Bundaberg tragedy: a diphtheria vaccine is contaminated with Staph. aureus bacterium, resulting in the deaths of twelve children in the Australian town of Bundaberg.

The Bundaberg tragedy was a medical disaster that occurred in January 1928, resulting in the deaths of 12 children in Bundaberg, Queensland, Australia. A royal commission concluded that the deaths were caused by the contamination of a diphtheria vaccine with the bacterium Staphylococcus aureus.

Staphylococcus aureus is a Gram-positive spherically shaped bacterium, a member of the Bacillota, and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin. It is often positive for catalase and nitrate reduction and is a facultative anaerobe, meaning that it can grow without oxygen. Although S. aureus usually acts as a commensal of the human microbiota, it can also become an opportunistic pathogen, being a common cause of skin infections including abscesses, respiratory infections such as sinusitis, and food poisoning. Pathogenic strains often promote infections by producing virulence factors such as potent protein toxins, and the expression of a cell-surface protein that binds and inactivates antibodies. S. aureus is one of the leading pathogens for deaths associated with antimicrobial resistance and the emergence of antibiotic-resistant strains, such as methicillin-resistant S. aureus (MRSA). The bacterium is a worldwide problem in clinical medicine. Despite much research and development, no vaccine for S. aureus has been approved.

Bundaberg is the major regional city in the Wide Bay-Burnett region of the state of Queensland, Australia. It is the ninth largest city in the state. The Bundaberg central business district is situated along the southern bank of the Burnett River about 20 km (12 mi) from its mouth at Burnett Heads, where it flows into the Coral Sea. The city is sited on a rich coastal plain, supporting one of the nation's most productive agricultural regions. The area of Bundaberg is the home of the Taribelang-Bunda, Goreng Goreng, Gurang, and Bailai peoples. The common nickname for Bundaberg is "Bundy", although its history as a major sugar producing region means it is often referenced as the "Rum City" or "Sugar City". The residents of the city are referred to colloquially as 'Bundabergians.' In the 2021 census, the Bundaberg urban area had a population of 73,747 people.