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Song Q.,U.S. Center for Disease Control and Prevention | Zhu Z.,Xiangshan Entry Exit Inspection and Quarantine Bureau | Chang Y.,Ningbo Medical Treatment Center Lihuili Hospital | Shen X.,U.S. Center for Disease Control and Prevention | And 2 more authors.
Journal of Food Science | Year: 2016

The aim of this study was to investigate the prevalence and characteristics of staphylococcal enterotoxin B (SEB) producing Staphylococcus aureus (S. aureus) isolated from food sources. A total of 412 S. aureus isolates were recovered from 1970 milk and dairy samples (n = 236) and 2450 meat samples (n = 176) in China from 2009 to 2014. Of the 412 isolates, 124 isolates were tested positive for 1 or more classical staphylococcal enterotoxin (SE) genes using PCR, and 31 isolates were positive for seb gene and further proved to be SEB-producing. Four SE profiles were observed among 31 SEB-producing isolates when investigated using ELISA kit, that is, SEB (16 isolates), SEA+SEB (6 isolates), SEB+SEC (6 isolates), and SEB+SED (3 isolates). Thirteen sequence types (STs) were identified in the 31 SEB-producing S. aureus isolates using multilocus sequence typing (MLST). The 3 most detected STs were ST1 (7 isolates), ST188 (6 isolates), ST59 (3 isolates). Two distinct clusters were identified by pulsed-field gel electrophoresis (PFGE), each of which showed excellent consistency with ST188 and ST1 achieved by MLST, respectively. In summary, this study reveals that various SE profiles are observed in SEB-producing S. aureus isolates and the great part of SEB-producing S. aureus isolates are showed as clusters. Especially, a particular cluster of ST188 strains was observed in SEB-producing S. aureus isolates which was associated with outbreaks of SFP and needs further attention. © 2016 Institute of Food Technologists®. Source


Chang Y.,Ningbo Medical Treatment Center Lihuili Hospital | Gao H.,U.S. Center for Disease Control and Prevention | Zhu Z.,Xiangshan Entry Exit Inspection and Quarantine Bureau | Ye S.,U.S. Center for Disease Control and Prevention | And 4 more authors.
Foodborne Pathogens and Disease | Year: 2016

Staphylococcus aureus with the ability of staphylococcal enterotoxins (SEs) production is one of the most common causes of bacterial foodborne outbreaks worldwide. In our study, 336 S. aureus isolates were recovered from 3476 food samples during 2010-2014. A total of 86 S. aureus isolates were proved to be enterotoxin-producing strains with PCR and enzyme-linked immunosorbent assay. In the 86 isolates, 20 STs were identified using multilocus sequence typing (MLST) and 20 isolates were typed as sequence type 5 (ST5), which was the most prevalent ST using MLST. There were six SE profiles and high carrier rates of sec (50%) and sed (75%) genes in the 20 S. aureus ST5 isolates. Additionally, 8 antibiotic resistance patterns were observed, and 10 multidrug-resistant isolates (50%) and 4 methicillin-resistant S. aureus isolates were identified. Our findings illustrate high prevalence of S. aureus ST5 isolates from food sources and diversity in SE profiles and antibiotic resistance patterns. These results indicate that great difference in the ability of obtaining SE production and antimicrobial resistance may exist between different genetic lineages of S. aureus strains. © Copyright 2016, Mary Ann Liebert, Inc. 2016. Source


Wang T.,Ningbo University of Technology | Chen Y.,Xiangshan Entry Exit Inspection and Quarantine Bureau | Hu M.,Ningbo University of Technology | Li X.,Xiangshan Entry Exit Inspection and Quarantine Bureau
Chinese Journal of Chromatography (Se Pu) | Year: 2012

A novel method for the extraction of inosinic acid in Smoked Katsuwonus pelamis based on water was developed. The inosinic acid was extracted by 95°C water for 5 min. The subsequent analysis of inosinic acid was achieved on an Agilent Zorbax SB-C18 column (l50 mm × 4.6 mm, 5 μm) with the mobile phase of methanol-50 mmol/L ammonium acetate (5=95, v/v) at a flow rate of 1. 0 mL/min at 30°C. The detection wavelength was set at 254 nm. The results showed that the linear range for inosinic acid in Smoked Katsuwonus pelamis was between 1.0 mg/L and 120.0 mg/L with the limit of detection (LOD, S/N=3) of 4 mg/kg and the limit of quantification (LOQ, S/N=10) of 12 mg/kg. At the spiked levels of 0.40, 2.00, 4.00 g/kg (n=3), the recoveries ranged from 84.6% to 100.2% with the relative standard deviations (RSDs) between 1.00% and 6. 12%. Compared with traditional extraction method by perchloric acid, the extraction efficiency was improved by 37.0%. The novel method is safe, stable and accurate for the determination of inosinic acid in Smoked Katsuwonus pelamis, which can also be applied to the determination of inosinic acid in other foods and deserved to be spread. © 2010 Editorial Office of Chinese Journal of Chromatography, Dalian Institute of Chemical Physics, CAS. Source

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