Molecular detection of Coxiella burnetii in heart valve tissue from patients with culture-negative infective endocarditis

Occult deterioration of an aortic annular abscess: how do we diagnose a pseudoaneurysm periaortic valve? A case report

BACKGROUND

Infectious endocarditis (IE) is a disease caused by the colonization of toxic microorganisms on the endocardium of heart valves [1]. Although much progress has been made in the diagnosis and treatment of IE, its complications, such as annular abscesses [2], still have a high mortality rate. In this case, we describe a patient with infective endocarditis complicated by occult deteriorated aortic annular abscess.

CASE PRESENTATION

A 44-year-old man was admitted due to weakness of his right limbs and unclear speech for 10 h. He had recurrent fevers for 1 month before admission. Transthoracic echocardiography showed a mix-echoic vegetation attached to the bicuspid aortic valve, moderate aortic regurgitation and a possible aortic annular abscess. Blood cultures were negative and empiric antibiotic therapy was begun. The patient did not have fever again and seem to be clinically improved. However, follow-up transesophageal echocardiography revealed a large periaortic abscess led to aortic sinus pseudoaneurysm. The patient underwent mechanical prosthetic valve replacement and annulus reconstruction successfully. Perivalvular abscess may be insidious deterioration in patients who seem to be clinically improved, which requires us to pay more attention.

DISCUSSION

Occult deterioration of an aortic annular abscess is rare and more attention should be paid. Re-evaluation of echocardiography is required even if the patient's symptoms improve.

Implantable Cardiac Defibrillator-Related Culture-Negative Infection: A Case of Coxiella burnetii Infection

Coxiella burnetii is one of the most common causes of blood culture-negative infective endocarditis (IE). However, only a few cases of cardiac implantable electronic devices (CIED) infection have been reported in the literature. Herein, we present a case of CIED-related blood culture-negative infection attributed to C. burnetii. A 54-year-old male was admitted to our hospital due to prolonged fatigue, a low-grade fever lasting more than a month, and weight loss. Three years ago, he received an implantable cardiac defibrillator (ICD) as a primary prevention measure against sudden cardiac death. An initial transthoracic and transesophageal echocardiography showed a dilated left ventricle with severely impaired systolic function, while the ventricular pacing wire was inside the right ventricle with a large echogenic mass (2.2 × 2.5 cm) adherent to it. Repeated blood cultures were negative. The patient underwent transvenous lead extraction. A transesophageal echocardiography after the extraction revealed multiple vegetations on the tricuspid valve with moderate to severe valve regurgitation. A surgical replacement of the tricuspid valve was determined after a multidisciplinary heart team approach. Serology tests showed increased IgG antibodies in phase I (1:16,394) and phase II (1:8192), and a definite diagnosis of CIED infection was made based on the serological tests.

Comparison of microflora isolated from peripheral blood and valvular structures of the heart in patients with infective endocarditis

Background. Infective endocarditis (IE) is defined as an infection of a native or prosthetic heart valve, endocardial surface, or permanent cardiac apparatus. Currently, the determination of microorganisms that induce a disease or are involved in the process of pathogenesis by PCR is one of the most modern and rapid tests.

The aim. To determine and to compare the spectrum of infectious pathogens in homogenate samples of native heart valves and blood of patients with IE.

Materials and methods. Twenty patients with confirmed IE diagnose were examined, admitted for hospitalization at the Research Institute for Complex Issues of Cardiovascular Diseases (Kemerovo, Russia) in 2019. The range of tests used in the study was aimed at detecting such microorganisms as Streptococcus pyogenes, Streptococcus agalactiae, Enterobacter spp., Klebsiella spp., Staphylococcus spp., Streptococcus spp., Bacteroides fragilis, Bacteroides vulgatus, Bacteroides thetaiotaomicron, and Bacteroides ovatus.

Results. The study found that 19 samples of heart valves were characterized by the presence of microorganisms from the genus Streptococcus spp., wherein Streptococcus agalactiae was found in two patients. Staphylococcus spp. Were found in 16 samples of valve homogenate. Detection of other pathogens revealed only two cases of Enterobacter spp., Klebsiella spp. When analyzing blood samples from patients with IE, not a single infectious agent was identified. The study revealed a statistically significant difference (p < 0.001) between the incidence of Staphylococcus spp. in samples of valve homogenate and peripheral blood of patients with IE. There was also a statistically significant difference (p < 0.001) for Streptococcus spp. both in samples of valve homogenate and peripheral blood from patients with IE.

