Genetic Divergence of Campylobacter fetus Strains of Mammal and Reptile Origins

Abstract

Campylobacter fetus is a gram-negative bacterial pathogen of both humans and animals. Two subspecies have been identified, Campylobacter fetus subsp. fetus and Campylobacter fetus subsp. venerealis, and there are two serotypes, A and B. To further investigate the genetic diversity among C. fetus strains of different origins, subspecies, and serotypes, we performed multiple genetic analyses by utilizing random amplification of polymorphic DNA (RAPD), pulsed-field gel electrophoresis (PFGE), and DNA-DNA hybridization. All 10 primers used for the RAPD analyses can distinguish C. fetus strains of reptile and mammal origin, five can differentiate between C. fetus subsp. fetus and C. fetus subsp. venerealis strains, and four showed differences between type A and type B isolates from mammals. PFGE with SmaI and SalI digestion showed varied genome patterns among different C. fetus strains, but for mammalian C. fetus isolates, genome size was well conserved (mean, 1.52 ؎ 0.06 Mb for SmaI and 1.52 ؎ 0.05 Mb for SalI). DNA-DNA hybridization demonstrated substantial genomic-homology differences between strains of mammal and reptile origin. In total, these data suggest that C. fetus subsp fetus strains of reptile and mammal origin have genetic divergence more extensive than that between the two subspecies and that between the type A and type B strains. Combining these studies with sequence data, we conclude that there has been substantial genetic divergence between Campylobacter fetus of reptile and mammal origin. Diagnostic tools have been developed to differentiate among C. fetus isolates for taxonomic and epidemiologic uses.

Campylobacter jejuni: A Review of its Characteristics, Pathogenicity, Ecology, Distribution, Subspecies Characterization and Molecular Methods of Detection

“…Campylobacter jejuni 277 C. fetus is known to be pathogenic for humans and animals (Tu et al, 2005). Two subspecies have been identified, C. fetus subsp.…”

Campylobacter fetus subsp. testudinum subsp. nov., isolated from humans and reptiles

“…Strains of C. fetus isolated from reptiles have previously been shown to be genetically divergent from strains of C. fetus isolated from humans, with the suggestion that they may represent a distinct taxonomic group, based on the results from 16S rRNA, recA and sapD gene sequence analyses and multi-locus sequence typing (Dingle et al, 2010;Tu et al, 2005); molecular methods to differentiate them have been developed (Tu et al, 2001). The first confirmed isolation from a human of strains of C. fetus with markers of reptile origin occurred in New York in 2003 (Tu et al, 2004b), with two isolates (strains 03-427 T and 03-445) recovered 37 days apart from a patient symptomatic due to recurrent C. fetus bacteraemia.…”

Human Infections with New Subspecies ofCampylobacter fetus

“…C. fetus has also been isolated from feces of a healthy western hognose snake ( Heterodon nasicus ) and a blotched blue-tongue lizard ( Tiliqua nigrolutea ) that had unformed feces and was losing weight ( 7 ). Substantial genetic divergence between C. fetus strains of reptile and mammal origin has been demonstrated ( 8 ). …”