Friday, December 17, 2010
Fertility ( Growth Promotion ) Test For Media
Ø Prepare media
Ø The selection of organisms depends on medium to be subjected to fertility test.
Ø Subculture the required organism ( like: - S. aureus, C.albicans, , B. subtilis, C. sporogenes,E.coli , Salmonella and Pseudomonas ) on Nutrient agar slants ( for bacteria ) and Soyabean casein digest agar ( for fungi ) , one day before, to get 24 hrs old culture.
Ø Prepare thin suspension and dilute it serially so as to get 10 - 100 cfu/ml which shall be determined by plate counts.
Ø Keep the inoculated plates for incubation and serial dilution tubes in the refrigerator.
Ø After confirmation of the counts, inoculate 1ml of suspension containing 10-100 cfu/ml into the media taken for growth promotion test and incubate them at the required temperatures ( i.e at 30 - 35°C for bacteria , 20-25°C for fungi ).
Ø If the growth occurs within three days in case of bacteria and five days in case of fungus the media is found suitable for microbiological testing.
Ø In case if the medium is not differential as in case of Tetrathionate broth , the subsequent tests, as per respective General procedure, shall be carried out to demonstrate the fertility of the medium
Ø Record the details
Ø Every new batch or lot of dehydrated media.
Ø MEDIA STOCK REOCRD
Take the stock of dehydrated media once in a six month.