Assessment of panel slides prepared by phenol ammonium sulphate and NALC methods for proficiency testing.
BACKGROUND
Existing methods for the preparation of panel slides necessitate handling high-grade acid-fast bacilli positive sputum samples.


OBJECTIVE
To compare panel slides prepared using the phenol ammonium sulphate sediment (PhAS) method with those prepared using the N-acetyl-L-cysteine  (NALC) method in proficiency testing.


METHODS
Pooled sputum specimens of known smear-positives and -negatives were divided into two parts: one part was used for preparing panel slides using the NALC method and the other using PhAS, a non-hazardous method. Respectively 413 and 384 smears  of different grades were prepared in three batches using the PhAS and NALC methods. Smear grade and quality were recorded by 121 microscopists during proficiency testing in different states. Agreement between reference and reported results was analysed using the kappa test.


RESULTS
The  overall agreement was 96% for the PhAS method and 91% for the NALC method. There were 37 errors using the NALC method compared to 21 for the PhAS method (P < 0.223). Smear quality was equally good in both methods; however, the cell count was significantly higher in the PhAS than  in the NALC method.


CONCLUSIONS
The PhAS method, a non-hazardous procedure with good-quality smears, may be further explored for the preparation of panel slides.
Department of Bacteriology, National Institute for Research in Tuberculosis, Chennai, India.
R
R
Radhakrishnan
M M P
MM
Kumar
S
S
Prabuseenivasan
S
S
Anbarasu
P
P
Nagarajan
M
M
Devisangamithirai
S
S
Sivagamasundari
C
C
Ponnuraja
V
V
Kumar
N
N
Selvakumar
D000111:Acetylcysteine; D000645:Ammonium Sulfate / Q000737:chemistry; D001431:Bacteriological Techniques; D006801:Humans; D008853:Microscopy / Q000379:methods; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D019800:Phenol / Q000737:chemistry; D013183:Sputum / Q000382:microbiology; D014376:Tuberculosis / Q000175:diagnosis* / Q000382:microbiology
D019800:Phenol; D000645:Ammonium Sulfate; D000111:Acetylcysteine