Abstract
ABSTRACT
Humans have historically been considered the only natural host of typical enteropathogenic
Escherichia coli
(tEPEC), a cause of human infantile diarrhoea. Recent findings of bat‐specific tEPEC in two Australian bat species (
Pteropus poliocephalus
and
Pteropus conspicillatus
) revealed that these
Pteropus
spp. are also tEPEC hosts. tEPEC pathogenicity is associated with key virulence factors including intimin (
eae
) and the bundle‐forming pilus (
bfp
) operon, which contains the
bfpA
gene. This study characterised 63 tEPEC isolates from five Australian
Pteropus
spp.; four from mainland Australia (
P. poliocephalus
,
P. conspicillatus, P. alecto
and
P. scapulatus
) and one from Christmas Island (
P. natalis)
. The 63 tEPEC isolates included 10 novel tEPEC strains and eight previously identified
Pteropus
tEPEC strains. Faecal DNA samples (
n
= 386) from the five Australian
Pteropus
spp. were screened for
eae
and
bfpA
genes to identify tEPEC‐positive samples. The estimated true prevalence of tEPEC ranged from 14.2% to 37.0% across the five
Pteropus
spp. Typing of 119
bfpA
alleles (63 tEPEC isolates and 56 faecal DNA samples) from the five
Pteropus
spp. identified 27
bfpA
allele types, 24 of which belonged to bat‐specific
bfpA
lineages. Bat‐specific
bfpA
alleles were shared between tEPEC strains,
Pteropus
spp. and across regions, including the geographically isolated
P. natalis
endemic to Christmas Island. This study reveals that diverse bat‐specific tEPEC strains and
bfpA
types have evolved in
Pteropus
spp. and have been circulating among populations for an extensive period, thereby confirming that all Australian
Pteropus
spp. are natural tEPEC hosts.