Bailey Flashcards
6 steps in the infectious disease process
- encounter
- entry
- colonization/ invasion
- multiplication/spread
- damage
- outcome
Entry can be thought of as 2 different processes
- ingress of microorganisms into body cavities that are continuous with outside world
- penetration into deeper tissues after crossing epithelial layer (cuts, insect bites, organ transplantations)
To colonize, the pathogen must
be adapted for growth in a given niche
To invade, pathogens must
have specific virulence factors that allow them to invade the host
Pathogen must first colonize surface before causing disease. Pathogen must adhere, the 2 types of adherence are
- non specific- reversible
2. specific- irreversible
Specific adherence involves…
adhesins
Adhesions are substances
on the surface of microbes that are involved with adherence to host tissue
Adhesins are often found on… but can also be found in… or…
fimbrae (pili)
capsules
cell surface
Adhesion receptors are… for adhesins
specific
Streptococcus mutano bind to the tooth pellicle via the adhesion… which binds to a salivary protein that is involved in pellicle formation
glucose transferase
Some pathogens only… but most must…
- colonize
- invade
3 ways bacteria take up nutrients
- carrier-mediated diffusion
- phosphorylation-linked transport
- Active transport
Spread can occur through 2 different mechanisms
- lateral propagation
2. dissemination
Lateral propagation to…
… then…
contiguous tissues
multiply then spread
Dissemination to…
…then…
distant sites
spread then multiply
Disease symptoms are also dependent on… load
pathogen
The incubation period is when host is…. but there are no… this is because there are no… not enough… or the immune system doesn’t know yet
infected
symptoms
virulence factors
pathogen
Damage can be direct or indirect from… response or the … organism
- host response
- infectious organism
Toxins can be… or …
Endotoxins or exotoxins
Exotoxins are… secreted into host tissues
soluble substances
There can be 4 different outcomes in disease
- death
- recurrent illnesses
- recovery and cure
- asymptomatic infection
The body contains…. as many microbes as host cells
10x
Many places on the body can safely harbor bacteria, for example… and …
GI (10^12)
mouth (500)
What 4 abilities makes a microbe a pathogen?
- adhere to host
- colonize the host
- replicate within given niche
- cause damage- invasion, toxins, activating immune system
There are differences between commensals and pathogens but…
no microorganism is intrinsically benign or pathogenic
Bacteria can respond to oxygen in 3 different ways
- strict aerobes
- obligate anaerobes
- facultative anaerobes
4 possible outcomes
- host … and clears infection
- parasite… host
- host and parasite… to e/o
- neither… and chronic infection continues indefinitely
- wins
- overcomes
- adapt
- win
Gram positive bacteria have a …cell wall made up of…
thick murein (peptidoglycan)
Murein is made up of long chains of…and… liked together by short polypeptides
N-acetylmuramic acid
N-acetylglucosamine
Gram negative bacteria have a … layer of … between two membranes (lipid bilayers)
thin
murein
Strict aerobes must…
Obligate anaerobes cannot…
Facultative anaerobes
- have O2 to grow
- tolerate O2
- can grown with out w.o O2
The outside of the outer membrane of gram negative bacteria is made up of
LPS (lipopolysaccharide)
Lipopolysaccharide is made up of (3) different complexes
- Lipid A (inner portion)
- Polysaccharide core
- O-antigen (outer portion)
Lipid A is made up of …. attached to a phosphorylated disaccharide (part of lipid bilayer)
fatty acids
The polysaccharide core is very similar between.. bacteria but has sugars that are somewhat unique to bacteria
Gram negative bacteria
The O-antigen is made up of…. repeating sugar subunits
highly variable
LPS is toxic even in its most purified form. LPS=
endotoxin
Why are LPS and cell surface structures important? because they are considered
PAMPs (pathogen associated molecular patterns)
Cells of the immune system can recognize PAMPs using….
pattern recognition receptors (PRRs)
3 PRRs
- toll-like receptor 4
- toll-like receptor 2
- toll-like receptor 2 and 6
toll-like receptor 4 recognizes..
