<prompt> In a patient with cystic fibrosis, high fever with productive cough. Most common causative organism isPseudomonas aerugenosaH influenzaeStaph aureusStreptococcus  <response>: Pseudomonas aeruginosa is the key bacterial agent of cystic fibrosis CF lung infections, and the most impoant pathogen in progressive and severe CF lung disease. Once these sticky biofilms are formed, inflammation results and, in some cases, leads to chronic infections that can last for months or years with productive cough and fever Ref Robbins 9e pg 178 