Bacterial Cell Components

• Also referred to as the peptidoglycan [main component], or murein layer

  Cell wall
• components of cell wall

  phospholipid bilayer and protein
• [Differential staining method → cell wall ang target]

  Gram Stain Reaction
• Gram Positive color


  Purple
• Gram Negative Color

  Red
• Primary Stain

  Crystal Violet
• Mordant [strengthen the affinity of the stain to the bacterial cell wall]

  Gram’s Iodine
• Decolorizer [95% ethanol or ethyl alcohol]

  ▪ Gram positive – purple

  ▪ Gram negative – colorless [thin peptidoglycan]


  Acetone Alcohol
• Secondary Stain/Counterstain

  ▪ Gram + - Purple

  ▪ Gram (-): Pink


  Safranin
• Before the staining process, the bacterial cell wall is


  colorless
• makikita lang sa gram-negative; gel-like substance that either contains enzymes that are degradative.

  Periplasmic Space
• important for invasion; capable of degrading the host’s surface; mabilis makakapag-attach

  Degradative enzymes
• organism that have greater virulence

  gran negative
• Gram (+)Phospholipid bilayer
• Gram (-)2 Phospholipid bilayer
• Has a very thick protective peptidoglycan (murein) layer


  gram positive cell wall
• Thin peptidoglycan layer

  gram negative cell wall
• a characteristic exhibited by gram positive bacteria

  gram variability
• old culture

  has been in the refrigerator for more than 24 hrs
• acid stain

  basic component
• alkaline stain


  acidic component
• primary stain and mordant staining rxn time

  1 minute
• decolorizer staining rnx time

  until colorless (2secs)
• secondary stain rxn time

  30 secs to 1 min
• All COCCI are Gram POSITIVE except Neisseria, Branhamella/Moraxella, Veillonella [NVM] sp.
• All BACILLI are Gram NEGATIVE except MBCCLLEARK

  [MyBELLCRACK]:

  Mycobacterium spp.

  Bacillus spp.

  Clostridium spp.

  Corynebacterium spp.

  Lactobacillus spp.

  Listeria spp.

  Erysipelothrix spp.

  Aerobic Actinomyces spp.

  Rothia spp.

  Kurthia spp.
• Mycoplasma spp., Ureaplasma spp., and Acholeplasma

  spp. usually have a gram-negative reaction NOT because it has a gram-negative cell wall but because they DO NOT HAVE a CELL WALL.
• Spirals are very difficult to stain using gram staining, however, stainable spirals are usually gram negative
• Mycobacterium & Nocardia spp. have a gram-positive cell wall structure, however, because 60% of the cell wall is made of hydrophobic lipids mainly mycolic acid, it affects its permeability this makes it difficult to gram stain.
• acid fast cell wall contain a waxy layer of glycolipids and fatty acids (mycolic acid)
• acid fast staining is specifically designed for a subset of bacteria whose cell walls contain long-chain fatty (mycolic) acids.
• Mycolic acids render the cells resistant to decolorization, even with acid alcohol decolorizers.
• Mycobacteria are the most commonly encountered acid-fast

  bacteria, typified by Mycobacterium tuberculosis,
• Partially Acid-Fast Organism (LRN)

  Legionella micdadei

  Rhodococcus

  Nocardia
• Distinctly Acid Fast(CI) Calamba Institute

  Cryptosporidium

  Isospora
• 2 methods of acid-fast staining (ZK)

  Ziehl-Neelsen Method or Hot Method

  Kinyoun Method
• Primary Stain of Ziehl - Neelsen Method

  Carbol Fuchsin
• Mordant of Ziehl - Neelsen Method

  Heat
• Decolorizer of Ziehl - Neelsen Method

  Acid Alcohol (3% HCL in 95% ethanol)
• Counterstain of Ziehl - Neelsen Method

  Methylene Blue or Malachite Green