Lecture 1, Infections Flashcards
What are the major groups of infectious agents?
- Protozoa
- Fungus
- Bacteria
- Virus
- Prion
What is the difference between prokaryotic and eukaryotic organisms?
Prokaryotes do not have membrane-bound genetic material.
What is the distinction between aerobic and anaerobic organisms?
Aerobic organisms need O2 to survive; anaerobic organisms can survive without O2.
Define microbe.
Organism/agents that are normally too small to see with the unaided eye.
Where are microbes normally not present in the human body?
- Blood
- Fat
- Organs
True or False: Viruses are considered living organisms.
False
What is a virus composed of?
- Protein
- Genome (can have DNA or RNA)
What type of organisms are obligate parasites?
Viruses, as they need a living host cell to replicate.
What is a prion?
Misfolded proteins that can cause diseases such as mad cow disease.
What defines bacteria?
Single-celled organisms that may or may not need oxygen to survive.
What are the two types of Gram staining in bacteria?
- Gram positive: thick peptidoglycan cell wall
- Gram negative: lipopolysaccharide
What is the consequence of Gram negative bacteria degrading?
It produces endotoxin, which can lead to severe fever or shock.
What do most antibiotics target in bacteria?
The peptidoglycan cell wall.
Define protozoa.
Single-celled organisms that can cause disease in humans.
What are helminths?
Animals, such as intestinal worms.
What are the two forms of fungi?
- Single-celled (yeast)
- Multicellular (mould)
Define pathogen.
Microbes with specific characteristics called virulence factors that enable them to cause harm.
What is an infection?
Microorganisms penetrate and invade tissues and usually multiply.
What is the difference between colonization and infection?
Colonization is the establishment of microbes without penetrating sterile tissues; infection involves tissue invasion.
What is post-infection sequelae?
A condition that persists even after recovery from disease.
Define acute disease.
Rapid onset of disease that typically does not recur if resolved.
What characterizes chronic disease?
The pathogen remains at high levels in the body and may be transmitted before symptoms appear.
What is latent disease?
An initial acute infection that is not entirely resolved, leading to dormancy of the microbe.
Define true pathogens.
Pathogens that invade tissue and can cause morbidity or mortality.
What are commensals?
Microbes that colonize surfaces without causing damage.
What is microbial antagonism?
Microbes protecting us by making it difficult for other microbes to colonize.
What is an opportunistic pathogen?
Commensals that can turn into pathogens in immunocompromised individuals.
What can cause an immunocompromised state?
- Oral antibiotics
- Corticosteroids
What are the symptoms of Clostrioides Difficile infection?
- Diarrhea
- Short term memory loss
Where is Clostrioides Difficile commonly found?
In ~20% of the adult GI tract.
What is a characteristic of Clostrioides Difficile spores?
They can survive a long time and resist disinfection.
What are the virulence factors of Clostrioides Difficile?
- Receptor proteins detect bile salts
- Toxin A causes intestinal tissue damage
What is MRSA?
Methicillin-resistant Staphylococcus aureus.
True or False: Staphylococcus Aureus can survive with or without oxygen.
True
How is Staphylococcus Aureus spread?
By contact and food.
