should i sue the hospital for severe infection i got while in the hospital a week after surgery?

It is difficult to answer your question given the lack of specific information. Generally speaking, you cannot maintain a cause of action for malpractice against a hospital for contracting an infection. There are a few exceptions to this rule, but the idea is that a hospital cannot eliminate the possibility that people will contract post-op infections. In fact, hospitals sometimes spawn bacterial infections that are resistant to treatment simply because their efforts to decontaminate their facilities result in the breeding of "super bacteria." MRSA infections are an example of this phenomenon. Malpractice cases related to post-op infections caused during hospitalization are usually about a failure to timely treat the infection. These cases are very difficult because it is difficult to prove that different treatment would have lead to a different outcome, since the more insidious an infection is and the more damage it causes, the less likely earlier intervention would have changed the outcome.