Bacteriology 1

Gram +

thick peptidoglycan
purple stain
spore formation

Gram -

thin peptidoglycan
sugars on exterior
inner/outer layer
stains pink

macroscopic

using naked eye
examines colony morphology, color, smell
non-specific

Microscopic

using microscope
examines shape/structures
staining
narrow down list using phenotype:
- aerobic/anaerobic
- biochemical pathways
- temp
- salt
- pH

Antigenic

specific
direct (bound) or indirect (bound to another bound, fc)
ELISA and western blot

ELISA

enzyme-linked immunosorbent assay
specific
antibody specific to target will bind to antigen if it's present
detects immune response not pathogen

Western Blot

view multiple proteins at once to identify specific bound targets
looks at immune response

PCR

Molecular
replicates DNA for analysis
if specific sequence isn't present there is no replication
uses RFLP

RFLP

enzymes that recognize and cut specific DNA
based on presence/absence of sequence

Bacterial gene expression

environment
growth levels

Bacterial transformation

DNA acquired form extracellular environment

Bacterial transduction

bacteriophage take DNA from one cell to a new cell

Bacterial conjugation

bacteria mate to transfer plasmids

Bacterial transposition

transposons jump from regular to plasmid DNA to transfer DNA
mutations and gene expression
involves plasmids replicating

Peptidoglycan

immune evasion
protects membrane from:
- MAC
- defensisns
- lysosomes

Capsules

immune evasion
sugar structure
hard to bind to/slippery
hard to penetrate
Protects from:
- macrophages
- MAC
- opsonization
can allow to enter cell through macrophage

biofilm

immune evasion
hard to penetrate/destroy

spores

immune evasion
inert
not recognized by immune system until active

protease

immune evasion
destroys host protein
breakdown antibodies

antigenic variation

immune evasion
changing surface epitopes to hide

Adhesion

mechanism
attaches to cilia, stops movement
binds to receptors on target cell surface

Endotoxins

mechanism/toxin
part of pathogen structure, released when cell destroyed
Ex. LPS

Exotoxin

mechanism/toxin
pathogen produced and released
A and B parts both needed to function
A: toxin
B: let's A in

Superantigens

mechanism/toxin
trigger over-release of CD4+ T cells
over immune response causes damage to make cell more hospitable for bacteria

Intoxication

immediate effect
large quantity of toxin
not infection/pathogen dependent
goes away once toxin is used up (no replication)

Infection

slow
accumulation of toxin as pathogen reproduces
reproduces until treated

Bacteriostatic agent

treatment
prevents growth, not kills
ex. fridge

Bactericidal agent

treatment
destroy bacteria
ex. bleach

Antibiotics

treatment
disruption of cell wall
inhibit protein and nucleic acid synthesis
effect metabolic pathways

Antibiotic resistance

changes it's target to avoid recognition
develop non-recognizable pathway
pump out antibiotic
degrade or modify antibiotic
antibiotic resistant forms (biofilms, spores, etc.)

Koch's postulates

1. present in every case
2. isolated and grown in new culture
3. reproduces in new host
4. recoverable from new host

Staph transmission

skin to skin (abrasions)
fomite
flora depletion

Staph virulence factors

adhesion (slime layer)
biofilms
capsule
enzymes (break down cells/tissues)
drug resistance (MRSA)
Toxins: superantigens, A-B, cytotoxins

Staph disease

toxic shock
scalded skin syndrome
bullous impetigo (blisters)
MRSA

Staph treatment

antibiotics

Staph epidemiology

Gram + cocci
normal flora

S. Pyogenes (Strep A) epidemiology

Gram + cocci

S. Pyogenes (Strep A) transmission

person to person
fomite

S. Pyogenes (Strep A) virulence factors

capsule
M protein (blocks C3b/opsonization)
C5a peptidase (block inflammation)
M and F proteins (adhesion)(disrupt junctions)
Toxins: A-B, superantigen

S. Pyogenes (Strep A) disease

Strep throat
scarlet fever
cellulitis
necrotizing fasciitis

S. Pyogenes (Strep A) treatment

antibiotics (unresistant)

S. agalactiac (Strep B) epidemiology

Gram + cocci
normal flora of vaginal tract

S. agalactiac (Strep B) transmission

flora of vaginal tract to baby during birth

S. agalactiac (Strep B) disease

neonatal infections: bacteremia, meningitis, pneumonia

S. agalactiac (Strep B) treatment

antibiotics (just before birth)
minimize exposure

S. pneumonia epidemiology

Gram + cocci
diplococci

S. pneumonia disease

pneumonia (lung infection)

S. pneumonia treatment

vaccine (targets capsule sugar structure)

