First case of infective endocarditis caused by Helicobacter cinaedi

Enterohepatic Helicobacter species - clinical importance, host range, and zoonotic potential

The genus Helicobacter defined just over 30 years ago, is a highly diverse and fast-growing group of bacteria that are able to persistently colonize a wide range of animals. The members of this genus are subdivided into two groups with different ecological niches, associated pathologies, and phylogenetic relationships: the gastric Helicobacter (GH) and the enterohepatic Helicobacter (EHH) species. Although GH have been mostly studied, EHH species have become increasingly important as emerging human pathogens and potential zoonotic agents in the last years. This group of bacteria has been associated with the development of several diseases in humans from acute pathologies like gastroenteritis to chronic pathologies that include inflammatory bowel disease, and liver and gallbladder diseases. However, their reservoirs, as well as their routes of transmission, have not been well established yet. Therefore, this review summarizes the current knowledge of taxonomy, epidemiology, and clinical role of the EHH group.

Molecular epidemiologic and clinical analysis of Helicobacter cinaedi bacteremia in Japan

BACKGROUND

Helicobacter cinaedi is an important pathogen that causes bloodstream infections. Owing to the challenges in its culture and identification, its clinical and bacterial characteristics remain unknown. Our study aimed to investigate the molecular epidemiology and antimicrobial susceptibility of H cinaedi.

MATERIALS AND METHODS

From 2003 to 2016, we analyzed 16 non-repetitive H cinaedi strains, isolated from blood, at the medical hospital of Tokyo Medical and Dental University. Multilocus sequence typing was performed to analyze the genetic relationship across the different isolates. The minimum inhibitory concentrations (MIC) of antibiotics were determined by the agar dilution method.

RESULTS

The median age of subjects in this study was 61 years (range, 18-84 years). The most common risk factors included the use of steroids (75.0%) and immunosuppressant drugs (37.5%). In addition, the most common symptoms of H cinaedi bacteremia included colitis (37.5%) and cellulitis (31.3%). The infection recurred in three of seven cases (42.8%) that underwent antibiotic therapy for <10 days. The strains were classified into five sequence types (ST), of which, ST 10 (43.8%) and ST 4 (31.3%) were predominant. The MIC₉₀ values of amoxicillin, gentamycin, imipenem, ciprofloxacin, and clarithromycin were 4, 0.5, 0.25, 64, and 128 mg/L, respectively.

CONCLUSIONS

Since there is no recommended guideline yet for the choice or duration of antibiotic therapy and antimicrobial break points, our results suggested, for the first time, that prolonged antibiotic therapy, except with ciprofloxacin and clarithromycin, would be required to ensure resolution of symptoms and prevention of recurrence.

Genome Sequencing Verifies Relapsed Infection of Helicobacter cinaedi

Background

Recurrent infections of Helicobacter cinaedi are often reported, and long-term antimicrobial treatment is empirically recommended to prevent such infections. However, there have been no studies examining whether recurrent infections are relapses of former infections or reinfections with different clones.

Methods

A 69-year-old woman presented with recurrent H cinaedi bacteremia-associated cellulitis after a 51-day interval. We isolated 10 colonies from the blood cultures obtained during each of the 2 episodes and subjected them to whole-genome sequencing (WGS). High-confidence single-nucleotide polymorphisms (SNPs) were identified by an assembly based method. Heterogeneous SNP sites were identified by read mapping. The susceptibility of a representative isolate to 14 antimicrobials was also examined.

Results

Whole-genome sequence analysis revealed only 6 SNP sites among the 20 isolates at the whole-genome level. Based on the 6 SNPs, 5 within-host variants (referred to as genotypes) were identified. All 5 genotypes were detected in the first infection; however, only 2 genotypes were detected in the second infection. Although the H cinaedi clone showed a higher minimum inhibitory concentration to fluoroquinolones and macrolides and responsible mutations were identified, none of the 6 SNPs appeared related to additional resistance.

Conclusions

The second infection analyzed here was a relapse of the first infection. A certain level of within-host genomic heterogeneity of the H cinaedi clone was already present in the first infection. Our results suggest the importance of longer treatment courses to eradicate H cinaedi for preventing the relapse of its infection.

