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The relationship between concentration of a dual marker strain of Salmonella Typhimurium in bovine faeces and its probability of detection by immunomagnetic separation and culture
- Source :
- Journal of Applied Microbiology. 97:1054-1062
- Publication Year :
- 2004
- Publisher :
- Oxford University Press (OUP), 2004.
-
Abstract
- To modify a strain of Salmonella serotype Typhimurium to express unique marker traits and then define how the concentration of the marker in bovine faeces affects the probability of its detection by culture preceded by immunomagnetic separation (IMS).DNA encoding for the production of green fluorescent protein (gfp) and resistance to kanamycin was inserted into the bacterial chromosome of Salm. Typhimurium. Transposon insertion was demonstrated by Southern blot hybridization. Varying amounts of one electroporant (gfpSal-1) were inoculated into suspensions of bovine faeces and attempts made to isolate gfpSal-1 using a protocol based on pre-enrichment incubation, IMS and enrichment in selective media. Isolates of gfpSal-1 were differentiated from wild strains of Salmonella using fluorescence under u.v. light and expression of kanamycin resistance. A logistic and Gompertz function each derived from the dose-response data partially explained the observations with the fit of the Gompertz function judged to be superior. The 10, 50 and 90% limits of detection from the Gompertz function were estimated to be 1.92, 2.03 and 2.27 CFU g(-1) respectively.Reliance on the traditional concept of 'limit of detection' could introduce unacceptable errors in the interpretation of test findings when the concentration of Salm. Typhimurium in bovine faeces (pooled or individual) is below ca 3 CFU g(-1) of faeces.The dose-response curve can be used to aid the design of protocols for detecting Salmonella in individual and pooled faecal specimens. The experiments demonstrate that both reporter genes in tandem are useful for studying the performance of culture-based methods for detecting pathogens in faeces.
- Subjects :
- Genetic Markers
Salmonella typhimurium
Kanamycin Resistance
Salmonella
Green Fluorescent Proteins
Gompertz function
Cattle Diseases
Immunomagnetic separation
medicine.disease_cause
Polymerase Chain Reaction
Applied Microbiology and Biotechnology
Microbiology
Feces
Genes, Reporter
Drug Resistance, Bacterial
medicine
Animals
Cloning, Molecular
Southern blot
Salmonella Infections, Animal
biology
Immunomagnetic Separation
Kanamycin
General Medicine
biology.organism_classification
Enterobacteriaceae
DNA Transposable Elements
Cattle
Genome, Bacterial
Bacteria
Biotechnology
medicine.drug
Subjects
Details
- ISSN :
- 13652672 and 13645072
- Volume :
- 97
- Database :
- OpenAIRE
- Journal :
- Journal of Applied Microbiology
- Accession number :
- edsair.doi.dedup.....b4dca9ace9ee9a228eec5d8837392ba0