Clinical and epidemiological analysis of Campylobacter fetus subsp. fetus infections in humans and comparative genetic analysis with strains isolated from cattle

Campylobacter species and genotype distribution in Finnish beef liver - Retail liver juice ideal for isolation and quantification

Campylobacteriosis, primarily caused by Campylobacter jejuni and C. coli, is the main bacterial zoonosis worldwide. While poultry is recognized as the main reservoir, bovines are considered another important reservoir for Campylobacter spp. found in human infections. In contrast to chicken, retail beef is seldom contaminated by Campylobacter species. However, beef liver is recognized to be frequently contaminated and has been linked to human infections via epidemiological investigations. Our aims were to evaluate the prevalence of Campylobacter spp. inside and on the surface of beef liver pieces at retail in Finland and to analyse the population in more detail using whole genome sequencing (WGS) to assess the public health relevance. A total of 90 retail beef livers were studied using both enrichment of the external peptone-saline rinse of the liver piece and direct culture from the inside after surface sterilization. Furthermore, 46 of the livers were also studied using direct culture of retail beef liver juice collected from the bottom of the consumer package to estimate the concentration of Campylobacter species. Overall, 44 (49 %) of the samples were positive for Campylobacter species, C. jejuni, C. fetus and C. lari being identified in 42 %, 8.9 % and 1.1 % of the samples, respectively. Direct culture of retail liver juice was a sensitive and convenient method for Campylobacter spp. detection, resulting in 48 % prevalence and a mean concentration of 49 cfu/ml (maximum 335 cfu/ml). Two samples (2.2 %), containing large hepatic ducts, were positive for C. jejuni internally, representing multilocus sequence typing (MLST) sequence type ST-19 and ST-21. WGS, core genome phylogeny and core genome MLST revealed that in most cases only one clearly distinct clone of clinically relevant C. jejuni or C. fetus was isolated from a single lot of samples. However, in some cases several distinct clones were identified simultaneously even from a single liver piece. In epidemiological investigations, it is thus highly advisable to genotype multiple isolates to capture the whole diversity of Campylobacter spp. from suspected food sources. Good kitchen hygiene, avoidance of cross-contamination and thorough cooking are important for limiting the transmission of campylobacteriosis.

Oncogenic potential of Campylobacter infection in the gastrointestinal tract: narrative review

BACKGROUND

Campylobacter jejuni is the leading cause of zoonotic gastroenteritis. The other emerging group of Campylobacters spp. are part of human oral commensal, represented by C. concisus (CC), which has been recently linked to non-oral conditions. Although long-term gastrointestinal (GI) complications from these two groups of Campylobacters have been previously reviewed individually, overall impact of Campylobacter infection on GI carcinogenesis and their inflammatory precursor lesions has not been assessed collectively.

AIMS

To evaluate the available evidence concerning the association between Campylobacter infection/colonization and inflammatory bowel disease (IBD), reflux esophagitis/metaplasia colorectal cancer (CRC) and esophageal cancer (EC).

METHODS

We performed a comprehensive literature search of PubMed for relevant original publications and systematic reviews/meta-analyses of epidemiological and clinical studies. In addition, we gathered additional information concerning microbiological data, animal models and mechanistic data from in vitro studies.

RESULTS

Both retrospective and prospective studies on IBD showed relatively consistent increased risk associated with Campylobacter infection. Despite lack of supporting prospective studies, retrospective studies based on tissue/fecal microbiome revealed consistent enrichment of Campylobacter in CRC samples. Studies on EC precursor lesions (esophagitis and metaplasia) were generally supportive for the association with Campylobacter, while inconsistent observations on EC. Studies on both IBD and EC precursors suggested the predominant role of CC, but studies on CRC were not informative of species.

CONCLUSIONS

There is sufficient evidence calling for concerted effort in unveiling direct and indirect connection of this organism to colorectal and esophageal cancer in humans.

