Virulence spectra of typed strains of Campylobacter jejuni from different sources: a blinded in vivo study

Abstract

Campylobacter jejuniis a major cause of human diarrhoeal disease, but specific virulence mechanisms have not been well defined. The aims of the present blinded study were to measure and compare thein vivoproperties of 40 serotyped, biotyped and genotypedC. jejuniisolates from different sources and genetic makeup. An 11-day-old chick embryo lethality assay, which measured embryo deaths and total viable bacteria over 72 h following inoculation of bacteria into the chorioallantoic membrane, revealed a spectrum of activity within theC. jejunistrains. Human and chicken isolates showed similar high virulence values for embryo deaths while the virulence of the bovine isolates was less pronounced. A one-way ANOVA comparison between the capacity of the strains to kill the chick embryos after 24 h with cytotoxicity towards cultured CaCo-2 cells was significant (P=0.025). After inoculation with aCampylobacterstrain, mouse ligated ileal loops were examined histologically and revealed degrees of villous atrophy, abnormal mucosa, dilation of the lumen, congestion and blood in lumen, depending on the isolate examined. A ‘total pathology score’, derived for eachC. jejunistrain after grading the pathology features for degree of severity, showed no apparent relationship with the source of isolation. Some relationship was found between amplified fragment length polymorphism groups and total ileal loop pathology scores, and a one-way ANOVA comparison of the mouse pathology scores against total chick embryo deaths after 72 h was significant (P=0.049).