Case records of the Massachusetts General Hospital. Case 8-2007. A 48-year-old man with chest pain followed by cardiac arrest

Helicobacter cinaedi bacterium association with atherosclerosis and other diseases

Helicobacter is a genus of spiral-shaped Gram-negative enterohepatic bacteria whose members are capable of causing bacteremia in humans. One of the poorly studied members of this genus is the bacterium Helicobacter cinaedi. This microorganism was first isolated from human fecal samples in 1984. Although it was long considered to be associated with only immunocompromised patients, more evidence in recent years has implicated H. cinaedi in causing serious pathologies in immunocompetent populations. In addition, H. cinaedi is also reported to be associated with a few chronic or severe illnesses, such as atherosclerosis, which in turn can lead to the development of other cardiovascular pathologies: one of the leading causes of mortality worldwide. Helicobacter cinaedi often goes unnoticed in standard diagnostic methods due to its slow growth under microaerobic conditions. This often leads to significant underdetection and hence undermines the role of this bacterium in the pathogenesis of various diseases and the extent of its spread in humans. In this review, we have compiled information on pathologies associated with H. cinaedi, the occurrence of the bacterium in humans and animals, and the latest developments in diagnosing the bacterium and treating associated diseases.

The role of Helicobacter cinaedi in the development of atherosclerosis

Helicobacter cinaedi (H. cinaedi) is a Gram-negative curved motile rod that causes bloodstream or enteric infections. It was suggested that H. cinaedi was involved in the progression of atherosclerosis. We aimed to investigate the presence of H. cinaedi DNA using a nested-polymerase chain reaction (PCR) in atheroma plaques from patients with atherosclerosis-induced vascular diseases. A total of 129 patients diagnosed with valvular heart disease due to atherosclerosis and 146 patients with non-atherosclerotic post-stenotic dilatation were included as the patient and the control groups, respectively. The ATCC BA847 H. cinaedi strain was used as the positive control for the nested-PCR method. We investigated H. cinaedi DNA in our study groups using the nested-PCR method and detected only six H. cinaedi DNA (4.65%) in the 129 atherosclerotic patient group. We detected significant difference between patient and control groups with respect to the presence of H. cinaedi on the basis of Fischer’s exact test (p = 0.010) by univariate analysis. Age (OR: 1.042, p = 0.016), total cholesterol (≥200 mg/dL) (OR: 1.849, p = 0.0001), and high-density lipoprotein (≥50 mg/dL) (OR: 0.745, p = 0.039) levels were detected as independent variables for the risk of atherosclerosis development in the patient group. The presence of H. cinaedi was not detected as an independent variable in a multivariate analysis. Previous studies suggested that H. cinaedi-induced oral infections might translocate to vascular tissue and induce chronic inflammation in the aorta, which subsequently may lead to atherosclerotic plaque formation. In conclusion, we could not suggest that there is a causal relationship between H. cinaedi and the development of atherosclerosis. However, age (OR: 1.042), total cholesterol (≥200 mg/dL, OR: 1.849), and high-density lipoprotein (≥50 mg/dL, OR: 0.745, as protective) levels have a significant role in the pathogenesis of atherosclerosis development. We also suggest that the presence of H. cinaedi may contribute to the risk of atherosclerosis development due to the univariate comparison result.

Culture-negative group B streptococcal pericarditis: A case report and literature review of the diagnostic use of polymerase chain reaction

Although conventional microbiology cultures may be negative, polymerase chain reaction (PCR) can effectively identify both typical and atypical microorganisms. With careful interpretation, PCR could become the gold-standard diagnostic test for culture-negative bacterial pericarditis.

Getting to the Heart of the Matter: A 20-Year-Old Man With Fever, Rash, and Chest Pain

Infection with Helicobacter cinaedi can encompass a wide spectrum of clinical manifestations, including fever, rash, endocarditis, osteomyelitis, and meningitis. The present case demonstrates the ability of H cinaedi to masquerade as acute rheumatic fever and represents the first reported case of cardiac tamponade caused by H cinaedi.

The Helicobacter cinaedi antigen CAIP participates in atherosclerotic inflammation by promoting the differentiation of macrophages in foam cells

Recent studies have shown that certain specific microbial infections participate in atherosclerosis by inducing inflammation and immune reactions, but how the pathogens implicated in this pathology trigger the host responses remains unknown. In this study we show that Helicobacter cinaedi (Hc) is a human pathogen linked to atherosclerosis development since at least 27% of sera from atherosclerotic patients specifically recognize a protein of the Hc proteome, that we named Cinaedi Atherosclerosis Inflammatory Protein (CAIP) (n = 71). CAIP appears to be implicated in this pathology because atheromatous plaques isolated from atherosclerotic patients are enriched in CAIP-specific T cells (10%) which, in turn, we show to drive a Th1 inflammation, an immunopathological response typically associated to atherosclerosis. Recombinant CAIP promotes the differentiation and maintenance of the pro-inflammatory profile of human macrophages and triggers the formation of foam cells, which are a hallmark of atherosclerosis. This study identifies CAIP as a relevant factor in atherosclerosis inflammation linked to Hc infection and suggests that preventing and eradicating Hc infection could reduce the incidence of atherosclerosis.

