Molecular Evidence for Zoonotic Transmission of an Emergent, Highly Pathogenic Campylobacter jejuni Clone in the United States

Abstract

Campylobacter jejuni is a major zoonotic pathogen. A highly virulent, tetracycline-resistant C. jejuni clone (clone SA) has recently emerged in ruminant reservoirs and has become the predominant cause of sheep abortion in the United States. To determine whether clone SA is associated with human disease, we compared the clinical isolates of clone SA from sheep abortions with the human isolates of the PulseNet National Campylobacter databases at the CDC and the FDA using pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and serotyping. The combined SmaI and KpnI PFGE pattern designations of clone SA from sheep were indistinguishable from those of 123 (9.03%) human C. jejuni isolates (total, 1,361) in the CDC database, among which 56 were associated with sporadic infections and 67 were associated with outbreaks that occurred in multiple states from 2003 to 2010. Most of the outbreaks were attributed to raw milk, while the sources for most of the sporadic cases were unknown. All clone SA isolates examined, including PFGE-matched human isolates, belong to sequence type 8 (ST-8) by MLST and serotype HS:1,8, further indicating the clonality of the related isolates from different host species. Additionally, C. jejuni clone SA was identified in raw milk, cattle feces, the feces and bile of healthy sheep, and abortion cases of cattle and goats, indicating the broad distribution of this pathogenic clone in ruminants. These results provide strong molecular and epidemiological evidence for zoonotic transmission of this emergent clone from ruminants to humans and indicate that C. jejuni clone SA is an important threat to public health.

Point mutations in the major outer membrane protein drive hypervirulence of a rapidly expanding clone of Campylobacter jejuni

“…1B). This finding is comparable with the time detected for the species shift from Campylobacter fetus to C. jejuni in the etiology of sheep abortion (15,16), which could be due to the deployment of C. fetus vaccines. Additionally, we performed animal infection experiments using clone SA and nonclone SA isolates, which showed IA3902 and D7324 (clone SA isolates) were highly abortifacient, whereas NCTC11168 and VDL2401 (nonclone SA isolates) did not induce any abortion in the inoculated guinea pigs (Fig.…”

“…S1). A whole genome phylogeny definitively confirmed the previous MLST data (15,16) that clone SA has undergone a recent, monophyletic clonal expansion into different hosts (cattle, goat, chicken, and human). This finding was supported by the tree topology (Fig.…”

“…Work presented in this study represents documentation of the key role of MOMP in systemic infection and abortion induction by C. jejuni. This finding is significant as it provides a potential target for controlling the spread of C. jejuni clone SA, which is a zoonotic pathogen causing abortion in ruminants and foodborne illnesses in humans (15,16). Additionally, we developed a directed genome evolution strategy for effective screening of causative mutations, which may be applied to understand the virulence mechanisms of other pathogenic organisms that are amenable to the same strategy.…”

“…The clonality of SA strains was established by multiple molecular typing methods, including pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) (ST-8) (15). Notably, C. jejuni clone SA is zoonotic and has been implicated in a number of outbreaks and sporadic cases of foodborne illnesses in humans (16). Clone SA infection is characterized by its extraordinary ability to translocate across the intestine, induce systemic infection, invade the uteroplacental unit with high titer, and cause abortion in pregnant animals compared with other strains of C. jejuni (15,17).…”

Scientific Opinion on the evaluation of molecular typing methods for major food‐borne microbiological hazards and their use for attribution modelling, outbreak investigation and scanning surveillance: Part 1 (evaluation of methods and applications)

“…The method is based on fragmentation of chromosomal DNA using rare-cutting restriction endonucleases, followed by the resolution of resultant DNA fragments by pulsed field gel electrophoresis (PFGE) (see Chapter 3). The method has been extended to encompass food-borne pathogens such as Salmonella Liebana et al, 2002;Peters et al, 2003), Listeria monocytogenes (Graves and Swaminathan, 2001;Graves et al, 2005;Martin et al, 2006;Felix et al, 2012)) and to a lesser extent Campylobacter (Ribot et al, 2001;Sahin et al, 2012). PFGE for food-borne pathogens has been standardised both nationally in the USA, and internationally through various PulseNet International networks in most continents to allow for inter-laboratory comparison.…”