Module 5.0 Flashcards
Name some basic criteria of bacteria.
- Unicellular microscopic living organisms
- Most are harmless
- Contain DNA AND RNA
- Rigid cell wall
- Most grow in artificial media
- Sensitive to antimicrobial agents
- Replicate by binary fission
List the basic structures of bacteria
Moving from out to in:
- Capsule
- Outer membrane
- Inner Membrane
- Flagella
- Pili, fimbriae
- Plasmid
- DNA
- Ribosomes
Describe flagella and pili
- filamentous proteinaceous structures
- flagella are for motility
- Common pili: adherence to cell surface
- Sex pili: genetic exchanges
Describe spores
- Most dormant form of bacteria
- Minimal metabolism and respiration
- Reduce Enzyme productivity
Common ways to identify bacteria
- morphology
- staining
- cultural characteristics
- biochemical reactions
- molecular methods
- immunological methods
What are the three basic bacteria shapes? (Morphology)
Sphere-shaped (cocci), rod-shaped (bacilli), spiral-shaped (spirochetes)
Describe the staining differences for gram positive versus gram negative
gram-Positive = purple, gram-negative = red
Do antibiotics react differently between GP and GN bacteria?
Yes, since the GP bacteria have a thick peptidoglycan layer and the GN have a high lipid layer the spectrum of antibiotics is not the same.
What is a catalase test?
Used to differentiate bacteria that produce the enzyme catalase to breakdown hydrogen peroxide to oxygen and water. If it bubbles it is catalase positive.
What is a coagulase test?-
Used to identify bacteria that produce the enzyme coagulase which converts fibrinogen to fibrin. If it forms a precipitate it is coagulase positive.
What are some pros about using molecular methods for bacteria ID?
- most advanced and accurate method
- bacteria can be classified into sub-species, strains. serotypes or pathovar levels
- methods include: PCR, DNA/RNA probe tests, microarray, eletrophoresis, proteomics
What is an obligate pathogen?
It must live inside a host to survive and reproduce
What is a primary pathogen?
Can cause disease in a healthy host, in contrast to needing the host to be compromised to attack.
What is an opportunist pathogen?
Can cause disease in a host with a weakened immune system when they let their guard down.
What are fungi?
- Eukaryotes (bacteria and prokaryotes)
- Can float anywhere and contaminate any kind of samples
- vast majority are saprophytes (live on dead organisms
- reproduce by spores
- Chitin cell wall
- unicellular or multicelluar
- includes yeasts, molds, mushrooms
List the 3 fungi types.
- yeast: single-celled, divide by budding, may have pseudohyphae
- molds: multicellular, grow by extension of asexual or sexual spore into tube-like structure (hypha), into cotton-wool mass (mycelium)
- dimorphic: have both yeast and mold like form
What is the sequence of pathogenesis?
Enter/attach to the body, evasion of host defenses, multiplication and colonization, damage to host, transmission to other hosts (infectious)
Which two types of pathogens are typically host specific?
Obligate and primary (essentially they need their host to survive and reproduce) whereas opportunists will take advantage of any opening
What are some common ways bacteria cause host damage?
toxins, lytic enzymes, inflammation in response to microorganisms and their products, immune-mediated destruction
LPS Endotoxin is a common virulence factor of which type of bacteria?
Gram negative, it can get through the lipid cell wall.
