INTRODUCTION TO BACTERIAL MORPHOLOGY Flashcards
- Smallest microbial group.
- Neither prokaryotic or eukaryotic.
- Prions are not cells, but rather infectious agents (proteins).
For this protein to infect you, a precursor is needed to manifest its infectious form - Example: Kuru. It is associated with prion mediated infection
that infects the brain (CNS).
PRIONS
- Neither prokaryotic nor eukaryotic
- Viruses are not cells, but rather they are nucleic acids.
- A virus can either be an RNA or DNA infectious agent (but it
can never be both).
VIRUSES
Prokaryotic cell (it only has a single and identical cell).
BACTERIA
Eukaryotic cell (made up of many cells).
FUNGI
- Largest microbial group
- Eukaryotic cell.
PARASITES
- Lack of true nucleus
- DNA is bound by the
cytoplasm. The nucleoid
region is scattered in the
cytoplasm. - 10 times smaller than
Eukaryotic cells - Size: 0.1-10 microns
Prokaryotes
- Has a true nucleus
- DNA, chromatin, and
significant markers for
replication are bound by the
nuclear membrane. - DNA is present inside the
nuclear membrane - Size: 10-100 microns
Eukaryotes
round-shaped bacteria.
COCCUS
Elongated and rod-shaped bacteria
- It is not found in clusters and they never tend to form in clusters
BACILLUS
Lengthy but with curvatures
- Called as spirochetes.
* Example: Treponema Pallidum is a microbe that causes syphilis.
SPIRAL
- If the organism is not identified to any of the morphology, it is pleomorphic.
Shape: Many forms of shape of the organism.
PLEOMORPHIC
Round-elongated bacteria.
COCCOBACILLI
Devised by Hans Christian Gram
- It has four (4) different reagents:
o Two of which are dyes (Crystal violet &
Safranin)
o One is a dye enhancer (Iodine)
o One is a decolorizer (Alcohol)
GRAM STAIN
dye enhancer
Iodine
a decolorizer
Alcohol
GRAM STAIN REAGENTS
- Crystal Violet (Primary Dye)
- Gram’s Iodine (Mordant)
- Alcohol/Acetone
(Decolorizer) - Safranin (Counterstain)
Primary Dye
- It stains the cell wall of the
organism
Crystal Violet
Mordant
- Enhances the affinity of the
primary stain (Crystal Stain)
Gram’s Iodine
Decolorizer
- Decolorize the primary stain
Alcohol/Acetone
Counterstain
- It will counter the attachment
or affinity to the cell of the
organism.
Safranin
- The primary stain needs to be removed because if the organism is not gram positive, when you add the decolorizer, the crystal violet gram’s iodine complex will be easily washed out, leaving the cell wall unstained.
Alcohol
DIFFERENTIAL STAINING
* Any staining method that has a decolorizer component of the
procedure.
* It is because you are differentiating one organism from the
other.
REGRESSIVE STAINING
- If an organism is a gram-positive bacterium, crystal violet will remain after the procedure of gram staining.
- It will not allow Safranin to stain.
- Color: Purple to Blue
GRAM POSITIVE
- If an organism is gram-negative bacteria, the crystal violet iodine complex is removed by the alcohol/acetone allowing
the entry of safranin. - Color: Pink to Red (because Safranin is known as red/pink
dye).
GRAM NEGATIVE
All cocci are Gram Positive (+) Except
o Neisseria
o Moraxella
o Veillonella
- All bacilli are Gram Negative (-) Except:
o Mycobacterium
o Corynebacterium
o Bacillus
o Clostridium
o Actinomyces
o Streptomyces
o Erysipelothrix
o Listeria
o Nocardia
o -bacterium (Bifido-, Propioni, Eu-, Arcano-)
Less common bacilli
Neisseria, Moraxella and Veillonella
Gram-negative
bacteria.
In gram staining, we are staining the cell wall or______ of an organism.
peptidoglycan
implies that the cell wall is thicker. (kaya mas nareretain yung stain)
Gram positive
implies that the cell wall is
thinner. (kaya easily washed out yung
primary dye)
Gram negative
- Gram: Both gram Positive (+) & Negative (-)
- Chemical composition: Polysaccharide gel
- Function:
o Pathogenicity/Virulence factor
o Protect against Phagocytosis until
Opsonized
o Immunogenic - A microorganism that possesses the capsule is very difficult to kill by a phagocyte.
CAPSULE (SLIME LAYER OR GLYCOCALYX)
Normally, a bacterium without a cell wall lies upon the rupture of this WBC. WBC has its Lytic enzyme in it, and it will be activated later on so it will eliminate the ingested bacteria.
Bacteria without a Capsule
They escape this process wherein the capsule serves as a shield for this microorganism. Later on, when the phagocyte bursts, they can still survive and still penetrate the body systems,
causing infection.
Bacteria with a Capsule
- Streptococcus pneumoniae
- Klebsiella pneumoniae
- Haemophilus influenzae
- Pseudomonas aeruginosa
- Neisseria meningitidis
- Cryptococcus neoformans - This is not a bacteria (it is a
fungi).
MICROORGANISMS THAT HAVE CAPSULE
These microorganisms have capsules (made up of polysaccharide gel) that can cause a severe infection because they can resist phagocytosis.
