BACTERIOLOGY Flashcards
What are the main differences between Prokaryotes and Eukaryotes?
Prokaryotes lack a nucleus and membrane-bound organelles, while Eukaryotes have both. Prokaryotes have a cell wall and ribosomes (70S), whereas Eukaryotes have ribosomes (80S) and may or may not have a cell wall. Prokaryotes reproduce asexually through binary fission, while Eukaryotes can reproduce sexually and asexually.
What is unique about Archaea compared to Prokaryotes?
Archaea are more closely related to Eukaryotes than Prokaryotes and lack the peptidoglycan layer.
What are the two main aspects of taxonomy?
Genotype refers to the genetic make-up, while phenotype refers to the observable physical and functional features of an organism.
What are the levels of classification in taxonomy?
Domain, Kingdom, Phylum, Class, Order, Family, Tribe, Genus, Species, and Subspecies.
What are the different shapes of bacteria?
Bacteria can be bacilli (rod-shaped), spiral, pleomorphic, or spheres. Examples include fusiform (tapered ends), vibrio (straight or curved), spirillum (rigid helical), and spirochete (flexible helical).
What are the arrangements of bacteria?
Bacteria can be arranged in pairs (diplococci, diplobacilli), chains (streptococci, streptobacilli), grape-like clusters (staphylococci), groups of four (tetrads), packets of eight, or palisades.
What is the structure and function of the bacterial cell wall?
The cell wall is made up of peptidoglycan/murein layer, providing protection and shape to the bacteria, and serving as a target for some antimicrobial agents.
What characterizes a Gram Positive cell wall?
A Gram Positive cell wall has a thick peptidoglycan layer, contains teichoic acid, and consists of alternating chains of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM).
What characterizes a Gram Negative cell wall?
A Gram Negative cell wall has a thin peptidoglycan layer, lacks teichoic acid, and contains an outer membrane composed of lipopolysaccharide (LPS), proteins, and phospholipids.
What are the components of the outer membrane in Gram Negative bacteria?
The outer membrane is composed of lipopolysaccharide (LPS), which includes lipid A (endotoxin), core polysaccharide, and O polysaccharide, along with proteins and phospholipids.
What are the functions of the outer membrane in Gram Negative bacteria?
The outer membrane acts as a barrier, serves as a sieve allowing water-soluble molecules to enter through porins, and provides attachment sites that enhance attachment to host cells.
What is the reporting method referenced?
Bailey and Scott’s
What is the magnification for Fuchsin stain?
1000x
What is the magnification for Fluorochrome?
450x
What is the field range for 1-2?
1-2/300 fields
What is the field range for 1-9?
1-9/100 fields
What is the field range for >9?
> 9/field
What is the field range for 2-18?
2-18/50 fields
What is the field range for 4-36?
4-36/10 fields
What is the field range for Fluorochrome at 250x?
250x
What is the field range for 1-2 at 250x?
1-2/30 fields
What is the field range for 10-90?
10-90/field
What does ‘No AFB seen’ indicate?
No AFB seen
What should be done if the result is indeterminate?
Request another specimen for repeat testing
What does a result of 1+ indicate?
1+
What does a result of 2+ indicate?
2+
What does a result of 3+ indicate?
3+
What does a result of 4+ indicate?
4+
What are obligate aerobes?
Require 21% oxygen and small amount (0.03%) of CO2.
What are obligate anaerobes?
Cannot grow in the presence of oxygen; atmosphere conditions should be 5-10% H2, 5-10% CO2, 80-90% N2, and 0% O2.
What are facultative anaerobes?
Aerobes that can grow anaerobically; most clinically significant bacteria.
What are aerotolerant anaerobes?
Can survive in the presence of oxygen but unable to perform metabolic processes unless situated in an anaerobic environment.
What are microaerophilic organisms?
Require only 5-10% O2.
What are capnophiles?
Require increased CO2 (5-10%).
What is an autotroph?
Uses CO2 as the sole carbon source.
What is a heterotroph?
Uses other organic molecules as carbon source.
What is a phototroph?
Uses light as their energy source.
What are chemotrophs?
Use energy from organic and inorganic compounds.
What are lithotrophs?
Use inorganic compounds as electron source.
What are organotrophs?
Use organic compounds such as carbohydrates and lipids.
What is a psychrophile/cryophile?
Organisms that grow at 0 to 20 degrees Celsius.
What is a mesophile?
Grow between 20-45 degrees Celsius.
What are thermophiles/hyperthermophiles?
Grow between 50 to 60 degrees Celsius.
What are acidophiles?
Grow in pH <5.5.
What are neutrophiles?
Grow between pH 5.5 and 8.0.
What are alkalophiles?
Grow between pH 8.5 and 11.5.
What are halophiles?
Require and grow in increased concentration of NaCl.
Example: Enterococci (6.5%); S. aureus (7.5%), Vibrio (8-10%).
What is Sterilization?
Destruction of all forms of life including spores.
What is Disinfection?
Elimination of a defined scope of organisms.
Applied on inanimate objects.
What is Antisepsis?
Performed on living tissue; does not kill spores.
What factors affect the degree of killing?
Types of organisms, number of organisms (microbial load), concentration of disinfecting agent, presence of organic material, nature of surface to be disinfected, contact time, temperature, pH, biofilms, compatibility of disinfectants and sterilants.
