Hello, acute pancreatitis may sometimes be complicated with infections. Part of the pancreas is destroyed and its remnants create a friendly environment for pathogens. Many doctors would prescribe antibiotics even before an infection is documented, as a preventive measure. I can t tell if this is the infection your brother has - obviously. His doctors have test results in their hands and should know better. Sometimes acute pancreatitis is attributed to an inflammed gallbladder. An inflammed gallbladder may harbor pathogens as well, so this is another potential cause. I hope I ve helped! Contact me again, if you d like more information or details. Kind Regards!