Question : A 58-year-old woman returns from a Nile cruise with bloody diarrhoea. She ate on the cruise ship for the majority of her trip, but also ate fruit from local street sellers. She is opening her bowels some 6-8 times/day, with copious amounts of bloody diarrhoea and mucus. On examination her BP is 100/60 mmHg, pulse is 92/min and regular. Her abdomen is soft but there is some left-sided tenderness in particular on palpation. Investigations: Haemoglobin 13.2 g/dl, White Cell Count (WCC) 11.1 x 109/1, Platelets 299 x 109/I, Sodium (Na+) 138 mmol/l, Potassium (K+) 3.3 mmol/l, Creatinine 135 pmol/l. Which of the following organisms would you consider as the most likely cause?