Chapter 8 - Infection and Defects in Mechanisms of Defense Flashcards
Communicability
ability to spread from one individual to others and cause disease
Infectivity
ability of a pathogen to invade and multiply in a host
Infectivity involves a_______, e_______, d_________
-attachment
-escape of phagocytes
-dissemination (spread)
Virulence
severity or harmfulness of a disease or poison
Toxigenicity
ability to produce toxins
What do toxins influence?
a pathogen’s virulence
Portal of Entry
route by which a pathogen infects the host
What are some mechanisms of portal of entry?
-direct contact
-inhalation
-ingestion
-animal or insect bite
Is the DNA in a prokaryote cell enclosed in a nucleus?
no, it only has a nucleoid
Are prokaryotes aerobic or anaerobic?
they can be either depending on the species
Are gram-positive or gram-negative bacteria more dangerous?
gram-negative due to their outer membrane and porin channels which make them more difficult to defeat
Staphylococcus aureus is a common n______ infection
nosocomial
Where are staphylococcus aureus housed as normal microbiota?
nasal passages and skin
S. aureus produces a protein that blocks…
compliment attack
How does S. aureus avoid innate immunity?
producing inhibitors that avoid recognition by the immune system
What enzyme does S. aureus resist when engulfed by a phagocyte? How?
resists Lysozyme by changing the chemistry of their cell walls
S. aureus resists the action of many of what kind of drugs?
antibiotics
Exotoxins are released from ____ the pathogen
inside
Endotoxins are released from ______ the pathogen.
outside, specifically the outer capsule
What are exotoxins?
enzymes that damage host cell plasma membranes or inactivate critical protein synthesis enzymes
What do endotoxins activate? What do they produce?
they activate the immune system and produce fever
Bacteremia and septicemia are a result of the failure of ______ _________
defense mechanisms
Bacteremia
presence of bacteria in the blood
Septicemia
growth of bacteria in the blood
What two systems that start with “C” are activated by endotoxins?
complement and clotting systems
Endotoxins increase capillary permeability which leads to…
large volumes of plasma leaking into surrounding tissue and thus HYPOTENSION
What is the most common cause of pain or distress in humans?
viral disease
Viruses must _____ the host cell to replicate
enter
What is the structure of a virus?
it is neither a eukaryote or prokaryote and is just DNA or RNA surrounded by a capsid or envelope
Viruses are self-limiting meaning…
they resolve spontaneously without treatment or intervention
How are viruses transmitted?
-aerosol
-blood
-sex
-vector (tick, mosquito, etc.)
Viruses have cytopathic effects meaning…
they cause damage to living cells
Viruses inhibit host cell DNA or RNA _______
synthesis
How do viruses kill cells?
release lysosomes into the cell
Viruses can cause the _____ of host cells into multicellular giant cells
fusion
Viruses can cause the alteration of host cell antigen properties causing the immune system to attack…
its own cells
Can viruses cause cancer?
yes, they can transform host cells into cancerous cells
Why do viruses need host cells to replicate?
need to use the host cell resources
What is influenza?
a highly contagious viral infection of the respiratory passages
Influenza has the ability to produce antigenic variation meaning…
ability to change viral antigen spikes yearly
Fungi
are large eukaryotes with thick, rigid cell walls
Why do fungi have the ability to resist penicillin?
penicillin is a fungus itself
Fungi can exist as _____, _____, or both
yeasts or mold
Yeasts are ____cellular
unicellular
Molds are _____cellular
multi
How do yeasts reproduce?
by simple division or budding
How do molds reproduce?
they have branching hyphae and form a mycelium (ie. ringworm)
Mycoses are diseases caused by ______
fungi
What are dermatophytes?
fungi that invade skin, hair, or nails
What are the diseases dermatophytes produce called?
“tineas” ie. tinea capitis (scalp)
Fungal infections adapt to the host environment by having wide t________ variations and requiring low levels of o______-
temperature; oxygen
A low count of what blood cell promotes fungal infections?
white-blood-cells
Which fungus is the most common cause of fungal infections?
Candida albicans, especially in cancer and transplant patients
Candida albicans is housed as normal microbiota in…
skin, GI tract, and the vagina
How might immunocompromised people be affected by Candida albicans?
it can result in a deep infection with high mortality rates
What is the death rate of disseminated (spread) cadidiasis?
30-40%
Parasites are ___cellular protozoa
unicellular
What are helminths?
large worms such as flukes, nematodes, tapeworms
How are parasites spread to humans?
vectors or ingestion of contaminated food or water
How do parasites damage tissue?
by toxins or the inflammatory/immune response
What is the virus that causes Malaria called?
plasmodium vivax
Where does the malaria infection occur?
red blood cells
Malaria results in anemia within __-__ hours
48-72 hours
What causes the symptoms of malaria (fever, chills, vomiting)?
cytokine release (TNF-a and IL-1)
What are antibiotics?
natural products of fungi or bacteria that affect the growth of specific microorganisms
Antimicrobials can be b_______ or b______
bactericidal or bacteriostatic
Bactericidal
agent that kills other microorganisms