A 68-year-old male with alcoholic cirrhosis presents with abdominal distension and hematemesis. Vital signs: BP 92/58, HR 108, RR 20, Temp 38.5°C, SpO2 98% on room air. Paracentesis fluid shows PMN count of 320/mm³ and protein <1 g/dL; blood cultures pending. Ascitic fluid Gram stain demonstrates no organisms. The patient takes propranolol but denies recent antibiotics. Which organism most likely caused spontaneous bacterial peritonitis in this cirrhotic patient?

1. A)Bacillus cereus
2. B)Clostridium difficile
3. C)Escherichia coliGABARITO
4. D)Giardia lamblia
5. E)Entamoeba histolytica