Biomedical subjects

Aysun Yilmaz

Publications and source records attributed to Aysun Yilmaz.

3 recordsLinked to original sources

PubMed2005

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.

The aim of this study was to detect VT1, VT2 and eaeA genes and to determine the frequency of these genes in Escherichia coli O157 and O157:H7 strains isolated from cattle, cattle carcasses and environmental samples of the 5 abattoirs located in Istanbul, Turkey. For this, the presence of VT1, VT2 and eaeA genes in 26 strains of E. coli O157:H7 and 6 strains of O157 was investigated by multiplex-PCR. The results have shown that eaeA gene was detected in all O157 and O157:H7 strains tested. Both VT2 and eaeA genes were detected in 4 (80%) of 5 strains of E. coli O157 and eaeA alone in 1 strain of O157. In 27 strains of O157:H7, 5 (18.5%) strains were found to be positive for VT1, VT2 and eaeA genes, 19 (70.3%) strains for both VT2 and eaeA and, 3 (11.1%) strains for only eaeA gene. Either VT1 alone or VT2 alone was not detected in any strains tested. eaeA gene alone in 2 strains, VT2-eaeA genes in 9 strains and VT1-VT2-eaeA genes in 2 strains were detected in 13 of E. coli O157:H7 strains isolated from cattle. eaeA alone in 1 strain, VT2-eaeA genes in 5 strains and VT1-VT2-eaeA genes in 2 strains were detected in 8 of E. coli O157:H7 strains isolated from carcasses. VT2-eaeA genes in 5 strains (isolated from hands, apron, knife and floor) and VT1-VT2-eaeA genes in 1 strain (isolated from knife) were also detected in 6 of E. coli O157:H7 strains isolated from environmental samples. This study reveals that most of the strains are found to be toxigenic and it is most likely that strains isolated from carcasses and abattoir environment originated from cattle feces. Therefore, HACCP systems are necessary from farm to table especially in the abattoirs to prevent contamination of meat and abattoir environment with intestinal content.

Abattoirs↗

PubMed2002

Frequency of Escherichia coli O157:H7 in Turkish cattle.

In this study, five abattoirs in Istanbul were visited between January 2000 and April 2001. During these visits, 330 cattle were selected by a systematic sampling method. Cattle were examined clinically and breed, age, and sex were recorded. Rectal swabs were taken immediately after slaughter. Immunomagnetic separation was performed, and sorbitol-negative colonies were selected on sorbitol MacConkey agar with cefixime and tellurite (CT-SMAC agar). These colonies were checked for 4-methylenebelliferyl-beta-D-glucuronide, indol, rhamnose, and urease activity and motility. Serotypes of bacteria were determined by using antisera specific for Escherichia coli O157 and H7. All cattle selected were clinically healthy. Of 88 sorbitol-negative colonies selected on CT-SMAC agar, isolates from only 14 (4.2%) cattle reacted with anti-O157, and 13 of these isolates also reacted with anti-H7. E. coli O157:H7 was isolated from all breeds, but the numbers of isolates were largest for Holstein and Swiss Brown cows. E. coli O157:H7 was most frequently isolated from 2-year-old cattle. Similarly, it was most frequently isolated from male cattle. E. coli O157:H7 was isolated from cattle slaughtered in four of the five abattoirs studied.

Abattoirs↗

PubMedDate not supplied

Sampling hazelnuts for aflatoxin: uncertainty associated with sampling, sample preparation, and analysis.

The variability associated with the aflatoxin test procedure used to estimate aflatoxin levels in bulk shipments of hazelnuts was investigated. Sixteen 10 kg samples of shelled hazelnuts were taken from each of 20 lots that were suspected of aflatoxin contamination. The total variance associated with testing shelled hazelnuts was estimated and partitioned into sampling, sample preparation, and analytical variance components. Each variance component increased as aflatoxin concentration (either B1 or total) increased. With the use of regression analysis, mathematical expressions were developed to model the relationship between aflatoxin concentration and the total, sampling, sample preparation, and analytical variances. The expressions for these relationships were used to estimate the variance for any sample size, subsample size, and number of analyses for a specific aflatoxin concentration. The sampling, sample preparation, and analytical variances associated with estimating aflatoxin in a hazelnut lot at a total aflatoxin level of 10 ng/g and using a 10 kg sample, a 50 g subsample, dry comminution with a Robot Coupe mill, and a high-performance liquid chromatographic analytical method are 174.40, 0.74, and 0.27, respectively. The sampling, sample preparation, and analytical steps of the aflatoxin test procedure accounted for 99.4, 0.4, and 0.2% of the total variability, respectively.

Aflatoxins↗