General Bacteriology Flashcards
Polyphasic Taxonomy
based on phenotypic, genotypic and phylogenetic properties
Bacterial Phylogeny
evolutionary relationship between bacteria
Peptidoglycan function
rigidity, protection against osmotic lysis
Gram + cell wall composition
capsule, cell wall w/ thick peptidoglycan, cytoplasmic membrane
Gram - cell wall composition
capsule, OUTER MEMBRANE, cell wall, cytoplasmic membrane, PERIPLASMIC SPACE
What does Ziehl-Neelsen staining look for?
mycolic acid in cell wall
In what type of bacteria is lipoteichoic acid present in?
Gram +
In what type of bacteria is Lipopolysaccharide in?
Gram -
Describe lipopolysaccharide
endotoxin (lipid A) activates immune system
Polysaccharide: antigenicity
What do mycobacteria use as a virulence factor?
mycolic acid
Flagella function
locomotion, motility, identification
Endoflagella
flagella in periplasmic space - causes corkscrew motility
Types of flagella
Monotrichous: single
Amphitrichous: double
Lophotrichous: ponytail
Peritrichous: everywhere
Pili/Fimbriae function
antigenicity, attachment and conjugation
Capsule function
nutrient reserve, protection, adherence, evasion of phagocytosis
What are endospores?
cryptobiotic state of dormancy
MOST DURABLE CELL TYPE IN NATURE
Endospore function
ensure survival in harsh conditions
What genera create endospores
Clostridium and Bacillus
What is sporulation?
formation of spores from vegetative cells in harsh conditions
What is germination?
return of dormant spores to growth via nutrients
Does mycoplasma have a cell wall?
No
What kind of chromosomes does Leptospira have?
two circular
What kind of chromosomes does Lymes have?
linear
4 phases of bacterial growth?
Lag, exponential, maximal stationary, death
What factors are needed for bacterial growth?
nutrients, metabolic energy source, various O2 and temp requirements
What temperature do food borne bacteria prefer?
colder (psychotrophs)
What temperature do most bacteria prefer?
normal body temp (mesophiles)
Exotoxin definition
protein toxins via bacteria, act on specific target
HEAT LABILE
Endotoxin definition
cell wall components, induce inflammation
HEAT STABLE
Superantigens
exotoxin causing IS dysfunction
How are super antigens activated
depends on variable B chain TCR - NO IMMUNE PROTECTION
Result of superantigens
massive t cell proliferation causing nausea, vomiting, fever, shock
What is a biofilm
bacterial population which are adherent to each other or surfaces enclosed in bi-polymer matrix surfaces
Examples of biofilms
dental plaques, catheters, UTI
Describe Quorum Sensing
Bacteria producing small signals to communicate when population reaches certain density behavior changes
Methods of virulence transfer
conjugation, transformation, transduction
New method of virulence transfer
outer membrane vesicles
What can mediate transfer?
bacteriophages and plasmids
What is virulence?
capacity of pathogen to damage host
Virulence factors
properties found in isolates that cause disease but that are not found in isolates of same species that lack ability to cause disease
T/F: All communicable diseases are infections but not all infectious diseases are communicable
True
What percent of microbes are pathogenic?
5%
Obligate intracellular pathogens
require host for replication and cause disease during replication
CANNOT BE COMMENSAL
Opportunistic pathogens
take advantage of situations where immune system or homeostasis is disturbed
How must a pathogen act? (5)
find host niche
evade/overcome defenses
beat normal microbiota
multiply
exert damage
T/F: All exposure leads to infection
False
