RESUMO
A novel Escherichia coli outer membrane protein A (OmpA) was discovered through a proteomic investigation of cell surface proteins. DNA polymorphisms were localized to regions encoding the protein's surface-exposed loops which are known phage receptor sites. Bacteriophage sensitivity testing indicated an association between bacteriophage resistance and isolates having the novel ompA allele.
Assuntos
Alelos , Proteínas da Membrana Bacteriana Externa/genética , Colífagos/fisiologia , Proteínas de Escherichia coli/genética , Escherichia coli/virologia , Sequência de Aminoácidos , Animais , Austrália , Proteínas da Membrana Bacteriana Externa/química , Escherichia coli/genética , Escherichia coli/isolamento & purificação , Proteínas de Escherichia coli/química , Humanos , Marsupiais , Dados de Sequência Molecular , Análise de Sequência de DNARESUMO
The occurrence of Cryptosporidium oocysts in feces from a population of wild eastern grey kangaroos inhabiting a protected watershed in Sydney, Australia, was investigated. Over a 2-year period, Cryptosporidium oocysts were detected in 239 of the 3,557 (6.7%) eastern grey kangaroo fecal samples tested by using a combined immunomagnetic separation and flow cytometric technique. The prevalence of Cryptosporidium in this host population was estimated to range from 0.32% to 28.5%, with peaks occurring during the autumn months. Oocyst shedding intensity ranged from below 20 oocysts/g feces to 2.0 x 10(6) oocysts/g feces, and shedding did not appear to be associated with diarrhea. Although morphologically similar to the human-infective Cryptosporidium hominis and the Cryptosporidium parvum "bovine" genotype oocysts, the oocysts isolated from kangaroo feces were identified as the Cryptosporidium "marsupial" genotype I or "marsupial" genotype II. Kangaroos are the predominant large mammal inhabiting Australian watersheds and are potentially a significant source of Cryptosporidium contamination of drinking water reservoirs. However, this host population was predominantly shedding the marsupial-derived genotypes, which to date have been identified only in marsupial host species.
Assuntos
Criptosporidiose/veterinária , Cryptosporidium/isolamento & purificação , Fezes/parasitologia , Macropodidae/parasitologia , Oocistos/isolamento & purificação , Abastecimento de Água , Animais , Austrália , Criptosporidiose/epidemiologia , Criptosporidiose/parasitologia , Cryptosporidium/classificação , Cryptosporidium/genética , Cryptosporidium/fisiologia , Genótipo , Oocistos/classificação , Oocistos/genética , Oocistos/fisiologia , Contagem de Ovos de Parasitas , PrevalênciaRESUMO
Escherichia coli has long been used as an indicator organism for water quality assessment. Recently there has been an accumulation of evidence that suggests some strains of this organism are able to proliferate in the environment, a characteristic that would detract from its utility as an indicator of faecal pollution. Phenotypic and genotypic characterization of E. coli isolated from blooms in two Australian lakes, separated by a distance of approximately 200 km, identified that the blooms were dominated by three E. coli strains. A major phenotypic similarity among the three bloom strains was the presence of a group 1 capsule. Genetic characterization of a conserved region of the cps gene cluster, which encodes group 1 capsules, identified a high degree of genetic variation within the bloom isolates. This differs from previously described encapsulated E. coli strains which are highly conserved at the cps locus. The phenotypic or genotypic profiles of the bloom strains were not identified in 435 E. coli strains isolated from vertebrates. The occurrence of these encapsulated strains suggests that some E. coli have evolved a free-living lifestyle and do not require a host in order to proliferate. The presence of the same three strains in bloom events in different geographical regions of a temperate climate, and at different times, indicates that free-living E. coli strains are able to persist in these water reservoirs. This study provides further evidence of circumstances where caution is required in using E. coli as an indicator organism for water quality.
Assuntos
Cápsulas Bacterianas/genética , Escherichia coli/crescimento & desenvolvimento , Escherichia coli/genética , Água Doce/microbiologia , Microbiologia da Água , Território da Capital Australiana , Cápsulas Bacterianas/isolamento & purificação , Cápsulas Bacterianas/ultraestrutura , Sequência de Bases , Análise por Conglomerados , DNA Bacteriano/química , DNA Bacteriano/genética , Escherichia coli/isolamento & purificação , Variação Genética , Dados de Sequência Molecular , New South Wales , Antígenos O/genética , Fenótipo , Reação em Cadeia da PolimeraseRESUMO
Molecular characterisation of Cryptosporidium oocysts isolated from faeces collected from eastern grey kangaroos Macropus giganteus inhabiting an Australian water catchment revealed that this host was susceptible to three types of Cryptosporidium. Nucleotide sequence analysis of the 18S rDNA, Cryptosporidium oocyst wall protein (COWP) and a 70kDa heat shock protein (HSP70) identified an isolate identical to the described Cryptosporidium 'marsupial' genotype. A second isolate had less than 0.5% variation, compared to the described Cryptosporidium 'marsupial' genotype, within the sequences of the 18S rDNA, COWP and HSP70 and 10% variation in the internal transcribed spacer 1 (ITS1). Multilocus analysis of the third Cryptosporidium revealed a novel genotype that had a degree of genetic variation, at the four loci characterised, which was greater than or equivalent to that used to discriminate between currently recognised Cryptosporidium species. These findings have increased our current understanding on the molecular epidemiology of Cryptosporidium in Australian wildlife and have provided information on the types of Cryptosporidium marsupials may shed into the environment.
