Phenol ammonium sulphate basic fuchsin staining of sputum in pot for the detection of acid-fast bacilli.

Selvakumar, N.; Premkumar, M.; Kumar, V.; Gopi, P.G.; Sivagamasundari, S.; Prabhakaran, E.; Narayanan, P.R.

Indian Journal of Medical Research; 2008; 128; 194-197.

Background & objectives : Improper practices of making direct smears of sputum for detection of acid-fast bacilli (AFB) and of disposing sputum cups are hazardous. The present study was undertaken with the objective to stain sputum samples in their containers by ‘phenol (10%) ammonium sulphate (4%) basic fuchsin (2%) solution' and to decolourize and counterstain their smears for detection of AFB- (henceforth called pot method) and to compare the smear results of pot method with the standard Ziehl-Neelsen (ZN) method.

Methods : A total of 575 selected sputum samples from pulmonary tuberculosis patients were stained by the standard ZN and pot methods and the proportions of AFB positive smears were compared.

Results : Of the 575 samples, 126 were AFB positive for both the staining methods and the difference was not statistically significant. Pot method missed 9 ZN positive smears (8 scanty and one 1+) and ZN method missed 9 pot positive smears (9 scanty) and the difference was not significant. High grade smears (3+) were seen more in pot method (42) than in ZN method (25) and the difference was significant.

Interpretation & conclusion : Our findings showed that pot method was comparable to standard ZN method and had many advantages. Pot method can be explored further for the detection of AFB in sputum samples obtained from pulmonary tuberculosis suspects.

Keywords: AFB - pot-staining - sputum - tuberculosis - ZN staining

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