Snapshot A 56-year-old man is admitted to the hospital for appendicitis. During the appendectomy, he had a foley inserted which was removed successfully post-operatively. A few days after the procedure, the patient started experiencing fevers, chills, and pain with urination. A urinalysis revealed increased white blood cells, red blood cells, and bacteria. A urine culture grew a catalase-positive, weakly lactose fermenting gram-negative bacilli. Introduction Classification Serratia marcescens a catalase-positive, weakly lactose fermenting, and gram-negative bacillus produces prodigiosin, a pale pink or dark red pigment clinical syndromes are often associated with recent instrumentation/procedure urinary tract infection wound infections pneumonia endocarditis meningitis Epidemiology demographics male > female children > adults risk factors hospital admission diabetes mellitus kidney failure chronic obstructive pulmonary disease immunocompromised status recent procedure at the site of infection i.e., instrumentation of urinary tract or bronchoscopy Pathogenesis the bacteria colonizes the respiratory and urinary tracts and causes nosocomial infections Prognosis Serratia meningitis and endocarditis have the highest mortality Presentation Symptoms fever and chills shortness of breath frequent urination dysuria Physical exam suprapubic tenderness Studies Urine dipstick nitrite positive leukocyte esterase positive Bacterial culture on EMB agar lactose fermenters grow as purple or black colonies Making the diagnosis based on clinical presentation and laboratory studies Differential E. coli urinary tract infection distinguishing factors no red pigment may not be associated with recent instrumentation Treatment Management approach Serratia is resistant to many antibiotics, including first-generation cephalosporins final choice of antibiotics depends on the sensitivities of cultured bacteria Medical 2nd generation or higher cephalosporins (cefoxitin, cefotaxime, and cefepime) indication all patients fluoroquinolones indications all patients Complications Septic shock