A contemporary 16-year review of Coxiella burnetii infective endocarditis in a tertiary cardiac center in Queensland, Australia

Fluorescence in situ hybridization for detecting Coxiella burnetii in tissue samples from chronic Q fever patients

OBJECTIVE

Detection of the intracellular bacterium Coxiella burnetii, causative agent of chronic Q fever, is notoriously difficult. Diagnosis of and duration of antibiotic treatment for chronic Q fever is partly determined by detection of the bacterium with polymerase chain reaction (PCR). Fluorescence in situ hybridization (FISH) might be a promising technique for detecting C. burnetii in tissue samples from chronic Q fever patients, but its value in comparison with PCR is uncertain. We aim to assess the value of FISH for detecting C. burnetii in tissue of chronic Q fever patients.

METHODS

FISH and PCR were performed on tissue samples from Dutch chronic Q fever patients collected during surgery or autopsy. Sensitivity, specificity, and overall diagnostic accuracy were calculated. Additionally, data on patient and disease characteristics were collected from electronic medical records.

RESULTS

In total, 49 tissue samples from mainly vascular walls, heart valves, or placentas, obtained from 39 chronic Q fever patients, were examined by FISH and PCR. The sensitivity and specificity of FISH compared to PCR for detecting C. burnetii in tissue samples from chronic Q fever patients was 45.2% (95% CI, 27.3% - 64.0%) and 84.6% (95% CI, 54.6% - 98.1%), respectively. The overall diagnostic accuracy was 56.8% (95% CI, 42.2% - 72.3%). Two C. burnetii PCR negative placentas were FISH positive. Four FISH results (8.2%) were deemed inconclusive because of autofluorescence.

CONCLUSION

With an overall diagnostic accuracy of 57.8%, we conclude that FISH has limited value in the routine diagnostics of chronic Q fever.

… İlindeki Q ateşi olgularının retrospektif olarak değerlendirilmesi

Amaç: Q ateşi, özellikle risk grubundaki bireylerde akut ve kronik formda görülebilen, özgül olmayan semptomları nedeniyle tanısı atlanabilen, zoonotik bir hastalıktır. Önceleri sıklıkla yanlış tanı alan bu hastalık olguları, ülkemizden de son yıllarda bildirilmeye başlamıştır. Bu çalışmada Q ateşi olgularının klinik ve laboratuvar parametrelerini retrospektif olarak değerlendirmeyi ve Q ateşi farkındalığını arttırmayı amaçladık. Gereç ve Yöntem: Retrospektif gözlemsel çalışmamızda, 1 Ocak 2018–1 Mart 2021 tarihleri arasında hastanemizde takip ve tedavi edilen, 18 yaş üstü, kesin tanı almış, Q ateşi olguları değerlendirildi. Hastalara ait yaş, cinsiyet, meslek, ikamet edilen yer gibi demografik veriler, kene teması öyküleri, hastalığın geliştiği zaman dilimi (yıl, mevsim, ay), eşlik eden komorbiditeler, semptomlar, fizik muayene ve laboratuvar bulguları, tedaviler, hastaların iyileşme ve mortalite durumları irdelendi. Bulgular: Çalışmaya yaş ortalaması 49,23±12,07 yıl, 7’si (%57) erkek olan 14 olgu dahil edildi. Olguların sadece 5’i (%35,7) çiftçi, dördü (%28,57) hayvancılık yapıyordu. Kırsal alanda yaşama 9 (%64,28) olguda mevcuttu. En sık semptomlar ateş yüksekliği (%100), öksürük (%71,42) ve miyalji (%57,14) idi. Olguların tamamı akut Q ateşi olgusu olup, endokardit hiçbir olguda saptanmadı. Sonuç: Ülkemizin Q ateşi hastalığı için olası endemik bölgelerden olması nedeniyle, özellikle kırsal kesimde yaşayan, hayvancılıkla uğraşma, pastörize edilmemiş süt/süt ürünü tüketme gibi risk faktörleri olan hastalarda pnömoni başta olmak üzere birçok hastalığın ayırıcı tanısında düşünülmesi gerektiğini vurgulamak istedik.