LPS
toll-like receptor 2 recognizes…
peptidoglycan
toll-like receptor 2 and 6 together recognize…
teichoic acids
Pili (fimbriae) are involved in the … of bacteria to cells and other surfaces
attachment
Adhesins (on tip of fimbriae) are specialized… that are more specifically developed for…
- proteins
- adherence
Fimbriae and flagella can be… (3)
monotrichous- 1
lopotricous- a couple
peritrichous- many
movement by flagella can be… or…
random or directed
When movement is directed it is referred to as…
taxis which can be directed toward something good or away from something bad
Bacterial glycocalyx is a substance that
surrounds a cell
Glycocalyx that is well organized, firmly attached is called…
capsule
Capsules are usually made of polysaccharides but can include… and …
monosaccharides and glycoproteins
Glycocalyx that is not well organized or firmly attached is called…
a slime layer
For some bacteria, encapsulation is
a necessary virulence factor
Can the immune system ever recognize a bacterium that has a capsule?
yes
toll-like receptor 5 can recognize… sometimes the capsular…. can be recognized
- flagella
- polysaccharide
Bacteria can be classified by surface antigens…
O refers to…
H refers to…
K refers to…
O=LPS (gram negative)
H= flagella
K= capsule
Antibiotics can have 2 different modes of action
bactericidal and bacteriostatic
Bactericidal…
Bacteriostatic…
- kill bacteria
- prevent microbes from replicating
5 ways that antibiotics inhibit bacteria
- inhibit cell wall synthesis
- disrupt cell membrane fxn
- inhibit protein synthesis
- inhibit nucleic acid synthesis
- action as antimetabolites
Many inhibitors of DNA replication bind to DNA and thus are too…
toxic for use
Inhibition of Nucleic acid synthesis: … is inert but can be converted to an active form by….
anaerobic microbes
Invasive bacterial pathogens like salmonella and shigella cause what kind of diarrhea?
- large intestine
- small volume
- bloody
- WBCs
- tissue ulcerations
Toxin producing bacterial pathogen like Vibrio, V. cholera and Enterotoxigenic E. coli (ETEC) produce what kind of diarrhea?
- small intestine
- large volume
- watery
- no RBCs, WBCS or ulcerations
The hybrid misfits like Enterohemoryhagic E. coli (EHEC) and Enteropathogenic E. coli (EPEC) cause what kind of issues?
- lower SI, upper LI
- colonization causes attaching and effacing lesion
- blood in stool and urine in EHEC
Vibrio cholerae is motile and naturally found in,,,
seawater (we get from shellfish thats from contaminated water)
2 main cholera types
- el tor
2. classical
There was a spread of El Tor (v. cholera) in 1961that mainly affected
children and elderly
There was an outbreak of el tor in 1992 that had a mutated …
O1 antigen
El tor had a new LPS serotype called…. which was encapsulated and affected
O139
all age groups
V. cholera has … which is important in seawater and GI tract
flagella
V. cholera has… which adhere to mucosal tissue
pili
In V. cholera, the shift from seawater to reduced ion levels found in the body leads to…
expression of pili and to the toxin
The cholera toxin is… encoded
phage
E. coli types…
- secretory diarrhea
- dysentery like
- UTIs
- secretory diarrhea=ETEC, EPEC
- dysentery like= EHEC
- UTIS= UPEC
…. is responsible for travelers diarrhea
ETEC
How to rule out V. cholera
- shellfish?
- TCBS agar
- Agglutination test (el tor)
- serological test
tx for secretory diarrhea
oral rehydration (mix of sugar and salt) and antibiotics can shorten duration or reduce severity
They cause movement when they rotate… and tumbling when rotate…
- CCW
- CW
The ideal antibiotic would have a … spectrum of activity, would not induce… has a …. therapeutic index and has… toxicity
- broad
- resistance
- high
- selective
High therapeutic index is the ratio between
toxic dose and effective dose
if ratio of high therapeutic index is 1 then you need… because the closer to 1=…
- toxic dose to eradicate microbe
- worse antibiotic
Clostidrium are strictly… and are gram… they produce…
anaerobic
positive
endospores
c. difficle causes
pseudomembranous colitis (PMC)
C. perfringens cause
cellulitis, gas gangrene and food posioning
c. botulinum and c. tetani cause
botulism, tetanus
Clostridial diseases are caused by toxin production or tissue invasiveness?
toxin production
Clostridium endospores are usually in an … state and resistant to….
