An International Outbreak ofSalmonellaInfections Caused by Alfalfa Sprouts Grown from Contaminated Seeds

Abstract

An outbreak of Salmonella serotype stanley infections occurred in the United States and Finland in 1995. The outbreak was investigated through case-control studies in Arizona, Michigan, and Finland; by isolate subtyping; and by tracing and culturing of the implicated food. Alfalfa sprout consumption was the only exposure associated with S. stanley infections in Arizona (matched odds ratio [MOR] = 11.1; 95% confidence interval [CI], 1.4-513), Michigan (MOR = 5.5; CI, 1.6-23), and Finland (MOR undefined; CI, 4.9-infinity). US and Finnish patient isolates were a unique outbreak strain distinct from S. stanley isolates not linked to the outbreak. Alfalfa sprouts eaten by patients in 6 US states and Finland were traced to seed shipped by a Dutch shipper. Thus, it was concluded that alfalfa sprouts grown from contaminated seed caused an international outbreak of > or =242 S. stanley infections in > or =17 US states and Finland. This outbreak illustrates a new mechanism through which contamination of fresh produce can cause large, widely dispersed outbreaks.

Microbiological quality of organic vegetables produced in soil treated with different types of manure and mineral fertilizer

“…This concern is directed to Salmonella spp. (24,27,40,47,49) and E. coli O157:H7, because cattle is its main reservoir, explaining the risk of transmission by manure (22,34,43,50).…”

Salmonella enterica Serotype Typhimurium DT 104 Antibiotic Resistance Genomic Island I in Serotype Paratyphi B

“…The fact that not all patients reported eating bean sprouts may be due to recall bias, since interviews took place 16 to 32 days after the onset of illness and sprouts are often served inconspicuously in salads, sandwiches, and other meals ( 11 , 12 ). Other explanations might be secondary transmission and cross-contamination of other food items.…”

Gene and genome trees conflict at many levels

“…Salmonella infection, known as salmonellosis, induces vomiting, diarrhoea, fever and abdominal cramps and can last several days. Outbreaks of YESS group-associated diseases are common (Tacket et al 1985;Mahon et al 1997;Lee et al 2000;Varma et al 2003), and consequently at the time of writing, this group of prokaryotes is the most extensively sampled in genome sequencing projects, making it useful to illustrate the points we wish to make.…”