Staphylococcal Food Poisoning-A Review. I. Characteristics and Isolation of Staphylococci, Properties of Enterotoxins, and Epidemiology of Staphylococcal Intoxications

Abstract

Each year, millions of people throughout the world are victims of a foodborne disease which results when an enterotoxin produced by the bacterium Staphylococcus aureus is ingested. This review describes these intoxications, the causative organism, the enterotoxins and describes some outbreaks of staphylococcal food poisoning. After considering the taxonomy and general characteristics of these gram-positive, facultative-anaerobic, mainly parasitic cocci; characteristics suggested as indices of enterotoxigenicity are discussed. The coagulase test is the most widely used of these indices; but, production of hemolysin, phosphatase, urease, deoxyribonuclease, and protein A; hydrolysis of gelatin; pigmentation; and mannitol fermentation also have been suggested. Virtually all selective and diiferential media used to isolate staphylococci, which include those employing tellurite, egg yolk, pyruvate, glycine, fibrinogen, sodium chloride, mannitol, polymyxin and sodium azide are somewhat inhibitory to growth of these organisms. Some studies are cited which compare the relative recovery efficiencies of these media.

Staphylococcal food poisoning is strictly an intoxication which is caused by a water-soluble protein called enterotoxin that is secreted by staphylococcal cells, i. e. an exotoxin. After a general discussion of the properties of the enterotoxins, methods and media employed for producing high toxin yields are detailed. Mechanisms whereby these toxins are secreted differ in that enterotoxin A behaves as a primary metabolite and enterotoxin B acts as a secondary metabolite. Some explanations for the synthesis of enterotoxins are presented. Assay methods for these toxins that are discussed include bioassay techniques and serological procedures. Finally, some general aspects of the epidemiology of staphylococcal intoxications are described and some outbreaks of staphylococcal food poisoning are discussed.