Effectiveness of bacteriophages in reducing Escherichia coli O157:H7 on fresh-cut cantaloupes and lettucet.
Consumption of produce contaminated with Escherichia coli O157:H7 has resulted in cases of foodborne illness. We determined the efficacy of a mixture of three E. coli O157:H7-specific bacteriophages (ECP-100) in reducing the number of viable E. coli O157:H7 on contaminated fresh-cut iceberg lettuce and cantaloupe. E. coli O157:H7 was spot inoculated on lettuce pieces (9 cm2) with a population of 3.76 log CFU/cm2, allowed to dry, and then sprayed with a control (phosphate-buffered saline) or ECP-100 to deliver 7.98 log PFU/cm2 to lettuce stored for 2 days at 4 degrees C. Cut pieces of cantaloupe were spot inoculated with E. coli O157:H7 (4.55 log CFU/ml) and treated with the control or ECP-100 (6.69 log PFU/ml), and then stored at 4 or 20 degrees C for up to 7 days. On days 0, 2, 5, and 7, cantaloupe samples were homogenized, and populations of E. coli O157:H7 were enumerated. Populations of E. coli O157:H7 on lettuce treated with ECP-100 on 0, 1, and 2 days (0.72, <0.22, and 0.58 log CFU/cm2 of lettuce) and stored at 4 degrees C were significantly (P < 0.05) lower than those treated with the control (2.64, 1.79, and 2.22 log CFU/cm2), respectively. Populations on cut cantaloupes treated with ECP-100 on days 2, 5, and 7 (0.77, 1.28, and 0.96 log CFU/ml) and stored at 4 degrees C were significantly lower than those cut cantaloupes treated with the control (3.34, 3.23, and 4.09 log CFU/ml), respectively. This study is the first to show the effectiveness of bacteriophages to reduce E. coli O157:H7 on fresh-cut lettuce and cantaloupes.
Sharma
Manan
M
Environmental Microbial and Food Safety Laboratory, U.S. Department of Agriculture, Agricultural Research Service, Animal and Natural Resources Institute, Beltsville, Maryland 20705, USA. manan.sharma@ars.usda.gov
Patel
Jitendra R
JR
Conway
William S
WS
Ferguson
Sean
S
Sulakvelidze
Alexander
A
D003090:Coliphages / Q000502:physiology*; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D028463:Cucumis melo / Q000382:microbiology*; D019453:Escherichia coli O157 / Q000254:growth & development* / Q000821:virology; D005506:Food Contamination / Q000032:analysis* / Q000517:prevention & control; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods*; D006801:Humans; D018545:Lactuca / Q000382:microbiology*