Investigation of virulence and cytolethal distending toxin genes in Campylobacter spp. isolated from sheep in Turkey

Campylobacter devanensis sp. nov., Campylobacter porcelli sp. nov., and Campylobacter vicugnae sp. nov., three novel Campylobacter lanienae-like species recovered from swine, small ruminants, and camelids

In a previous study characterizing Campylobacter strains deficient in selenium metabolism, 50 strains were found to be similar to, but distinct from, the selenonegative species Campylobacter lanienae. Initial characterization based on multilocus sequence typing and the phylogeny of a set of 20 core genes determined that these strains form three putative taxa within the selenonegative cluster. A polyphasic study was undertaken here to further clarify their taxonomic position within the genus. The 50 selenonegative strains underwent phylogenetic analyses based on the sequences of the 16S rRNA gene and an expanded set of 330 core genes. Standard phenotypic testing was also performed. All strains were microaerobic and anaerobic, Gram-negative, spiral or curved cells with some displaying coccoid morphologies. Strains were motile, oxidase, catalase, and alkaline phosphatase positive, urease negative, and reduced nitrate. Strains within each clade had unique phenotypic profiles that distinguished them from other members of the genus. Core genome phylogeny clearly placed the 50 strains into three clades. Pairwise average nucleotide identity and digital DNA-DNA hybridization values were all below the recommended cut-offs for species delineation with respect to C. lanienae and other related Campylobacter species. The data presented here clearly show that these strains represent three novel species within the genus, for which the names Campylobacter devanensis sp. nov. (type strain RM3662T=LMG 33097T=NCTC 15074T), Campylobacter porcelli sp. nov. (type strain RM6137T=LMG 33098T=CCUG 77054T=NCTC 15075T) and Campylobacter vicugnae sp. nov. (type strain RM12175T=LMG 33099T=CCUG 77055T=NCTC 15076T) are proposed.

Bacterial gastroenteritis caused by the putative zoonotic pathogen Campylobacter lanienae: First reported case in Germany

Foodborne campylobacteriosis is the most common cause of human bacterial enteritis in Germany. Campylobacter jejuni and Campylobacter coli are the main causative agents for enteric disease, but a number of other species are involved, including rare ones. These rare Campylobacter spp. are emerging zoonotic pathogens in humans due to increasing international movement of supplies, livestock and people. Campylobacter lanienae was first isolated from healthy abattoir workers in Switzerland and at first its pathogenic potential for humans was considered to be low. Recently, the first case of Campylobacter lanienae-associated human enteritis was reported in Canada. Here, we describe a case of mild Campylobacter lanienae-associated enteritis with subsequent asymptomatic excretion in a butcher. The isolate is available at the TLV strain collection (no. TP00333/18). This first reported case of human Campylobacter lanienae campylobacteriosis in Germany demonstrates the agent’s likely zoonotic pathogenicity.

No Clear Differences between Organic or Conventional Pig Farms in the Genetic Diversity or Virulence of Campylobacter coli Isolates

To evaluate the impact of pig farm management on the genetic diversity and on the virulence of Campylobacter coli, we characterized isolates from 19 organic pig farms (62 isolates) and from 24 conventional pig farms (58 isolates). The 120 C. coli isolates were typed using pulsed field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) and the presence of nine virulence genes was screened using real-time PCR. The capacity of adhesion and invasion of 61 isolates (32 from organic and 29 from conventional farms) were then tested on human intestinal Caco-2 cells. A total of 59 PFGE types and of 50 sequence types (STs) were identified. Twelve PFGE types and nine STs, accounting for 34 and 41.6% of the isolates, respectively, were common between the two production systems with ST854 dominating (18.3% of the isolates). Twenty-nine PFGE types and 25 STs were only found in isolates from organic farms, and 18 PFGE types and 16 STs from conventional farms. No significant differences were found in diversity despite the differences in rearing systems, except at the locus level for the glnA, gltA, and uncA genes. All isolates, regardless of their origin, carried the ceuE, iam, ciaB, and flaA genes and more than 95% of the isolates carried the cadF and cdtABC genes. No significant differences were found in pathogenicity between the two farming systems. The pathogenicity of the C. coli isolates was low compared to C. jejuni control strains tested. The plasmid gene virb11 was detected in only 13 isolates from organic farms; these isolates showed greater invasion capacity than those without this gene. Our study indicates that pig farm management does not significantly affect the diversity and the virulence of Campylobacter coli isolated from pigs. The common genotypes between conventional and organic farms may indicate that some genotypes are adapted to pigs.