Conclusion. Molecular genetic research using PCR technologies has low efficiency in detecting the pathogen in the circulating bloodstream, as well as in blood culture. However, the study of homogenized biopsy specimens of the heart valve structures removed during surgery may allow correcting antimicrobial tactics in the early postoperative period of prosthetics.

Diagnosis of Coxiella burnetii infection via metagenomic next-generation sequencing: a case report

BACKGROUND

Coxiella burnetii, the etiologic agent of Q fever, is mainly responsible for endocardite. But there are only a few cases of Coxiella burnetii-caused wound infection have been published, because the pathogen is very difficult to isolate using conventional culture methods.

CASE PRESENTATIONS

A 76-year-old man, underwent endovascular repair of ruptured left iliac aneurysm plus abdominal aortic aneurysm under general anesthesia in 2018. Left iliac fossa mass resection was performed in 2020. After operation, the wound in the left iliac fossa was repeatedly ruptured and not healing. We used the wound tissue to perform the Metagenomics next-generation sequencing (mNGS), Coxiella burnetii was detected. Sanger sequencing and serologic verification of Coxiella burnetii all showed positive results.

CONCLUSIONS

This study proved that mNGS was an effective method to detect clinically unexplained infections, and showed the ability of pathogen identification with high sensitivity and accuracy.

Molecular diagnosis of Coxiella burnetii in culture negative endocarditis and vascular infection in South Korea

BACKGROUND

Q fever endocarditis is a major cause of culture-negative endocarditis. The role of Coxellia burnetii is underestimated because it is difficult to diagnose. We investigated the significance of C. burnetii as the cause of culture-negative endocarditis and vascular infection by examining blood and tissue specimens using serological testing and polymerase chain reaction (PCR).

METHODS

All patients with infective endocarditis or large vessel vasculitis were prospectively enrolled at a tertiary-care hospital from May 2016 through September 2020. Q fever endocarditis and vascular infection were diagnosed based on: (1) positive PCR for a cardiac valve or vascular tissue, (2) positive PCR for blood or phase I immunoglobulin G (IgG) ≥ 6400, or (3) phase I IgG ≥ 800 and < 6400 with morphologic abnormality. PCR targeted C. burnetii transposase gene insertion element IS1111a.

RESULTS

Of the 163 patients, 40 (25%) had culture-negative endocarditis (n = 35) or vascular infection (n = 5). Of the 40 patients, 24 (60%) were enrolled. Eight (33%) were diagnosed with Q fever endocarditis or vascular infection. Of these 8 patients, 6 had suspected acute Q fever endocarditis or vascular infection with negative phase I IgG. Six patients were not treated for C. burnetii, 4 were stable after surgery. One patient died due to surgical site infection after 5 months post-operatively and one died due to worsening underlying disease.

CONCLUSIONS

Approximately one-third of patients with culture-negative endocarditis and vascular infection was diagnosed as Q fever. Q fever endocarditis and vascular infection may be underestimated in routine clinical practice in South Korea.KEY MESSAGEQ fever endocarditis and vascular infection may be underestimated in routine clinical practice, thus, try to find evidence of C. burnetti infection in suspected patients by all available diagnostic tests including PCR.

Evaluation of 16S rDNA Heart Tissue PCR as a Complement to Blood Cultures for the Routine Etiological Diagnosis of Infective Endocarditis

Identification of the causative pathogen is required to optimize the effective therapy in infective endocarditis (IE). The aim of this study was to assess a 16S rDNA PCR to identify bacteria from heart valve tissues and to evaluate its usefulness as a complement to blood and removed valves cultures. A total of 266 patients diagnosed with IE from January 2015 to December 2019 were evaluated. Results between 16S rDNA PCR from heart valve tissues were compared with microbiological cultures. Blood cultures were positive in 83.5% of patients diagnosed with IE, while 39.6% and 71.8% of the evaluated heart valve samples were positive by culture and 16S rDNA PCR, respectively. For 32 (12%) patients, 16S rDNA tissue PCR provided valuable information supporting the results of blood cultures in the case of bacteria characteristic from the skin microbiota. Additionally, a microorganism was identified by using 16S rDNA PCR in 36% of blood culture-negative cases. The present study reveals that molecular diagnosis using 16S rDNA tissue PCR provides complementary information for the diagnosis of IE, and it should be recommended in surgical endocarditis, especially when blood cultures are negative.

