Rare Presentation of Toxoplasma Pneumonitis in the Absence of Neurological Symptoms in an AIDS Patient and Use of Next-Generation Sequencing for Diagnosis

Abstract

Toxoplasma gondii is a known cause of encephalitis in human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) patients. Toxoplasma pneumonitis is a manifestation of extracerebral toxoplasmosis and can be clinically indistinguishable from other opportunistic infections including Pneumocystis jirovecii pneumonia (PJP) and miliary tuberculosis. In this case report, Toxoplasma pneumonitis and disseminated toxoplasmosis was diagnosed using next-generation sequencing (NGS) and polymerase chain reaction (PCR) assessment. NGS can detect microbial cell-free DNA (cfDNA) circulating in the plasma of over 1,000 pathogens. This case is a rare presentation of Toxoplasma pneumonitis in the absence of neurological symptoms and we discuss the use of NGS of microbial cfDNA and PCR tests that may be utilized for the timely diagnosis of such challenging cases.

Learning points: Next-generation sequencing can help make a correct diagnosis and detect culture-negative opportunistic infections.Recognition of Toxoplasma pneumonitis as a rare presentation of disseminated toxoplasmosis.In cases of Toxoplasma pneumonitis, brain imaging should be conducted to rule out CNS involvement even in the absence of neurological symptoms.

Keywords: AIDS; Disseminated toxoplasmosis; Toxoplasma pneumonitis, next-generation sequencing, HIV.

Figure 1

Chest x-ray with multinodular changes in both lungs

Figure 2

(A) CT chest axial lung window showing miliary changes in both lungs; (B) CT chest axial lung window showing several nodules with developing central cavitation and bilateral consolidation; (C) coronal window showing bibasilar airspace disease with confluent consolidation throughout the lung bases

Figure 3

(A) T1 axial MRI brain image showing bilateral lesions with hyperintensity peripherally and low signal centrally; (B) T2 FLAIR MRI brain image with multiple lesions and findings suggestive of haematogenously disseminated toxoplasmosis; (C) diffusion-weighted axial brain MRI with lesions noted; (D) sagittal MRI showing lesions in the cerebellum. Leftward arrows in all images show multiple brain lesions at different stages