A 28-year-old woman is brought to the emergency department due to abrupt onset of high fever, severe headache, photophobia, and confusion. Temperature is 38.9 C (102 F), blood pressure is 90/60 mm Hg, and pulse is 118/min. On examination, the patient is obtunded and diaphoretic. There is increased resistance to passive neck flexion. Pupillary reflexes are brisk and symmetric, and the patient moves all extremities equally to painful stimuli. Lumbar puncture is performed, and cerebrospinal fluid (CSF) analysis reveals neutrophilic pleocytosis, elevated protein, and low glucose. CSF Gram stain shows no bacteria, and fungal antigen testing is negative. Wet mount preparation of the CSF shows motile trophozoites. Which of the following most likely predisposed this patient to her current condition?

Question

A 28-year-old woman is brought to the emergency department due to abrupt onset of high fever, severe headache, photophobia, and confusion.  Temperature is 38.9 C (102 F), blood pressure is 90/60 mm Hg, and pulse is 118/min.  On examination, the patient is obtunded and diaphoretic.  There is increased resistance to passive neck flexion.  Pupillary reflexes are brisk and symmetric, and the patient moves all extremities equally to painful stimuli.  Lumbar puncture is performed, and cerebrospinal fluid (CSF) analysis reveals neutrophilic pleocytosis, elevated protein, and low glucose.  CSF Gram stain shows no bacteria, and fungal antigen testing is negative.  Wet mount preparation of the CSF shows motile trophozoites.  Which of the following most likely predisposed this patient to her current condition?

Quizplus · Accepted Answer

11ec160b_3846_d482_9249_1b48efc6e23a_MD0001_00 This patient has meningeal signs, confusion, and trophozoites in her cerebrospinal fluid (CSF), raising strong suspicion for primary amebic meningoencephalitis (PAM). PAM is caused by Naegleria fowleri, a free-living, motile, protozoan parasite that lives in warm water and soil worldwide. Exposure primarily occurs when humans inadvertently inhale the organism during recreational water activities such as swimming, diving, or using hot springs. Most individuals do not become ill, but a minority develop fatal meningoencephalitis after N fowleri penetrates the olfactory mucosa, crosses the cribriform plate, and invades the olfactory bulb. Patients with PAM usually develop acute confusion, high fever, photophobia, and meningeal symptoms (eg, neck stiffness, headache). Lumbar puncture opening pressures are often markedly elevated, and CSF analysis typically reveals neutrophilic pleocytosis, high protein, and low glucose. Suspicion is usually raised when CSF testing is negative for bacterial, viral, or fungal pathogens. The diagnosis is confirmed when wet mount of the CSF reveals motile trophozoites. Antibiotics (eg, amphotericin B) are often administered, but PAM is almost always fatal. (Choice A) Neisseria meningitidis is a gram-negative bacterium that is typically spread by close contact with a carrier or infected individual. It is a common cause of community-acquired bacterial meningitis and usually presents with rapidly progressive headache, myalgia, confusion, sepsis, and death. Patients also frequently have an ecchymotic/purpuric rash. Diagnosis is often made with blood culture and/or CSF Gram stain. (Choice B) Lyme disease, a tick-borne illness caused by the spirochete Borrelia burgdorferi, is endemic to the wooded areas of New England. Patients with early disseminated Lyme disease can sometimes develop cranial nerve palsies or lymphocytic meningitis, but wet mount of the CSF would not show trophozoites. Diagnosis of early disseminated Lyme disease is usually made with serology. (Choice D) Malaria is a mosquito-borne protozoal illness that is endemic to Southeast Asia. Patients with malaria can develop encephalopathy (cerebral malaria) with confusion, headache, and delirium. However, CSF analysis is usually fairly normal, and trophozoites are not typically seen in the CSF. Malaria is usually diagnosed when trophozoites are isolated on peripheral blood smear. (Choice E) Syphilis is caused by the spirochete Treponema pallidium and is transmitted primarily by unprotected sexual intercourse. Patients with syphilis infections can occasionally develop lymphocytic meningitis early in infection. However, syphilis is usually diagnosed with serology; trophozoites would not be present in the CSF. Educational objective: Naegleria fowleri is a free-living, motile protozoan that lives in warm water. Exposure can result in primary amebic encephalitis, which is characterized by acute fever, headache, confusion, and neck stiffness. The diagnosis is confirmed when motile trophozoites are seen on cerebrospinal fluid wet mount. Nearly all patients die.

A 28-Year-Old Woman Is Brought to the Emergency Department Due