Molecular tests for infectious causes of intracranial mass lesions

Etiology	Availability*	When inclusion of NAT is indicated	Preferred testing method(s)^¶
Bacteria
Abscess^Δ	Limited	Gram stain positive, culture negative; prior antibacterial therapy	Gram stain, culture prior to antibacterial therapy
Mycobacterium tuberculosis^◊	Yes	Potentially	AFB stain, culture, histologic exam, and NAT
Viruses
Epstein-Barr virus (primary central nervous system lymphoma)	Yes	Yes	NAT, preferably quantitative
JC virus (progressive multifocal leukoencephalopathy)	Yes	Yes	NAT, preferably quantitative
Spirochetes
Treponema pallidum (syphilis)	Limited	No	Serology, CSF VDRL
Fungal
Cryptococcus	Yes	No	Antigen detection, culture
Other	Limited	Rarely	Culture, serology, histologic exam
Parasites	Limited	Rarely (eg, amebic brain abscess or immunocompromised hosts)	Stains, serology, histologic exam, and NAT for select pathogens

PPV: positive predictive value; PCR: polymerase chain reaction; CDC: Centers for Disease Control and Prevention; NAT: nucleic acid amplification testing; CSF: cerebrospinal fluid; AFB: acid-fast bacilli; VDRL: Venereal Disease Research Laboratories.
* Widespread: readily available; Yes: consistently available, but not yet common; Limited: one or two specialized laboratories (eg, CDC or research groups).
¶ Testing on brain mass tissue.
Δ 16s rDNA "universal" PCR.
◊ Limited experience, presumably poor sensitivity, high PPV.

Graphic 68813 Version 8.0

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Molecular tests for infectious causes of intracranial mass lesions