A rural worker infected with a bovine-prevalent genotype of Campylobacter fetus subsp. fetus supports zoonotic transmission and inconsistency of MLST and whole-genome typing

Abstract

Whole-genome characterisation in clinical microbiology enables to detect trends in infection dynamics and disease transmission. Here, we report a case of bacteraemia due to Campylobacter fetus subsp. fetus in a rural worker under cancer treatment that was diagnosed with cellulitis; the patient was treated with antibiotics and recovered. The routine typing methods were not able to identify the microorganism causing the infection, so it was further analysed by molecular methods and whole-genome sequencing. The multi-locus sequence typing (MLST) revealed the presence of the bovine-associated ST-4 genotype. Whole-genome comparisons with other C. fetus strains revealed an inconsistent phylogenetic position based on the core genome, discordant with previous ST-4 strains. To the best of our knowledge, this is the first C. fetus subsp. fetus carrying the ST-4 isolated from humans and represents a probable case of zoonotic transmission from cattle.

Whole genome sequence analysis indicates recent diversification of mammal-associated Campylobacter fetus and implicates a genetic factor associated with H2S production

“…The division of clades was consistent with the serotypes of the strains; clades 1 and 2 consist of serotype B strains and clades 3, 4 and 5 consist of serotype A strains. The division of clades was also consistent with the classification of MLST sequence types (STs), except for Cff strain H1-UY, which has the Cfv-associated MLST ST-4 genotype [13]. Interestingly, SNP phylogeny showed the divergence of clade 4 and clade 5 from a common Cff ancestor.…”

“…Since available PCR methods and MLST typing schemes are not able to identify C. fetus strains correctly to subspecies level [13, 15], Cfv/Cfvi-specific SNPs could be used to develop new diagnostic methods, such as a SNP probe-PCR, or to improve the current MLST scheme. However, two drawbacks of a PCR based on Cfv/Cfvi-specific SNPs are that the stability of such SNPs is unknown and that the design of a reliable PCR based on specific SNPs requires a high degree of optimization [31, 32].…”

“…venerealis and only one non-clonal C. fetus strain was found (H1-UY). Cff strain H1-UY was isolated from the blood of a rural worker in 2013, who was diagnosed with cellulitis and was in daily contact with cattle [13]. …”

“…The molecular method multi-locus sequence typing (MLST) was recommended to differentiate Cff and Cfv strains [8]. However, a recent study showed that the current MLST scheme was not able to reliably differentiate the C. fetus subspecies, as a Cff strain was isolated with the Cfv-associated MLST ST-4 genotype [13]. …”

A novel real-time PCR assay for quantitative detection of Campylobacter fetus based on ribosomal sequences

“…Campylobacter fetus fetus infects the intestinal tract of several mammalian species and induces abortion in cattle and sheep [2, 5, 6]. In humans, it is an opportunistic pathogen that mainly infects immune-compromised patients [7, 8]. Campylobacter fetus venerealis is a cattle-restricted pathogen with tropism for genital tissues and is the etiological agent of bovine genital campylobacteriosis (BGC), a serious reproductive disease that causes infertility and abortion [9].…”