Antimicrobial resistance in Campylobacter fetus: emergence and genomic evolution

Campylobacter fetus is a pathogen, which is primarily associated with fertility problems in sheep and cattle. In humans, it can cause severe infections that require antimicrobial treatment. However, knowledge on the development of antimicrobial resistance in C. fetus is limited. Moreover, the lack of epidemiological cut-off values (ECOFFs) and clinical breakpoints for C. fetus hinders consistent reporting about wild-type and non-wild-type susceptibility. The aim of this study was to determine the phenotypic susceptibility pattern of C. fetus and to determine the C. fetus resistome [the collection of all antimicrobial resistance genes (ARGs) and their precursors] to describe the genomic basis of antimicrobial resistance in C. fetus isolates over time. Whole-genome sequences of 295 C. fetus isolates, including isolates that were isolated in the period 1939 till the mid 1940s, before the usage of non-synthetic antimicrobials, were analysed for the presence of resistance markers, and phenotypic antimicrobial susceptibility was obtained for a selection of 47 isolates. C. fetus subspecies fetus (Cff) isolates showed multiple phenotypic antimicrobial resistances compared to C. fetus subspecies venerealis (Cfv) isolates that were only intrinsic resistant to nalidixic acid and trimethoprim. Cff isolates showed elevated minimal inhibitory concentrations for cefotaxime and cefquinome that were observed in isolates from 1943 onwards, and Cff isolates contained gyrA substitutions, which conferred resistance to ciprofloxacin. Resistances to aminoglycosides, tetracycline and phenicols were linked to acquired ARGs on mobile genetic elements. A plasmid-derived tet(O) gene in a bovine Cff isolate in 1999 was the first mobile genetic element observed, followed by detection of mobile elements containing tet(O)-aph(3')-III and tet(44)-ant(6)-Ib genes, and a plasmid from a single human isolate in 2003, carrying aph(3')-III-ant(6)-Ib and a chloramphenicol resistance gene (cat). The presence of ARGs in multiple mobile elements distributed among different Cff lineages highlights the risk for spread and further emergence of AMR in C. fetus. Surveillance for these resistances requires the establishment of ECOFFs for C. fetus.

Campylobacter fetus Cellulitis

Campylobacter fetus, a bacteria of the Campylobacter genus that are a group of bacteria known to cause intestinal infections, is a particular microbial agent due to its most common presentation being as a non-intestinal systemic infection and rarely as a focal infection, most frequently cellulitis. C. fetus's main reservoirs are cattle and sheep. Humans are usually infected by consuming raw milk and/or meat. Infection in humans is rare and generally related to immune deficiencies, malignancy, chronic liver disease, diabetes mellitus and elderly age, among other factors. Diagnosis is usually achieved by blood cultures due to the lack of focalized signs/symptoms and the pathogen's endovascular tropism. The authors present a case of cellulitis due to Campylobacter fetus, a microbial agent that affects susceptible patients with a mortality rate of up to 14%. We aim to emphasize the importance of potential bacterial seeding sites secondary to bacteremia given the agent tropism for vascular tissue. The medical diagnosis was performed by the identification of bacteria in blood cultures. Campylobacter spp. infections are more frequently related to undercooked poultry or meat, but in this case, the consumption of fresh cheese was considered the most likely source of infection. A literature review showed that, in patients with previous antibiotic cycles, a combination of carbapenem and gentamicin had better outcomes and lower relapse rates. Due to typical surface antigenic variation, immune control may not be attainable and may account for relapsing infections, even after appropriate therapy. The duration of treatment has yet to be well established. Based on other reported cases, we considered a four-week treatment to be sufficient, given clinical improvement and absence of recurrence in the follow-up time.