- Streptococcus pneumoniae
- Klebsiella pneumoniae
- Haemophilus influenzae
- Pseudomonas aeruginosa
- Neisseria meningitidis
- Cryptococcus neoformans - This is not a bacteria (it is a
fungi).
Poly D-glutamate capsule
Bacillus anthracis
Meningeal strains have
capsule, mostly K1
Escherichia coli
(virulence) capsular antigen
Salmonella typhi
When first isolated; nonimmunogenic (but antiphagocytic) hyaluronic acid
capsule
Streptococcus pyogenes
- Gram: Gram Negative (-) only
- Chemical composition Phospholipid/proteins:
o Lipopolysaccharide (LPS)
o Lipid A
o Polysaccharide
Function: Hydrophobic Membrane
o LPS - endotoxin
o Lipid A - Toxic moiety
o PS (Polysaccharide Gel) =
Immunogenic
= are found in GRAM NEGATIVE microbes/bacteria
OUTER MEMBRANE (MAJOR PERMEABILITY BARRIER)
- Gram: Gram positive (+) = Thick cell wall; Gram negative (-)
= Thin cell wall.
o Found in all free-living bacteria EXCEPT in
Mycoplasma It is a → wall-less bacteria; No peptidoglycan layer.
Chemical composition: Peptidoglycan; polymer of peptides (typically 4 amino acids long, cross-linked to other chains)
and glycans (made of alternating amino sugars).
o Sugars found in peptidoglycan:
▪ 1. N-acetylglucosamine (NAG).
▪ 2. N-acetylmuramic acid (NAM).
FUNCTION: * Rigid support, cell shape, protection from osmotic damage, confer Gram reaction
CELL WALL (PEPTIDOGLYCAN LAYER)
- Gram: Acid-fast organism only
- Chemical composition: Mycolic acids
- Function:
o Acid fastness
o Resistance to drying and chemicals.
CELL WALL
they have a cell wall with a Mycolic
acid layer.
resist drying and chemicals.
Acid-fast organisms
Made up of a long chain of fatty acids that
makes them very difficult to stain. Hence, a method has been made (aside from gram-staining) to show acid-fast microbes
called Acid-fast staining method
Mycolic acids
ALL ORGANISMS ARE NON-ACID FAST EXCEPT:
- Cryptosporidium sp.
- Legionella micdadei
- Isospora sp.
- Mycobacterium sp.
- Nocardia sp
______ are gram-positive but these two contain mycolic acids. In other books, these two
organisms are labeled as ‘gram-positive or gram-variable’ organisms because of the acid-fast.
Mycobacterium sp. and Nocardia sp.
Because they are difficult to stain, they are known as ______ (alanganin maging → purple alanganin maging
red/pink.)
Gram variable
an example of a differential stain similar
to gram staining.
Acid fast staining
- Gram: Gram negative (-) ONLY
- Chemical composition: “Storage space” between the inner
and outer membranes (lumen) - Function:
o Stores degradative enzymes which
break down large molecules; (β-
lactamases).
o Aids in regulation of osmolarity.
PERIPLASMIC SPACE
an enzyme capable of destroying the betalactam ring of an antibiotic (especially beta-lactam).
Β-lactamases
- Because gram-negative bacteria have a space na may degradative enzyme wherein when it meets a beta-lactam
antibiotic, the beta lactamase stored in here will destroy the beta lactam ring. - When the beta-lactam ring of an antibiotic is destroyed, the
antibiotic will no longer be effective
INEFFECTIVITY IN KILLING A MICROBE
- Spheroplasts - Gram Positive (+) OM
- Protoplasts - Gram Negative (-) OM; Spherical shape
- Both of these refer to the altered form of a plant or bacterial
cell from which has been partially or completely removed.
WALL-LESS FORMS OF BACTERIA
Both of these refer to the altered form of a plant or bacterial cell from which has been partially or completely removed.
Spheroplasts and Protoplasts
- Gram: Both gram positive (+) and gram negative (-)
- Chemical composition: Phospholipid bilayer with many
embedded proteins. - Functions:
o Energy metabolism occurs here
o Hydrophobic cell “sack”
o Selective permeability and active
transport
CYTOPLASMIC MEMBRANE
- Gram; Primarily gram negative (-)
- Chemical composition: Glycoprotein (pilin)
- Function: Adherence to cell surfaces (common), including
attachments to other bacteria during conjugation (Sex).
PILUS/FIMBRIA
for conjugation (genetic transfer from one organism to another).
Sex pili
contains a DNA that is
resistant to antibiotics.
male genetic donor
non-resistant to any antibiotic
female
genetic recipient
- Gram:
o Flagellum: Both gram positive (+)
and negative
(-)
o Axial Filaments: Spirochetes (Spiral
microorganisms)
Chemical composition:
- Flagellum: Protein (Flaggellin)
- Axial Filaments: Protein
Function: Both functions for motility
FLAGELLUM AND AXIAL FILAMENTS
FLAGELLA NAME BASED ON LOCATION OF TAILS
A. Monotrichous
B. Lophotrichous
C. Ampitrichous
D. Peritrichous
SINGLE flagellum is found on one
end of the microbe.
Monotrichous
MULTIPLE flagella are found on one
end of the microbe
Lophotrichous
Flagella are at both ends.
Ampitrichous
Flagella are found all over or around
the perimeter of the microorganism.
Peritrichous
