45-Intro to Medical Microbiology 1 Flashcards
5 obligatory capabilities of medically important microbes
Attachment Spread Replication Evasion of host defenses Transmission/shedding
colonize
Exists without causing disease
infection
Organism is causing disease
commensal
Live on/in without causing disease
parasite
Live on/in and causes illness
reservoir
Where organisms is maintained (human, environment, animals)
Gram stain
Used to see shape, arrangement, and color
Gram positive
Thick peptidoglycan, hold violet stain, appear dark blue
Gram negative
thin peptidoglycan, lose violet stain, appear pink
Shape of bacteria
cocci-round
Bacillus-rod
Spirochete-spiral
Arrangement of bacgteria
Cluster
Chain
diplo
peptidoglycan made of what
Interlinked polysaccharide and peptide chains cross linked with NAM and NAG
Target for B-lactam (penicillin)
Function of peptidoglycan
structure and rigidity of bacteria
porins
Gram negative
Passage of nutrients and antibiotics
lipopolysaccharides
Gram negative
Caused endotoxin and illness
Recognized by MAMPs
Beta lactamases
Produced by bacteria to hydrolyzed B-lactam antibiotics
Also used to kill other bacteria
Bacterial DNA
prokaryote
1-10 megabases
Distinct transmissible DNA units (plasmids, transposons, bacteriophages)
Bacterial DNA replication
Requires DNA polymerase
DNA gyrate and topoisomerase for unwinding-targeted by fluoriquinolones
Eukaryotic ribosomes
80S (60S and 40S)
Bacteria ribosomes
70S (50S and 30S)
Growth curve depends on
nutrient availability, pH, bacterial concentration
When are toxins produced
Stationary phase
What is a biofilm
Produced by bacteria to protect from immune system
Phases of growth curve
Lag
Log/exponential
Stationary
death
What are spores
Formed from bacteria
Highly resistant to drying, heat, chemicals
Can regenerate when conditions permit
obligate aerobes
require oxygen for survival
TB
anaerobes
Killed by oxygen
Colon bacteria
Facultative anaerobes
grow aerobically or anaerobically
microaerophilic
grow best at low oxygen
Innate immunity
Respond to foreign material
Genetically encoded from birth
Barriers-skin and mucosa
Preformed proteins-complement system, natural antibodies
phagocytes-neutrophils, macrophages
microbe associated molecular pattern MAMPs
Innate immune system recognizes these non self
Pattern recognition receptors
Damage associated molecular pattern DAMPs
Body senses signs of injury
Role of phagocytes
confine, kill and clear invaders
pathogen
Organisms that make us ill
Hard for organism to usually live on us
Pathogens have factors to evade host defense
Virulence factor
Factors that permit infection
Equation for a disease
Organisms inoculum * virulence
________________
Host defense
Adaptive immune system
Once exposed to substance
generate specific cells and antibodies to respond to it and prevent disease
Coat and kill microbes
Antibodies, complement proteins, enzymes
opsonization
Coat particle with proteins
Make it easier for host to phagocyte and ingest
Most important opsonic proteins
Antibodies and complement
Examples of virulence factors
Escape phagosome
Alter membrane to prevent lysosome fusion
Capsule to block complement and antibody binding
Toxins-disrupt cell function
Enzymes-protect against microbicidal
lipid membranes of + vs -
+ cytoplasmic
- cytoplasmic and outer membrane
Gram - harder to access for antibiotics
Unique features of + vs -
+ teichoic and lipteichoic acids
- lipopolysaccharide
Important MAMPs sensed by innate immune system
Shared structures of + and -
flagella, pili, membrane proteins
capsule
Surface polysaccharide
Inhibit ingestion by phagocytes
toxins
Staph aureus
enterotoxigenic E coli
secretion
Gram - require specific structures to secrete
sense extracellular infections
Toll like receptor
Sense intracellular infection
Nod like receptors
mycobacteria
Acid fast
Waxy wall, mycolic acid, and LAM make it hard to stain
TB
Acquisition of microbes
Another person
Own microbiota
Animal
Environment
Cononizing
Bacteria can start as colonizers and then cause disease
Or never colonize and still cause disease