First case report of thyroid abscess caused by Helicobacter cinaedi presenting with thyroid storm

Background

Helicobacter cinaedi is a microaerobic Gram-negative spiral-shaped bacterium that causes enteritis, cellulitis, and bacteremia in both immunocompromised and immunocompetent patients. While there have been increasing numbers of reported H. cinaedi infections recently, there has been no thyroid abscess case caused by H. cinaedi presenting with thyroid storm.

Case presentation

A 50-year-old Japanese man presented with a 9-day history of high fever associated with palpitations, dry cough, and chronic diarrhea. The patient had a history of Basedow’s disease that had been treated with thiamazole in the past. During the current episode, the patient was diagnosed with thyroid storm and treated accordingly. The blood culture taken on admission was positive for H. cinaedi. This finding was confirmed by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOFMS). A systemic computed tomography (CT) scan revealed a thyroid abscess as the site of infection and cause of the bacteremia. The 16S rRNA gene sequencing identified the pathogen of thyroid abscess as H. cinaedi. Clinical symptoms and laboratory data normalized on admission day 7 after treatment with both effective antibiotics and antithyroid drugs.

Conclusions

The case study described a patient with a history of Basedow’s disease that presented with a thyroid abscess caused by H. cinaedi with symptoms similar to those of thyroid storm. While this bacterium has been implicated in other infections, we believe this is the first time the bacteria has been documented to have caused a thyroid abscess.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-3808-7) contains supplementary material, which is available to authorized users.

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.

Mutations in Genes Encoding Penicillin-Binding Proteins and Efflux Pumps Play a Role in β-Lactam Resistance in Helicobacter cinaedi

β-Lactams are often used to treat Helicobacter cinaedi infections; however, the mechanism underlying β-lactam resistance is unknown. In this study, we investigated β-lactam resistance in an H. cinaedi strain, MRY12-0051 (MICs of amoxicillin [AMX] and ceftriaxone [CRO], 32 and 128 μg/ml; obtained from human feces). Based on a comparative whole-genome analysis of MRY12-0051 and the CRO-susceptible H. cinaedi strain MRY08-1234 (MICs of AMX and CRO, 1 and 4 μg/ml; obtained from human blood), we identified five mutations in genes encoding penicillin-binding proteins (PBPs), including two in pbpA, one in pbp2, and two in ftsI Transformation and penicillin binding assays indicated that CRO resistance was mainly associated with mutations in pbpA; mutations in ftsI also led to increased resistance to AMX. Knocking out cmeB and cmeD, which encode resistance-nodulation-division-type efflux pump components, in H. cinaedi type strain CCUG18818 (AMX MIC, 4 to 8 μg/ml) resulted in 8- and 64-fold decreases, respectively, in the AMX MIC. Hence, MICs of AMX in H. cinaedi become similar to those of Helicobacter pylori isolates in the absence of cmeD In conclusion, the difference in susceptibility to β-lactams between H. pylori and H. cinaedi is explained by differences in efflux pump components. Mutations in pbpA are the primary determinant of high resistance to β-lactams in H. cinaedi.

Bacteremia and Skin Infections in Four Patients Caused by Helicobacter-Like Organisms

Background

Enterohepatic Helicobacter-like organisms (HLO) have been recognized as causes of human infection since 1984, primarily as a cause of bacteremia and cellulitis in immunocompromised individuals, but the spectrum of illness due to HLO has expanded based on numerous reports from Japan.

Methods

We report 4 epidemiologically unrelated immunocompetent patients with HLO bacteremia diagnosed within a 2-year period. Three patients had cellulitis and 1 patient had unexplained fever. 16S ribosomal deoxyribonucleic acid (rDNA) sequence analysis of 2 isolates suggested that they were Helicobacter cinaedi, and whole-genome sequencing showed that they differed only slightly from reference strains.

Conclusions

We believe that this syndrome is more common than reported, but it is easily overlooked because the skin lesions resemble streptococcal cellulitis and respond very rapidly to β-lactam antibiotics, and the organism is difficult to isolate from the blood. All HLO in our series were isolated from blood using the ESP system and were not detected in 2 other widely used commercial blood culture systems.

