The estimation of extracellular protein production in detecting enterotoxigenic staphylococci

294 strains of staphylococci isolated from feces, throat and nasal swabs were assayed for production of enterotoxin, coagulase, thermostable deoxyribonuclease (thermonuclease) and high levels of global extracellular protein (ECP). The relationship observed among these biochemical features suggested that the determination of ECP can be an useful test in detecting enterotoxigenic staphylococcal strains which do not exhibit coagulase and thermonuclease production. In fact, among 17 strains which produced large amounts of ECP, but were coagulase- and thermonuclease-negative, 4 were found to be enterotoxigenic, while of 95 strains which produced low levels of ECP and were coagulase and thermonuclease-negative, none was enterotoxigenic.