LOEFFLER’S METHYLENE BLUE by Pro-Lab Diagnostics

 

Foto : cientificlabs.co.uk

INTENDED USE 

For use as a bacterial stain in prepared slides from clinical specimens. 

SUMMARY AND EXPLANATION 

Loeffler’s methytlene blue is recognized as a simple stain for determining bacterial morphology. The stain may also be used in the presumptive identification of Corynebacterium diphtheriae.  

PRINCIPLE  

Loeffler’s methylene blue is a cationic dye which stains the cell blue. The presence of negatively charged molecules in the cell causes the staining phenomenon, as the positively charged dye is attracted to negatively charged particles, such as polyphosphates like DNA and RNA. 

MATERIALS REQUIRED BUT NOT PROVIDED

• Glass slides 
• Inoculating loop  
• Immersion oil PL.396
• Microscope 

STABILITY AND STORAGE 

Loeffler’s methylene blue should be stored at 15-25oC in its original container.  Product stored under these conditions will be stable until the expiry date shown on the product label. 

PRECAUTIONS 

 For In Vitro Diagnostic Use only. 

 For professional use only.   

 Directions should be read and followed carefully. 

 Do not use beyond the stated expiration dates.  

 Microbial contamination may decrease the accuracy of the staining.  

 Safety precautions should be taken in handling, processing and discarding all clinical specimens.   

 Process slides in the correct containment level conditions. 

 Dispose of all material in accordance with local regulations. 

PROCEDURES 

1. Prepare a smear on a clean glass slide and allow to air dry.  

2. Heat fix or fix with methanol. 

3. Flood the slide with Loeffler’s methylene blue for 1 to 3 minutes. 

4. Wash the slide gently with tap water and blot dry. 

5. Examine using a microscope. 

INTERPRETATION OF RESULTS 

When observed microscopically using oil immersion, bacterial cells stain a medium blue colour, and the background stains lighter blue. When C. diptheriae cells are stained they appear banded or beaded with deep blue staining metachromatic granules. 

LIMITATIONS 

 Only experienced personnel should carry out the interpretation of stained slides  

 Read prepared slides as soon as possible after staining. Failure to do so may affect the results.  

 Some strains of Propionibacterium, Actinomyces, and pleomorphic forms of streptococci may mimic the characteristic stained appearance of C. diphtheriae.