What could be the cause of infection after surgery of perforated Megacolon.

[nchandrani]

My nephew is suffering from Ulcerative colitis and hospitalised. He was under treatment and was given Pentasa granules , T PAN (40mg), Tab wysolone and Pentasa Anema. As there was no improvement. Doctor adviced to have Exemptia (Adalimumab) injection. 4 injections (40mg 8ml) was given. Next day he was having stomach pain, tight and rigid stomach, and fast breathing. He was immediately admitted in the nearby hospital and doctor found he was suffering from megacolon (toxic colon). After taking x-ray and CT scan, it was found that there was perforation in his stomach. The Doctors who adviced injection told immediate surgery is needed for this megacolon and perforation problem. After surgery my nephew was unable to response problem and doctor informed that he had a infection after surgery. Doctor told that he had a infection and due to infection there was liver problem. They gave antibiotics but it was not working. The infection started increasing and affected the liver and brain. My question is what could be the cause of infection. Is Exemptia injection has any side affect  ? or the infection my be caused by Megacolon after surgery. Please advice? He is in ICU and in critical condition