A 12-year-old girl is brought to the emergency department with meningitidis. What motile amoeba is likely found in the CSF?

The correct answer is Naegleria fowleri trophozoites because this organism is a free-living amoeba that can cause primary amoebic meningoencephalitis (PAM), a severe and often fatal infection of the central nervous system. When a person is exposed to contaminated freshwater, Naegleria fowleri can enter the body through the nasal mucosa, travel up the olfactory nerve, and reach the central nervous system, leading to inflammation and significant neurological symptoms.

In cases of meningitis, particularly in a child, the presence of Naegleria fowleri in the cerebrospinal fluid (CSF) is a key finding. The PS symptoms include headaches, fever, nausea, and stiff neck, which align with the clinical presentation of meningitis here. Therefore, when examining CSF of someone diagnosed with meningitis, detecting Naegleria fowleri trophozoites would confirm a diagnosis of PAM.

Other amoebae listed do not cause meningitis like Naegleria fowleri does. Iodamoeba butschlii, Endolimax nana, and Dientamoeba fragilis are non-pathogenic or primarily associated with intestinal infections rather than central nervous