An uncommon Helicobacter isolate from blood: evidence of a group of Helicobacter spp. pathogenic in AIDS patients

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.

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.

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.

[Clinical and bacteriological examination in hospital of Helicobacter cinaedi (H. cinaedi)]

The spiral Gram-negative bacterium Helicobacter cinaedi (H. cinaedi) is usually isolated from immunocompromized patients, and the number of patients in whom H. cinaedi is isolated from their blood culture is increasing in Japan. To elucidate why the number of cases is increasing, we tried to analyze separate cases of H. cinaedi. H. cinaedi was isolated from the blood culture of 24 cases, and the isolate was from the pleural effusion of 1 cases between September 2009 and March 2010. In our cases, H. cinaedi was frequently isolated after anticancer chemotherapies (44 isolates) and steroid therapies (42 isolates). The patients' clinical symptoms were fever (43 isolates), gastrointestinal symptoms (4 isolates) and skin symptoms (8 isolates). In all cases, the H. cinaedi growth was found only in an aerobic bottle, and it needed a long time (2-7 days) to grow. In 14 cases out of 25 cases, H. cinaedi bacteremia was recurred. We analyzed recurrent cases statistically. The result showed there was a significant difference between the kinds of quinolones (p = 0.0018). H. cinaedi infections have a good prognosis, but the infection tends to recur after anticancer chemotherapies. A report has suggested that the minimal inhibitory concentrations of quinolones increased is case of recurrence, we should pay attention to the use of antibacterial agents. Furthermore, the effective method to eliminate or prevert infection [recurrence] remains unknown. Our results show that H. cinaedi infections may prolong the duration of hospitalization. If H. cinaedi is isolated in a patient, it is necessary to set the culture conditions for H. cinaedi. Furthermore, there is a need for appropiate antibiotic selection and medication for H. cinaedi.

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.

Development of a simple and rapid method based on polymerase chain reaction-based restriction fragment length polymorphism analysis to differentiate Helicobacter, Campylobacter, and Arcobacter species

Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis of amplified DNA fragment of the 16S and 23S rRNA genes was performed on 35 Helicobacter, 24 Campylobacter, and 15 Arcobacter strains. PCR amplification generated a 1004-bp fragment of 16S rDNA and a 2.6-Kbp fragment of 23S rDNA from each strain. The amplicons were digested with DdeI and HpaII, respectively. For both assays, distinctive profiles were obtained for each genus. 23S rDNA PCR-RFLP analysis with HpaII enzyme identified Campylobacter and Helicobacter strains at the species level. Analysis of 16S rRNA gene with DdeI enzyme was not useful for the specific identification of Campylobacter and Arcobacter, although it discriminated among Helicobacter species. The PCR-RFLP technique allowed for the discrimination among these three related genus with only one restriction enzyme; therefore it can be a simple, rapid, and useful method for routine identification.

Unique case of Helicobacter sp. osteomyelitis in an immunocompetent child diagnosed by broad-range 16S PCR

We report the first case of Helicobacter sp. osteomyelitis in an immunocompetent child. The infection was diagnosed by broad-range 16S PCR followed by sequencing of the resulting amplicon. All other microbiological investigations proved negative. This case highlights the importance of molecular methods in the diagnosis of unsuspected etiological agents and the potential role of Helicobacter sp. in human infection.

Captive rhesus monkeys (Macaca mulatta) are commonly infected with Helicobacter cinaedi

Helicobacter cinaedi may cause proctocolitis or bacteremia in homosexual men infected with human immunodeficiency virus or occasionally in other immunocompromised hosts. There are scattered reports of H. cinaedi isolated from a variety of animal hosts, but to date only hamsters have been found to be a common natural reservoir. Microaerophillic cultures of feces from 5 of 16 asymptomatic rhesus monkeys (Macaca mulatta) (31%) were positive for a curved gram-negative rod. A polyphasic taxonomic approach was used to identify the organism as H. cinaedi. These results show that H. cinaedi frequently colonizes asymptomatic captive rhesus monkeys, which may serve as another potential reservoir for human infection.

