When you hear hoofbeats, look for horses... but watch out for zebras. 

The crazy patients, drugs, alcohol, all three combined, all need an extra look in the ER... They may be many things, but there's no law says they can't be gravely ill.

That said, I'm not seeing signs of infection in anything in the article. It's impossible to judge whether the doctor made appropriate assessments based on the article. 

Sometimes, people do things right, and they still die. At times doctors do due diligence and the patient expires. 

I'd like to see a more thorough account of the events leading to the death of the patient.