Pheno-genotypic characterisation of Escherichia coli O157:H7 isolates from domestic and wild ruminants.

Shiga toxin-producing Escherichia coli (STEC) O157:H7 represents a major public health concern worldwide, with ruminants recognised as their main natural reservoir. The aim of this work was to determine the phenotypic features and genetic relationships of 46 E. coli O157:H7 isolates obtained from sheep, cattle and deer faeces and from unpasteurised goat milk in Spain over a period of 11 years. Characterisation was performed by polymerase chain reaction (PCR), phage typing and pulsed-field gel electrophoresis (PFGE). An atypical E. coli O157:H7 strain (sorbitol-fermenting and beta-glucuronidase positive) originating from deer faeces was detected. Genes encoding Shiga toxins were detected in 69.6% of isolates, all of them carrying only the stx(2) gene. The isolates were from nine different phage types, although 67.4% were restricted to only three: PT14, PT34 and PT54. PT54 was the most prevalent phage type and contained isolates from cattle, sheep and deer. Majority of the isolates were from phage types previously found in strains associated with human infection. XbaI-PFGE identified 33 different types and 11 groups of closely related types (more than 85% similarity), one of which included 21 (45.7%) isolates originating from different animal species, including deer. These results indicate common origin or inter-species spread of genetically similar E. coli O157:H7 isolates and contribute to earlier investigations identifying deer as a natural source of E. coli O157:H7. The study also highlights the emergence of phenotypic variants of E. coli O157:H7, which may not be identified by routine culture methods or by biochemical tests used to characterise serotype O157:H7.

Sánchez S ，Martínez R ，Rey J ，García A ，Blanco J ，Blanco M ，Blanco JE ，Mora A ，Herrera-León S ，Echeita A ，Alonso JM ... -  《-》

Phage types, virulence genes and PFGE profiles of Shiga toxin-producing Escherichia coli O157:H7 isolated from raw beef, soft cheese and vegetables in Lima (Peru).

Mora A ，León SL ，Blanco M ，Blanco JE ，López C ，Dahbi G ，Echeita A ，González EA ，Blanco J ... -  《INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY》

Detection and characterisation of O157:H7 and non-O157 Shiga toxin-producing Escherichia coli in wild boars.

The aim of this work was to determine the prevalence and characteristics of Escherichia coli O157:H7 and non-O157 Shiga toxin-producing E. coli (STEC) in free-ranging wild boars killed during the hunting season in southwest Spain. Faecal samples from 212 wild boars (Sus scrofa) were collected and examined for STEC. Characterisation of isolates was performed by PCR, serotyping, phage typing, and pulsed-field gel electrophoresis (PFGE). E. coli O157:H7 and non-O157 STEC were isolated from 7 (3.3%) and 11 (5.2%) animals, respectively, and the resulting 19 isolates were characterised. The PCR procedure indicated that 4 isolates carried the stx(1) gene, 12 carried the stx(2) gene, and 1 contained both of these genes. The ehxA, eae, and saa genes were detected in 13, 8, and 1 of the isolates, respectively. The eae-positive isolates comprised the types eae-gamma 1 and eae-zeta. The isolates belonged to 11 O:H serotypes, including 4 new serotypes not previously reported within STEC strains, and the majority of them were from serotypes previously associated with human infection. E. coli O157:H7 isolates belonged to phage types associated with severe human illness: PT14, PT34, and PT54. Indistinguishable PFGE types were found in E. coli O157:H7 isolates recovered from a wild boar and from a human patient with diarrhoea living in the same geographic area.

Sánchez S ，Martínez R ，García A ，Vidal D ，Blanco J ，Blanco M ，Blanco JE ，Mora A ，Herrera-León S ，Echeita A ，Alonso JM ，Rey J ... -  《-》

Isolation of a rare Escherichia coli O157:H7 strain from farm animals in Greece.

Dontorou A ，Papadopoulou C ，Filioussis G ，Apostolou I ，Economou V ，Kansouzidou A ，Levidiotou S ... -  《COMPARATIVE IMMUNOLOGY MICROBIOLOGY AND INFECTIOUS DISEASES》

Escherichia coli O157:H7 and non-O157 Shiga toxin-producing E. coli in healthy cattle, sheep and swine herds in Northern Spain.

Three-hundred and forty-five herds (17 swine, 122 dairy sheep, 124 beef and 82 dairy cattle) were investigated for prevalence of Shiga toxin-producing Escherichia coli (STEC). Rectal faecal samples were selectively enriched and then examined by immunodetection techniques (Immunomagnetic Separation with anti-E. coli O157 Dynabeads, ImmunoMagnetic cell Separation (IMS) and automated enzyme-linked fluorescent immunoassay using VIDAS) and polymerase chain reaction (PCR) (rfbE and fliC genes) to assess the prevalence of E. coli O157:H7. Prevalence of non-O157 STEC was estimated by PCR screening for stx genes of 10 lactose-positive colonies grown on MacConkey agar after enrichment. PCR was used on all STEC isolates to detect stx(1), stx(2), eaeA and E-hlyA genes. Both immunodetection methods showed a moderate-good level of agreement (kappa = 0.649) but IMS showed 87.5% complementary sensitivity. Prevalence of positive herds for E. coli O157:H7 was estimated at 8.7% for sheep and 3.8% for cattle, whereas all the porcine herds tested negative. Non-O157 STEC were also absent from swine, but were isolated more frequently from ovine (50.8%) than bovine herds (35.9%). Within-herd prevalences of excretion of E. coli O157:H7 established by individual testing of 279 sheep (six herds) and 30 beef cattle (one herd) were 7.3% and 6.7% respectively. PCR analysis of 49 E. coli O157:H7 and 209 non-O157 isolates showed a different distribution of virulence genes. All E. coli O157:H7 were stx(2) gene-positive, eaeA was detected in 95.9%, and the toxigenic profile stx(2)/eaeA/E-hlyA was present in 75.5% of the isolates. Among the non-O157 STEC, prevalence of eaeA was significantly lower (5.3%) and E-hlyA was present in 50.2% of the isolates but only sporadically associated with eaeA. stx(2) was predominant in non-O157 isolates from cattle, whereas in sheep the combination stx(1)/stx(2) was more prevalent. This study demonstrated the wide distribution of STEC in ruminant herds, which represent an important reservoir for strains that pose a potential risk for human infections.

Oporto B ，Esteban JI ，Aduriz G ，Juste RA ，Hurtado A ... -  《Zoonoses and Public Health》