Sensitivity and specificity of fluorescence microscopy for diagnosing pulmonary tuberculosis in a high HIV prevalence setting.
METHODS
Mulago Hospital, Kampala, Uganda.


OBJECTIVE
To evaluate the diagnostic performance of fluorescence microscopy (FM) for diagnosing pulmonary tuberculosis (TB) in a high human immunodeficiency virus (HIV) prevalence setting.


METHODS
Consecutive in-patients with cough for >2 weeks submitted two sputum specimens for smear microscopy. Smears were examined by conventional light microscopy (CM) and FM. The performance of the two methods was compared using mycobacterial culture as a reference standard.


RESULTS
A total of 426 patients (82% HIV-infected) were evaluated. FM identified 11% more smear-positive patients than CM (49% vs. 38%, P < 0.001). However, positive FM results were less likely than positive CM results to be confirmed by culture when smears were read as either 'scanty' (54% vs. 90%, P < 0.001) or 1+ (82% vs. 91%, P = 0.02). Compared to CM, the sensitivity of FM was higher (72% vs. 64%, P = 0.005), and the specificity lower (81% vs. 96%, P < 0.001). In receiver operating characteristic analysis, maximum area under the curve for FM was obtained at a threshold of >4 acid-fast bacilli/100 fields (sensitivity 68%, specificity 90%).


CONCLUSIONS
Although FM increases the sensitivity of sputum smear microscopy, additional data on FM specificity and on the clinical consequences associated with false-positive FM results are needed to guide implementation of this technology in high HIV prevalence settings.
Cattamanchi
A
A
Division of Pulmonary and Critical Care Medicine, University of California, San Francisco, California, USA. acattamanchi@medsfgh.ucsf.edu
Davis
J L
JL
Worodria
W
W
den Boon
S
S
Yoo
S
S
Matovu
J
J
Kiidha
J
J
Nankya
F
F
Kyeyune
R
R
Byanyima
P
P
Andama
A
A
Joloba
M
M
Osmond
D H
DH
Hopewell
P C
PC
Huang
L
L
D000328:Adult; D001431:Bacteriological Techniques / Q000592:standards; D015169:Colony Count, Microbial; D003371:Cough / Q000382:microbiology; D005189:False Positive Reactions; D005260:Female; D015658:HIV Infections / Q000150:complications* / Q000453:epidemiology; D006801:Humans; D008297:Male; D008856:Microscopy, Fluorescence / Q000592:standards; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D011237:Predictive Value of Tests; D015995:Prevalence; D011446:Prospective Studies; D012372:ROC Curve; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology; D013194:Staining and Labeling / Q000592:standards; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000453:epidemiology / Q000382:microbiology; D014454:Uganda / Q000453:epidemiology