A 35-year-old woman comes to the emergency department due to an itchy rash that appeared earlier this morning. She recently returned from a family vacation at a resort in Cancun. Two days ago, the patient's husband developed similar symptoms. The patient has no significant past medical history and takes no medications. She has no known allergies. Her temperature is 37.6 C (99.7 F). On examination, there is a diffuse, pruritic, papulopustular rash that is most noticeable on the trunk and extremities. Microbiologic analysis of a pustular fluid sample demonstrates oxidase-positive gram-negative rods that produce pigment on culture medium. Which of the following is the most likely source of this patient's infection?

Question

A 35-year-old woman comes to the emergency department due to an itchy rash that appeared earlier this morning.  She recently returned from a family vacation at a resort in Cancun.  Two days ago, the patient's husband developed similar symptoms.  The patient has no significant past medical history and takes no medications.  She has no known allergies.  Her temperature is 37.6 C (99.7 F).  On examination, there is a diffuse, pruritic, papulopustular rash that is most noticeable on the trunk and extremities.  Microbiologic analysis of a pustular fluid sample demonstrates oxidase-positive gram-negative rods that produce pigment on culture medium.  Which of the following is the most likely source of this patient's infection?

Quizplus · Accepted Answer

The clinical syndrome described is consistent with "hot tub folliculitis," a superficial pseudomonal infection of the hair follicle. This condition, characterized by a pruritic, papulopustular rash, is most commonly seen with outbreaks from public or hotel swimming pools or hot tubs where the chemicals in the pool water have not been maintained at appropriate concentrations, thereby allowing Pseudomonas aeruginosa proliferation. P aeruginosa is ubiquitous in nature. Many P aeruginosa infections often begin with exposure to a water source or creation of a moist environment (ie, swimmer's ear, hot tub folliculitis, burn wound). P aeruginosa is a motile gram-negative rod that is oxidase-positive, produces green pigment (pyocyanin, pyoverdin) during culture, and is nearly always implicated in "hot tub folliculitis." (Choices A, B, and C) Scabies can be transmitted by human contact but is due to a mite. P aeruginosa is not transmitted by food or insects. (Choice D) Cat scratch disease is due to the oxidase-negative gram-negative Bartonella henselae and can present as vesicular, erythematous, or papular lesions localized to the site of primary inoculation. (Choice F) Although P aeruginosa grows in soil, the most likely source of this patient's infection is exposure to water. Educational objective: "Hot tub folliculitis" is a superficial and self-limited Pseudomonas aeruginosa infection of the hair follicles that tends to occur in minor outbreaks following exposure to a pool or spa in which the chemicals have not been maintained at appropriate concentrations. Pseudomonas are gram-negative, oxidase-positive, nonlactose-fermenting, motile rods that produce green pigment.

A 35-Year-Old Woman Comes to the Emergency Department Due to an Itchy