Figure 3. Survival of E. coli O157:H7 ATCC 700728 and EC4045 on inoculated lettuce in a growth chamber.

E. coli O157:H7 cell amounts were measured by plate count (culturable), real-time PCR (total), and PMA real-time PCR (viable) methods. Plants were inoculated with a spray bottle (A) or by drop (B) and incubated at a relative humidity of 30%. The mean ± stdev of 15 lettuce plants or leaves at each sampling time for three replicate experiments is shown.