Staphylococcus:Detection by Cultural and Modern Techniques
Résumé
Staphylococcus aureus is an opportunistic pathogen of humans and warm-blooded animals. Staphylococcus sp. was first described in 1882 by Sir Alexander Ogston who observed the presence of cocci in purulent lesions in humans. These cocci formed grape-like clusters, and Ogston named this organism Staphylococcus (Staphylo means grape in Greek). In 1884, Rosenbach studied this organism in pure culture and named the orange colony-forming coccus, Staphylococcus pyogenes aureus. Soon after, in 1884, Staphylococci entered the history of food poisoning with a large outbreak in Michigan caused by the consumption of a cheese-containing cocci. In 1914, Barber clearly demonstrated that refrigerated stored milk from a mastitic cow caused staphylococcal food poisoning in humans. In 1930, Dack isolated a S. aureus strain from a Christmas cake involved in a food poisoning causing typical symptoms of staphylococcal intoxication. Staphylococcal culture filtrates were injected intravenously to rabbits and ingested by human volunteers, leading to the onset of Staphylococcal food poisoning (SFP), 3 h post ingestion. Dack thus associated food-poisoning outbreak to the presence of a toxin produced by a S. aureus strain. This article, after some general considerations regarding taxonomy, types of strains, reservoir, contamination, and conditions leading to an SFP, will describe the main criteria and identification methods used for S. aureus identification in food samples. The phenotype-based methods will be presented first followed by the molecular-based methods.