Integrated strategies to optimize sputum smear microscopy: a prospective observational study.
BACKGROUND
Smear-positive tuberculosis (TB) case detection rates are far below targets in most low-income countries. The standard approach to smear microscopy involves sputum collection over multiple days and examination of sputum smears by light microscopy (LM), an insensitive and time-consuming technique.


OBJECTIVE
To determine whether two alternative approaches can increase smear-positive case detection by increasing the efficiency (single-specimen microscopy) or sensitivity (light-emitting diode [LED] fluorescence microscopy [FM]) of TB suspect evaluation.


METHODS
We enrolled patients with cough of 2 weeks or more admitted to Mulago Hospital in Kampala, Uganda and collected spot and early morning sputum specimens. We compared the diagnostic accuracy of four prespecified strategies based on the number of sputum specimens collected (one specimen versus two specimens) and the type of microscopy (LM versus LED FM) using mycobacterial culture as a reference standard.


RESULTS
Two hundred thirty-three of 464 (50%) patients had culture-positive TB. There was no difference in sensitivity between single-specimen and two-specimen strategies when smears were examined with LM (55 vs. 56%; difference, -1%; 95% confidence interval [CI], -5 to +2%) or LED FM (61 vs. 64%; difference, -3%; 95% CI, -7 to +1%). LED FM was more sensitive than LM with both the single-specimen (61 vs. 55%; difference, 6%; 95% CI, 2-10%) and two-specimen strategies (64 vs. 56%; difference, 8%; 95% CI, 3-12%). Findings were similar among the HIV-infected patient subset (n = 321 patients).


CONCLUSIONS
In low-income, high TB burden settings, single-specimen microscopy and LED FM, either alone or in combination, could considerably increase identification of smear-positive TB cases.
Cattamanchi
Adithya
A
Division of Pulmonary and Critical Care Medicine, San Francisco General Hospital, University of California, San Francisco, California, USA. acattamanchi@medsfgh.ucsf.edu
Huang
Laurence
L
Worodria
William
W
den Boon
Saskia
S
Kalema
Nelson
N
Katagira
Winceslaus
W
Byanyima
Patrick
P
Yoo
Samuel
S
Matovu
John
J
Hopewell
Philip C
PC
Davis
J Lucian
JL
D000328:Adult; D006801:Humans; D008297:Male; D008856:Microscopy, Fluorescence / Q000379:methods; D008859:Microscopy, Polarization / Q000379:methods; D011446:Prospective Studies; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013048:Specimen Handling; D013183:Sputum / Q000382:microbiology*; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000382:microbiology*; D014454:Uganda