Q Fever Endocarditis: A Review of Local and all Reported Cases in the Literature

BACKGROUND

Q fever endocarditis by Coxiella burnetii is rare and presents a diagnostic challenge. With limited data available, the aim of this study was to review all reported cases together with unpublished local cases to understand risk factor profiles, diagnostic methods, clinical features, treatments and outcomes.

METHODS

A search of the PubMed database using the term 'Q fever endocarditis' identified cases between 1950-2019. Included cases had positive polymerase chain reaction testing, valve culture or serology. Separately, to identify local cases meeting our criteria we queried the Western Australian Health Open Patient Administration System at two local hospitals for the ICD-10-AM diagnosis code A78 between 2013-2019.

RESULTS

We identified 181 cases from 31 publications and four local cases to create a combined series of 185 cases. The majority 141 (76%) were male and only 11% had normal cardiac valves. Most (72%) of patients had a history of contact with animals or travel. Nearly all (98%) cases had positive serology and over half (56%) had surgery performed. Overall mortality was 17%, and mortality for native valve endocarditis and prosthetic valve endocarditis was 12% and 3% respectively. No patients treated with doxycycline and hydroxychloroquine died. Mortality prior to 1999 was 28%, compared with 5% for more recent cases.

CONCLUSION

Serological diagnosis is key in Q fever endocarditis and possible risk factors exist such as male gender, pre-existing valvular conditions and contact with animals or travel. Native valve endocarditis and treatment with drugs other than doxycycline and hydroxychloroquine increase the risk of death.

Acute Q Fever Endocarditis: A Paradigm Shift Following the Systematic Use of Transthoracic Echocardiography During Acute Q Fever

BACKGROUND

As Q fever, caused by Coxiella burnetii, is a major health challenge due to its cardiovascular complications, we aimed to detect acute Q fever valvular injury to improve therapeutic management.

METHODS

In the French national reference center for Q fever, we prospectively collected data from patients with acute Q fever and valvular injury. We identified a new clinical entity, acute Q fever endocarditis, defined as valvular lesion potentially caused by C. burnetii: vegetation, valvular nodular thickening, rupture of chorda tendinae, and valve or chorda tendinae thickness. To determine whether or not the disease was superimposed on an underlying valvulopathy, patients' physicians were contacted. Aortic bicuspidy, valvular stenosis, and insufficiency were considered as underlying valvulopathies.

RESULTS

Of the 2434 patients treated in our center, 1797 had acute Q fever and 48 had acute Q fever endocarditis. In 35 cases (72%), transthoracic echocardiography (TTE) identified a valvular lesion of acute Q fever endocarditis without underlying valvulopathy. Positive anticardiolipin antibodies (>22 immunoglobulin G-type phospholipid units [GPLU]) were independently associated with acute Q fever endocarditis (odds ratio [OR], 2.7 [95% confidence interval {CI}, 1.3-5.5]; P = .004). Acute Q fever endocarditis (OR, 5.2 [95% CI, 2.6-10.5]; P < .001) and age (OR, 1.7 [95% CI, 1.1-1.9]; P = .02) were independent predictors of progression toward persistent C. burnetii endocarditis.

CONCLUSIONS

Systematic TTE in acute Q fever patients offers a unique opportunity for early diagnosis of acute Q fever endocarditis and for the prevention of persistent endocarditis. Transesophageal echocardiography should be proposed in men, aged >40 years, with anticardiolipin antibodies >60 GPLU when TTE is inconclusive or negative.

