The first victim was a premature boy in the intensive care unit whose mother noticed a mysterious irritation in his groin; it grew into an open wound burrowing into the baby's abdomen. The last patient to die was a 10-year-old girl, whose face was ravaged. Three other patients at Children's Hospital here were also stricken, including a 13-year-old boy who his parents said endured over 20 surgical procedures in 54 days in a futile effort to save him. Like the others, Zachary Malik Tyler, the 13-year-old, arrived at Children's Hospital battling a serious illness before being overwhelmed by an infection. "What haunts me more than anything is thinking about what he suffered," said Stephen Tyler, his father.