Introduction to Infectious Agents 3 Flashcards
infectious disease is caused by
infectious agent such as bacterium, virus, protozoan, fungus and can be passed to other
what is infection
infectious agent enters body and reproduces. doesn’talways lead to disease
what is ano organism that causes disease
pathogen
what is organism infected by another organism
host
ability of an agent to cause rapid and severe disease in a host is what
virulence
infectious diseases give rise to how many deaths
1/3 of all deaths worldwide
more than half of death from children due to infectious diseases could be eliminated with what
vaccines
infectious diseases account for more than how much of all deaths in children undera age five
1/2
is HIV/AIDS a single agent killer
no - it will never be HIV/AIDS itself that kills, it will be opportunistic infection
how much of bacteria are non-pathogens
95%
what percent of bacteria cause human diseases
1%
what percent of bacteria cause plant diseases
4%
what percent of cells in our body are microbes
90%
what is benefit of normal flora
they compete with pathogens for nutrients
they produce antimicrobial substances that help get rid of pathogens
provide nutrients (vitamin K and B12)
block host receptors for pathogens
antimicrobal substances due to normal flora
they stimulate our cells to create antimicrobal substances and they themselves do it
explain
Skin: Staphylococcus epidermidis, Candida albicans
Nose: Staphylococcus aureus
GI: Bacteroides fragilis, Escherichia coli
and how it relates to the normal flora
The bacteria are part of normal flora but could also cause disease if they are in wrong spot or if immune system is compromised
what is true pathogen
will cause disease
what is opportunisitc pathogen and describe how it occurs
cause diseases if immune system is compromised, if there is overgrowth of normal flora, or normal flora introduced into inappropriate body cavity
what are the ways infectious disease can be classified by duration
acute
chronic
latent
what is latent duration
periods of no symptoms b/w outbreaks of illness
latent infectious examples
herpes
mono
what are three general classifications of infectious diseases
duration
location
timing
what are ways location can classify infectious diseas
local
systemic
what does systemic infection mean
a generalized illness that infects most of the body with pathogens distributed widely in tissues.
what is example of systemic infection
smallpox
what are ways infectious diseases can be classified by timing
primary
secondary
what is primary infection
– initial infection in a previously healthy person.
what is secondary infection
infection that occurs in a person weakened by a primary infection.
period b/w infection and presentation of symptoms is called what
incubation period
first symptoms that appear are called what
prodromal phase
describe prodromal phase
cold and flu type symptoms you will get before you have the normal symptoms of disease
if disease will present with symptoms, what is the phase while they are presenting
clinical phase
why will some individuals not have clinical phase
they are carriers of the disease
when there is subsidence of symptoms what is phase
decline phase
symptoms gone, tissues heal, body regains strength is what phase
recovery phase
list the time course of infectious disease
Transmission: source/reservoir Entry: skin, mucus membranes Adherence: fimbriae, adhesion molecules Invasion: enzymes Propagation: essential nutrients Damage: virulence factors, toxins Resolution: immune response (pg 12) "TEA Idolazies Parties: Democrats & Republicans"
what does propagation mean
they have to proliferate so they need nutrients
what can immune system do that is harmful of body in response to infectious disease
the immune system can harm the body’s own cells
what are two ways transmission can take place
human:human
non human: human
what is horizontal transmission
direct contact, fecal-oral, respiratory
what is verticle transmission
mother to offspring
transplacental
parturition (birth)
breast milk
what are hte ways non human to human transmission can take place
soil/water source
animal: direct, fluids (bite of rabid dog), feces, via vector
formite
what is formite
infected non-living material
like lab coat with blood on it
after pathogen is acquired what must it do
enter
how do bacteria and fungi enter/adhere
external structures: capsulse, surface antigens, flagella, fimbriae
how do viruses enter/adhere
external features: envelopes, peplomer, capsids
what are the things that allow themt o hook on
flagella (bacteria), peplomers (viruses), hooks (paraistes)