New insights in Coxiella burnetii infection: diagnosis and therapeutic update

Introduction: Coxiella burnetii infection is still challenging physicians, mainly because no international coordination has been stated to standardize the therapeutic strategy and improve the clinical outcomes.Areas covered: Based on the recent knowledge on Q fever, we review here the clinical practices from Q fever diagnosis to therapy. We searched PubMed and Google Scholar to perform the qualitative synthesis.Expert opinion: Four major critical points are highlighted in this review. The first point is that Q fever diagnosis has been reviewed in the light of the new diagnosis tools, including molecular biology, transthoracic echocardiography, and 18F-FDG-PET/CT-scan imaging. Q fever diagnosis results from the presence of a microbiological criterion in addition to a lesional criterion. Second, the identification of the anticardiolipin antibodies as a novel biological predictive marker for acute Q fever complications (hemophagocytic syndrome, acute Q fever endocarditis, alithiasic cholecystitis, hepatitis, and meningitis). Third, the observation of a coincidence between Q fever and non-Hodgkin lymphoma that has made persistent C. burnetii infection a risk of non-Hodgkin lymphoma. Finally, we expose here the close follow-up we proposed from the French National Reference Center for patients with Q fever infection to detect relapse and complications.

Molecular detection and genetic characterization of the potentially pathogenic Coxiella burnetii and the endosymbiotic Candidatus Midichloria mitochondrii in ticks infesting camels (Camelus dromedarius) from Tunisia

Tick-borne bacteria are considered to be emerging in camels, but data about their occurrence in Tunisian dromedaries and their infesting ticks remain scarce. In this study, 412 camel blood samples and 327 partially engorged ticks were collected and tested for the presence of Coxiella burnetii and/or related strains, and Rickettsiales bacteria. Coxiella burnetii was detected in 9 Hyalomma impeltatum and 3 H. dromedarii with an overall prevalence rate of 3.6% (12/327). Candidatus Midichloria mitochondrii DNA was identified in 16 H. impeltatum and 10 H. dromedarii with an overall prevalence rate of 8% (26/327). Six ticks (2%) were found to be co-infected with these two bacteria. No positive DNA camel blood sample was observed for both bacteria. Genotyping and phylogenetic analysis of obtained C. burnetii partial sequences based on the IS1111 and htpB genes revealed 99-100% similarity to the pathogenic C. burnetii strains isolated from humans, ruminants and ticks, and that were genetically distant to those isolated from all endosymbiotic related strains (Coxiella-like bacteria). The analysis of the rickettsial partial sequences of the 16S rRNA gene showed 100% similarity to Ca. M. mitochondrii strains infecting Ixodid ticks and dogs. This is the first time that C. burnetii and Ca. M. mitochondrii have been detected in ticks from Tunisia, which raises the possibility of the involvement of Hyalomma tick species in the active diffusion of these bacteria among camels, other domestic animals and humans.

Ten-year experience of Q fever endocarditis in a tertiary cardiac center in Saudi Arabia

BACKGROUND

Q fever endocarditis (QFE) is considered rare in the Middle East, with only a few cases reported in Saudi Arabia. The aim of this study is to report on the experience of our centre on QFE.

METHODS

We searched the medical records for cases of QFE at our cardiac center from 2009-2018. Demographic data, clinical features, serology and echocardiography results, treatments, and outcomes were assessed.

RESULTS

Five hundred and two cases of infective endocarditis were detected over the 10 years period. Among the 234 patients with blood culture-negative endocarditis (BCNE), 19 (8.10%) had QFE. All patients had a previously diagnosed congenital heart disease except for one patient with rheumatic heart disease. Eleven patients had received a bovine jugular vein-related implant, e.g., a Melody valve (seven patients) or Contegra conduit (four patients). Coinfection was detected in three patients, and immunologic and embolic phenomena were observed in five patients. All patients received a combination of hydroxychloroquine and doxycycline, with good outcomes. Only two patients required surgery while on treatment. Two patients died several months after treatment; the cause of death was not identified.

CONCLUSION

This study indicates that Q fever exists in our population. The majority of the patients had congenital heart disease (CHD) and underwent bovine jugular vein implants. Patients with CHD are at increased risk of infective endocarditis. Bovine jugular vein implants increase the risk of infective and possibly QFE. Proper exclusion of Q fever is warranted in all BCNE and possibly in culture-positive endocarditis cases in areas endemic to Q fever.

KEY POINTS

We presented the largest series of Q fever endocarditis cases in Saudi Arabia. We showed that Q fever is not rare in the Middle East and suggest that it should be considered in all blood culture-negative endocarditis cases.