Helicobacter cinaedi induced typhlocolitis in Rag-2-deficient mice

BACKGROUND

Helicobacter cinaedi, an enterohepatic helicobacter species (EHS), is an important human pathogen and is associated with a wide range of diseases, especially in immunocompromised patients. It has been convincingly demonstrated that innate immune response to certain pathogenic enteric bacteria is sufficient to initiate colitis and colon carcinogenesis in recombinase-activating gene (Rag)-2-deficient mice model. To better understand the mechanisms of human IBD and its association with development of colon cancer, we investigated whether H. cinaedi could induce pathological changes noted with murine enterohepatic helicobacter infections in the Rag2(-/-) mouse model.

MATERIALS AND METHODS

Sixty 129SvEv Rag2(-/-) mice mouse were experimentally or sham infected orally with H. cinaedi strain CCUG 18818. Gastrointestinal pathology and immune responses in infected and control mice were analyzed at 3, 6 and 9 months postinfection (MPI). H. cinaedi colonized the cecum, colon, and stomach in infected mice.

RESULTS

H. cinaedi induced typhlocolitis in Rag2(-/-) mice by 3 MPI and intestinal lesions became more severe by 9 MPI. H. cinaedi was also associated with the elevation of proinflammatory cytokines, interferon-γ, tumor-necrosis factor-α, IL-1β, IL-10; iNOS mRNA levels were also upregulated in the cecum of infected mice. However, changes in IL-4, IL-6, Cox-2, and c-myc mRNA expressions were not detected.

CONCLUSIONS

Our results indicated that the Rag2(-/-) mouse model will be useful to continue investigating the pathogenicity of H. cinaedi, and to study the association of host immune responses in IBD caused by EHS.

First case of infective endocarditis caused by Helicobacter cinaedi

BACKGROUND

Up to 20% of all infective endocarditis are blood culture-negative and therefore a diagnostic challenge. Here we present the case of an infective endocarditis due to Helicobacter cinaedi finally diagnosed using different molecular methods. This highly fastidious gram-negative spiral rod is increasingly recognized as a human pathogen, above all in immunocompromised patients. So far H. cinaedi has been associated with bacteremia, cellulitis, arthritis and meningitis.

CASE PRESENTATION

A 71-year-old man presented with fever and progressive dyspnea for weeks. He was immunocompromised by long-term steroid therapy. As one major and two minor Duke's criteria (vegetation, fever and aortic valve stenosis as predisposition) were present, an infective endocarditis was suspected and an empiric therapy with amoxicillin/clavulanic acid and gentamicin was established. The persistent severe aortic regurgitation resulted in a valve replacement. Histological evaluation of the aortic valve showed a polypous-ulcerative endocarditis. Gram stain and culture remained negative. Broad-range bacterial PCR targeting the 16S rRNA gene on the biopsy of the aortic valve identified H. cinaedi as the causative agent. The antibiotic therapy was simplified accordingly to ceftriaxone and gentamicin with a recommended duration of 6 weeks. Ten days after valve replacement the patient was discharged. To complete our molecular finding, we sequenced nearly the complete 16S rRNA gene (accession number KF914917) resulting in 99.9% identity with H. cinaedi reference sequences. Based on this result, 2 species-specific PCR tests amplifying part of the ctd gene were established and applied to the valve specimen. The 2 PCRs confirmed H. cinaedi. In addition, we analyzed stool, urine and saliva from the patient using H. cinaedi PCR. The fecal and urine specimen showed a positive signal, saliva was PCR-negative.

CONCLUSION

We identified H. cinaedi as causative agent of a culture-negative endocarditis in an immunocompromised patient using broad-range and specific PCR. In addition to 2 cases from Japan presented on international meetings in 2010 and 2013, our case report shows that H. cinaedi should be recognized as additional causative organism of infective endocarditis. The use of molecular diagnostic techniques proved to be a powerful complement for the detection of blood culture-negative infective endocarditis.

Pericoronary pseudotumor caused by helicobacter cinaedi

Cardiac tumors and tumor-like lesions are uncommon; most are true neoplasms. We here report a case of a pericoronary tumor-like lesion surrounding the right coronary artery in a 39-year-old man who presented with fever and chest pain. Although clarithromycin was administered for 1 week, his fever persisted. Helicobacter cinaedi (H. cinaedi) was isolated from blood cultures and found to be sensitive to ceftriaxone. A computed tomography scan showed a tumor-like lesion with no (18)F-fl uorodeoxyglucose uptake surrounding the right coronary artery. After administration of ceftriaxone, the tumor-like lesion diminished in size according to meticulous computed tomography examinations. We therefore concluded that it was caused by H. cinaedi infection. The patient has been followed up closely for 1 year and remains asymptomatic.

