 Historically, many rectal abscesses are caused by bacteria common in the digestive system, such as E. coli.While this still continues often to be the case, there has recently been an increase in the causative organism being staphylococcus, as well as the difficult to treat community-acquired methicillin-resistant S. aureus.Because of the increasing appearance of more exotic bacteria in anal abscesses, microbiological examination will always be performed on the surgical exudate to determine the proper course of any antibiotic treatment.