General Principles of Microbiology Flashcards
What is the composition of viruses and how do the replicate and how do the affect host cell?
nucleic acids and sometimes proteins shells (capsid)
- enter cells and divert the synthetic processes of those cells for replication
- can kill or not kill host cell
How does the bacteria ,Chlamydia, differ/ similar from viruses?
differ
- more complex
similar
- can only multiple in living cells
- recognizable morphology and life cycle
What are the characteristics of prokaryotic bacteria?
- rigid cell wall with cytoplasm
- genetic material is organized in circular chromosomes
How do mycoplasmas differ from other bacteria?
- similar but don’t have rigid cell wall
- lack of rigid cell wall makes them more delicate than other bacteria
What are eukaryotes and how do they differ from prokaryotes?
- include all unicellular and multicellular animals and plants
- have their genetic material organized into a nucleus
What is the difference between resident and transient bacterial flora?
RF - permanent microbial populations that live in specific areas of the body
TF - temporary population that often appear due to injury, trauma, or behavior
How does infection occur with bacteria and what determines the outcome?
- infection happens when a single bacterial species becomes dominant or invades a normally sterile site
- the outcome is determined by both the pathogenicity of the and the host’s immune response
Why is normal bacterial flora important for health?
- protection: against infection by invasive organisms
- metabolism: help synthesize vitamins (e.g., K)
- antibiotic disturbance: antibiotics disturb balance causing issues like antibiotic-induced diarrhea
- host defense: helps immune system; deficiencies may lead to infections
- lab confusion: can interfere with the interpretation of lab results
What are the key defense mechanisms when it comes the interactions between pathogenicity mechanisms and host defenses?
- normal flora control: host defenses prevent invasive disease and keep normal flora in check
- Invasive infection: the outcome of an infection depends on the interaction between host defenses and bacterial pathogenicity mechanisms
What are the key physical factors that bacteria must overcome to become infectious?
Mechanical Barriers: Skin acts as a physical barrier to prevent bacterial entry.
Adherence: Bacteria attach to host tissues using specific ligands and receptors.
What causes patients to become compromised?
Deficiencies in defenses: conditions or treatments can impair antimicrobial defenses
Examples:
- Phagocytosis (e.g., leukopenia): increases risk for Staph and Strep due to them producing protective polysaccharide capsule
- Antibody-mediated immunity: increases susceptibility to Strep and viral infections
- Cell-mediated immunity (e.g., AIDS): increases risk for infection like Tuberculosis
What are the key defense mechanisms the body uses against bacterial infection when is comes to macrophages?
Cell-Mediated Immunity: Activated macrophages and immune system cells (ex. T-cells) target and kill specific bacteria like Mycobacterium tuberculosis and Legionella.
Phagocytosis: Macrophages and neutrophils ingest and destroy bacteria, though some bacteria protect themselves with capsules.
Antibodies: Bind to bacteria to enhance phagocytosis or directly kill the bacteria.
What is the spread of bacterial infections called and how does it happen?
Metastatic spread
- Bacteremia/ Septicemia: bacteria spread through the bloodstream from the primary site of infection
- Dissemination: Bacteria can cause symptoms in distant sites from the original infection focus
What are the key defense mechanisms the of body, when it comes to plasma and exotoxins, that protects against bacterial infection?
Complement System: Plasma proteins work together to help resist bacterial infections.
Exotoxin Production: Some bacteria release exotoxins that damage tissue; antibodies help neutralize these toxins.
What are the main defense mechanisms of the body against bacterial infections?
- mechanical barrier
- phagocytosis
- antibodies to bacteria
- complement
- cell mediated immunity
- exotoxins (host produces antibodies in the process)
If the host defense is missing (or deficient in) phagocytic cells, antibody mediated immunity, and cell mediated immunity?
- Staph and Strep
- Strep and viral infection
- TB, legionella and AIDS related infections
What are microbial diseases?
interaction between microorganisms and the host organism, including processes like adhering, penetrating, and multiplying
What are microorganisms and what are their characteristics?
Organism that is invisible to the naked eye
- majority are harmless or beneficial; only a small amount causes harm to animals and plants
What is an infection and what are the different 3 types?
penetration of a microorganism into a host organism which multiplies and causes disease (apparent) or no disease (inapparent)
1. colonization: microorganism establish themselves and multiply without causing disease
2. contamination: microorganism deposit without multiplication (e.g., water contaminated with sewage)
3. clinical infections
What are the 3 types of clinical infections?
Clinical infection: functional damage to the host (disease)
factors:
- large vs. small # or microbes
- high virulence vs. attenuated virulence
- susceptible vs. resistant host
Subclinical infection: without apparent symptoms (asymptomatic)
No infection: host remain unaffected
What is the difference between pathogenicity and virulence?
P - the ability of a microorganism to produce disease
V - microorganisms relative capacity to cause damage (i.e., degree of pathogenicity)
What is opportunistic pathogens?
microorganisms that do not usually cause disease but can do so when defense mechanisms are breached or compromised
What are the opposing force operate in infection?
Microorganism: strives to multiply and invade tissues
Host: strives to block invasion and destroy microorganism
What is transmissibility and what are the different ways of entry?
the ability of a microorganism to transfer an effective amount from a source to a host
- inhalation
- ingestion
- break in protective barrier
- direct deposit
What is pathogenicity and what are the 3 kinds?
the ability of a microorganism to cause disease
- invasiveness: overcoming host defenses to multiply
- toxigenicity: production of toxins
- combination of the both: both
What are some mechanisms microorganisms use for adherence and evading host defense?
- Surface structures adhere to specific receptors on host cell surface
- Capsules: polysaccharides that protect microorganisms from immune cells like leukocytes
What role do enzymes play in the virulence of microorganisms?
- Coagulase: accelerates clotting of plasma, forming a barrier around the infection site
- Hyaluronidase: breaks down hyaluronic acid, allowing bacterial spread through tissues
What is toxigenicity?
is the production of toxins by microorganisms that damage host tissues or disrupt vital systems
What are the two types of toxins produced by bacteria?
- exotoxins
- endotoxins
What are 4 characteristics of exotoxins?
- proteins secreted by living bacteria
- have specific attraction for host systems (e.g., botulinum toxin affects nervous tissue)
- active in very small concentrations and highly toxic
- often thermolabile (sensitive to heat)
What are 3 characteristics of endotoxins?
- associated with the bacterial cell structure and released when the cell die
- less specific and potent than exotoxins, but can cause fever, malaise, and shock (septic)
- Thermostable (resistant to heat)
