A 39-year-old paraplegic man with an indwelling bladder catheter comes to the emergency department complaining of 24 hours of rigors, nausea, and vomiting. His temperature is 38.9 C (102 F). Physical examination shows suprapubic and costovertebral angle tenderness. Urinalysis shows 3+ leukocyte esterase and numerous white blood cells. Urine and blood cultures grow non-lactose-fermenting Gram-negative rods. Which of the following pathogens is the most likely culprit?

Question

A 39-year-old paraplegic man with an indwelling bladder catheter comes to the emergency department complaining of 24 hours of rigors, nausea, and vomiting.  His temperature is 38.9 C (102 F).  Physical examination shows suprapubic and costovertebral angle tenderness.  Urinalysis shows 3+ leukocyte esterase and numerous white blood cells.  Urine and blood cultures grow non-lactose-fermenting Gram-negative rods.  Which of the following pathogens is the most likely culprit?

Quizplus · Accepted Answer

Patients with indwelling bladder catheters are at increased risk for urinary tract infections (UTIs) caused by both typical (eg, Escherichia coli, Klebsiella pneumoniae, Staphylococcus saprophyticus, Proteus mirabilis) and opportunistic (eg, Pseudomonas, Enterococcus, other Staphylococci, fungal) organisms. This patient's culture results are consistent with Pseudomonas aeruginosa, the only non-lactose-fermenting, Gram-negative rod listed. It is also the only one that is oxidase positive. (Choice A) Enterobacter cloacae is a lactose-fermenting, Gram-negative rod characterized by extensive antibiotic resistance. It causes nosocomial infections, including UTIs, pneumonia, and surgical site infections. (Choice B) Enterococcus faecalis is a Gram-positive coccus in the Enterococcaceae family that is a common cause of opportunistic UTIs. Vancomycin-resistant Enterococcus is a particularly fearsome isolate that is increasing in prevalence. (Choice C) Escherichia coli is a lactose-fermenting, Gram-negative rod and the leading cause of both complicated (including catheter-associated) and uncomplicated UTIs. (Choice D) Klebsiella pneumoniae is a lactose-fermenting, Gram-negative rod. It is a common cause of spontaneous bacterial peritonitis and nosocomial pneumonias as well as UTIs. (Choice F) Staphylococcus saprophyticus is a catalase-positive, coagulase-negative, Gram-positive coccus that typically causes UTIs in sexually active women. It is differentiated from S epidermidis by being novobiocin resistant. Educational objective: Pseudomonas aeruginosa is an oxidase-positive, non-lactose-fermenting, Gram-negative organism. It is a common cause of urinary tract infections in patients with indwelling bladder catheters.

A 39-Year-Old Paraplegic Man with an Indwelling Bladder Catheter Comes