Light-emitting diode with various sputum smear preparation techniques to diagnose tuberculosis.
METHODS
Mawenzi Regional Hospital, northern Tanzania.


OBJECTIVE
To determine the value of light-emitting diode (LED) microscopy in diagnosing tuberculosis (TB) on bleach-treated and direct sputum smears.


METHODS
Sputum samples were collected from patients suspected of pulmonary  TB who presented consecutively at the laboratory for smear evaluation between December 2009 and February 2010. Four smears were prepared from each specimen: conventional Ziehl-Neelsen (ZN), direct auramine, bleach centrifugation and bleach short sedimentation auramine smears. A light microscope  was used to examine ZN smears and an LED fluorescent microscope to examine auramine-stained smears.


RESULTS
Of the 267 sputum samples examined, respectively 78 (29%), 62 (23%), 74 (28%) and 48 (18%) were acid-fast bacilli (AFB) positive by the bleach centrifugation, bleach short sedimentation,  direct auramine and ZN methods. Bleach centrifugation identified 30 (11%) more positives than ZN microscopy (P < 0.001), but was not superior to the direct auramine method (P = 0.46), which yielded 26 (10%) more positives than ZN microscopy (P < 0.001). Fluorescent  LED required a shorter smear reading time (1.5 min on average), while the light microscope took 4 min (P < 0.001).


CONCLUSIONS
Fluorescent LED microscopy with direct smear preparation is rapid and effective. Further studies are needed to ascertain its performance under routine  conditions.
Kilimanjaro Clinical Research Institute, Kilimanjaro Christian Medical Centre, Moshi, Kilimanjaro Region, Tanzania. mekonnen.meseret@gmail.com
M
M
Habtamu
J
J
van den Boogaard
A
A
Ndaro
R
R
Buretta
C F
CF
Irongo
D A
DA
Lega
B M
BM
Nyombi
G S
GS
Kibiki
D001431:Bacteriological Techniques / Q000379:methods; D001576:Benzophenoneidum / Q000737:chemistry; D002498:Centrifugation / Q000379:methods; D006801:Humans; D008856:Microscopy, Fluorescence / Q000379:methods*; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D012973:Sodium Hypochlorite / Q000737:chemistry; D013183:Sputum / Q000382:microbiology*; D013194:Staining and Labeling / Q000379:methods; D013636:Tanzania; D013997:Time Factors; D014376:Tuberculosis / Q000175:diagnosis* / Q000382:microbiology
D001576:Benzophenoneidum; D012973:Sodium Hypochlorite