for E. coli O157:H7 by PCR amplification using primers for the E. coli O157:H7–specific eae gene. Under laboratory
conditions, house flies were confined on manure or agar medium containing E. coli O157:H7 tagged with green fluorescent
protein (GFP) and then tested for their capacity to transfer the microbes to spinach plants. GFP-tagged bacteria were detected
on surfaces of 50 to 100% of leaves examined by fluorescence microscopy and in 100% of samples tested by PCR. These
results indicate that flies are capable of contaminating leafy greens under experimental conditions and confirm the importance
of further investigation of the role of insects in contamination of fresh produce.