Great work! You were able to distinguish between pneumonitis vs. pneumonia at the start of the case, recognizing the patient's stability from a pulmonary standpoint in the face of an abnormal radiograph. However, that did change over the next few days, requiring recognition of when to consider and treat pneumonia.
Similarly, a positive respiratory culture in isolation does not necessarily constitute pneumonia, nor warrant treatment, as it might just represent colonization. We must evaluate whether these other clinical features are present as well.
You can usually accomplish this with IV vancomycin and cefepime or piperacillin/tazobactam. Of course, we should try to get culture data to help guide narrowing of this regimen as soon as possible.