Introduction

Methylene Blue Loeffler reagent is used for staining acidoresistant bacteria according to Ziehl-Neelsen, utilizing the dye’s property to stain almost all the bacterial cell’s elements in a mildly alkaline medium (Methylene Blue Loeffler reagent has pH value of 8-8.5). This does not apply to acid fast bacteria – they remain stained in their primary color. Methylene Blue Loeffler reagent is suitable for staining and monitoring genera such as Gonococcus, Lactobacillus and for visualizing genus Pasteurella. It is also suitable for staining bacterial nucleus and cytoplasm. Methylene Blue Loeffler reagent is slightly toxic. It can cause cell mutation in very high doses.