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Featured researches published by Aysun Yilmaz.


Journal of Food Protection | 2002

Frequency of Escherichia coli O157:H7 in Turkish Cattle

Aysun Yilmaz; Huseyin Gun; Huseyin Yilmaz

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.


Food Additives and Contaminants Part A-chemistry Analysis Control Exposure & Risk Assessment | 2008

Factors influencing fungal and aflatoxin levels in Turkish hazelnuts (Corylus avellana L.) during growth, harvest, drying and storage: a 3-year study.

Guner Ozay; Ferda Seyhan; Ceyda Pembeci; Sena Saklar; Aysun Yilmaz

The levels aflatoxins in Turkish hazelnuts have been monitored over a 3-years period (2002–2004). Periodical sampling was made in 72 different orchards at different locations representative of the hazelnut-growing areas and post-harvest applications. Various parameters (aflatoxins, water activity, moulds) were analysed and environmental conditions (temperature and relative humidity) recorded during growing and at different stages of harvest and post-harvest processing, involving three different harvesting methods (collection in nets, from the ground, etc.) and four drying techniques (traditional sun-drying, mechanical drying, etc.). Fungal and aflatoxin analyses (HPLC) showed no significant difference except between samples which had been in contact with the ground and those which had not (at 95% confidence level). Aflatoxins levels from the orchard recorded a maximum of 0.77 ± 0.08 ng g−1 from a total of 1624 samples. Regarding harvesting and post-harvest processes, the only application where aflatoxins were detected was in samples which had been in direct contact with the ground (max. 3.18 ± 0.03 ng g−1). Aflatoxin formation was low during storage (max. 0.34 ± 0.003 ng g−1). As a result of mycological studies, a total of 5546 Aspergillus flavus (89%) and A. parasiticus (11%) species were isolated and identified from samples. The results indicated that harvesting hazelnuts into a canvas by shaking the trees, manual harvesting of mature hazelnuts where possible, use of jute instead of nylon sacks and mechanical drying technique would minimize aflatoxin levels in hazelnuts. These recommendations have been implemented and about 4000 people in the hazelnut industry have been trained in these practices.


Journal of Clinical Virology | 2011

Frequency and phylogeny of norovirus in diarrheic children in Istanbul, Turkey

Ayşe A. Ozkul; Bekir Kocazeybek; Nuri Turan; Gábor Reuter; Kamil Bostan; Aysun Yilmaz; Eda Altan; Gulsah Uyunmaz; Ali Rıza Karakose; Karlo Muratoglu; Murat Elevli; Christopher R Helps; Huseyin Yilmaz

BACKGROUND Norovirus (NoV) is recognised as one of the most common causes of foodborne infections. Contaminated shellfish, food, water and hospitals are well documented sources of the virus. OBJECTIVE NoV in diarrheic children has not previously been investigated in Istanbul, Turkey, hence the aim of this study was to detect and investigate the frequency and phylogeny of human NoV genogroups I and II in children with acute gastroenteritis. STUDY DESIGN 238 stool samples were collected from diarrheic children from 2 hospitals (Cerrahpasa Medical School and Haseki) in Istanbul and analysed by ELISA, RT-PCR and real-time RT-PCR using both SYBR Green and probe-based assays for human NoV. Primers targeting the RNA-polymerase gene were used for RT-PCR to allow DNA sequencing of Turkish NoV strains and phylogenetic analysis to be performed. RESULTS NoV GII was detected in 36 (15.1%) of 238 samples by SYBR Green real-time RT-PCR, 10.9% by a probe-based real-time RT-PCR and 10.5% by ELISA (Ridascreen). Genogroup II (GII) the Turkish NoVs clustered with including GII4 (72.2%), GII16 (5.5%), GIIb (16.7%) and GIIe (5.5%). Two variants of GII4 (GII4-2006b and GII4-2008), GII16 and recombinant noroviruses (GIIb and GIIe) were identified. CONCLUSION This study shows a high frequency and genetic diversity of NoV GII infections in children with acute gastroenteritis in Istanbul, Turkey.


