Lecture 2: Intro Flashcards
How do we classify bacteria?
- Morphology
- Biochemical Reactions
- Serology
- Nucleic Acid Profiles
Spherical organisms
Cocci
Rod-shaped organisms
Rod or Bacillus
Organisms in chains
Strep
Organisms in clusters
Staph
Club-shaped organisms
Diptherioid
Are Gram stains good for cytology?
NO, good for identifying Gram +/- bacteria and presence/absence of other cells, not what type
What color are G+ bacteria?
PURPLE
What color are G - bacteria?
RED
What color are mycobacteria?
clear/white
Why is the capsule/slime layer important?
Anti-phagocytic! Also, helps adherence and longevity in environment
Are capsules antigenically diverse?
YES, hard to mount Humoral Immune response
How is the Cell Wall important?
20% of dry weight of bacteria
Helps determine what kind of bacteria (ie: Gram Stain)
Describe Gram Staining Method:
- Fixation with heat
- stain with crystal violet - enters organisms cell wall
- Rinse
- Iodine mordant - binds CV and makes larger complex
- Rinse
- De-colorize w/ 95% ethanol - dehydrates G+ cell wall, trapping I-CV complex OR washes awayI-CV complex and cell wall of G-
- Counter stain w/ Safranin stain - G- bacteria uptake and stain Red/Pink
What is the order of efficacy of detergents against bacteria?
Efficacy greatest for G+ > G- > AF (acid fast)
List characteristics of G+ Bacteria and how different from others.
- Thicker cell wall of peptidoglycan
- peptidoglycan dessicates upon declorization (ethanol)
- more resistant to MECHANICAL damage
- Peptidoglycan is target of antimicrobials and LYSOZYME
List characteristics of G- Bacteria and how different from others.
- LPS is MAJOR Virulence Factor!!
- They have Porins
- less peptidoglycan
- more resistant to DETERGENTS
List characteristics of Acid Fast Bacteria and how different from others.
- Cell envelope contains: MYCOLIC ACID, glycolipids and polypeptides
- difficult to stain (won’t take up stain)
- intense cell envelope allows them to survive well in the environment
- cell envelope allows INTRACELLULAR survival (difficult to kill, can often result in chronicity)
- antibiotics target this CELLULAR ENVELOPE
What are FLAGELLA important for?
Motility
What are FIMBRIAE/PILI important for?
Adherence
What are SPORES important for?
Long Term Survival and Physical Resistance
What are BIOFILMS important for?
Allows Bacteria to attach to each other
- aiding in colonization
- avoid phagocytosis
- avoid antibiotics
- allows “quorom sensing” – bacteria act as a single organism
What is clonal expansion?
On an agar plate, a SINGLE COLONY is the clonal expansion of a SINGLE BACTERIUM
- SMALL colonies = slow growing
- LARGE colonies = fast growing
In general, is an organism that divides more rapidly more virulent than the alternative?
NO.
What is the optimal pH for bacterial growth?
Neutral to alkaline
What is the optimal tonicity (osmotic balance) for bacterial growth?
Isotonic to hypOtonic
What is the optimal Temperature for bacterial growth?
Our body temperature = 98.6˚F
- most can grow 68-113˚F
- Listeria grow in COLD temperatures (39˚F)
What kind of environment do strict/obligate aerobes require?
Oxygen present
What kind of environment do strict/obligate anaerobes require?
NO oxygen
What kind of environment to Facultative Anaerobes (FA) require?
Can grow with or without oxygen
What kind of environment do microaerophiles require?
Require Reduced Oxygen (
Where in your body are anaerobic conditions?
ORAL CAVITY and INTESTINES:
- Mucus, Facultative Anaerobes, Anaerobes, Healthy Tissue
Also, areas of NECROSIS
Identify the Genetic Elements of bacteria.
Bacterial Genome (haploid, circular chromosome, double stranded DNA)
Plasmid (Small circular DNA, autonomous replication)
Bacteriophage (Virus that infect bacteria and insert DNA)
What Genetic Element(s) of bacteria may encode virulence, toxins, or antibacterial resistance?
PLASMIDs and BacterioPHAGES
With respect to genotypic variation of bacteria, what is a MUTATION?
Change in chromosomal DNA
With respect to genotypic variation of bacteria, what is a RECOMBINATION?
Exchange of DNA between bacteria
With respect to genotypic variation of bacteria, what is a TRANSPOSITION?
Relocation of PARTS of DNA in the genome mediated by transposable elements
With respect to RECOMBINATION, what is TRANSDUCTION?
Phage-mediated transfer
With respect to RECOMBINATION, what is CONJUGATION?
Plasmid mediated transfer
With respect to RECOMBINATION, what is TRANSFORMATION?
Uptake of naked segment of DNA
What is mostly responsible for genetic variation of bacteria?
Recombination via CONJUGATION
What antimicorbials target the peptioglycan in the cell wall of bacteria?
Beta-Lactams
