Introduction to Medical Microbiology Flashcards
Which is the smallest microbe?
viruses
Viruses
require host cell for replication
difficult to treat
Bacteria
simple unicellular organisms
prokaryotes
Ways to test for bacteria clinically
microscopy detection of bacterial antigens detection of bacterial nucleic acids Culture Detection of antibody response to bacteria
Ways to test for bacteria microscopy
morphology
gram stain
Ways to test for bacterial antigens
flagella
capsule
LPS
Ways to culture for bacteria
metabolic properties
biochemical tests
Ways to test bacterial nucleic acids
PCR
sequencing
Ways to test for antibody response to bacteria
ELISA
Western Blot
Immuno staining
Bacterial cytoplasm
made of chromosome, mRNA, ribosomes, proteins, and metabolites
Cell wall of bacteria is made of
peptoglycan
Proinflammatory effects of bacterial cell wall
fixes complement
binds pattern recognition receptors
triggers TNF production
Gram negative cell wall contains
outer membrane
peptidoglycan (thin)
perplasmic space
plasma membrane
Which is more complex, gram neg or positive?
negative
What color does gram positive and negative stain?
negative - red
positive - purple
Gram negative enveliope
made of peptidoglycan
acts like a stiff canvas sack around bacteria
has asymmetric phospholipid bilayer
Where is LPS found?
outer leaflet of phospholipid bilayer in gram NEGATIVE bacteria only
What is LPS made of?
Lipid A
Core polysaccharide
O antigen
Lipid A
responsible for endotoxin activity
fatty acids anchor it into OM
Core polysaccharide
branches polysaccharide
required to bacterial structure and viability
O antigen
lots of species variation
helps classify different bacteria
What does LPS/endotoxin do?
causes inflammation, septic shock
activates immune system
binds to CD14 and TLR4 on phagocytes/antigen presenting cells
What does gram positive bacteria cell wall contain?
thick peptidoglycan
plasma membrane
components of gram positive envelope
peptidoglycan
teichoic acid
Teichoic acid
only associated with gram positive
LTA and teichoic acid promote what
attachment to other bacteria and to host cells
Acid fast bacteria
have complex cell envelop
structurally similar to gram positive
contains LAM and arabinogalactins
Fungi
more complex
eukaryotes
can be unicellular or filamentous
Parasites
most complex
eukaryotes
unicellular to multicellular
Prokaryotes
no nucleus
circular DNA
smaller ribosome
mesh-like peptidoglycan cell wall
What are pili/fimbrae made of?
protein subunits called pilin which forms a tube with a small hollow core
Two types of pili
common, somatic
Sex pili
only one per cell
involved in gene transfer
bind to other bacteria and a tube for transfer of genetic material, usually a plasmid
Flagella
locomotion
has H-antigen
Capsule
loose polysaccharide (or protein) layer surrounding some gram positive or negative bacteria hydrophilic
Biofilm
organized community of bacteria that has capsule/slime
What can capsule be detected by
quelling reaction
Where do endospores happen
only in gram negative bacteria
Endospores
bacteria convert from a vegetative state to a dormant state.
give rise to a single bacteria when environmental conditions are favorable
Structure of endospores
dehydrated multishelled structure
contents of endospores
complete copy of chromosome
proteins and ribosomes
high concentration of calcium bound to dipicolinic acid
Why are endospores important?
Can be aerosolized
Can be found in a lot of environments
Can withstand extreme environments
Can exist for centuries
