Prevalence and characteristics of intimin- and Shiga toxin-producing Escherichia coli from gulls, pigeons and broilers in Finland

Verocytotoxin-producing Escherichia coli in wild birds and rodents in close proximity to farms

Wild animals living close to cattle and pig farms (four each) were examined for verocytotoxin-producing Escherichia coli (VTEC; also known as Shiga toxin-producing E. coli). The prevalence of VTEC among the 260 samples from wild animals was generally low. However, VTEC isolates from a starling (Sturnus vulgaris) and a Norway rat (Rattus norvegicus) were identical to cattle isolates from the corresponding farms with respect to serotype, virulence profile, and pulsed-field gel electrophoresis type. This study shows that wild birds and rodents may become infected from farm animals or vice versa, suggesting a possible role in VTEC transmission.

Interaction between attaching and effacing Escherichia coli serotypes O157:H7 and O26:K60 in cell culture

Ruminants harbour both O157:H7 and non-O157 Attaching Effacing Escherichia coli (AEEC) strains but to date only non-O157 AEEC have been shown to induce attaching effacing lesions in naturally infected animals. However, O157 may induce lesions in deliberate oral inoculation studies and persistence is considered dependent upon the bacterially encoded locus for enterocyte effacement. In concurrent infections in ruminants it is unclear whether non-O157 AEEC contribute either positively or negatively to the persistence of E. coli O157:H7. To investigate this, and prior to animal studies, E. coli O157:H7 NCTC 12900, a non-toxigenic strain that persists in conventionally reared sheep, and non-toxigenic AEEC O26:K60 isolates of sheep origin were tested for adherence to HEp-2 tissue culture alone and in competition one with another. Applied together, both strains adhered in similar numbers but lower than when either was applied separately. Pre-incubation of tissue culture with either one strain reduced significantly (P < 0.05) the extent of adherence of the strain that was applied second. It was particularly noticeable that AEEC O26 when applied first reduced adherence and inhibited microcolony formation, as demonstrated by confocal microscopy, of E. coli O157:H7. The possibility that prior colonisation of a ruminant by non-O157 AEEC such as O26 may antagonise O157 colonisation and persistence in ruminants is discussed.

Investigation of shiga toxin-producing Escherichia coli in avian species in India

AIMS

To investigate the presence or absence of shiga toxin-producing Escherichia coli (STEC) in avian species in India.

METHODS AND RESULTS

Faecal samples originating from 500 chicken and 25 free flying pigeons were screened for the presence of E. coli. A total of 426 (chicken, 401; pigeons, 25) E. coli strains were isolated. Of 426 E. coli strains, 387 were grouped into 77 serogroups, while 70 and 59 strains were untypable and rough, respectively. All isolates were subjected to multiplex polymerase chain reaction (m-PCR) for the detection of stx(1), stx(2), eaeA, hlyA and saa genes. None of the E. coli strains studied showed the presence of stx(1), stx(2) or their variants and saa genes. Overall 11 (2.74%) and seven (1.74%) strains from chickens possessed eaeA and hlyA genes, respectively, while as only six (1.49%) strains from chickens possessed both eaeA and hlyA genes. O9, O8, O60 and O25 serogroups were most predominant of which there were 24 (5.63%), 23 (5.39%), 23 (5.39%) and 20 (4.69%) strains, respectively. None of the isolates from pigeons showed the presence of any of the virulence genes studied.

CONCLUSIONS

STEC are absent in chickens and pigeons. However, further studies are required in this direction to confirm or contradict our findings. E. coli strains originating from birds are carrying a low percentage eaeA or hlyA genes.

SIGNIFICANCE AND IMPACT OF THE STUDY

The present study is the first attempt to investigate STEC in chickens and free flying pigeons in India. The chickens and pigeons cannot be considered as important carrier of STEC in India.

Prevalence and characteristics of eae-positive Escherichia coli from healthy cattle in Japan

The prevalence of eae-positive Escherichia coli (eaeEC) in Japan was examined using rectal stool samples taken from 35 calves less than 1 month old, 107 calves more than 1 to 3 months old, 88 heifers more than 3 to 6 months old, 214 heifers over 6 months old, and cows from 95 farms. Screening with eae PCR revealed the prevalence to be, with increasing age, 31.4, 8.4, 26.1, and 14.5%, respectively. Of 51 selected eaeEC strains, more than 40% were serotyped as O26, O103, O111, O145, or O157, which are frequently detected as enterohemorrhagic E. coli types. Four strains were identified as recently reported intimin types eta, iota, and kappa.