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E. albertii can grow in poultry at refrigeration temperatures.

E. albertii is the newest species designated in the genus Escherichia. It has been associated with diarrheal disease in developing nations. The impact of food preservation treatments against E. albertii has been studied, but data on how the organism behaves in food is lacking.

Scientists at Texas A&M University and elsewhere set out to measure the growth characteristics of three strains of E. albertii--strains 9194, 10457 and 19982-in ground turkey stored at refrigeration and abusive temperatures. Their work shows that E. albertii is capable of growth in poultry at refrigeration temperatures, and, as expected, in poultry stored at abusive temperatures.

In experiments, the researchers applied gamma irradiation at a dose of 5 kGy to ground turkey. The samples were inoculated separately with each strain at a population of 4 log CFU per gram. The samples were stored at 5 C, 15 C and 30 C. At predetermined intervals, 25-gram samples of inoculated turkey were withdrawn, blended with 225 ml of diluent, and enumerated onto a culture medium of 1% L-Rhamnose MacConkey agar (RMAC). The scientists incubated the plates at 37 C for 24 hours before counting presumptive colonies of E. albertii.

Uninoculated turkey was plated on tryptic soy agar as well as RMAC. Plates were incubated similarly. After 21 days at 5 C, the amount of strains 9194, 10457 and 19982 increased by 1.40 log CFU per gram, 1.97 log CFU per gram and 1.02 log CFU per gram, respectively, although populations had remained static until 14 days.

When the samples were stored at 15 C, strains 9194, 10457 and 19982 increased by 4.51 log CFU per gram, 4.89 log CFU per gram and 4.71 log CFU per gram, respectively. Strain 10457 increased to 8.65 log CFU per gram after seven days at 15 C, while the other strains were about 1 log lower. At 30 C, levels of all three strains increased by approximately 4 log CFU per gram by the second day of storage.

Although aerobic microorganisms were recovered from uninoculated turkey on tryptic soy agar, no colonies characteristic of E. albertii were recovered on RMAC.

Further information. Thomas Matthew Taylor, Department of Animal Science, Texas A&M University, Room 310 Kleberg, 2471 TAMU, College Station, TX 77843; phone: 979-845-3935; fax: 979-845-6433; email:
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Publication:Microbial Update International
Date:Apr 1, 2010
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