Diagnostic accuracy of intracellular mycobacterium tuberculosis detection for tuberculous meningitis.
BACKGROUND
Early diagnosis and treatment of tuberculous meningitis saves lives, but current laboratory diagnostic tests lack sensitivity.


OBJECTIVE
We investigated whether the detection of intracellular bacteria by a modified Ziehl-Neelsen stain and early secretory antigen target (ESAT)-6 in cerebrospinal fluid leukocytes improves tuberculous meningitis diagnosis.


METHODS
Cerebrospinal fluid specimens from patients with suspected tuberculous meningitis were stained by conventional Ziehl-Neelsen stain, a modified Ziehl-Neelsen stain involving cytospin slides with Triton processing, and an ESAT-6 immunocytochemical stain. Acid-fast bacteria and ESAT-6-expressing leukocytes were detected by microscopy. All tests were performed prospectively in a central laboratory by experienced technicians masked to the patients' final diagnosis.


RESULTS
Two hundred and eighty patients with suspected tuberculous meningitis were enrolled. Thirty-seven had Mycobacterium tuberculosis cultured from cerebrospinal fluid; 40 had a microbiologically confirmed alternative diagnosis; the rest had probable or possible tuberculous meningitis according to published criteria. Against a clinical diagnostic gold standard the sensitivity of conventional Ziehl-Neelsen stain was 3.3% (95% confidence interval, 1.6-6.7%), compared with 82.9% (95% confidence interval, 77.4-87.3%) for modified Ziehl-Neelsen stain and 75.1% (95% confidence interval, 68.8-80.6%) for ESAT-6 immunostain. Intracellular bacteria were seen in 87.8% of the slides positive by the modified Ziehl-Neelsen stain. The specificity of modified Ziehl-Neelsen and ESAT-6 stain was 85.0% (95% confidence interval, 69.4-93.8%) and 90.0% (95% confidence interval, 75.4-96.7%), respectively.


CONCLUSIONS
Enhanced bacterial detection by simple modification of the Ziehl-Neelsen stain and an ESAT-6 intracellular stain improve the laboratory diagnosis of tuberculous meningitis.
1 Department of Neurology.
Guo-dong
GD
Feng
Ming
M
Shi
Lei
L
Ma
Ping
P
Chen
Bing-ju
BJ
Wang
Min
M
Zhang
Xiao-lin
XL
Chang
Xiu-chu
XC
Su
Yi-ning
YN
Yang
Xin-hong
XH
Fan
Wen
W
Dai
Ting-ting
TT
Liu
Ying
Y
He
Ting
T
Bian
Li-xin
LX
Duan
Jin-ge
JG
Li
Xiao-ke
XK
Hao
Jia-yun
JY
Liu
Xin
X
Xue
Yun-zhang
YZ
Song
Hai-qin
HQ
Wu
Guo-qiang
GQ
Niu
Li
L
Zhang
Cui-juan
CJ
Han
Hong
H
Lin
Zhi-hui
ZH
Lin
Jian-jun
JJ
Liu
Qian
Q
Jian
Jin-she
JS
Zhang
Ye
Y
Tian
Bai-yu
BY
Zhou
Jing
J
Wang
Chang-hu
CH
Xue
Xiao-fang
XF
Han
Jian-feng
JF
Wang
Shou-lian
SL
Wang
Guy E
GE
Thwaites
Gang
G
Zhao
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000942:Antigens, Bacterial / Q000134:cerebrospinal fluid*; D001426:Bacterial Proteins / Q000134:cerebrospinal fluid*; D015415:Biomarkers / Q000134:cerebrospinal fluid; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007962:Leukocytes / Q000382:microbiology*; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000276:immunology / Q000302:isolation & purification*; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013194:Staining and Labeling; D014390:Tuberculosis, Meningeal / Q000134:cerebrospinal fluid / Q000175:diagnosis*; D055815:Young Adult
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D015415:Biomarkers; C093276:ESAT-6 protein, Mycobacterium tuberculosis