Placentitis and abortion caused by a multidrug resistant strain of Campylobacter fetus subspecies fetus in a sheep in Uruguay

Campylobacter fetusfetus (Cff) is a major infectious cause of abortion in sheep worldwide, and an opportunistic human pathogen. Information on Cff as an ovine abortifacient in South America is limited. We describe a case of abortion caused by a multidrug resistant strain of Cff in a sheep in Uruguay. In August 2017, 3/57 pregnant ewes (5.3%) aborted whithin one week. Histopathologic examination of the placenta of an aborted ewe revealed severe neutrophilic and fibrinonecrotizing placentitis with vasculitis and thrombosis of the chorionic arterioles. Cff was isolated on microaerobic culture in Skirrow agar, and further confirmed by 16S rDNA PCR amplification and sequencing, and endpoint and real time PCR assays. Antimicrobial sensitivity testing revealed resistance to tetracyclines, nalidixic acid, telithromycin and clindamycin. Other abortifacients were not detected. Further studies are necessary to determine the geographic distribution, ecology, epidemiology, economic impact, and antimicrobial resistance of Cff in sheep flocks in Uruguay.

Phenotypic and genetic analyses of two Campylobacter fetus isolates from a patient with relapsed prosthetic valve endocarditis

Campylobacter fetus can cause intestinal and systemic disease in humans and are well established veterinary and economic pathogens. We report the complete genomic sequences of two C. fetus subsp. fetus (Cff) isolates recovered in 2017 (CITCf01) and 2018 (CITCf02) from a case of recurrent prosthetic valve endocarditis. Both were capable of growth aerobically. Their genomes were found to be highly conserved and syntenic with 99.97% average nucleotide identity (ANI) while differences in their respective sap loci defined the temporal separation of their genomes. Based on core genome phylogeny and ANI of 83 Cff genomes belonging to the previously described human-associated Cff lineage, CITCf01 and CITCf02 grouped in a clade of eleven sequence type (ST)3 Cff (including the Cff type strain NCTC 10842T). CITCf01 and CITCf02 were marked for their lack of unique genomic features when compared to isolates within the subspecies and the type strain in particular. We identified point mutations in oxidative stress response genes, among others, that may contribute to aerobiosis. We report a case of Cff causing relapsed prosthetic valve endocarditis and we highlight the sap island as a polymorphic site within the genetically stable ST3 lineage, central to pathogenicity.

Campylobacter fetus releases S-layered and immunoreactive outer membrane vesicles

The study of outer membrane vesicles (OMVs) became relevant because of their probable important role in the transfer of virulence factors to host cells. Campylobacter fetus is mainly a mammal pathogen whose virulence characterization is still limited. The aim of this study was to evaluate and to characterize the secretion of OMVs in this bacterium. By transmission electron microscopy, we confirmed the production of OMVs in all the strains assayed. Purified OMVs showed a spherical shape and variable size, although comparable to those of other gram-negative bacteria. We also confirmed the presence of the S-layer on the surface of the OMVs of all the strains assayed with the exception of those derived from the NTCC reference strain. In addition, we demonstrated their immunoreactivity by the dot-blot assay. Hence, C. fetus OMVs could contribute to the modulation of the host response and constitute a candidate to be evaluated as an adjuvant of current vaccines used in the veterinary field. This work represents a platform to drive future studies towards the role of these subcellular structures in C. fetus-host interaction.

Phylogenomic analysis for Campylobacter fetus ocurring in Argentina

Background and Aim:

Campylobacter fetus is one of the most important pathogens that severely affects livestock industry worldwide. C. fetus mediated bovine genital campylobacteriosis infection in cattle has been associated with significant economic losses in livestock production in the Pampas region, the most productive area of Argentina. The present study aimed to establish the genomic relationships between C. fetus strains, isolated from the Pampas region, at local and global levels. The study also explored the utility of multi-locus sequence typing (MLST) as a typing technique for C. fetus.

Materials and Methods:

For pangenome and phylogenetic analysis, whole genome sequences for 34 C. fetus strains, isolated from cattle in Argentina were downloaded from GenBank. A local maximum likelihood (ML) tree was constructed and linked to a Microreact project. In silico analysis based on MLST was used to obtain information regarding sequence type (ST) for each strain. For global phylogenetic analysis, a core genome ML-tree was constructed using genomic dataset for 265 C. fetus strains, isolated from various sources obtained from 20 countries.

