Performance assessment of the RIDA COUNT method for the enumeration of bacteria in milk

[摘要] The method of Rida Count plates is used in the world with a demonstrated reliability, but as being introduced for the first time in Cuba, a verification of its operation was carried out. For that reason, the method was compared with the conventional methods used for the enumeration of total bacteria, total coliforms, enterobacteria, Escherichia coli, and Salmonella spp. in agreement with the standard ISO/IEC 16140:2003 for the use of alternative microbiological methods. Reconstituted sterile milk samples were inoculated with strains of Escherichia coli (ATCC 25922), Salmonella enterica serovar typhimurium (Laboratory of Microbiological Control, CENSA) and Staphylococcus aureus (ATCC 6538). The linear correlation coefficients of Rida Count for total count, total coliforms, enterobacteria, Escherichia coli, and Salmonella spp. in relation to the conventional contaminated sterile milk method were of 0.997, 0.999, 0.998, 0.996 and 0.997; in the case of raw milk, they were of 0.998, 0.991, 0.994, 0.991 and 0.996, respectively. The experimental and practical results demonstrated that the operation of the method was in agreement with that described in literature and it constituted a convenient alternative for the milk laboratories of the country with limited resources for the quantification of microorganisms since it reduced the time and labor in the laboratory, offering results between 24-48 hours and increasing the yield in a 95%.

[学科分类] 兽医学

[关键词] Rida Count;enumeration of microorganisms;conventional method