Objectives: To evaluate the routine performance and the
technical parameters of different acid-fast staining methods: Kinyoun,
Ziehl-Neelsen (ZN), auramine, and auramine-rhodamine.
and participants: The performance of 167 laboratories was
analyzed using prestained and unstained slides.
Setting: Laboratories holding New York State permits.
Results: The results revealed that Kinyoun’s cold carbol
fuchsin method is inferior to both the ZN and fluorochrome (auramine
and/or auramine-rhodamine) methods. Even though 91% of the
participants used commercial staining kits, the study identified
unexpected errors concerning the concentration of carbol fuchsin, time
for staining and counterstaining, and the concentration of acid alcohol
for decolorization, which may significantly influence the sensitivity.
Besides these findings, the present study showed that the examination
of < 300 view fields may also decrease the sensitivity of acid-fast
microscopy. In addition, we found that the sensitivity and specificity
of the ZN and fluorochrome methods are comparable if the procedural
standards are followed.
Conclusions: The strict and
ongoing quality control of the “simple to perform” acid-fast
microscopy and the immediate review of commercially available staining
kits are necessary. Because of the rapidity of the fluorochrome method,
laboratories with large specimen numbers should use this technique. In
all other cases, the ZN method should be used. Moreover, all clinicians
should be aware of the method of acid-fast microscopy used and the
proficiency of the laboratory in performing the