Bacteriology 1

Gram +

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)