inactive
changes in environment (hot, dry, radiation, chemical)
Clostridium produce spores when there is.. environmental conditions and they will readily … when conditions become favorable for vegetative growth
unfavorable
germinate
is c difficle easy to culture
no
pseudomembranous colitis is yellow plaques containing …. and… in ulcers of colonic mucosa
fibrin and cellular debris
c. difficle is the leading cause of… and is transferred by… and
nosocomial diarrhea (leads to hospitalization) -endospore, hands
c. difficle is not invasive but it colonizes and the… it produces causes disease
toxin
c. difficle causes toxin… and …
A and B
c. difficle toxin A is an … which causes fluid production and damage to mucosa
enterotoxin
both toxin a and b in c diff act in … of host cell to glycosylate…. and cell loses cytoskeletal structure and die
- cytoplasm
- gtp binding proteins
…. detection of toxin A c diff is diagnostic
ELISA
c diff toxin b is a… toxin
cytotoxin
c. perfringens is found in…. and …
soil and intestinal animal tracts
c. perfringens is a major pathogen of… and can have… and … effects
- wound infections (war wounds)
- local and systemic
severe trauma introduces spores from the environment that germinate under these conditions- (4) (damaged tissue)
- anaerobic
- compromised blood supply
- calcium ions
- peptides and aa availability
toxins produced in c. perfringens typically cause cellulitis that can lead to…. which is a necrotizing, gas forming process of muscle associated with systemic signs of shock
gas gangrene
c. perfringens produces how many toxins? which one causes gas gangrene?
12
alpha-toxin (lecithinase)
alpha-toxin (lecithinase) is a ….which causes…. and has a 100% fatality rate if not treated
phospholipace type C
- muscle tissue damage
- shock/renal failure
c. perfrigens treatment
surgical removal (necessary) and antibiotics and possibly antitoxin from horses and high O2. EARLY care is important
c. perfrigens is more likely to cause… than gangrene
food poisoning (diarrhea in 12-24 hours) self limiting and disappears in 1-3 days
c. botulinum have… spores found in… that can survive…
heat resistant, soil, food processing
c. botulinum germinate and grow under… conditions
anaerobic
botulism is caused by…. of preformed toxin (dont need organism to be present) and there is concern that it can be used as…
- intoxication of ingestion
- bioweapon, bioterrorism
c. botulinum produces 8 neurotoxin serotypes (A-G) 2 C forms… but…. are most common in humans
A,B,E (extremely potent)
purified BoNT us produced as a stable 900 kDa protein complex containing….
150 kDa toxic component
750 kDa non toxic component
(multi subunit)
c. botulinum prevents release of…. resulting in…and starts in …first and then ultimately can cause…
ach neurotransmitter
flaccid paralysis (12-36 hours)
cranial nerves
respiratory failure
3 types of botulism
- food borne
- wound
- infant (slow onset)
c. botulinum mortality rate
25%
c botulinum treatment
antitoxin (from horses) ASAP
antibiotics not necessary because toxin is in body not cells
c. tetani is found in … and produces…and infection is associated with…
soil, spores, traumatic wounds
major toxin in c. tetani…. which is responsible for all symptoms… and has a … and … individual chains are non toxic
tetanospasmin
heavy and light chain
c. tetani ihibits nuerotransmitter release of … which causes…
GABA - spastic paralysis
first sign of tetanus… descends to …. causes…. and eventually….
trismus (lockjaw)
neck and back muscles
tonic seizures
respiratory failure
treatment of tetani
- vaccine DPT, tetanus toxoid
- human globulin
- antitoxin
- penicillin G
chlamydia are large or small? and are gram… and they have no … in cell walls
small
negative (LPS outer membrane)
peptidoglycan
chlamydia will only grow…. and are considered…
in host cell (humans, animals, insects)
energy parasites - depend on host for ATP
4 species in chlamydia
trachomatis (human)
pneumoniae (human)
chlamydia is the leading cause of … and is most common agent of…
preventable blindness in world
sexually transmitted bacterial infection
chlamydia are spread by 4 F’s
fingers
flies
fomites
fornification
chlamydia infect mucosal epithelial cells in the ….
eyes lungs and genitalia
c. trachomatis causes…. in men
prostitis, epididymitis
c. trachomatis causes … in women
cervicitis, PID, premature birth, pelvic pain, newborn eye and lung infections
c. trachomatis is usually … in females and chronic and repeat infectons can cause…
asymptomatic
ectopic pregnancy or sterility
c. trachomatic infectons can cause… or … in newborns
conjunctivitis and pneumonia
