Snapshot A 55-year-old man presents to the emergency department from a subacute rehabilitation center for altered mental status. The patient has been slowly becoming confused over the course of a few days. His temperature is 102°F (38.8°C), blood pressure is 138/101 mmHg, pulse is 102/min, and respirations are 18/min. On physical exam, the patient is only oriented to self but not to place or time. His short-term memory is impaired. Of note, the patient has a Foley catheter. Chest auscultation is unremarkable. The patient grimaces upon palpation of the suprapubic area. Laboratory studies are significant for a leukocytosis with left shift and positive blood and urine cultures grow Pseudomonas aeruginosa. (Urosepsis) Introduction Aerobic, non-lactose fermenting, oxidase-positive, gram-negative bacillus Microbiology culture has a sweet and grape-like odor green pigment Associated conditions cystic fibrosis ecthyma gangrenosum hot tub folliculitis osteomyelitis burns nosocomial infections (e.g., catheter use) otitis externa (swimmers ear) Epidemiology Risk factors hot tubs contaminated contact lenses contaminated water ventilator use burns immunocompromised cystic fibrosis most common pathogen found in this patient population ETIOLOGY Pathogenesis Pseudomonas aeruginosa has the ability to be an indolent colonizer within the lungs (which explains why it is associated with cystic fibrosis) invade tissue resulting in pneumonia and bacteremia Presentation Symptoms/physical exam depends on which organ is involved (e.g., pneumonia can lead to a cough, fever, and shortness of breath) Studies Lab studies complete blood count may reveal a leukocytosis with a left shift blood culture urine culture Gram staining of the cerebral spinal fluid if meningitis is suspected Differential Upper respiratory tract infection caused by other organisms differentiating factors patients with have microbiologic testing suggestive of a different pathogen Treatment Conservative source control indication should be performed in all patients in which a source (e.g., catheter) is introducing the pathogen into the host Medical antipseudomonal antibiotics indication first-line medical treatment to eradicate the pathogen medications penicillins piperacillin-tazobactam ticarcillin-clavulanate cephalosporins ceftazidime cefepime monobactam aztreonam fluoroquinolones ciprofloxacin levofloxacin carbapenems meropenem doripenem Complications Septic shock Prognosis Varied due to causing a wide spectrum of disease pseudomonas bacteremia can lead to septic shock if untreated