Enterococcus epidemiology

Gram + cocci
normal flora of GI tract

Enterococcus transmission

person to person
fecal to oral
fomite
disruption of normal flora

Enterococcus virulence factors

wide growth range (salt, pH, aerobic/anaerobic)
biofilm
antibiotic resistance

Enterococcus treatment

antibiotics (resistant)

Bacillus anthracis (anthrax) epidemiology

gram + rod
in air spores travel far

Bacillus anthracis (anthrax) transmission

ingestion (livestock)
cutaneous
inhalation

Bacillus anthracis (anthrax) virulence factors

spores (stability)
capsule
Exotoxin:
PA+LF= edema (swelling) toxin
LF+EF= lethal toxin

Bacillus anthracis (anthrax) disease

anthrax poisoning
swelling, death

Bacillus anthracis (anthrax) treatment

antibiotics (resistance)

Bacillus cereus epidemiology

gram + rod
food poisoning

Bacillus cereus transmission

ingestion (foodborne)

Bacillus cereus virulence factors

spores
Exotoxins:
Heat stable form: emetic (vomiting) (fast, no replication)
Heat liable form: diarrheal (slow, toxin build-up)

Bacillus cereus disease

diarrhea
vomiting
cramps

Bacillus cereus treatment

pepto-bismol (for symptoms)
antibiotics (immunocompromised) (resistance)

Listeria epidemiology

gram + rod
viable in/out of cells (facultative intracellular pathogen)
grows at fridge temp
can grow in high salt or wide pH

Listeria transmission

contaminated food/dairy

Listeria virulence factors

cell invasion
escapes lysosome

Listeria disease

spontaneous abortion
diarrhea
meningitis (rare)

Listeria treatment

self limiting
antibiotics if severe (resistance)

Corynebacterium diphtheriae epidemiology

gram + rod
normal flora
facultative anaerobes

Corynebacterium diphtheriae virulence factors

Exotoxin: A-B (regulated expression) (A blocks eukaryotic translation)

Corynebacterium diphtheriae treatment

antibiotics
passive immunization against exotoxin

Clostridium difficile (Cdif) epidemiology

gram + rod
normal flora
obligate anaerobes

Clostridium difficile (Cdif) transmission

antibiotic usage (depletion of flora)
hospital acquisition (spores)

Clostridium difficile (Cdif) virulence factors

spores
A-B exotoxin

Clostridium difficile (Cdif) disease

Diarrhea (mild)
colitis (death of colon) (severe)

Clostridium difficile (Cdif) treatment

antibiotics
fecal transplant

Clostridium perfinges epidemiology

gram + rod
obligate anaerobes
not killed by heat or refrigiration

Clostridium perfinges transmission

contaminated meat
cutaneous (spores)

Clostridium perfinges virulence factors

neurotoxin
spores

Clostridium perfinges disease

cellulitis (tissue death) (mild)
myonecrosis (muscle necrosis) (severe)

Clostridium perfinges treatment

antibiotics
debridement (manual removal, death in oxygen)

Clostridium tetani epidemiology

gram + rod
obligate anaerobes

Clostridium tetani transmission

cutaneous (spores)

Clostridium tetani virulence factors

neurotoxin (interferes w/muscle communication)
spores

Clostridium tetani disease

localized muscle spasms (mild)
global muscle spasms (severe)
tetanus

Clostridium tetani treatment

antibiotics
debridement
passive immunization

Clostridium botulinum epidemiology

gram + rod
obligate anaerobes
toxin used in botox

Clostridium botulinum transmission

contaminated food (spores)
canned food, dairy, infant formula

Clostridium botulinum virulence factors

neurotoxin (release of transmitters)
spores

Clostridium botulinum disease

Botulism: paralysis and respiratory arrest

Clostridium botulinum treatment

antibiotic
passive immunization

Mycobacterium tuberculosis epidemiology

slow growing
not gram + or - (acid-fast)
no LPS
granuloma formation
structure unrecognizable to disinfectants/antibiotics (lipid-rich cell wall)

Mycobacterium tuberculosis transmission

aerosol

Mycobacterium tuberculosis virulence factors

prevents fusion to lysosome
resistant to nitric oxide-mediated killing
immune controlled but not cleared
granuloma (little prison cells made up of immune cells in lungs)

Mycobacterium tuberculosis disease

tuberculosis
blood in cough
systemic in immunocompromised

Mycobacterium tuberculosis treatment

controlled in healthy patients
long antibiotic treatment in immunocompromised (resistant)

Staph prevention

hygiene
clean medical equipment

S. pyogenes (Strep A) prevention

hygiene

S. agalactiac (Strep B) prevention

hygiene

S. pneumonia prevention

vaccine (capsule targeted antibodies)

Bacillus anthracis (anthrax) prevention

toxoid vaccine in animals
protective equipment (gardening)