A RAPID METHOD FOR DETERMINATION OF STAPHYLOCOCCUS-AUREUS BASED ON MILK COAGULATION BY USING A SERIES PIEZOELECTRIC QUARTZ-CRYSTAL SENSOR

A series piezoelectric quartz crystal (SPQC) sensor was utilized to de termine the number of bacteria based on the coagulation of milk in whi ch Staphylococcus aureus (S. aureus) had grown. Compared with the meth od based on a PQC coated with a thin film, earlier it had the advantag e that no dilution of the medium was needed and cease of the oscillati on can be avoided throughout the experiment. Moreover, it was rapid, t he turning-point time (TT) for quantitative detection which was the ti me at which the frequency begins to return after a drop in response cu rve was easy to determine and there was a good relation between TT and logarithm of the initial concentration of S. aureus in the range of 2 .4 x 10(2)-2.4 x 10(5) cells ml(-1). (C) 1998 Elsevier Science B.V. Al l rights reserved.