your case will lead to more awareness amongst clinicans on dual pathogen endocarditis. I have very minor comments. 1. You provided the exact right amount of details. All clinically relevant data are there, and no unnecessary details have been provided. 2. Out of curiosity: did you perform a C burnetii PCR on serum or whole blood? 3. I completely agree with your recommendation in line 151-155, especially that with negatieve findings serology must be considered since the …
Comments to Author
I would like to compliment the authors on this excellent case-report. It is very well-written and very clinically relevant. It reads like a novel! Thank you for sharing this case. Although your patient recovered fully, this might not be the case for other patients with chronic Q fever endocarditis and a second pathogen. I hope your case will lead to more awareness amongst clinicans on dual pathogen endocarditis. I have very minor comments. 1. You provided the exact right amount of details. All clinically relevant data are there, and no unnecessary details have been provided. 2. Out of curiosity: did you perform a C burnetii PCR on serum or whole blood? 3. I completely agree with your recommendation in line 151-155, especially that with negatieve findings serology must be considered since the sensitivity of serology is considered higher than for PCR . 4. In the Dutch chronic Q fever national database cohort we evaluated the number of dual pathogen endocarditis in 2017, with data complete up to 2015 at that time. These results have never been published formally in an English journal, but in the Dutch Society for microbiology theme issue only. Amongst 130 patients with proven or probable chronic Q fever endocarditis, 9% (!) had dual pathogen endocarditis. I can imagine that you cannot or do not want to use this additional information for you article, but if you do, feel free to. Ref https://www.nvmm.nl/ntmm/artikeloverzicht/december-2017/thema-endocarditis-chronische-q-koortsendocarditis/
Please rate the quality of the presentation and structure of the manuscript
Very 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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