exam 1 Flashcards
what shape is bacillus
rod
what shape is coccus
spheres/ round
what shape is spirochete
flexible, thin, spiral-shaped rod
what shape is spirillum
rigid, spiral-shaped rod
what are pleomorphic bacteria
no defined shape, variety of shapes in one species
what is diplo
pair
what is strepto
chain
what is staphylo
grape-like cluster
what is tetrads
packets of 4 cells
what is sarcina
packet of 8 cells
what are the three main types of cell walls that bacteria have
gram-negative
gram positive
acid-fast
what are the main components common to all three cell wall types of bacteria
peptidoglycan
lipoprotein
(provide structure support)
what is the peptidoglycan layer made up of?
backbone
tetra peptide side chains
peptide cross-bridge
what are the antimicrobial enzymes found in secretions and granules of peripheral mononuclear cells? and what is their function?
lysozymes
-weakens the cell integrity
do gram positive bacteria have a thick or thin peptidoglycan layer
thick
do gram negative bacteria have a thick or thin peptidoglycan layer?
thin
what is the primary stain
crystal violet
what is the counterstain
safranin
what color are gram negative cells
they retain the counter stain so they are red
what color are the gram positive cells
they retain the primary stain and stain purple
what is the periplasmic space
space between the inner and outer membrane
what is a distinct component of the outer layer of gram negative cells
lipopolysaccharides (LPS)
LPS is also known as
endotoxin
what structures is the LPS composed of
O antigen
core polysaccharide
lipid A
what does the O antigen serve a purpose for in the LPS
serves as attachment sites
what does the lipid A serve a purpose for in the LPS
virulence factor of LPS
-this is the part responsible for the endotoxic activity
what are the two key components unique to gram positive bacteria
teichoic acid (WTA)
lipoteichoic acid (LTA)
what is the function of WTA/LTA in gram positive cells
allow for adherence of bacterial cells to host cells
what does teichoic acid adhere to
peptidogylcan
what does lipoteichoic acid adhere to
anchors to cell membrane
when an host is infected with a gram negative bacteria cell what can WTA/LTA initiate
WTA/LTA along with peptidoglycan can initiate endotoxin-like activities when released upon bacterial lysis
-but not truly an endotoxic reaction
what are structures that are unique to the acid-fast bacteria cell wall
mycotic acid layer (outer)
tetrameric porins
what is the function of mycolic acid layer of acid-fast bacteria
waxy coat
-provide resistance to desiccation, some antibiotics and inhibits phagocytosis
what are the two clinically relevant genera that are acid fast
mycobacterium
nocardia
what is the primary stain for acid-fast bacteria
carbolfuchsin
(acid-fast=red)
what is the counterstain for acid-fast bacteria
methylene blue (nonacid-fast=blue)
what is the point of the hot plate for an acid fast stain
to open that waxy coat to allow the stain to penetrate the cell to color
a foal was diagnosed with endotoxemia caused by endotoxins released into the bloodstream. the bacterial cell wall structure causing the patient’s symptom is what?
lipid A
a stained tracheal mucus specimen was collected from a cattle shows acid-fast bacilli. what genera should be included in your differential diagnosis?
mycobacterium
what are two forms of glycocalyx
slime layer
capsule
what is the function of glycocalyx
-promotes adherence of bacteria to surfaces to biofilm formation
-protects against desiccation
-acts as barrier to toxic hydrophobic molecules- antibiotics
-inhibits phagocytosis
function of slime layer of glycocalyx
protects bacteria cells from environmental dangers such as antibiotics and desiccation
what is the test quelling reaction used for
to determine whether bacteria have a capsule or not
describe how the quelling reaction works
antigen-antibody reaction causes a change in the refractive index of the capsule so that it appears “swollen” and more visible
what are the three major components of flagellum
filament
hook
basal body (anchor flagellum in cell membrane)
what protofilaments are each flagellum made up of?
composed of flagellin (H antigens)
-highly antigenic
what are the two main classes of pili
-ordinary/common pili
-sex pilus/conjugated pilus/F pilus
what does ribosome consist of
mRNA
protein
what are bacterial ribosomes made up of
50S and 30S subunits
ribosomes are important and are good for antimicrobial activity
:)
importance of inclusion bodies (internal structure)
various granules, vesicles and vacuole within cytoplasm
-can aid in identification of some bacteria
properties if endospores
core
spore wall
cortex
coat
exosporium
sporulation vs vegetative growth
-vegetative growth: a single endospore will create two daughter cells
-sporulation: go through process to make a spore coat and then a spore and the spore then gets activated from resting stage once there is lack of nutrients or something
two clinically relevant genera that produce endospores
bacillus
clostridium
what pH are transport media and culture media buffered at
~7.0
explain oxygen requirement for facultative anaerobes
no oxygen requires but will used if there is any available
do aerotolerant anaerobes require oxygen
no oxygen required and can tolerate some oxygen because it has reactive oxygen species (ROS), which knock out other reactive oxygen
what type of bacteria are capnophiles and where do they commonly reside
microaerophiles
-cheek/mouth is favorable area bc requires some CO2
what is an example of species that resist desiccation
staphylococcus spp
what is an example of species that can desiccation and needs transport media
haemophilus
what bacteria do not require NaCl but can grow under saline conditions (increase osmotic pressure)
halotolerant bacteria
what are chemohetertrophs
using organic compounds as sources of energy and carbon
what are fastidious bacteria
requiring additional organic compounds in their culture media (vitamins, aa)
what are solid media used for
isolation of pure cultures (agars)
-estimate the number of viable bacteria in a sample
-colony characterization can be used for microbial ID
what is a colony
population of cells arising from a single cell or spore, or from a group of cells of the same species or strain
what are liquid media (broths) used for
ideal for growing large numbers of bacteria (can’t actually visually determine number of species present)
what are semi-solid agars used for
determining motility, growing microaerophiles, some transport media
*agar is a solidifying agent, NOT a nutrient
man said its gonna be on exam
what is basal media and what are some types
sustain growth of less fastidious bacteria
-nutrient agar, nutrient broth, tryptic soy agar
what is enriched media and what are some types
basal media + additional nutrients (eg blood, egg yolk) used to cultivate fastidious organisms
-blood agar, chocolate agar