Bacteremia caused by a Helicobacter pullorum-like organism

We report a case of bacteremia caused by a Helicobacter pullorum-like organism in a 35-year-old man with pyrexia of unknown origin. Culture of blood samples obtained at admission yielded a motile, spiral-shaped gram-negative rod, and 16S rRNA gene sequencing identified this organism as Helicobacter pullorum-like, showing 23 base differences compared with the recently described "Helicobacter canadensis" (a recently proposed group that had previously been classified within H. pullorum). We believe that this is the first report of bacteremia caused by this organism.

"Helicobacter rappini" isolates from 2 homosexual men

We report 2 cases of bacteremia due to "Helicobacter rappini" in 2 young, homosexual men, including the first report of H. rappini in a human immunodeficiency virus-positive patient. Blood cultures showed a spiral, fusiform, gram-negative bacterium with bipolar sheathed flagella.

Emergence of diverse Helicobacter species in the pathogenesis of gastric and enterohepatic diseases

Since Helicobacter pylori was first cultivated from human gastric biopsy specimens in 1982, it has become apparent that many related species can often be found colonizing the mucosal surfaces of humans and other animals. These other Helicobacter species can be broadly grouped according to whether they colonize the gastric or enterohepatic niche. Gastric Helicobacter species are widely distributed in mammalian hosts and are often nearly universally prevalent. In many cases they cause an inflammatory response resembling that seen with H. pylori in humans. Although usually not pathogenic in their natural host, these organisms serve as models of human disease. Enterohepatic Helicobacter species are an equally diverse group of organisms that have been identified in the intestinal tract and the liver of humans, other mammals, and birds. In many cases they have been linked with inflammation or malignant transformation in immunocompetent hosts and with more severe clinical disease in immunocompromised humans and animals. The purpose of this review is to describe these other Helicobacter species, characterize their role in the pathogenesis of gastrointestinal and enterohepatic disease, and discuss their implications for our understanding of H. pylori infection in humans.

A probable new Helicobacter species isolated from a patient with bacteremia

A probable new Helicobacter species was isolated from the blood of a 14-month-old aboriginal child who presented with vomiting, diarrhea, fever, and dry cough. The most similar 16S rRNA gene sequence was that of Helicobacter fennelliae CCUG 18820(T) but the new sequence differed from it by at least 32 base substitutions and by the presence of a large (353-nucleotide) intervening sequence.

Identification of a unique Helicobacter species by 16S rRNA gene analysis in an abdominal abscess from a patient with X-linked hypogammaglobulinemia

A unique Helicobacter species, MZ640285, was isolated from a patient with X-linked hypogammaglobulinemia suffering from recurrent abdominal abscesses and was identified by 16S rRNA gene sequence analysis. In the phylogenetic tree, the isolate fell into a cluster which included Flexispira rappini, Helicobacter bilis, and Helicobacter sp. strain Mainz. Helicobacters are being increasingly recognized as pathogens in immunocompromised hosts. These fastidious bacteria are not easily cultured in the routine diagnostic laboratory, and this is the first report of their identification by 16S rRNA gene sequencing performed directly from a clinical specimen.

Misidentifying helicobacters: the Helicobacter cinaedi example

Whole-cell protein electrophoresis and biochemical examination by means of a panel of 64 tests were used to identify 14 putative helicobacters to the species level. The results were confirmed by means of DNA-DNA hybridization experiments and were used to discuss misidentification of helicobacters based on 16S rRNA gene sequence data. The data indicated that comparison of near-complete 16S ribosomal DNA sequences does not always provide conclusive evidence for species level identification and may prove highly misleading. The data also indicated that "Helicobacter westmeadii" is a junior synonym of Helicobacter cinaedi and that Helicobacter sp. strain Mainz belongs to the same species. H. cinaedi occurs in various animal reservoirs, including hamsters, dogs, cats, rats, and foxes. Appropriate growth conditions and identification strategies will be required to establish the genuine significance of this widely distributed Helicobacter species.