Results:

The local core genome phylogenetic tree analysis described the presence of two major clusters (A and B) and one minor cluster (C). The occurrence of 82% of the strains in these three clusters suggested a clonal population structure for C. fetus. The MLST analysis for the local strains revealed that 31 strains were ST4 type and one strain was ST5 type. In addition, a new variant was identified that was assigned a novel ST, ST70. In the present case, ST4 was homogenously distributed across all the regions and clusters. The global analysis showed that most of the local strains clustered in the phylogenetic groups that comprised exclusively of the strains isolated from Argentina. Interestingly, three strains showed a close genetic relationship with bovine strains obtained from Uruguay and Brazil. The ST5 strain grouped in a distant cluster, with strains obtained from different sources from various geographic locations worldwide. Two local strains clustered in a phylogenetic group comprising intercontinental Campylobacter fetus venerealis strains.

Conclusion:

The results of the study suggested active movement of animals, probably due to economic trade between different regions of the country as well as with neighboring countries. MLST results were partially concordant with phylogenetic analysis. Thus, this method did not qualify as a reliable subtyping method to assess C. fetus diversity in Argentina. The present study provided a basic platform to conduct future research on C. fetus, both at local and international levels.

Genomic and Phenotypic Characterization of Campylobacter fetus subsp. venerealis Strains

The pathogenesis mechanisms of Campylobacter fetus subsp. venerealis (Cfv), the etiologic agent of Bovine Genital Campylobacteriosis remain elusive. This study evaluated the virulence potential and biovar characteristics of Cfv isolates (n = 13) by PCR screening of putative virulence-factor (VF) genes, Multilocus Sequence Typing (MLST) analysis, antimicrobial susceptibility to tetracycline, penicillin, enrofloxacin and streptomycin testing and whole-genome sequencing (WGS; n = 5), also comparing the latter with 26 other whole-genome sequences of Cfv strains. The putative VF genes encoding type IV secretion system of Cfv (virB2-virB11/virD4) were absent in 92% of isolates, including isolates from aborted foetuses, evidencing that these VF genes are not essential for Cfv pathogenicity. The parA gene, used as a Cfv diagnostic molecular target, was detected in only 3 of 13 isolates, invalidating its use for diagnosis purposes. Three novel sequence types were identified by MLST. Although no in vitro antimicrobial resistance was detected, WGS identified antimicrobial resistance-related genes, including those encoding the multidrug efflux pumps CmeABC and YkkCD, indicating that their presence is not enough to provide antimicrobial resistance. The SNP and accessory protein families analysis segregated the Cfv and Cfv biovar intermedius (Cfvi) strains into different clusters. In conclusion, this study evidenced virulence potential and biovar characteristics of Cfv and Cfvi, which are of relevance for the control of Bovine Genital Campylobacteriosis.

Isolation of Campylobacter fetus subspecies fetus from an abdominal abscess in an adult mare

A 12-year-old Warmblood mare was referred for evaluation of behavioral changes not explained by general physical examination or lameness evaluation. Transrectal ultrasound examination was performed to determine if the behavioral changes were related to ovarian abnormalities, and a large abscess was found near the base of the cecum. Laparoscopic-guided aspiration and lavage of the abscess cavity followed by injection of benzyl penicillin G was carried out. Culture of the lavage sample yielded Campylobacter fetus subspecies fetus, an organism not previously reported as an etiological agent in abdominal abscesses in horses. The mare was treated after surgery with an extended course of antibiotics (minocycline per os q12h for 10 days followed by enrofloxacin per os q24h for 42 days). The mare resumed work in competitive eventing 10 months after surgery, and the behavioral complaints had resolved according to the owner. Key clinical message: We describe the diagnosis and treatment of a mare with an abdominal abscess from which Campylobacter fetus subspecies fetus was cultured. This organism has not previously been reported as an etiological agent in abdominal abscesses in horses.

Determinants of sporadic Campylobacter infections in Denmark: a nationwide case-control study among children and young adults

BACKGROUND

Each year more than 4,000 cases of campylobacteriosis are reported in Denmark, making it the most common bacterial gastrointestinal infection. Here we describe a case-control study to identify sources of infection with a focus on environmental factors.

