Microbiology

• Simple Stains


  • Crystal Violet
  • Methylene Blue
  • Lactophenol Cotton Blue
  • Iodine
• Simple Stains


  Impart color contrast to bacteria; cationic; lack structural detail
• Methylene Blue Stain


  Emphasizes specific structures, shapes, and arrangements
• Organisms stained by Methylene Blue

  • Corynebacterium diphtheriae
  • Neisseria meningitidis
  • Haemophilus influenzae
• Gram Stain


  1. Crystal Violet (primary stain)

  2. Iodine (mordant)

  3. Decolorizer (acetone/alcohol)

  4. Safranin/Carbol Fuchsin (counterstain)
• Gram Positive Cell Wall

  Retains crystal violet-iodine complex due to thick peptidoglycan layer
• Gram Negative Cell Wall

  Loses crystal violet-iodine complex due to thin peptidoglycan layer and lipids in the outer layer
• Gram Stain

  Distinguishes between Gram-positive cocci and Gram-negative bacilli/rods
• Acid-Fast Stain


  For Mycobacterium species
• Acid-Fast Stain Types


  • Ziehl-Neelsen (Hot)
  • Kinyoun (Cold)
• Acid-Fast Ziehl-Neelsen Stain


  1. Carbol Fuchsin

  2. HCl decolorizer

  3. Methylene Blue counterstain
• Organisms stained by Acid-Fast Stain

  • Mycobacterium tuberculosis
  • Nocardia spp.
  • Rhodococcus spp.
• Giemsa Stain

  Azure, methylene blue, and eosin dye mixture; stains nucleic acids
• Applications of Giemsa Stain


  • Plasmodium
  • Toxoplasma gondii
  • Histoplasma capsulatum
  • Yersinia pestis
  • Chlamydia inclusion bodies
• Acridine Orange Stain

  Fluorescent nucleic acid selective dye
• Applications of Acridine Orange Stain


  • Blood cultures
  • Detecting cell wall-deficient bacteria
  • Malaria screening
• Special Stains


  • Endospore Stain
  • Capsule Stain
  • Flagella Stain
  • Calcoflour White
• Endospore Stain


  Schaeffer-Fulton and Dorner methods; organisms like Bacillus and Clostridium
• Capsule Stain


  Congo Red, India Ink, Methylene Blue; organisms like Streptococcus pneumoniae and Klebsiella pneumoniae
• Flagella Stain


  Wet-mount (Ryu method), Dried-smear (Leifson method); various bacterial species with flagella
• Calcoflour White


  Fluorescent stain for chitin and cellulose; aids in fungal and non-fungal agent detection
• Corynebacterium diphtheriae


  Causes diphtheria, a respiratory infection with a characteristic pseudomembrane in the throat
• Neisseria meningitidis


  Causes meningococcal meningitis, a severe infection of the brain and spinal cord membranes
• Haemophilus influenzae


  Can cause respiratory tract infections and, in some cases, meningitis
• Gram-positive cocci

  • Staphylococcus aureus
  • Streptococcus pneumoniae
• Gram-negative bacilli/rods

  • Escherichia coli
  • Klebsiella pneumoniae
  • Pseudomonas aeruginosa
• Acid-Fast Stain (Ziehl-Neelsen Method)


  Identifies Mycobacterium species
• Mycobacterium tuberculosis


  Causes tuberculosis (TB), a respiratory disease affecting the lungs primarily
• Other Acid-Fast Organisms


  • Nocardia spp.
  • Rhodococcus spp.
• Giemsa Stain


  Stains nucleic acids
• Organisms stained by Giemsa

  • Plasmodium
  • Toxoplasma gondii
  • Histoplasma capsulatum
• Acridine Orange Stain


  Fluorescent stain for nucleic acids
• Applications of Acridine Orange Stain

  • Blood cultures
  • Detecting cell wall-deficient bacteria
  • Malaria screening
• Hepatitis B Virus (HBV)


  Causes hepatitis B, which can lead to liver cirrhosis and cancer
• Hepatitis B Vaccine


  Recommended for infants, healthcare workers, people with high-risk sexual behavior, and those traveling to areas with high HBV prevalence
• Measles Virus (MeV)


  Causes measles, a highly contagious viral infection causing fever, rash, and respiratory symptoms
• Measles, Mumps, and Rubella (MMR) Vaccine


  Recommended for children, adults born after 1957 who lack immunity, healthcare workers, travelers to measles-endemic areas
• Influenza Virus


  Causes influenza (flu), with symptoms like fever, cough, sore throat, body aches
• Seasonal Influenza Vaccine


  Recommended annually for everyone above six months, especially high-risk groups like elderly, pregnant women, healthcare workers
• Human Papillomavirus (HPV)


  Infection can lead to genital warts and various cancers like cervical, anal, and throat cancers