Multifocal Septic Arthritis Secondary to Infective Endocarditis: A Rare Case Report

Introduction:

Infective endocarditis (IE) is a rare cause of septic arthritis. We report a patient who presented with multifocal septic arthritis as a result of IE, which is an extremely rare condition.

Case Report:

This 69-year-old gentleman presented to the emergency department (ED) with a 3-day history of acute right knee pain. Initial investigations demonstrated chondrocalcinosis on knee radiographs, acute renal failure with rhabdomyolysis and a CRP of 520. After treatment with intravenous fluid rehydration and analgesia, the knee aspiration grew a Group B Streptococcus, and the patient underwent arthroscopic washout. 48 h after admission the patient developed left wrist and right elbow pain. Further aspirations revealed Group B Streptococcus and the patient underwent further washouts. A multidisciplinary approach was used. Due to ongoing sepsis, an echocardiogram was performed identifying IE. The patient eventually died due to ongoing sepsis and duodenal ulceration.

Conclusion:

This case highlights the importance of considering a systemic cause such as IE for patients presenting with features of multifocal septic arthritis and ensuring all patients undergo a full medical examination as part of the clerking process. Furthermore, it emphasizes the need to adopt a multi-disciplinary approach when presented with complex patients so that the best medical care can be given to prevent morbidity and mortality.

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.

Epithelial Coculture and l-Lactate Promote Growth of Helicobacter cinaedi under H2-Free Aerobic Conditions

Helicobacter cinaedi is an emerging opportunistic pathogen associated with infections of diverse anatomic sites. Nevertheless, the species demonstrates fastidious axenic growth; it has been described as requiring a microaerobic atmosphere, along with a strong preference for supplemental H₂ gas. In this context, we examined the hypothesis that in vitro growth of H. cinaedi could be enhanced by coculture with human epithelial cells. When inoculated (in Ham's F12 medium) over Caco-2 monolayers, the type strain (ATCC BAA-847) gained the ability to proliferate under H₂-free aerobic conditions. Identical results were observed during coculture with several other monolayer types (LS-174T, AGS, and HeLa). Under chemically defined conditions, 40 amino acids and carboxylates were screened for their effect on the organism's atmospheric requirements. Several molecules promoted H₂-free aerobic proliferation, although it occurred most prominently with millimolar concentrations of l-lactate. The growth response of H. cinaedi to Caco-2 cells and l-lactate was confirmed with a collection of 12 human-derived clinical strains. mRNA sequencing was next performed on the type strain under various growth conditions. In addition to providing a whole-transcriptome profile of H. cinaedi, this analysis demonstrated strong constitutive expression of the l-lactate utilization locus, as well as differential transcription of terminal respiratory proteins as a function of Caco-2 coculture and l-lactate supplementation. Overall, these findings challenge traditional views of H. cinaedi as an obligate microaerophile.

IMPORTANCE

H. cinaedi is an increasingly recognized pathogen in people with compromised immune systems. Atypical among other members of its bacterial class, H. cinaedi has been associated with infections of diverse anatomic sites. Growing H. cineadi in the laboratory is quite difficult, due in large part to the need for a specialized atmosphere. The suboptimal growth of H. cinaedi is an obstacle to clinical diagnosis, and it also limits investigation into the organism's biology. The current work shows that H. cinaedi has more flexible atmospheric requirements in the presence of host cells and a common host-derived molecule. This nutritional interplay raises new questions about how the organism behaves during human infections and provides insights for how to optimize its laboratory cultivation.