Frenemies within: An Endocarditis Case in Behçet's Disease

A 57-year female patient diagnosed with Behçet's disease, on azathioprine, was noticed to have at a routine examination antinuclear and antiphospholipid antibodies. An overlapping lupus-like syndrome was diagnosed; hydroxychloroquine and aspirin were added. Three years later, the patient presented with dyspnea and sweating, with no fever. A cardiac bruit was noted; a giant vegetation was detected by echocardiography. Laboratory revealed severe thrombocytopenia, antiphospholipid antibodies and low complement. Blood cultures were positive for Abiotrophia defectiva serology and also revealed a chronic Coxiella burnetii infection. Antibiotic therapy, low-dose anticoagulation and control of the underlying disease mildly improved the platelet count, which fully recovered only after cardiac valve replacement. However, the Behçet's disease, initially quiescent, flared after the therapy of infections. We discuss potential links between Behçet's disease and the occurrence of antinuclear and antiphospholipid antibodies and Coxiella endocarditis in this setting. We also highlight the differences between the endocarditis in Behçet's disease, antiphospholipid syndrome, Coxiella burnetii and Abiotrophia defectiva infection, respectively. Intracellular infections may modify the presentation of autoimmune diseases. Confounding clinical features of Coxiella persistent infection and non-bacterial thrombotic endocarditis in Behçet's disease warrant further insight.

High prevalence of Coxiella burnetii infection in humans and livestock in Assiut, Egypt: A serological and molecular survey

BACKGROUND AND AIM

Q fever is considered a neglected zoonotic disease and is caused by Coxiella burnetii. Very little information is available on C. burnetii infections in cattle, sheep, and goat populations in Egypt. The aim of this study was to identify the seroprevalence of C. burnetii in humans and livestock and to test for the presence of C. burnetii DNA in sera from seropositive animals and humans.

MATERIALS AND METHODS

Blood samples were collected from 160 apparently healthy farm animals and 120 patients from three hospitals of the Assiut Governorate throughout 2017/2018. These populations were tested for antibodies against C. burnetii phase II antigen by immunofluorescence assay [IFA] and enzyme-linked immunosorbent assay (ELISA). Seropositive samples were subjected to real-time quantitative polymerase chain reaction (RT-qPCR).

RESULTS

The results of the IFA revealed C. burnetii seroprevalence rates of 45.3%, 56.0%, 45.7%, and 53.3% in cattle, sheep, goats, and humans, respectively. In humans, the seroprevalence rates were 52.1%, 30.4%, 37.5%, 74.1%, and 62.5% in patients with fever of unknown origin, influenza, kidney dialysis, hepatitis C virus, and hepatitis B virus, respectively. Likewise, by ELISA, the seroprevalence in bovine was 50.7%; sheep, 60.0%; goats, 51.4%; and humans, 55.0% (54.3%, 30.4%, 37.5%, 77.8%, and 62.5% in patients with fever of unknown origin, influenza, kidney dialysis, hepatitis C virus, and hepatitis B virus, respectively). RT-qPCR targeting the repetitive element IS1111 confirmed the presence of C. burnetii DNA.

CONCLUSION

These results proved that apparently healthy cattle, sheep, and goats may be very important reservoirs of C. burnetii infection. In light of these data, the effect of Q fever on the replication of hepatitis virus remains unclear. Although hepatitis is one of the main aspects of acute Q fever, the influence of hepatitis on Q fever remains to be investigated. Q fever is not a reportable disease in Egypt, and clinical cases may rarely be recognized by the health-care system. Additional information on the epidemiology of C. burnetii in Egypt is warranted, including other associated problems such as the distribution of infections, pathologic hallmarks, and molecular typing.