The Practitioner's Mastitis Laboratory

Abstract

Samples should be plated as soon as possible after taking; however, they may be refrigerated for a period of time prior to plating. If samples are refrigerated for a 12- to 18-hour period, many times a preincubation of samples is advisable for an hour or two prior to plating. I personally find that this procedure is unnecessary many times. I have included a handwritten sheet indicating the method I follow in inoculating the culture plate.
I will concentrate primarily on reading and interpreting the results of inoculating this particular plate. There are three types of media: the bright red media is blood agar and naturally permits the growth of almost all mastitis pathogens. The purple-red media is a special strep media, permitting the growth of only streptococci. The restrictive or inhibitory nature of this medium is due to the inclusion of thallium and crystal violet in media. The clear purple-blue-colored media is a media that permits only the growth of coliform organisms.