title: Clinical and epidemiological analysis of Campylobacter fetus subsp. fetus infections in humans and comparative genetic analysis with strains isolated from cattle.
abstract: BACKGROUND
  Campylobacter fetus subspecies fetus (CFF) is an important pathogen for both cattle and humans. We performed a systematic epidemiological and clinical study of patients and evaluated the genetic relatedness of 17 human and 17 bovine CFF isolates by using different genotyping methods. In addition, the serotype, the dissemination of the genomic island containing a type IV secretion system (T4SS) and resistance determinants for tetracycline and streptomycin were also evaluated.
  
  
  METHODS
  The isolates from patients diagnosed with CFF infection as well as those from faecal samples of healthy calves were genotyped using pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), as well as single locus sequence typing (SLST) targeting cmp1 and cmp2 genes encoding two major outer membrane proteins in CFF. The presence of the genomic island and identification of serotype was determined by PCRs targeting genes of the T4SS and the sap locus, respectively. Tetracycline and streptomycin resistance phenotypes were determined by minimal inhibitory concentration. Clinical data obtained from medical records and laboratory data were supplemented by data obtained via telephone interviews with the patients and treating physicians.
  
  
  RESULTS
  PFGE analysis defined two major clusters; cluster A containing 16 bovine (80 %) isolates and cluster B containing 13 human (92 %) isolates, suggesting a host preference. Further genotypic analysis using MLST, SLST as well as sap and T4SS PCR showed the presence of genotypically identical isolates in cattle and humans. The low diversity observed within the cmp alleles of CFF corroborates the clonal nature of this pathogen. The genomic island containing the tetracycline and streptomycin resistance determinants was found in 55 % of the isolates in cluster A and correlated with phenotypic antibiotic resistance.
  
  
  CONCLUSIONS
  Most human and bovine isolates were separated on two phylogenetic clusters. However, several human and bovine isolates were identical by diverse genotyping methods, indicating a possible link between strains from these two hosts.
authors.affiliation: Department of Medicine, Spital Emmental, Burgdorf, Switzerland. robert.escher@spital-emmental.ch.
authors.forename: Robert
authors.initials: R
authors.lastname: Escher
authors.affiliation: Department of Medicine, Spital Emmental, Burgdorf, Switzerland.
authors.forename: Colette
authors.initials: C
authors.lastname: Brunner
authors.affiliation: Institute for Infectious Diseases, University of Bern, Bern, Switzerland.
authors.forename: Niklaus
authors.initials: N
authors.lastname: von Steiger
authors.affiliation: Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Brodard
authors.affiliation: Institute for Infectious Diseases, University of Bern, Bern, Switzerland.
authors.forename: Sara
authors.initials: S
authors.lastname: Droz
authors.affiliation: Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Bern, Switzerland.|Current address: Institute of Virology and Immunology, University of Bern, Bern, Switzerland.
authors.forename: Carlos
authors.initials: C
authors.lastname: Abril
authors.affiliation: Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
authors.forename: Peter
authors.initials: P
authors.lastname: Kuhnert
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002169:Campylobacter Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology / Q000662:veterinary; D002168:Campylobacter fetus / Q000187:drug effects* / Q000235:genetics* / Q000472:pathogenicity; D002417:Cattle; D024881:Drug Resistance, Bacterial / Q000187:drug effects / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D058885:Multilocus Sequence Typing; D010641:Phenotype; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D013307:Streptomycin / Q000494:pharmacology; D013557:Switzerland / Q000453:epidemiology; D013752:Tetracycline / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D013752:Tetracycline; D013307:Streptomycin
keywords: Campylobacter fetus subspecies fetus; Epidemiology; Major outer membrane protein (MOMP); Multilocus sequence typing (MLST); Pulsed-field gel electrophoresis (PFGE); Type IV secretion system (T4SS)