Journal of Food Protection | 2011

Investigations on the frequency of norovirus contamination of ready-to-eat food items in Istanbul, Turkey, by using real-time reverse transcription PCR

Aysun Yilmaz; Kamil Bostan; Eda Altan; Karlo Muratoglu; Nuri Turan; Derya Tan; Christopher R Helps; Huseyin Yilmaz

Investigation of norovirus (NoV) contamination of food items is important because many outbreaks occur after consumption of contaminated shellfish, vegetables, fruits, and water. The frequency of NoV contamination in food items has not previously been investigated in Turkey. The aim of this study was to investigate the frequency of human NoV genogroups (G) I and II in ready-to-eat tomatoes, parsley, green onion, lettuce, mixed salads, and cracked wheat balls. RNA was extracted with the RNeasy Mini Kit, and a real-time reverse transcription (RT) PCR assay was performed using primers specific for NoV GI and GII. Among the 525 samples analyzed, NoV GII was detected in 1 green onion sample and 1 tomato sample by both SYBR Green and TaqMan real-time RT-PCR assays; no GI virus was detected. The Enterobactericaeae and Escherichia coli levels in the NoV-positive green onion were 6.56 and 1.28 log CFU/g, and those in the tomato were 5.55 and 1.30 log CFU/g, respectively. No significant difference in the bacterial levels was found between the NoV-positive and NoV-negative samples. This study is the first in which NoV GII was found in ready-to-eat food collected from Istanbul, Turkey; thus, these foods may be considered a risk to human health. Epidemiological studies and measures to prevent NoV infection should be considered.


Journal of Feline Medicine and Surgery | 2017

Frequency, clinicopathological features and phylogenetic analysis of feline morbillivirus in cats in Istanbul, Turkey:

Huseyin Yilmaz; Bilge Kaan Tekelioglu; Aydın Gürel; Ozge Erdogan Bamac; Gulay Yuzbasioglu Ozturk; Utku Y. Cizmecigil; Eda Altan; Ozge Aydin; Aysun Yilmaz; E. Berriatua; Christopher R Helps; Juergen A. Richt; Nuri Turan

Objectives The aim of the study was to investigate feline morbillivirus (FmoPV) frequency, phylogeny and associated pathology in cats in Istanbul, Turkey. Methods Samples from sick (n = 96) and dead (n = 15) cats were analysed using reverse transcription PCR. Blood and urine analyses and histopathology were also performed. Results FmoPV RNA was detected in six cats (5.4%), including three sick (in the urine) and three dead cats (tissues). A significantly greater proportion of FmoPV RNA-positive cats had street access compared with non-infected cats. Blood samples from the morbillivirus-positive cats were negative for morbillivirus RNA. Tubular parenchymal cells, lymphoid and plasma cells in kidney and hepatocytes, lymphoid and plasma cells in liver from dead cats were also positive by immunohistochemistry for the viral N protein. Two FmoPV-positive cats were also positive for feline coronavirus RNA and one cat for feline immunodeficiency virus RNA and feline leukaemia virus proviral DNA. Phylogenetic analysis of the six FmoPV-positive cats showed that the strains were grouped into cluster D and had high similarity (98.5–100%) with strains from Japan and Germany. In the three FmoPV RNA-positive sick cats, respiratory, urinary and digestive system signs were observed as well as weight loss, fever and depression in some cats. Similar clinical signs were also seen in the morbillivirus RNA-negative sick cats. FmoPV RNA-positive cats had lower median red blood cell count, haemoglobin, albumin, albumin/globulin and urobilinogen and higher alanine transaminase, alkaline phosphatase and bilirubin compared with non-infected cats. Significant histopathology of FmoPV RNA-positive dead cats included tubulointerstitial nephritis characterised by severe granular and vacuolar degeneration of the epithelial cells of the cortical and medullary tubules as well as mononuclear cell infiltrates. Widespread lymphoid cell infiltrates were detected in the renal cortex and medullary regions of the kidneys. Cellular infiltration, cholangiohepatitis and focal necrosis in the liver were also found. Although virus-infected cells were found in the kidney and liver of FmoRV RNA-positive cats, tubulointerstitial nephritis, cholangiohepatitis and focal necrosis seen in FmoRV RNA-positive cats were similar to those observed in FmoRV RNA-negative cats. Conclusions and relevance This is the first study to show the presence of FmoPV infection in cats in Turkey. Sick cats, particularly those with kidney disease, should be tested for this virus. The genotypes found in this study were similar to previously reported strains, indicating that circulating morbilliviruses in Turkey are conserved.


