Native wild mammals as Escherichia albertii carriers in the Chugoku and Kinki regions of western Japan

Abstract

Escherichia albertii, a zoonotic pathogen, is reported to cause frequent food poisoning outbreaks in Japan. Although some studies have identified avian carriers of E. albertii, the carrying potential of wild mammals has not been well studied. In this study, we analyzed 147 samples from wild mammals, including 46 raccoon dogs, 32 badgers, 23 deer, 15 martens, 10 wild boars, 9 foxes, 9 masked palm civets, and 3 wild rabbits, which were collected as roadkill in the Chugoku and Kinki regions of western Japan. PCR-based screening revealed E. albertii in 26 raccoon dogs (56.5%), 23 badgers (71.9%), 2 deer (8.7%), 8 martens (53.3%), 1 wild boar (10.0%), 3 foxes (33.3%), 5 masked palm civets (55.6%), and 1 wild rabbit (33.3%). A total of 38 strains were isolated, including 15, 10, 6, 3, and 4 strains from 14 raccoon dogs, 8 badgers, 5 martens, 2 foxes, and 4 masked palm civets, respectively. Escherichia albertii genotyping assigned 33 of these strains to 15 combinations of O- and H-genotypes (EAOgs:EAHgs), and five O-untypable strains were assigned to three combinations. In terms of phenotype, all strains were assigned to E. albertii biogroup 3. Identical or highly similar fragment patterns among the same EAOg:EAHg profiles were observed in XbaI-digested genomic DNA during pulsed-field gel electrophoresis, regardless of animal species or sampling prefecture, indicating narrow genetic diversity. Potent novel carriers of E. albertii such as raccoon dogs and badgers were identified, and E. albertii detection and isolation suggested that some mammals may act as natural reservoirs.