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Year : 2001  |  Volume : 19  |  Issue : 4  |  Page : 233-

Evaluation of a novel, two component, two step AFB cold staining method

S Gokhale 
 Classified Specialist in Microbiology and Pathology, Command Hospital (CC), Lucknow - 226 002, UP, India

Correspondence Address:
S Gokhale
Classified Specialist in Microbiology and Pathology, Command Hospital (CC), Lucknow - 226 002, UP
India

How to cite this article:
Gokhale S. Evaluation of a novel, two component, two step AFB cold staining method.Indian J Med Microbiol 2001;19:233-233

How to cite this URL:
Gokhale S. Evaluation of a novel, two component, two step AFB cold staining method. Indian J Med Microbiol [serial online] 2001 [cited 2020 Jul 10 ];19:233-233
Available from: http://www.ijmm.org/text.asp?2001/19/4/233/11030

Full Text

Dear Editor,

This letter is an response to the communication “Evaluation of a novel, two component, two step AFB cold staining method” by Tripathi, Desai and Mesquita in IJMM 2001;19:163-5. The search for simpler staining techniques for detection of Mycobacterium tuberculosis is still on but all newer techniques must be rigorously evaluated before accepting them. Following points must be taken into account while interpreting this paper:

1. Our knowledge of staining properties of various microorganisms and other artifacts is still in infancy. All that is acid and alcohol fast is not necessarily Mycobacterium and all mycobacteria are not necessarily AFB. Variations in staining characters is well known. This is an important reason for the so called false positive/false negative results of Z N technique.

2. Acid and Alcohol Fast Bacillus (AFB) is the descriptive term signifying the ability of the bacillus to resist decolourisation when stained by Z N technique. When a technique other than Z N technique is used, the organism cannot be called AFB.

3. The authors have not disclosed the composition of the two reagents used in this “Novel” method. The principles and criteria of staining, decolourisation and counterstaining to accord the smear positivity/negativity have also not been mentioned in this paper. Therefore the term AFB cannot be used to describe the results of this staining technique. Comparing observations of this “Novel” technique with classical ZN technique is fallacious.

4. The number of positive specimen (21) in this study is too small for any statistical analysis and correct interpretation.

5. The observation that “Novel” staining technique increased the positivity by whopping 91% itself raises doubts about the specificity of this technique. Specificity for diagnosis should not be sacrificed at the altar of rapidity and simplicity for the technician as it has long-term effects on the patient and the antituberculosis treatment.

This “Novel” technique needs more rigorous and controlled trials before accepting it for diagnosis of tuberculosis. It is suggested that authors should disclose all relevant information for the benefit of readers.