METHODS

From January to December 2016, we conducted a prospective case-control study among Danish persons aged 1-30 years. Participants were invited by letter to complete an online questionnaire. Crude and adjusted ORs were calculated and final parsimonious multivariate models developed using logistic regression.

RESULTS

The study recruited 1366 cases and 4,418 controls, of whom 65% and 66%, respectively, completed the questionnaire. A multivariate model for domestically acquired cases showed, among others, increased risk of infection with bathing in fresh water (OR=5.1), contact to beach sand (OR=1.8), owning a pet dog with diarrhea (OR=4.6), and eating minced beef (OR=2.6) or chicken (OR=2.5). The model for children highlighted similar risk factors but also included bathing in a paddling pool (OR=13.6) and eating fresh strawberries (OR=5.3). A separate analysis for persons reporting foreign travel showed increased infection risk when traveling to Asia, Africa, or Turkey and that eating from street kitchens and having contact to water during traveling were also risk factors.

CONCLUSION

Environmental factors and animal contact account for a sizeable proportion of domestic Campylobacter infections in the age group studied. The study also re-confirmed handling/consumption of chicken as an important risk factor while highlighting minced beef as a potential new risk factor. Overall, these results contribute to a better understanding of the transmission dynamics of Campylobacter and will be used to improve national guidelines for prevention of infection.

Inquiring into the Gaps of Campylobacter Surveillance Methods

Campylobacter is one of the most common pathogen-related causes of diarrheal illnesses globally and has been recognized as a significant factor of human disease for more than three decades. Molecular typing techniques and their combinations have allowed for species identification among members of the Campylobacter genus with good resolution, but the same tools usually fail to proceed to subtyping of closely related species due to high sequence similarity. This problem is exacerbated by the demanding conditions for isolation and detection from the human, animal or water samples as well as due to the difficulties during laboratory maintenance and long-term storage of the isolates. In an effort to define the ideal typing tool, we underline the strengths and limitations of the typing methodologies currently used to map the broad epidemiologic profile of campylobacteriosis in public health and outbreak investigations. The application of both the old and the new molecular typing tools is discussed and an indirect comparison is presented among the preferred techniques used in current research methodology.

Assessing the intra-species genetic variability in the clonal pathogen Campylobacter fetus: CRISPRs are highly polymorphic DNA markers

Campylobacter fetus is a Gram-negative, microaerophilic bacterium that infects animals and humans. The subspecies Campylobacter fetus subsp. fetus (Cff) affects a broad range of vertebrate hosts and induces abortion in cows and sheep. Campylobacter fetus subsp. venerealis (Cfv) is restricted to cattle and causes the endemic disease bovine genital campylobacteriosis, which triggers reproductive problems and is responsible for major economic losses. Campylobacter fetus subsp. testudinum (Cft) has been isolated mostly from apparently healthy reptiles belonging to different species but also from ill snakes and humans. Genotypic differentiation of Cff and Cfv is difficult, and epidemiological information is scarce because there are few methods to study the genetic diversity of the strains. We analyze the efficacy of MLST, ribosomal sequences (23S gene and internal spacer region), and CRISPRs to assess the genetic variability of C. fetus in bovine and human isolates. Sequences retrieved from complete genomes were included in the analysis for comparative purposes. MLST and ribosomal sequences had scarce or null variability, while the CRISPR-cas system structure and the sequence of CRISPR1 locus showed remarkable diversity. None of the sequences here analyzed provided evidence of a genetic differentiation of Cff and Cfv in bovine isolates. Comparison of bovine and human isolates with Cft strains showed a striking divergence. Inter-host differences raise the possibility of determining the original host of human infections using CRISPR sequences. CRISPRs are the most variable sequences analyzed in C. fetus so far, and constitute excellent representatives of a dynamic fraction of the genome. CRISPR typing is a promising tool to characterize isolates and to track the source and transmission route of C. fetus infections.