Previous Article | Next Article 
Journal of Clinical Microbiology, July 2003, p. 3459, Vol. 41, No. 7
0095-1137/03/$08.00+0 DOI: 10.1128/JCM.41.7.3459.2003
Comparison of Two Different Strengths of Carbol Fuchsin in Ziehl-Neelsen Staining for Detecting Acid-Fast Bacilli

LETTER
Selvakumar et al. (
5) compared smear staining of acid-fast bacilli
(AFB) by two different strengths of carbol fuchsin in Ziehl-Neelsen
staining. First we would like to applaud the authors for providing
a study on an important test method, the Ziehl-Neelsen AFB staining
procedure, which receives little attention relative to its critical
importance in worldwide tuberculosis control. We are also asking
why the concentration of basic fuchsin was changed from about
1%, as published in the original study by Neelsen (
4) to 0.3%
(
1) (we could trace back to this article only). We presume that
there were earlier comparative studies for which we can find
no reference. The use of 0.3% carbol fuchsin is documented as
far back as 1948 and has been published in early Centers for
Disease Control and Prevention (CDC) (
6) manuals in addition
to the International Union against Tuberculosis and Lung Disease
(IUATLD) (
3) and World Health Organization (WHO) (
7) manuals.
A concern, however, is the method the authors used to derive
the study concentration of 0.3% carbol fuchsin. In a comparative
study it is imperative that laboratories use comparable methods
for stain preparation. This study did not follow the standard
procedure for making the study concentration of 0.3% carbol
fuchsin. The authors did not consider the final concentration
of phenol in preparing the concentration of 0.3% carbol fuchsin.
The concentration of phenol is 5% according to WHO (
7), IUATLD
(
3), and CDC (
6) manuals. The authors diluted the 1% carbol
fuchsin with water to make it 0.3% carbol fuchsin, which would
also dilute the phenol concentration to

1.7%. The role of phenol
is critical in the staining process (
2). The concentration of
phenol is 5% in previous (
1,
4) studies and in the WHO (
7),
IUATLD (
3), and CDC (
6) manuals. This may have contributed to
the lower percentage of smear positives. We believe this study
should be repeated using the concentration of 0.3% fuchsin and
5% phenol so that a definite conclusion can be reached.
Ed. Note: The authors of the original article did not respond.

REFERENCES
1 - Darrow, M. A. 1948. Staining the tubercle organism in sputum smears. Stain Technol. 24:93-94.
2 - Lamana, C. 1946. The nature of the acid-fast stain. J. Bacteriol. 52:99-103.[Free Full Text]
3 - Laszlo, A. 2000. Sputum examination for tuberculosis by direct microscopy in low income countries. IUATLD Technical Guide. International Union against Tuberculosis and Lung Disease, Paris, France.
4 - Neelsen, F. 1883. Ein casuistischer Beitrag zur Lehre von der Tuberkulose. Centrabl. Med. Wissenschaften 28:497-501.
5 - Selvakumar, N., F. Rahman, S. Rajasekaran, P. R. Narayanan, and T. R. Frieden. 2002. Inefficiency of 0.3% carbol fuchsin in Ziehl-Neelsen staining for detecting acid-fast bacilli. J. Clin. Microbiol. 40:3041-3043.[Abstract/Free Full Text]
6 - Vestal, A. 1969. Procedures for the isolation and identification of mycobacteria. Public Health Service publication no. 1995. Centers for Disease Control, Atlanta, Ga.
7 - Weyer, K. 1998. Laboratory services in tuberculosis control. Part II. Microscopy. WHO technical bulletin 98.258. World Health Organization, Geneva, Switzerland.
| | | | | |
Pawan Angra* John Ridderhof Ronald Smithwick
Centers for Disease Control and Prevention PHPPO/DLS and NCID/DASTLR Atlanta, GA 30341-3717
|
| | | | | |
* Phone: (770) 488 8184 Fax: (770) 488 8282 E-mail: pea6{at}cdc.gov |
Journal of Clinical Microbiology, July 2003, p. 3459, Vol. 41, No. 7
0095-1137/03/$08.00+0 DOI: 10.1128/JCM.41.7.3459.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.