Molecular epidemiologic and clinical analysis of Helicobacter cinaedi bacteremia in Japan

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.

Helicobacter zhangjianzhongii sp. nov., isolated from dog feces

In 2019, two distinct bacterial isolates were independently isolated from the fecal samples of separate dogs in Beijing, China. These cells exhibit microaerobic, are Gram-negative, motile, and possess a characteristic spiral shape with bipolar single flagellum. They display positive results for the oxidase test while being negative for both catalase and urease. These organisms measure approximately 0.2-0.3 μm in width and 4.5-6 μm in length. The colonies are wet, flat, grey, circular, and smooth with sizes ranging from 1 to 2 mm in diameter after 2 days of growth. However, strains may exhibit variations in size and morphology following extended incubation. Phylogenetic analyses based on the 16S rRNA gene and core genome indicated that these two isolates belong to the genus Helicobacter and formed a robust clade that was remains distinctly separate from currently recognized species. These two isolates shared low dDDH relatedness and ANI values with their closest species Helicobacter canis CCUG 32756T, with these values falling below the commonly cutoff values for strains of the same species. The genomic DNA G + C contents of strain XJK30-2 were 44.93 mol%. Comparing the phenotypic and phylogenetic features between these two isolates and their closely related species, XJK30-2 represents a novel species within the genus Helicobacter, for which the name Helicobacter zhangjianzhongii sp. nov. (Type strain XJK30-2T = GDMCC 1.3695T) is proposed.

Helicobacter cinaedi Infections in Emergency Departments: A Descriptive Study

AIM

Helicobacter cinaedi, a Gram-negative spiral bacterium, is a rare cause of bacteremia in humans. Unfortunately, little is known about H. cinaedi infections in emergency departments (EDs). We aimed to describe the clinical features of H. cinaedi infections in the ED.

METHODS

We conducted a descriptive study at the ED of Kobe City General Hospital (KCGH) in Japan between November 2011 and December 2020. We included all ED patients with H. cinaedi infections. We retrospectively obtained the patient data from electronic medical records and described the patient characteristics, clinical course, and management of H. cinaedi infections.

RESULTS

A total of 22 patients in the ED were diagnosed with H. cinaedi infections, and all of them were detected through blood cultures. The chief complaints were vague: fever (18/22, 81.8%), chills (10/22, 45.5%), and localized pain or tenderness (8/22, 36.4%). Patients with complicated cases were also reported in the ED; three patients had vertebral osteomyelitis, two had infected aortic aneurysms, and another two had infected cysts (renal cyst and pancreatic cyst with concomitant empyema). Tetracycline (minocycline) was primarily prescribed and administered intravenously in five of 15 (33.3%) and orally in nine of 20 (45.0%) patients. Only one (4.5%) patient required surgical interventions. None of the patients died in the hospital.

CONCLUSIONS

We reported the clinical features of H. cinaedi infections in the ED. Although some patients developed complicated infections, the prognosis was not poor under appropriate treatment, and most of them were successfully treated with antibiotics, primarily tetracycline.

Helicobacter cinaedi is a human-adapted lineage in the Helicobacter cinaedi/canicola/'magdeburgensis' complex

Helicobacter cinaedi is an enterohepatic Helicobacter that causes bacteremia and other diseases in humans. While H. cinaedi-like strains are isolated from animals, including dog isolates belonging to a recently proposed H. canicola, little is known about the genetic differences between H. cinaedi and these animal isolates. Here, we sequenced 43 H. cinaedi- or H. canicola-like strains isolated from humans, hamsters, rats and dogs and collected 81 genome sequences of H. cinaedi, H. canicola and other enterohepatic Helicobacter strains from public databases. Genomic comparison of these strains identified four distinct clades (clades I–IV) in H. cinaedi/canicola/‘magderbugensis’ (HCCM) complex. Among these, clade I corresponds to H. cinaedi sensu stricto and represents a human-adapted lineage in the complex. We identified several genomic features unique to clade I. They include the accumulation of antimicrobial resistance-related mutations that reflects the human association of clade I and the larger genome size and the presence of a CRISPR-Cas system and multiple toxin-antitoxin and restriction-modification systems, both of which indicate the contribution of horizontal gene transfer to the evolution of clade I. In addition, nearly all clade I strains but only a few strains belonging to one minor clade contained a highly variable genomic region encoding a type VI secretion system (T6SS), which could play important roles in gut colonization by killing competitors or inhibiting their growth. We also developed a method to systematically search for H. cinaedi sequences in large metagenome data sets based on the results of genome comparison. Using this method, we successfully identified multiple HCCM complex-containing human faecal metagenome samples and obtained the sequence information covering almost the entire genome of each strain. Importantly, all were clade I strains, supporting our conclusion that H. cinaedi sensu stricto is a human-adapted lineage in the HCCM complex.

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.

