The prevalence of Escherichia coli O157 and O157:H7 in ground beef and raw meatball by immunomagnetic separation and the detection of virulence genes using multiplex PCR.

The present study was conducted to investigate the presence of Escherichia coli O157 and O157:H7 strains and to detect the presence of the stx1, stx2, and eaeA genes in isolates derived from 200 samples (100 samples from fresh ground beef and 100 samples from raw meatball). The samples were purchased from the Samsun Province in Turkey, over a period of 1 year. Enrichment-based immunomagnetic separation and multiplex polymerase chain reaction were applied for these analyses. E. coli O157 was detected in five of the 200 (2.5%) samples tested (one isolated from ground beef and four from meatball samples), whereas E. coli O157: H7 was not detected in any sample. During the analysis, eight strains of E. coli O157 were obtained. The genes stx1, stx2, and eaeA were detected in two E. coli O157 isolates obtained from two meatball samples, whereas only the eaeA and the stx2 genes were detected in four E. coli O157 strains that were isolated from one meatball sample. None of the stx1, stx2, and eaeA was detected in the E. coli O157 isolates obtained from the ground beef and the one meatball samples.

Cadirci O ，Siriken B ，Inat G ，Kevenk TO ... -  《-》

Incidence of Escherichia coli O157:H7 and E. coli virulence factors in US bulk tank milk as determined by polymerase chain reaction.

Samples of bulk tank milk from dairies across the United States, taken as part of the National Animal Health Monitoring Dairy 2002 survey, were analyzed for the presence of several genes encoding virulence factors associated with enterohemorrhagic forms of Escherichia coli (EHEC) using real-time and conventional PCR assays. Samples from 859 farms in 21 states were collected and enriched in EC medium at 42.5 degrees C to amplify any E. coli present, and DNA was isolated from the resulting biomass. The eaeA gene encoding intimin, a virulence factor associated with enteropathogenic forms of E. coli and EHEC, was detected in 199 (23%) of the samples. Thirty-six samples (4.2%) were positive for eaeA, the gamma allele of the translocated intimin receptor (gamma-tir), found in EHEC strains of O157:H7, and one or both shiga-like toxin genes (stx1 and stx2), a combination that may be indicative of the presence of O157:H7 EHEC. Testing these 36 samples with a commercially available real-time PCR kit for detection of O157:H7 indicated that 5 samples could be contaminated with O157:H7. A multiplex PCR to detect the presence of fliC, rfbE, and hlyA genes found in O157:H7 reduced to 2 (0.2% of all samples) the number of samples likely to be contaminated with this organism. A strain of O157:H7 (eaeA+, gamma-tir+, stx2+, rfbE+, fliC+, hlyA+) was subsequently isolated from one sample. Thirty-four eaeA-positive samples did not contain detectable gamma-tir but did contain one or both of the stx genes suggesting the presence of EHEC strains other than O157:H7. These results indicate a low incidence of O157:H7 in bulk tank milk but suggest that a risk from other enteropathogenic and EHEC forms of E. coli may exist and that PCR targeting virulence factors associated with highly pathogenic forms of E. coli may be an effective means of detecting potential dangers in raw milk.

Karns JS ，Van Kessel JS ，McClusky BJ ，Perdue ML ... -  《-》

PCR detection of Shiga toxins, enterohaemolysin and intimin virulence genes of Escherichia coli O157:H7 strains isolated from faeces of Anatolian water buffaloes in Turkey.

Seker E ，Kuyucuoğlu Y ，Sareyyüpoğlu B ，Yardımcı H ... -  《-》

Detection and frequency of VT1, VT2 and eaeA genes in Escherichia coli O157 and O157:H7 strains isolated from cattle, cattle carcasses and abattoir environment in Istanbul.

Yilmaz A ，Gun H ，Ugur M ，Turan N ，Yilmaz H ... -  《INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY》

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》