Recurring genotypes of Campylobacter jejuni involved in human infection in Luxembourg and associated to specific phenotypic traits

Abstract S7

Presenter: Nennig Morgane (National Health Laboratory - Dudelange - Luxembourg)

Authors: Morgane Nennig (1-2), Arnaud Clment (3), Emmanuelle Longueval (4), Thierry Bernardi (3), Catherine Ragimbeau (1)

Campylobacter emerged as the leading cause of bacterial gastroenteritis worldwide. Since 2006, an increased trend for human campylobacteriosis has been observed in Luxembourg, which motivated the monitoring of the circulating genetic profiles. Isolates from diverse sources (human, food, veterinary and environment) were collected in routine for molecular typing purposes. By comparing of genomic profiles, an unexpected endemic pattern was discovered in the spatio-temporal distribution of human genotypes over a 13-year period. Regardless the typing scheme used, the results support the clonal expansion of stable genomes in Campylobacter populations. The strains belonging to the recurring genotypes are multi-host and are accounting for the majority of human clinical strains in Luxembourg. In this study, specific phenotypical traits, previously shown to contribute to persistence in the environment and human transmission, were investigated on a collection of representative strains. Campylobacter jejuni strains isolated between 2005 and 2018 from multi-hosts and with recurrent or sporadic profiles were selected (N=84). Among those, recurrent strains belonging to four recurring lineages (lineages A, B, C and D) as previously described by Nennig et al. (2021) 1 . Acclimation to aerobic conditions, survival to peroxide and superoxide stresses using hydrogen peroxide (H 2 O 2 ) and Paraquat (PQ), respectively, and bacterial adhesion to an inert surface and biofilm formation using BioFilm Ring test® were assessed. Data were analysed statistically and relationships between genotypes and phenotypes were explored using correlation models.

Of the 84 strains studied, 43 were acclimated to aerobic conditions and 45 and 31 were able to survive at a concentration above 0.25 mM PQ and H 2 O 2 , respectively. Overall, when a strain survives to a concentration of 0.25 mM PQ, it is 6 times more likely to survive to H 2 O 2 at the same concentration (chi-squarest test, p<0.0001). A high adhesion capacity was measured for 39 strains and 27 strains developed a biofilm. When a strain has strong adhesion, it is 14 times more likely to develop a biofilm (chi-squarest test, p<0.0001). In addition, recurrent lineages have developed more phenotypic adaptations: lineage A survives PQ stress significantly more than lineages C and D (ANOVA, p-value=0.0393 and 0.0234, respectively) and it survives H 2 O 2 stress significantly more than the lineage D (ANOVA, p-value=0.0151). While lineage D has the highest capacity for adhesion and biofilm formation (ANOVA, p<0.0001).

Presenting in Speaking session 4 - Survival and application