Interferon gamma quantification in cerebrospinal fluid compared with PCR for the diagnosis of tuberculous meningitis.
OBJECTIVE
To assess the utility of interferon gamma (INF-gamma) levels in cerebrospinal fluid (CSF), for the diagnosis of tuberculous meningitis (TBM), and compare these results with aPCR technique.


METHODS
We studied CSF samples from patients with proven or probable TBM and a control group, composed by patients with other causes of meningitis and without meningitis. INFgamma levels were measured by radioimmunoassay. A PCR technique was performed using IS6110 primers.


RESULTS
Of the 127 patients studied, 20 (15.6%) had TBM, 59 (46%) had meningitis of another aetiology and 49 (38.4%) had were HIV and non-HIV patients with normal CSF. The area below the ROC curve for interferon gamma levels in the diagnosis of TBM was 0.94. A cut-off of 6.4 IU/mL yielded a sensitivity of 70% and a specificity of 94%. False positive results were observed in 7 of the 59 patients (11.8%) with non-TB meningitis, (patients with herpetic meningoencephalitis and meningitis due to intracellular microorganisms). INF-gamma sensitivity was higher than PCR (70% vs. 65%). Both tests performed together showed higher sensitivity (80%) and specificity (92.6%).


CONCLUSIONS
CSF INF-gamma levels (> 6.4 IU/mL) are very valuable in TBM diagnosis. PCR and INF-gamma could be simultaneously used to increase the diagnostic yield.
Juan
Rafael San
RS
Infectious Diseases Unit, Hospital General Universitario "Doce de Octubre", Carretera de Andalucía Km. 5.4., 28041, Madrid, Spain. rafasjg@yahoo.es
Sánchez-Suárez
Carmen
C
Rebollo
María J
MJ
Folgueira
Dolores
D
Palenque
Elia
E
Ortuño
Blanca
B
Lumbreras
Carlos
C
Aguado
José M
JM
D000293:Adolescent; D000328:Adult; D000368:Aged; D019540:Area Under Curve; D003937:Diagnosis, Differential; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000134:cerebrospinal fluid* / Q000235:genetics; D008297:Male; D008582:Meningitis, Aseptic / Q000134:cerebrospinal fluid; D016920:Meningitis, Bacterial / Q000134:cerebrospinal fluid / Q000235:genetics / Q000382:microbiology; D008587:Meningitis, Viral / Q000134:cerebrospinal fluid / Q000235:genetics / Q000821:virology; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000254:growth & development; D011446:Prospective Studies; D012372:ROC Curve; D011863:Radioimmunoassay; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014390:Tuberculosis, Meningeal / Q000134:cerebrospinal fluid / Q000175:diagnosis* / Q000235:genetics / Q000382:microbiology
D007371:Interferon-gamma