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level: L10 Detection Limit Enrichment

Questions and Answers List

level questions: L10 Detection Limit Enrichment

QuestionAnswer
Detection limit- refers to sensitivity of method - sensitivity: lowest number of target organisms that can be detected by the method
Enrichment- technique involving use of a nutrient medium (usually broth) that allows growth of microorganisms to detectable levels - qualitative test - use non-selective or selective media
Non-selective enrichmentallows growth of all organisms (target organism and background microorgansims)
Selective enrichment- allows growth of target organism to detectable levels while inhibiting growth of background microorgansims - commonly used for pathogens (Tetrathionate broth for salmonella, listeria enrichment broth for listeria)
Specificity- ability of a method to differentiate the target organism from background microflora in a sample - a method with high specificity will commonly produce fewer false positive results
False positive- a sample that tests positive by the microbiological analysis but tests negative based on cultural methods
False negative- a sample that tests negative by the microbiological analysis but tests positive based on cultural methods