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

Gordon, David M.; FitzGibbon, F

doi:10.1099/00221287-145-10-2663

Cited by 78 publications

(92 citation statements)

References 32 publications

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“…That is, the specificity for Salmonella in causing disease more readily in particular hosts may be intimately associated with that serovar's ability to avoid the predators within that host; Salmonella must avoid predation before it invades intestinal epithelium. Consistent with this hypothesis, Salmonella and E. coli have been found to be differentially distributed among the intestinal environments of their hosts (Boyd et al, 1993;Gordon & FitzGibbon, 1999;Gordon et al, 2002;Gordon & Cowling, 2003;Rabsch et al, 2002). We found similar results here where, for example, the serovars of Salmonella within turtles and bearded dragons were significantly different from those we isolated from birds (Table 1).…”

Section: Differential Distribution Of Salmonella May Results From Predsupporting

confidence: 81%

Differential Salmonella survival against communities of intestinal amoebae

Wildschutte

Lawrence

2007

Microbiology

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Predation from intestinal amoebae may provide selective pressure for the maintenance of high genetic diversity at the Salmonella enterica rfb locus, whereby serovars better escape predators in particular environments depending on the O-antigens they express. Here, the hypothesis that amoebae from a particular intestinal environment collectively prefer one serovar over another is tested. Collections of Acanthamoeba, Tetramitus, Naegleria and Hartmannella were isolated from the intestinal tracts of several vertebrate hosts, including bullfrog tadpoles, goldfish, turtles and bearded dragons, and their feeding preferences were determined. Congeneric amoebae from the same environment had significantly similar feeding preferences. Strikingly, even unrelated amoebae -such as Naegleria and Tetramitus from goldfish -also had significantly similar feeding preferences. Yet amoebae isolated from different environments showed no similarity in prey choice. Thus, feeding preferences of amoebae appear to reflect their environment, not their taxonomic relationships. A mechanism mediating this phenotypic convergence is discussed.

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Section: Differential Distribution Of Salmonella May Results From Predsupporting

confidence: 81%

Differential Salmonella survival against communities of intestinal amoebae

Wildschutte

Lawrence

2007

Microbiology

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“…The manner in which the characterized isolates were obtained has varied among studies, and these isolates may represent clones collected from single populations, clinical isolates, or subsamples of strains collected in an ad hoc fashion. Recent work has demonstrated that a number of species of enteric bacteria are non-randomly distributed with respect to either the taxonomic family of the host from which they were isolated or the geographical locality where the host was collected (Gordon & FitzGibbon, 1999). Such an observation demonstrates the existence of population structure and suggests that these species may exhibit adaptations specific to particular types of primary (host environment) and secondary (external environment) habitats (sensu Savageau, 1983).…”

Section: Introductionmentioning

confidence: 99%

“…Faecal swabs were obtained from a variety of mammalian hosts representing 79 species from 16 families collected from over 75 localities throughout Australia (Gordon & FitzGibbon, 1999). Primary isolation of the strains was performed by streaking the swabs for single colonies on a MacConkey agar plate (Power & McCuen, 1988).…”

