A 65-year-old man is admitted to the intensive care unit with second- and third-degree burns over 25% of his total body surface area. Intravenous fluids and analgesics are administered, and his wounds are cleaned and debrided. After 7 days, the patient develops a fever and his leukocyte count rises to 16,000 cells/µL. Examination of the burns on his left leg shows surrounding warmth, erythema, and induration. Gram stain of his wound tissue is shown in the image below. Culture on MacConkey agar grows oxidase-positive colonies that do not ferment lactose. Which of the following is the best initial treatment for this patient?

Question

A 65-year-old man is admitted to the intensive care unit with second- and third-degree burns over 25% of his total body surface area.  Intravenous fluids and analgesics are administered, and his wounds are cleaned and debrided.  After 7 days, the patient develops a fever and his leukocyte count rises to 16,000 cells/µL.  Examination of the burns on his left leg shows surrounding warmth, erythema, and induration.  Gram stain of his wound tissue is shown in the image below.  Culture on MacConkey agar grows oxidase-positive colonies that do not ferment lactose.  Which of the following is the best initial treatment for this patient?

Quizplus · Accepted Answer

11ec160b_385b_6e0b_9249_0f2b000fbcd8_MD0001_00 Burn patients are at increased risk of bacterial infection due to loss of the barrier function of the skin, post-burn immune dysfunction, and lack of blood flow to necrotic areas. Common pathogens include Gram-positive (eg, Staphylococcus aureus, Enterococcus species) and Gram-negative (eg, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, and Acinetobacter species) bacteria. This patient's burn is infected with Gram-negative rods that are oxidase-positive and non-lactose- fermenting, making P aeruginosa the most likely pathogen. Cephalosporins such as cefepime and ceftazidime have good anti-pseudomonal coverage. (Choice B) Ceftriaxone is a third-generation cephalosporin used primarily for the treatment of community-acquired pneumonia and bacterial meningitis. It has activity against some Gram-positive (eg, Streptococcus pneumoniae, S pyogenes) and Gram-negative (eg, Haemophilus influenzae, K pneumoniae, E coli) pathogens. Unlike ceftazidime, it has poor activity against P aeruginosa. (Choice C) Doxycycline is effective against Lyme disease and many tickborne rickettsial diseases but does not have good anti-pseudomonal coverage. (Choice D) Moxifloxacin is a fluoroquinolone used mainly for the treatment of bacterial infections that cause exacerbation of chronic obstructive pulmonary disease, sinusitis, and community-acquired pneumonia. Unlike ciprofloxacin and levofloxacin, moxifloxacin has poor anti-pseudomonal activity. (Choice E) Trimethoprim-sulfamethoxazole is used to treat susceptible organisms that cause urinary tract, gastrointestinal, and skin infections. It is the drug of choice for organisms such as Pneumocystis jiroveci, Toxoplasma gondii, Nocardia, and Stenotrophomonas maltophilia. It does not have activity against P aeruginosa. Educational objective: Pseudomonas aeruginosa is a major pathogen in burn patients. Only a few specific penicillins (eg, ticarcillin, piperacillin) and cephalosporins (eg, ceftazidime, cefepime) have activity against it. Certain aminoglycosides, fluoroquinolones (eg, ciprofloxacin, levofloxacin), and carbapenems (eg, imipenem, meropenem) are also effective. __________ References: Update on the treatment of Pseudomonas aeruginosa pneumonia. (http://www.ncbi.nlm.nih.gov/pubmed/19520717)

A 65-Year-Old Man Is Admitted to the Intensive Care Unit