İstanbul Üniversitesi Veteriner Fakültesi Dergisi | 2009

Isolation of Mannheimia haemolytica from the UHT milk.

Aysun Yilmaz; Gözde Dalkiliç Kaya

ABSTRACT This study describes the isolation and identification of Mannheimia haemolytica from the UHT milk. This is important for public health since human might get infected with this bacteria. Three package of semi-skimmed UHT drinking milk with cacao was obtained from a commercial company and analysed in a private laboratory (Istanbul, Turkey) bacteriologically. The gross apparence of the milk was not normal. It was thickened and clotted. Milk homogenates were analysed by using PCA and sheep blood agar. After Grams staining Gram negative coccobasils were observed. Pasteurella pneumotropical Mannheimia haemolytica was identified according to the API 20E. Key Words: Isolation, Mannheimia haemolytica , UHT milk UHT SUTTEN Mannheimia haemolytica IZOLASYONU OZET Bu calisma ile UHT sutten Mannheimia haemolytica izolasyonu ve identifikasyonu tanimlandi. Etken insanlarda da infeksiyona neden oldugu icin onemlidir. Bu calismada, 2008 yilinda ticari bir firmadan temin edilen yari-yagli, 3 paket UHT sutun bakteriyel analizi yapildi. Sutte organoleptik acidan anormal gorunum ve pihti saptandi. Sut homojenize edildikten sonra PCA ve koyun kanli agara ekimler yapildi. Gram boyama sonucunda Gram negatif kokobasiller goruldu ve etken API-20E identifikasyon sistemi kullanilarak Pasteurella pneumotropical Mannheimia haemolytica olarak identifiye edildi. Anahtar Kelimeler: Izolasyon, Mannheimia haemolytica , UHT sut


International Journal of Food Microbiology | 2006

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

Aysun Yilmaz; Huseyin Gun; Muammer Ugur; Nuri Turan; Huseyin Yilmaz


Journal of AOAC International | 2006

Sampling Hazelnuts for Aflatoxin: Uncertainty Associated with Sampling, Sample Preparation, and Analysis

Guner Ozay; Ferda Seyhan; Aysun Yilmaz; T. B. Whitaker; Andrew B. Slate; Francis G. Giesbrecht


Journal of AOAC International | 2007

Sampling Hazelnuts for Aflatoxin: Effect of Sample Size and Accept/Reject Limit on Reducing the Risk of Misclassifying Lots

Guner Ozay; Ferda Seyhan; Aysun Yilmaz; T. B. Whitaker; Andrew B. Slate; Francis G. Giesbrecht


Food and Environmental Virology | 2010

Real-Time PCR Detection of Norovirus in Mussels Collected from the Bosphorus in Istanbul, Turkey

Huseyin Yilmaz; Kamil Bostan; Nuri Turan; Karlo Muratoglu; Aysun Yilmaz; Ayşe A. Ozkul; Bekir Kocazeybek; Christopher R Helps

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Guner Ozay

Scientific and Technological Research Council of Turkey

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Huseyin Gun

Scientific and Technological Research Council of Turkey

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