Abstract
The necessity of developing a quick, sensitive, and reliable test for Salmonella in nonfat dry milk (NDM) is evident from the recent tracing of Salmonella outbreaks to this product. Normally, coagulation of casein occurs when assaying NDM under regular cultural conditions, raising the possibility of trapped bacteria. After 20 hr of incubation of NDM in preenrichment lactose broth, enrichment was achieved by using Selenite-Cystine Broth. Smears from the enrichment broth were examined by the fluorescent-antibody technique (FAT) with a commercially available polyvalent O globulin conjugated with fluorescein. Standard cultural methods (SCM) were performed for comparison with FAT. Sensitivity of FAT was definitely improved by the use of trypsin. Casein coagulation of NDM can be avoided by addition of trypsin to samples during initial preenrichment in lactose broth. Samples containing approximately one Salmonella per 10 g were easily detected by FAT with the use of trypsin-treated samples. The method required only 42 hr to complete. Additionally, the use of trypsin enhanced recovery of Salmonella by use of SCM, as evidenced by alteration in the observed coliform to Salmonella ratios.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- GEORGALA D. L., BOOTHROYD M. A RAPID IMMUNOFLUORESCENCE TECHNIQUE FOR DETECTING SALMONELLAE IN RAW MEAT. J Hyg (Lond) 1964 Sep;62:319–327. doi: 10.1017/s0022172400040031. [DOI] [PMC free article] [PubMed] [Google Scholar]
- HAGLUND J. R., AYRES J. C., PATON A. M., KRAFT A. A., QUINN L. Y. DETECTION OF SALMONELLA IN EGGS AND EGG PRODUCTS WITH FLUORESCENT ANTIBODY. Appl Microbiol. 1964 Sep;12:447–450. doi: 10.1128/am.12.5.447-450.1964. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Insalata N. F., Schulte S. J., Berman J. H. Immunofluorescence technique for the detection of salmonellae in various foods. Appl Microbiol. 1967 Sep;15(5):1145–1149. doi: 10.1128/am.15.5.1145-1149.1967. [DOI] [PMC free article] [PubMed] [Google Scholar]
- NORTH W. R., Jr Lactose pre-enrichment method for isolation of Samonella from dried egg albumen. Its use in a survery of commercially produced albumen. Appl Microbiol. 1961 May;9:188–195. doi: 10.1128/am.9.3.188-195.1961. [DOI] [PMC free article] [PubMed] [Google Scholar]