 Most E. coli strains do not cause disease , but virulent strains can cause gastroenteritis , urinary tract infections , and neonatal meningitis . It can also be characterized by severe abdominal cramps , diarrhea that typically turns bloody within 24 hours , and sometimes fever . In rarer cases , virulent strains are also responsible for bowel necrosis ( tissue death ) and perforation without progressing to hemolytic @-@ uremic syndrome , peritonitis , mastitis , septicemia , and gram @-@ negative pneumonia . 
