Isolation and characterization of staphylococcus aureus from two large-scale food poisoning outbreaks in Vietnam

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Lam Quoc Hung1, Huong Minh Nguyen3, Ta Thi Yen2, Le Vinh Hoa2, Tran Hong Ba2, Pham Le Quyen2,4, Do Thi Thu Huong5, Nguyen Thanh Trung2, Le Thi Hong Hao2


1Vietnam Food Administration, 1135 Pho Nui Truc, Giang Vo, Ba Dinh, Hanoi, Vietnam
2National Institute for food control, NIFC-Vietnam, 65 Pham Than Duat, Hanoi, Vietnam
3Institute of Biotechnology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, CauGiay, Hanoi, Vietnam
4Quang Binh Center for Disease Control and Prevention, 3150 Rampart Road, Fort Collins, USA
5National Agro-Forestry Fisheries Quality Assurance Department, 10 Nguyen Kong Hoan, Ba Đình, Hanoi, Vietnam


In Vietnam and around the world, Staphylococcus aureus remains a major hazard of food safety and food poisoning. S. aureus is present in many places and easily contaminates food production during processing chains.
In this study, we successfully isolated S. aureus strains from suspected samples of two food borne poisoning outbreaks in Ha Giang and Vinh Phuc in 2017 and 2018, respectively. The collected samples were examined for presence of staphylococcal enterotoxins (SEs) by using 3MTMTECRATM Staph Enterotoxin kit, from there all the samples were positive with SEs. Different strains of S. aureus were isolated and then confirmed by MALDI-TOF technique. Those strains then were stored in Brain heart solution with 15% glycerol until further analysis.
Our results identified three STs, ST96, ST88 (spa type t7558), and ST72 (spa type t3092), were responsible for two outbreaks. Two virulence genes detected from the above strains were sea and sec. Furthermore, these strains are test for antibiotic resistance susceptibility with commonly antibiotics. Penicillin are found to be resisted by all three STs, in particularly, ST96 and ST88 are both resistant to erythromycin while ST72 is resistant to gentamicin.
Taken together, our study highlights the usefulness of molecular characterization to study and monitor bacterial pathogens associated with food poisoning outbreaks in Vietnam.

antibiotic-resistant, food poisoning, β-lactamase, ESBL, ampC β-lactamases, Staphylococcus areus, MLST, Spa genes, staphylococcal toxins.
Lam Quoc Hung, Huong Minh Nguyen, Ta Thi Yen, Le Vinh Hoa, Tran Hong Ba, Pham Le Quyen, Do Thi Thu Huong, Nguyen Thanh Trung, Le Thi Hong Hao. Isolation and characterization of staphylococcus aureus from two large-scale food poisoning outbreaks in Vietnam. Health Risk Analysis, 2020, no. 3, pp. 139–147. DOI: 10.21668/health.risk/2020.3.17.eng
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