A 62-year-old man is brought to the emergency department due to a hand wound and "not feeling very well." He cut his right hand while cleaning a tropical fish tank at his pet shop yesterday. Although he applied topical antiseptics to the wound, it progressively became more painful and swollen. The patient also developed fever and generalized weakness. He has a history of type 2 diabetes mellitus, hypertension, and chronic kidney disease due to diabetic nephropathy. He takes methotrexate and intermittent glucocorticoids for rheumatoid arthritis. The patient drinks 1 or 2 cans of beer daily but does not use tobacco or illicit drugs. Temperature is 38.9 C (102 F), blood pressure is 96/50 mm Hg, pulse is 114/min, and respirations are 22/min. The patient appears ill. The right hand is diffusely erythematous with hemorrhagic bullae surrounding a 3-cm dorsal laceration. Laboratory results are as follows: Which of the following is the most likely causative organism of this patient's current condition?

Question

A 62-year-old man is brought to the emergency department due to a hand wound and "not feeling very well."  He cut his right hand while cleaning a tropical fish tank at his pet shop yesterday.  Although he applied topical antiseptics to the wound, it progressively became more painful and swollen.  The patient also developed fever and generalized weakness.  He has a history of type 2 diabetes mellitus, hypertension, and chronic kidney disease due to diabetic nephropathy.  He takes methotrexate and intermittent glucocorticoids for rheumatoid arthritis.  The patient drinks 1 or 2 cans of beer daily but does not use tobacco or illicit drugs.  Temperature is 38.9 C (102 F), blood pressure is 96/50 mm Hg, pulse is 114/min, and respirations are 22/min.  The patient appears ill.  The right hand is diffusely erythematous with hemorrhagic bullae surrounding a 3-cm dorsal laceration.  Laboratory results are as follows:  Which of the following is the most likely causative organism of this patient's current condition?

Quizplus · Accepted Answer

Explanation: 11ec2b69_c17e_dd23_8f63_2f4eb8599183_MD0005_00 This patient cut his hand cleaning a saltwater fish tank and developed rapidly progressive cellulitis with hemorrhagic bullae, raising suspicion for Vibrio vulnificus infection. V vulnificus is a free-living, gram-negative bacterium that grows in brackish coastal water and marine environments. Infections are acquired primarily through the consumption of raw oysters or through wound contamination during recreational activities or raw seafood handling. Illness tends to be mild in most patients, but those with underlying liver disease (eg, cirrhosis, viral hepatitis) or certain chronic medical conditions (eg, diabetes mellitus, rheumatoid arthritis) are at risk for life-threatening infection. V vulnificus wound infections are often associated with rapidly progressive cellulitis with hemorrhagic bullous lesions, and septic shock. Laboratory studies usually show leukocytosis with a left shift and renal insufficiency. Diagnosis is made by blood and wound cultures; treatment with doxycycline and ceftriaxone should not be delayed due to the high risk of death. cellulitis (Choice A) Mycobacterium marinum is found in salt and fresh water and can cause wound infections. However, lesions are usually papular and ulcerative (not necrotizing and bullous) and develop over several days (not hours). (Choice B) Pseudomonas skin infections are associated with hot tub exposure and usually result in folliculitis (tender papules or nodules). This patient with rapidly progressive cellulitis with hemorrhagic bullae after injury in a marine environment is more likely to have V vulnificus. (Choice C) Sporotrichosis is a subacute or chronic fungal infection that arises after skin inoculation with contaminated organic material (eg, soil, moss). Patients develop an ulcerative papule with similar lesions along the proximal lymphatic chain. (Choice D) Staphylococcus aureus is a common cause of skin abscess and cellulitis. However, this infection usually arises over a few days (not hours) and is typically not associated with marine environments. Educational objective: Vibrio vulnificus is a free-living, gram-negative bacterium found in estuary and marine environments. Infections occur following ingestion or wound contamination. Patients with certain characteristics (eg, liver disease, diabetes mellitus) are at high risk for fatal infection, including rapidly progressive cellulitis, hemorrhagic bullae, and septic shock. Diagnosis requires blood and wound cultures; treatment with intravenous antibiotics should not be delayed.

A 62-Year-Old Man Is Brought to the Emergency Department Due