Community Acquired Pneumonia

Please answer all four questions in the case study:
LT is a 62 yo male diagnosed with community acquired pneumonia.

1). As the patients primary care provider what antibiotic would be a good first line therapy to try and why?

2). What are the monitoring parameters of efficacy and side effects of the agent you picked?

3). How would your therapy change if the patient had received antibiotic therapy several weeks prior for a different infection?

4). After being treated for pneumonia LT the 62 yo developed severe diarrhea, how will you determine if this is simple antibiotic associated diarrhea or a Clostridium Difficile infection?  If a C.Diff infection how will you treat it?