Helicobacter cinaedi bacteraemia secondary to enterocolitis in an immunocompetent patient

Background

Helicobacter cinaedi are motile, gram-negative spiral rods with a natural reservoir in the intestinal tract of hamsters and rhesus monkeys. In humans, H. cinaedi has been reported in different human infections like fever, abdominal pain, gastroenteritis, proctitis, diarrhoea, erysipelas, cellulitis, arthritis, and neonatal meningitis typically diagnosed by positive blood cultures. Even though H. cinaedi has been detected from human blood and stool the entry of H. cinaedi into the blood stream was undocumented until quite recently. The use of pulse-field gel electrophoresis (PFGE) demonstrated that stool- and blood-derived H. cinaedi strains were consistent.

Case presentation

Here, we describe a rare Danish case of H. cinaedi bacteraemia in an immunocompetent 44-year-old male with diarrhoea. We isolated H. cinaedi from a blood culture taken at admission, and from a FecalSwab taken at day six despite ongoing antibiotic therapy. Next, we made a genetic comparison of both isolates by use of Multi-locus sequence typing (MLST)- and Single nucleotide polymorphism (SNP)-analysis. The two isolates were identical with zero SNPs and by use of MLST the isolate was identified as a novel ST20, confirming previous data of the intestinal tract as a route of H. cinaedi bacteraemia. The results of our AST showed a resistance pattern with higher MICs for ciprofloxacin and clarithromycin than for ampicillin, amoxicillin, gentamicin, and imipenem. The patient was cured with targeted therapy with pivampicillin; however, the primary source of transmission was unknown.

Conclusions

In conclusion, this case of H. cinaedi bacteraemia secondary to enterocolitis in an immunocompetent patient provide clear evidence that one route of infection occurs through translocation from the intestinal tract to the bloodstream. Helicobacter cinaedi from blood and faeces were identical with a novel ST20, resistant to ciprofloxacin and clarithromycin however, the patient was cured with oral pivampicillin.

Systemic Helicobacter infection and associated mortalities in endangered Grand Cayman blue iguanas (Cyclura lewisi) and introduced green iguanas (Iguana iguana)

The Blue Iguana Recovery Programme maintains a captive breeding and head-starting program for endangered Grand Cayman blue iguanas (Cyclura lewisi) on Grand Cayman, Cayman Islands. In May 2015, program staff encountered two lethargic wild Grand Cayman blue iguanas within the Queen Elizabeth II Botanic Park (QEIIBP). Spiral-shaped bacteria were identified on peripheral blood smears from both animals, which molecular diagnostics identified as a novel Helicobacter species (provisionary name Helicobacter sp. GCBI1). Between March 2015 and February 2017, 11 Grand Cayman blue iguanas were identified with the infection. Two of these were found dead and nine were treated; five of the nine treated animals survived the initial infection. Phylogenetic analysis of the 16S rRNA gene suggests Helicobacter sp. GCBI1 is most closely related to Helicobacter spp. in chelonians. We developed a Taqman qPCR assay specific for Helicobacter sp. GCBI1 to screen tissue and/or blood samples from clinical cases, fecal and cloacal samples from clinically healthy Grand Cayman blue iguanas, including previously infected and recovered iguanas, and iguanas housed adjacent to clinical cases. Fecal and/or cloacal swab samples were all negative, suggesting that Grand Cayman blue iguanas do not asymptomatically carry this organism nor shed this pathogen per cloaca post infection. Retrospective analysis of a 2014 mortality event affecting green iguanas (Iguana iguana) from a separate Grand Cayman location identified Helicobacter sp. GCBI1 in two of three cases. The source of infection and mode of transmission are yet to be confirmed. Analysis of rainfall data reveal that all infections occurred during a multi-year dry period, and most occurred shortly after the first rains at the end of seasonal drought. Additionally, further screening has identified Helicobacter sp. GCBI1 from choanal swabs of clinically normal green iguanas in the QEIIBP, suggesting they could be asymptomatic carriers and a potential source of the pathogen.

Review: Other Helicobacter species

This review covers the most important, accessible, and relevant literature published between April 2019 and April 2020 in the field of non-Helicobacter pylori Helicobacter species (NHPH). The initial part of the review covers new insights regarding the presence of gastric and enterohepatic NHPH in humans and animals, while the subsequent section focuses on the progress in our understanding of animal models, the pathogenicity and omics of these species. Over the last year, the clinical relevance of gastric NHPH infections in humans was highlighted. With regard to NHPH in animals, the ancestral source of Helicobacter suis was further established showing that Cynomolgus macaques are the common ancestor of the pig-associated H. suis population, and 3 novel Helicobacter species isolated from the gastric mucosa of red foxes were described. "Helicobacter burdigaliensis" sp nov. and "Helicobacter labetoulli" sp nov. were proposed as novel enterohepatic Helicobacter species associated with human digestive diseases. An analysis of Helicobacter cinaedi recurrent infections in humans proposed long-term antibiotic therapies. Several studies using rodent models further elucidated the mechanisms underlying the development of NHPH-related disease, as well as intestinal immunity in inflammatory bowel disease models. Omics approaches supported Helicobacteraceae taxonomy and unraveled the transcriptomic signatures of H. suis and Helicobacter heilmannii upon adherence to the human gastric epithelium. With regard to virulence, data showed that the nuclear remodeling promoted by cytolethal distending toxin of Helicobacters involves the MAFB oncoprotein and is associated with nucleoplasmic reticulum formation in surviving cells.