The Cytolethal Distending Toxin Contributes to Microbial Virulence and Disease Pathogenesis by Acting As a Tri-Perditious Toxin

This review summarizes the current status and recent advances in our understanding of the role that the cytolethal distending toxin (Cdt) plays as a virulence factor in promoting disease by toxin-producing pathogens. A major focus of this review is on the relationship between structure and function of the individual subunits that comprise the AB₂ Cdt holotoxin. In particular, we concentrate on the molecular mechanisms that characterize this toxin and which account for the ability of Cdt to intoxicate multiple cell types by utilizing a ubiquitous binding partner on the cell membrane. Furthermore, we propose a paradigm shift for the molecular mode of action by which the active Cdt subunit, CdtB, is able to block a key signaling cascade and thereby lead to outcomes based upon programming and the role of the phosphatidylinositol 3-kinase (PI-3K) in a variety of cells. Based upon the collective Cdt literature, we now propose that Cdt is a unique and potent virulence factor capable of acting as a tri-perditious toxin that impairs host defenses by: (1) disrupting epithelial barriers; (2) suppressing acquired immunity; (3) promoting pro-inflammatory responses. Thus, Cdt plays a key role in facilitating the early stages of infection and the later stages of disease progression by contributing to persistence and impairing host elimination.

First reported case of Campylobacter lanienae enteritis in a human

Introduction:

Campylobacters are the most frequently identified bacteria causing diarrhoea in humans worldwide. Campylobacter lanienae was isolated for the first time in 2000 from faecal samples of two asymptomatic abattoir workers in Switzerland during a routine hygiene screen, but has never been associated with human disease.

Case presentation:

At hospital admission, the patient reported diarrhoea, lower abdominal cramps, nausea, one episode of bilious vomiting and low-grade fever of 38 °C. The patient was having 10 or more diarrheic stools per day as well as during the night, and had noticed blood mixed with the stools on several occasions. Stool cultures were negative for species of Salmonella and Shigella, Escherichia coli O157:H7 and Yersinia enterocolitica, but were positive for C. lanienae. Identification was made by classical biochemical testing, as well as 16S rRNA gene and cpn60 sequencing. The patient slowly improved without antibiotic treatment and was discharged nine days after admission with complete resolution of symptoms.

Conclusion:

On the whole it seems very likely that C. lanienae was the causative agent. Clinical microbiologists should be aware of this micro-organism which can be identified by phenotypic and molecular methods. The real burden of C. lanienae infection in humans might be underestimated and should be further investigated as a potential cause of human diarrhoea disease.

Caracterização de estirpes de Campylobacter coli isoladas de carcaças de ovinos e de efluentes de abatedouro do estado de São Paulo

Doença bacteriana zoonótica, a campilobacteriose é responsável mundialmente por frequentes casos de gastroenterite humana. Campylobacter spp. apresenta fator de virulência associado à diarreia, denominado toxina citoletal distensiva (CDT), sendo codificado pelos genes do complexo cdt. Os objetivos do presente estudo foram: 1) isolar e identificar estirpes de Campylobacter spp. de 102 suabes de carcaças e 102 suabes retais de ovinos (Ovis aries) e de sete amostras de água dos efluentes, antes e depois do tratamento de desinfecção de abatedouro localizado no estado de São Paulo; e 2) detectar, pela técnica de multiplex-PCR, a presença do complexo de genes cdt. Foram isoladas e identificadas, por métodos fenotípicos e genotípicos, sete estirpes de Campylobacter coli provenientes de 4/102 (3,92%) das amostras de suabes retais, 1/102 (0,98%) de suabes de carcaças e 2/7 (28,5%) das águas dos efluentes. Dos isolados de suabes retais, em 2/7 (28,6%) estirpes foi detectada a presença dos genes cdt. Trata-se do primeiro relato de isolamento de estirpes de Campylobacter coli provenientes de abatedouro de ovinos e das estirpes portadoras do complexo de genes cdt nessa espécie animal no Brasil.