Baloch A.B.,Northwest University, China |
Yang H.,Institute of Quality and Standard for Agro Products |
Yang H.,Zhejiang Academy of Agricultural Sciences |
Feng Y.,Northwest University, China |
And 8 more authors.
Journal of Food Protection | Year: 2017
The aim of this study was to determine the presence and characteristics of Escherichia coli in ready-to-eat (RTE) foods. A total of 300 RTE foods samples were collected in Shaanxi Province, People's Republic of China: 50 samples of cooked meat, 165 samples of vegetable salad, 50 samples of cold noodles, and 35 samples of salted boiled peanuts. All samples were collected during summer (in July to October) 2011 and 2012 and surveyed for the presence of E. Coli. E. Coli isolates recovered were classified by phylogenetic typing using a PCR assay. The presence of Shiga toxin genes 1 (stx1) and 2 (stx2) was determined for these E. Coli isolates by PCR, and all isolates were analyzed for antimicrobial susceptibility and the presence of class 1 integrons. Overall, 267 (89.0%) RTE food samples were positive for E. Coli: 49 cold noodle, 46 cooked meat, 150 salad vegetable, and 22 salted boiled peanut samples. Of the 267 E. Coli isolates, 73.0% belong to phylogenetic group A, 12.4% to group B1, 6.4% to group B2, and 8.2% to group D. All isolates were negative for both Shiga toxin genes. Among the isolates, 74.2% were resistant to at least one antimicrobial agent, and 17.6% were resistant to three or more antimicrobial agents. Resistance to ampicillin (75.6% of isolates) and tetracycline (73.1% of isolates) was most frequently detected; 26.2% of E. Coli isolates and 68.8% of multidrug-resistant E. Coli isolates were positive for class 1 integrons. All isolates were sensitive to amikacin. Our findings indicate that RTE foods in Shaanxi were commonly contaminated with antibiotic-resistant E. Coli, which may pose a risk for consumer health and for transmission of antibiotic resistance. Future research is warranted to track the contamination sources and develop appropriate steps that should be taken by government, industry, and retailers to reduce microbial contamination in RTE foods. Copyright © International Association for Food Protection.
Li R.,Institute of Quality and Standard for Agro products |
He L.,National Shanghai Center for New Drug Safety Evaluation and Research |
Zhou T.,Agriculture and Agri Food Canada |
Ji X.,Institute of Quality and Standard for Agro products |
And 3 more authors.
Analytical and Bioanalytical Chemistry | Year: 2014
A rapid, specific, and sensitive method based on modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) coupled to gas chromatography tandem mass spectrometry (GC-MS/MS) was developed and validated for simultaneous determination of chlorpyrifos (CP) and its metabolite 3,5,6-trichloro-2- pyridinol (TCP) in duck muscle. The residues of CP and TCP were extracted by acidified acetonitrile. The fat layer of the extract was removed under-20 °C, then the organic layer was evaporated. The analytes were derivatized by N-(tert-butyldimethylsilyl)-Nmethyltrifluoroacetamide (MTBSTFA) and cleaned up by a mixture of 150 mg MgSO4, 25 mg graphitized carbon black (GCB), and 50mg N-propylethylenediamine (PSA) to remove interference. The final extract was analyzed by GC-MS/MS. Recovery values at the spiking concentrations ranged from 86.2 to 92.3 % for CP and from 74.8 to 81.8 % for TCP, with relative standard deviations (RSDs) lower than 9.5 and 12.3, respectively. The correlation coefficients of CP (from 2 to 2,000 μg/kg) and TCP (from 1 to 1,000 μg/kg) were equal to or higher than 0.998. The limits of detection (LODs) were 0.3 and 0.15 μg/kg, and the limits of quantification (LOQs) were 1.0 and 0.5 μg/kg for CP and TCP in duck muscle, respectively. The average intra- and inter-day accuracy ranged from 84.6 to 91.2 % for CP and 75.6 to 82.3 % for TCP, and the intra- and inter-day precisions were from 5.8 to 8.2 % for CP and 6.5 to 11.9 % for TCP. Furthermore, the CP and TCP residues in duck muscle samples were detected for dietary risk assessment using the validated method.