A Staphylococcus aureus Foodborne Outbreak Linked to Hand-Shredded Chicken in a Corporate Canteen in Shenzhen, China

A point-source staphylococcal foodborne outbreak occurred in a corporate canteen in Shenzhen, China, in April 2024, affecting 16 of 107 exposed employees (attack rate, 15.0%). A retrospective cohort study identified a hand-shredded chicken dish as the vehicle of transmission (relative risk = 5.91; 95% confidence interval, 1.41 to 24.76). S. aureus and its enterotoxin A were recovered from patient specimens and from the implicated chicken, whereas three other retained dishes yielded the organism without detectable toxin; S. aureus was also isolated from an asymptomatic food handler. Approximately 15 kg of cooked chicken was shredded by hand and held overnight in a covered basin filled to a depth of roughly 15 cm, in a crowded refrigerator, giving an interval of about 20 h between the estimated point of contamination and consumption. A one-dimensional cooling estimate suggests that the interior of such a mass would have remained above 20 °C for 10-14 h, conditions under which published data for cooked chicken are compatible with the accumulation of enterotoxin A to an illness-inducing level. Brief steaming before service would not have removed preformed toxin. This outbreak illustrates two preventable failures common in mass catering: bare-hand contact with cooked, ready-to-eat food, and inadequate cooling of large batches during storage.