SUMMARY The indirect immunofluoresceuce (FA) technique was used. Absolute correlation between culture and FA results was observed in the aualysis of dried foods. The FA procedure was significantly more sensitive than cultural methods for quantitative and qualitative analysis of Salmonella in liquid eggs.

No abstract

Nitric oxide, as well as several other oxides of nitrogen, were assayed for their antibacterial action. It is shown that nitric oxide has virtually no effect on bacteria, whereas both NaNO 3 and NaNO 2 appear to have either neutral or stimulatory effects. It is suggested that the formation of nitrous acid is mainly responsible for the quantitative as well as the qualitative changes that occur in the bacterial flora of cured meat. A pH-dependent “nitrite cycle” is presented to account for the production of nitrous acid in cured meat systems.

A commercial DNA hybridization assay (DNAH) for rapid detection of Salmonella in foods was compared to the conventional culture procedure. The DNAH method employed preenrichment, selective, and post-enrichment steps (4424hr) prior to performing the assay (4hr).Confirmation of positive DNAH assays was accomplished using standard culture methods for isolation of Salmonella. More than 1,600 samples were tested, representing 23 food types and including naturally contaminated, artificially inoculated, and uninoculated foods. Based on the data generated, the DNAH method was as productive as the standard culture method for detection of Salmonella in all foods and was significantly better than the culture method for certain foods.

An interstate common-source outbreak of salmonellosis was first detected in the United States in September and October, 1975, when a tenfold increase in Salmonella newport isolates was noted through routine salmonella surveillance by the Colorado Department of Health. Eighteen primary cases with a distinctive antibiotic resistance pattern (tetracycline, streptomycin, and sulfonamides) were evaluated in a case-control study, and illness was found to be associated with eating raw hamburger (p less than .001) from any store of one grocery chain (p less than .001). A Dallas, Texas, processing plant that supplied the Colorado markets also supplied other states, and these other states were alerted. Maryland discovered nine S. newport isolates with the same antibiogram and, as in the Colorado outbreak, illness was associated with eating raw or very rare ground beef from the same grocery chain (p less than .03). A third outbreak of S. newport with the same antibiogram occurred on a Florida military base. S. newport with the same antibiogram and a phage lysis pattern identical to those of the human epidemic isolates was cultured from frozen hamburger recovered in Colorado and Florida. The associated hamburger originated at the same Dallas, Texas, processing plant. A source of the epidemic strain was not identified, but the organism probably originated before delivery to the plant.