Section: Methodsmentioning

confidence: 99%

The genetic structure of enteric bacteria from Australian mammals

Gordon

Lee

1999

Microbiology

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A total of 246 isolates representing five species of the family Enterobacteriaceae, taken from a variety of Australian mammal species, were characterized using multi-locus enzyme electrophoresis. Genome diversity estimates varied significantly among species, with the Klebsiella pneumoniae sample exhibiting the lowest diversity and the Citrobacter freundii sample the highest. Multi-locus linkage disequilibrium estimates revealed that alleles were non-randomly associated in all five species samples, but the magnitude of the estimates differed significantly among species. Escherichia coli had the lowest linkage disequilibrium estimate and Klebisella oxytoca the largest. Molecular analyis of variance was used to determine the extent to which population structure explained the observed genetic variation in a species. Two population levels were defined : the taxonomic family of the host from which the isolate was collected and the geographical locality where the host was collected. The amount of explained variation varied from 0 % for K. oxytoca to 22 % for K. pneumoniae. Host locality explained a significant amount of the genetic variation in the C. freundii (12 %), E. coli (5 %), Hafnia alvei (17 %) and K. pneumoniae (22 %) samples. Host family explained a significant fraction of the variation in E. coli (6 %) H. alvei (7 %) and K. pneumoniae (20 %). Estimates of effective population size for all five species, based on the probability that two randomly chosen isolates will be identical, failed to reveal any relationship between the effective population size and the genetic diversity of a species.

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“…Consequently, E. coli will only be detected if it represents, on average, more than 1 % of the total number of bacterial cells capable of growth on this medium. MacConkey medium is non-selective with respect to members of the Enterobacteriaceae (Ewing, 1986), but it inhibits the growth of Gram-positive and many Gramnegative species, to the extent that about 92 % of the bacteria recovered from mammals were members of the Enterobacteriaceae (Gordon & FitzGibbon, 1999). Relative to other members of the Enterobacteriaceae, E. coli has a distinct colony morphology and colour on MacConkey agar and consequently is unlikely to be overlooked.…”

Section: Definition Of Prevalencementioning

confidence: 99%

“…However, in a study of E. coli isolated from non-domesticated Australian mammals, Gordon & FitzGibbon (1999) showed that the probability of isolating E. coli from an individual depended on the taxonomic family of the host and on the geographic locality from which the host was collected. In an investigation of the genetic structure of E. coli isolated from Australian mammals using the technique of multi-locus enzyme electrophoresis, Gordon & Lee (1999) demonstrated that host taxonomic family and geographic locality explained a small but significant amount of the observed genetic variation.…”

Section: Introductionmentioning

confidence: 99%

The distribution and genetic structure of Escherichia coli in Australian vertebrates: host and geographic effects

2003

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Escherichia coli was isolated from more than 2300 non-domesticated vertebrate hosts living in Australia. E. coli was most prevalent in mammals, less prevalent in birds and uncommon in fish, frogs and reptiles. Mammals were unlikely to harbour E. coli if they lived in regions with a desert climate and less likely to have E. coli if they lived in the tropics than if they lived in semi-arid or temperate regions. In mammals, the likelihood of isolating E. coli from an individual depended on the diet of the host and E. coli was less prevalent in carnivores than in herbivores or omnivores. In both birds and mammals, the probability of isolating E. coli increased with the body mass of the host. Hosts living in close proximity to human habitation were more likely to harbour E. coli than hosts living away from people. The relative abundance of E. coli groups A, B1, B2 and D strains in mammals depended on climate, host diet and body mass. Group A strains were uncommon, but were isolated from both ectothermic and endothermic vertebrates. Group B1 strains could also be isolated from any vertebrate group, but were predominant in ectothermic vertebrates, birds and carnivorous mammals. Group B2 strains were unlikely to be isolated from ectotherms and were most abundant in omnivorous and herbivorous mammals. Group D strains were rare in ectotherms and uncommon in endotherms, but were equally abundant in birds and mammals. The results of this study suggest that, at the species level, the ecological niche of E. coli is mammals with hindgut modifications to enable microbial fermentation, or in the absence of a modified hindgut, E. coli can only establish a population in 'large-bodied' hosts. The non-random distribution of E. coli genotypes among the different host groups indicates that strains of the four E. coli groups may differ in their ecological niches and life-history characteristics.

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

Cited by 78 publications

References 32 publications

Differential Salmonella survival against communities of intestinal amoebae

Differential Salmonella survival against communities of intestinal amoebae

The genetic structure of enteric bacteria from Australian mammals

The distribution and genetic structure of Escherichia coli in Australian vertebrates: host and geographic effects

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