Spinach infected with E. coli, SEM

Scanning electron micrograph (SEM) of Escherichia coli bacteria localized near a stoma from the common spinach leaf (Spinacia oleracea). Escherichia coli is a Gram-negative, enteric, facultatively anaerobic, rod prokaryote (bacterium). Toxic E. coli strains, such as the E. coli 0157:H7 strain, are a health hazard and cause severe food poisoning and sometimes death. E. coli may grow on vegetables if the water used for irrigation is contaminated with animal faecal material. Even though washing is recommended, this electron micrograph shows that the E. coli bacteria are present in higher concentrations around stomata (openings for respiration in leaves) and can enter the leaves through the stomata. Once inside the leaf bacteria would be hard to remove by washing. Similar bacterial contamination has been found in lettuce and green onions. Magnification: x800 when shortest axis printed at 25 millimetres.