how do parasites adhere/enter
external features: surface antigens, mechanical attachemtn
what can use endocytosis to enter
bacteria, fungi, viruses, paraiste
how must viruses enter body
via host cell from fusion or endocytosis
what is unusual about parasite larvae and entrance
they can enter skin directly
what are the three main portals of entery into body
mucus membrane
skin
parenteral
what is parenteral transmission
below skin and mucous membrane, so into tissue
what is the most common and easiest portal of entry into body
mucus membrane
how do microbes enter vmucus membrane
via respiratory tract, microbes inhaled into mouth or nose in droplets of moisture or dust particles
what are some common diseases that enter via respiratory tract
Common cold Flu Tuberculosis Whooping cough Pneumonia Measles Strep Throat Diphtheria
besides repiratory what is another way microbes can enter via mucus membrane
GI tract - contaiminated hand and touch mouth
most microbes that enter GI tract are destroyed how
HCL and enzymes of stomach or bile & enzymes of SI
What are some common disease that are contracted vi GI tract
Salmonellosis Salmonella sp. Shigellosis Shigella sp. Cholera Vibrio cholorae Ulcers Helicobacter pylori Botulism Clostridium botulinum
through unbroken skin how do some microbes enter skin
openings in skin: hair follicles, sweat glands
parenteral transmission is most commonly through what
breakage in skin
microorganisms are deposited into tissues below skin or mucus membrane
what are some methods that parenternal entry can happen
Punctures Injections Bites Scratches Surgery Splitting of skin due to swelling or dryness
what are different shapes of bacteria
Cocci Bacilli-rods Spirochetes Pleomorphic (pg 26)
what is the ssize range of bacteria
.2 to 5 microns
what is mycoplasma
bacteria with no cell wall
smallest bacteria
e. coli is what shape
rod
staphyloccus is a what shape
coccus (cocci)
what is tightly packed chromosome in bacteria called
nucleoid
what are 5 things almost always in structure of prokaryotic
- Cell Wall
- Plasma Membrane
- Cytoplasm
- Ribosomes
- Nucleoid
what are optional additions for prokaryotic
- +/- Plasmids
- +/- Capsule
- +/- Biofilms
- +/- Flagella
- +/- Pili/Fimbrae
- +/-Axial Filaments
+/- Spores
Plus Bacterial Products
describe capsule in bacteria
outer layer around cell wall.
difficult for immune system to engulf via phagocytosis
what is another name for capsule
slime layer
describe biofilms in bacteria
similar to capsules - cover bacterial colony
prevent penetration of antibiotics
describe axial filament in bacteria
specialized flagellum that doesn’t go all the way to outside
what do endospores do
let bacteria live in bad conditions until they are able to live/reproduce
what is function of bacterial cell wall
support - helps it not collapse or expand in hypertonicity or hypotonicity
describe gram positive & gram negative & acid fast stain what is it used for
to see cell wall characteristics of bacteria
how is gram stain done
fix bacteria on slide stain what is in it fix crystal violet iodine treatment decolorization counter stain safranin
gram positive are what color
blue/purple
gram negative stain what color
pink
bacterial cell wall made of what
peptidoglycan
in gram positive
there is enough peptidoglycan to stain
gram negative - what happens when it is washed after it is stained?
not enough peptidoglycan to fix the crystal violet so it’s washed out
why is gram stain useful
can be done quickly and help you know how you will treat pt
arrangement of cell wall in gram neg vs pos
gram pos - cell wall outside of plasma membrane
gram neg - two membranes, outer and inner. periplasmic space in b/w them which is where the peptidoglycan is
what is example of gram pos bacteria
Staphylococcus aureus
describe cell wall in gram positive
thick peptidoglycan layer
teichoic acids & lipoteichoic aids are what
a part of cell wall in gram positve bacteria
look at gram pos pics
32 & 33
components of cell wall of gram negative
outer membrane - lipoplysaccharide
thin layer of peptidoglycan b/w inner and outer membrane
thinner than in gram pos
lipopolysaccharide is also referred to:
endotoxin
LPS stands for
lipopolysaccharide
is lipopolysaccharide found in gram pos?
no
what are three main parts of lipopolysaccharide
O-Antigen
Core polysaccharide –
Lipid A
what is lipid A?
toxic component of endotoxin
what is gram negative bacilli
E.Coli
look at pics of gram neg.
36 37
what is space b/w inner and outer membrane in gram neg
periplasmic space
streptocci is a what
cocci
what is a cocci
shape of bacteria - round
