Falsecolour transmission electron micrograph TEM of a colony of Staphylococcus aureus a species of spherical Gram positive nonmotile bacteria Many species of Staphylococcus cause disease in man through secretion of exotoxins S aureus is commonly present on skin and mucous membranes and causes boils and internal abscesses and is the commonest cause of pyogenic pusforming infections in man Other species produce toxins causing food poisoning Staphylococcal enteritis severe potentially fatal results from use of broadspectrum antibiotics which allows S aureus to proliferate in the intestines Magnification X at mm size