The distribution of enteric bacteria from Australian mammals: host and geographical effects

Bacteria of the family Enterobacteriaceae were isolated from 642 mammalian hosts, representing 16 families and 79 species, collected from throughout A ustralia. Escherichia coli was the most common of the 24 enteric species re covered and represented almost half of the isolates. Association analysis r evealed that most other species of bacteria were less likely to be recovere d from hosts in which E. coli was present. The composition of the enteric c ommunity of a host was found to be determined by both the taxonomic family to which the host belonged and the geographical area from which the host wa s collected. Hosts collected from the northern areas of Queensland and the Northern Territory had more diverse enteric communities than hosts collecte d from New South Wales or Western Australia. Hosts of the families Petaurid ae and Vespertilionidae had more diverse enteric communities than did membe rs of the Macropodidae or Phalangeridae. The probability of occurrence of C itrobacter freundii, Enterobacter cloacae, Escherichia coli, Hafnia alvei, Klebsiella oxytoca and K. pneumoniae in a host was found to vary with respe ct to host family and/or host locality. The non-random distribution of thes e species demonstrates the presence of extensive population structure and m ay suggest the existence of adaptations specific to both the primary and se condary habitats of these enteric bacteria.