engleski

Evaluation of the new "Chromogenic Salmonella Agar" for the selective isolation of Salmonella spp. from stools

Objectives: The purpose of this research was to evaluate suitability of the new 'Chromogenic Salmonella Agar', CSA (Biolife, Italy) in comparison with 'Salmonella Shigella Agar' CSA (Biolife, Italy) for the selective isolation of Salmonella spp. from stools. Methods: One Gram of stool was put in 9mL of Selenite-F enrichment medium (Biolife-Italy) at 37 ºC for 24 h followed by streaking onto SSA as a referent medium and CSA as a test medium. After incubation at 37 ºC/24 h, suspect colonies from both media were transfered onto Kligler Iron Agar, KIA (Biolife-Italy) for preliminary testing. Strains showing typical reactions on KIA were confirmed by biochemical tests using API 10s gallery (bioMeriew, France) followed by final identification with sera manifactured by Immunology Institut, Zagreb. Specificity and sensitivity was calculated and compared by McNamara test. Results: During September to November 2000, total of 300 stools were examined. 45 out of 76 suspected colonies were confirmed to be Salmonella spp. on SSA (sensitivity 100%, specificity 88%). From the same number of stool samples, 45 out of 46 suspected colonies showing magenta colour on CSA, were confirmed to belong to genus Salmonella with one false positive reaction due to Pseudomonas spp. (sensitivity 100%, specificity 99%). In comparison these two media CSA showed better results in preliminary test (x2 = 28, d.f. = 1, P< 0.01). Confirmation test gave the same results on both media. Serotyping confirmed all isolates as: somatic antigen 0 1, 9, 12 ; flagellar antigen H 1 fase: gm - Salmonella enterica serotype Enteritidis. Conclusion: Due to its good sensitivity and specificity, CSA can be recommended for the use for screening of human stools when Salmonella spp. are concerned and may help to reduce the work load when this medium is used for plating after enrichment.

"Chromogenic Salmonella Agar" ; Salmonella

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