Pope Francis has a "polymicrobial respiratory tract infection." Here's what that means.

Pope Francis has a complex infection in his respiratory system and will require more targeted drug treatment, according to Vatican authorities Monday. He has been hospitalized since Friday at Rome's Gemelli hospital after coming down with bronchitis the week before, the Vatican said.

Officials said the 88-year-old pope is suffering from a "polymicrobial respiratory tract infection," but gave no further details on the severity of his illness or what would change in his treatment. 

Here's a look at the Pope's latest diagnosis and what his treatment could involve.