Clonal analysis of Escherichia coli of serogroups O9, O20, and O101 isolated from Australian pigs with neonatal diarrhea

Abstract

The genetic diversity of 87 isolates ofEscherichia coli recovered from Australian pigs with neonatal diarrhea was examined by multilocus enzyme electrophoresis. The isolates were of serogroups 09, 020, and 0101, and although most isolates lacked K88(F4), K99(F5), 987P(F6), and F41 fimbriae, they were considered to be involved in the etiology of the diarrhea. The isolates were extremely diverse, considering their origin from a single pathological condition in one country. There were estimated to be 18, 16, and 12 clones of the three respective serogroups in the collection, with serogroup diversities of 0.387, 0.448, and 0.275, respectively. Comparison with the results previously obtained for isolates from piglets with postweaning diarrhea suggested that bacteria from piglets with these two conditions did not come from any particular common genetic background. The overall genetic diversity for the combined collection was the same as that reported by others for representative isolates selected from throughout the species (0.47). The current results indicate that if isolates of these 0 groups are involved in porcine diarrhea, their pathogenicity is directly linked to their 0 somatic antigen type and is not simply due to the wide distribution of a small number of virulent clones.

Rapid identification of virulence genes in enterotoxigenic Escherichia coli isolates associated with diarrhoea in Queensland piggeries

“…13,14 These strains possessed F4:STa or F5:STa pathotypes or did not possess any of the commonly recognised fimbriae. 16 The serotyping and pathotyping results for the 17 ND isolates from New South Wales mirrored these previous findings. None of the isolates belonged to serotype O149 and only a single serotype O8 isolate possessed the F4:STa:STb:LT pathotype.…”

“…The clonality of serotype O149 strains is in contrast to other serotypes associated with ND, which show considerable genetic diversity. Woodward and coworkers 16 analysed the population structure of 87 non-haemolytic ETEC isolates belonging to serotypes O9, O20 and O101 that originated from Victoria and New South Wales. Although the majority of these isolates did not possess any of the recognised fimbriae (F4, F5, F6), they were considered to be pathogens and each serotype showed considerable genetic diversity with an absence of clonality.…”

“…[13][14][15] In recent reports from Victoria and New South Wales, the majority of ETEC isolates from severe outbreaks of ND belonged to serotypes O8, O9, O20 and O101, but did not possess recognised fimbriae. 2,14,16 It was suggested that ETEC strains lacking recognised fimbriae were becoming more common, perhaps due to the widespread use of vaccines incorporating fimbriated strains, or alternatively, the isolates may carry novel, unrecognised fimbriae. Surprisingly, there are few reports of which ETEC pathotypes and serotypes are present in Queensland piggeries, although early studies indicated the predominance of serotypes O8, O149 and O141 in both ND and PWD.…”

Etiology of Acute Diarrhea in Children and Adults in Tunis, Tunisia, with Emphasis on Diarrheagenic Escherichia coli: Prevalence, Phenotyping, and Molecular Epidemiology

“…Such genetic heterogeneity among E. coli strains belonging to the same serotypes has been recorded previously. 36,37 Serotype heterogeneity within genetically derived clusters should not be a source of great concern in evaluating the validity of genotyping methods. Beltran and others 38 speculated that this pattern might be the result of horizontal transfer of genes for the O and H antigens forming the basis of serotype classification.…”

Clonal analysis of Escherichia coli strains isolated from pigs with post-weaning diarrhea by pulsed-field gel electrophoresis

“…The clonal nature of ETEC has been shown by the results of several studies of human enterotoxigenic isolates [10–12]. However, molecular typing methods, including restriction fragment length polymorphism (RFLP) have not been often applied for the analysis and epidemiological characterization of porcine ETEC bacteria [13–16]. Differentiation of chromosomal DNA based on RFLP and pulsed‐field gel electrophoresis (PFGE) is a good, sensitive molecular method to analyze the degree of genetic relatedness or variability among different ETEC serotypes as well as among the strains of the same serogroup.…”