The First Case Report of Cerebral Cyst Infection Due to Helicobacter cinaedi

We report the first case of cerebral cyst infection by Helicobacter cinaedi, a fastidious spiral-shaped gram-negative rod bacterium. A 70-year-old man visited Tokyo Medical University Hospital with persisting fever since 2 weeks. He underwent surgery and radiotherapy for parapharyngeal space squamous cell carcinoma 10 years ago. The radiotherapy resulted in a cerebral cyst as a side effect, and an Ommaya reservoir was inserted into the cyst. Blood culture and analysis of the brain cyst fluid revealed the presence of spiral-shaped gram-negative rod bacteria, which were identified as H. cinaedi by polymerase chain reaction. Initially, we administered clarithromycin (400 mg per day). After H. cinaedi infection was confirmed, the treatment was changed to meropenem (MEPM 6 g per day). The patient was treated for 43 days in the hospital with intravenous meropenem, and his clinical course was satisfactory. On the 44th day, he was discharged and prescribed oral minocycline (MINO 200 mg per day). After discharge, the patient's H. cinaedi infection did not recur. Our case illustrated the wide clinical spectrum of H. cinaedi as well as the effectiveness of antibiotic therapy comprising MERM and MINO for treating central nervous system infection by this organism.

Helicobacter cinaedi bacteremia in four renal transplant patients: clinical features and an important suggestion regarding the route of infection

Helicobacter cinaedi can cause bacteremia mainly in immunocompromised patients. We present the clinical characteristics of H. cinaedi bacteremia in 4 renal transplant patients. Interestingly, all cases showed triggers of bacterial translocation: 2 cases developed after colonic perforation caused by diverticulitis, 1 case developed post cholecystectomy, and the remaining patient had chronic diarrhea. Accordingly, bacterial translocation caused by severe gastrointestinal complication could be a cause of H. cinaedi bacteremia.

Preterm labor and neonatal sepsis caused by intrauterine Helicobacter cinaedi infection

Helicobacter cinaedi is a rare pathogen but known to cause bacteremia, cellulitis and enterocolitis. Recently, cases of involving various organs are increasingly reported such as endocarditis, meningitis, and kidney cyst infection. We report a case of intrauterine H. cinaedi infection leading preterm birth and neonatal sepsis. A 29-year-old pregnant women who was no underlying disease hospitalized due to threatened preterm labor at 22 weeks of gestation. Clinical findings showed uterine tenderness, fever, leukocytosis and elevated C-reactive protein. H. cinaedi was isolated from amniotic fluid obtained by transabdominal amniocentesis. We diagnosed as intrauterine H. cinaedi infection and administered intravenous ampicillin followed by oxytocin to terminate pregnancy. A live 446 g male infant was delivered. The patient was no signs of infection throughout postpartum course and discharged on post-delivery day 5. The neonate was admitted in neonatal intensive care unit and administered ampicillin and amikacin. H. cinaedi was isolated from umbilical cord blood culture. He has no signs of infection on day 5 but died from uncontrollable hyperglycemia and ketoacidosis on 15 days of age. H. cinaedi can cause intrauterine infection during pregnancy and lead preterm labor and neonatal sepsis.

The Other Helicobacters

In the past year, a substantial number of (putative) novel Helicobacter species have been described, including Helicobacter himalayensis colonizing the Himalayan marmot and Helicobacter apodemus, colonizing the Korean striped field mouse. In addition, a putative novel gastric Helicobacter species was identified in wild gorillas and chimpanzees, for which the name "Candidatus H. homininae" was proposed. A high incidence of gastric non-H. pylori Helicobacter infection was described in China and multiple case reports have described the involvement of enterohepatic Helicobacter species, especially Helicobacter cinaedi, in a wide range of diseases. Several studies in rodent models further elucidated the mechanisms underlying the development of gastric mucosa-associated lymphoid tissue lymphoma during infection with gastric non-H. pylori Helicobacters. The effects of infection with gastric Helicobacters on the development of neuroinflammation were investigated and several enterohepatic Helicobacter species were shown to affect the composition of the gut microbiota, to influence vaccine efficiency as well as the progression of cancer in distant sites of the body.

Vertebral Osteomyelitis Caused by Helicobacter cinaedi

Helicobacter cinaedi causes bacteremia, cellulitis, and gastroenteritis. We report the first case of vertebral osteomyelitis caused by H. cinaedi in an elderly man with low back pain and fever. The pathogen was detected in blood and lumbar disc, and the infection was successfully treated with oral doxycycline for 11 weeks.