Promotion of atherosclerosis by Helicobacter cinaedi infection that involves macrophage-driven proinflammatory responses

Helicobacter cinaedi is the most common enterohepatic Helicobacter species that causes bacteremia in humans, but its pathogenicity is unclear. Here, we investigated the possible association of H. cinaedi with atherosclerosis in vivo and in vitro. We found that H. cinaedi infection significantly enhanced atherosclerosis in hyperlipidaemic mice. Aortic root lesions in infected mice showed increased accumulation of neutrophils and F4/80⁺ foam cells, which was due, at least partly, to bacteria-mediated increased expression of proinflammatory genes. Although infection was asymptomatic, detection of cytolethal distending toxin RNA of H. cinaedi indicated aorta infection. H. cinaedi infection altered expression of cholesterol receptors and transporters in cultured macrophages and caused foam cell formation. Also, infection induced differentiation of THP-1 monocytes. These data provide the first evidence of a pathogenic role of H. cinaedi in atherosclerosis in experimental models, thereby justifying additional investigations of the possible role of enterohepatic Helicobacter spp. in atherosclerosis and cardiovascular disease.

Identification of and screening for human Helicobacter cinaedi infections and carriers via nested PCR

Helicobacter cinaedi is the most frequently reported enterohepatic Helicobacter species isolated from humans. Earlier research suggested that certain patients with H. cinaedi infection may remain undiagnosed or incorrectly diagnosed because of difficulties in detecting the bacteria by conventional culture methods. Here, we report a nested PCR assay that rapidly detects the cytolethal distending toxin gene (cdt) of H. cinaedi with high specificity and sensitivity. Specificity of the assay was validated by using different species of Helicobacter and Campylobacter, as well as known H. cinaedi-positive and -negative samples. The sensitivity of detection for the cdt gene in the assay was 10(2) CFU/ml urine or 10(2) CFU/10(5) infected RAW 264.7 cells. In an H. cinaedi-infected mouse model, the cdt gene of H. cinaedi was effectively detected via the assay with urine (6/7), stool (2/3), and blood (2/6) samples. Importantly, it detected H. cinaedi in blood, urine, and stool samples from one patient with a suspected H. cinaedi infection and three patients with known infections. The assay was further used clinically to follow up two H. cinaedi-infected patients after antibiotic treatment. Stool samples from these two patients evaluated by nested PCR after antibiotic therapy showed clearance of bacterial DNA. Finally, analysis of stool specimens from healthy volunteers showed occasional positive reactions (4/30) to H. cinaedi DNA, which suggests intestinal colonization by H. cinaedi in healthy subjects. In conclusion, this nested PCR assay may be useful for the rapid diagnosis, antimicrobial treatment evaluation, and epidemiological study of H. cinaedi infection.

Markedly Elevated Cardiac Bio-Markers at Presentation With Normal Ventricular Function: A Novel Clinical Subset of Myocarditis Manifestation

We present a case of a 19-year-old woman with myocarditis who had significantly elevated cardiac markers at presentation even before any myocardial damage ensued. The patient had complicated clinical course with ventricular arrhythmia and cardiac arrest requiring resuscitation but eventually recovered completely. Though there is limited information available regarding such cases, the significantly elevated initial cardiac markers in the absence of left ventricular decompensation may probably represent a clinical subset of myocarditis and may portend an impending complicated clinical course. Further systematic research is required to define the clinical phenotype and elucidate underlying mechanisms.

Identification of the major antigenic protein of Helicobacter cinaedi and its immunogenicity in humans with H. cinaedi infections

Helicobacter cinaedi infection is now recognized as an increasingly important emerging disease. Its pathogenesis and epidemiological features are not fully understood, however. Here, we investigated the antigenic protein of H. cinaedi and the immunological response to it in H. cinaedi-infected patients. We constructed a genomic library of H. cinaedi from an H. cinaedi clinical isolate, and various H. cinaedi recombinant proteins were expressed. We identified the 30-kDa protein, encoded in an 822-bp H. cinaedi genome, as a major antigen, which was specifically recognized by serum from an H. cinaedi-immunized rabbit and H. cinaedi-infected patients. The gene encoding this 30-kDa antigen had high sequence similarity with genes encoding putative membrane proteins of bacteria. To evaluate whether the 30-kDa protein can be applied in serological testing for H. cinaedi infections, the recombinant protein was expressed in Escherichia coli as a His-tagged fusion protein and purified by Ni(2+) affinity chromatography. Western blot analysis revealed strong immunoreactivity of the 31-kDa fusion protein with serum antibody from patients infected with H. cinaedi, but such an immunoreaction was absent or was very weak with uninfected control serum. An enzyme-linked immunosorbent assay using this H. cinaedi major antigen showed significantly high antibody titers for H. cinaedi-infected subjects compared with those of various control groups. We therefore conclude that the 30-kDa putative membrane protein is a major antigen of H. cinaedi and is useful for immunological and serological testing for clinical diagnosis and for further epidemiological study of H. cinaedi infection in humans.