Bacterial Structure and Classification-Dr. Kell Lecture Flashcards
Microbiology includes
viruses, bacteria, fungi and parasites
what are the three different ways to classify bacteria
phenotypic methods, analyitic and genotypic
chocolate agar is known as a
selective agar
MaConkey is good for screening for
gram neg bacteria
___is type of agar used for hemolysis
blood agar
alpha hemolysis
partial hemolysis of RBC’s
beta hemolysis
all blood cells are lysed
gamma hemolysis
no hemolysis
What are some examples of organisms that grow on chocolate agar
fastidious organisms, H. influenze, and N. gonorrhea
________-type of agar selects for enterics
Macconkey
________inhibits gram positive organisms
MacConkey
_______differentiates between lactose fermenters and nonfermenters
Maconkey agar
if something grows on buffered charcoal yeast it is probably
legionella
if something grows on sabouraud dextrose it probably is
candida albicans
if something gorws on lowenstein jensin it is
mycobacterium tuberculosis
what are the reagents used in a gram stain procedure
crystal violet, grams iodine, decolorizer and safranin
gram positive bacteria appear _____on a gram stain
purple
gram negative bacteria appear ______on a gram stain
pink or red
acid fast staining is particularly useful in staining
cell walls that contain waxes such as mycobacterium and nocardia sp
__________ and ______-do NOT gram stain
mycobacteirm and nocardia sp
if something appears to have grown “red snappers” and their cell walls contain waxes what is the most likely type of bacteira
mycobacterium sp
catalase tests for
streptococci and staphhylococci (+)
coagulase test for
staphylococci aurieus (+) between other staphylococci
indole test for
enterics and ecoli (+)
the urease test tests for
proteus species
the _________test for presence of cytochrome oxidase C and tests for __________-
oxidase test psuedomonas aeruginosa
serotyping
can identify those that are inert in biochemical testing, identify organisms that cannot be cultured, rapid identification, and involves antibody to organism sometimes flourecent tagging
________-are often used for gonorrhea and chlaymydia and look for specific sequences unique to a genus, species or subspecies
molecular probes
_________-is extrachromosomal DNA not essential for survival but are responsible for antimicrobial resistance and is more common in gram negative organisms
Plasmids
plasmids are more common in what type of organism
gram negative
what is the action of quinolones in gram negative bacteria
inhibition of DNA gyrase, unable to pack DNA into the cell, specific for bacterial DNA gyrase
what is the action of quinolons in gram positive bacteria
inhibition of topoisomeriase IV
what is the mechanism of flouroquinolones
bind two nuclear enzymes inhibitng DNA replication
what are the different ribosome subunits in bacteria
30S and 50S=70S ribosome
why is transcription and translation coupled in bacteira
allows the organism to grow very very quickly and you can have an enormous amount of growth
chloroamphenicol, erthytromycin, tetraclcyine, and streptomycin all commonly do what ?
inhibit protein synthesis of antibiotics
what type of bacteria have sterols
mycoplasma
what is a mesosome
invagination where DNA binds to replicate; segregation of chromosomal DNA into daughter cells
the bacterial cell wall is composed of what
peptidoglycan
general characteristics of mycoplasma species
lack cell wall
sterols in membrane
require special media to grow
not visible on the gram stain
what type of bacteria have a thick peptidoglycan
gram positive
characteristics of gram positive peptidogycna
highly polar
surface is hydrophilic
lysozyme can digest, (bactericidal)
bile resistant
__________interfere with the formation of the peptide side chains between adjacent strands of PTG by inhibitng the penicillin binding proteins
beta lacatam drugs
________binds to the amino acid side chain of NAM molecules interfering with peptidoglycan synthesis
vancomycin
___________interferes with the transport of peptidoglycan precursors across the cytoplasmic membrane
bacitracin
__________inhibits reactions involved in the incorporation of alanine into the cell wall precursor
cyclyserine
_________–bind to the terminal D ala, D alal residues preventing the incorporation of subunit into growing peptidoglycan
glycopeptides
synthesis of peptidoglycan occurs in the
cytosol, cell membrane and periplasm or exteria
teichoic acid and lipoteichoci acid are only found in
gram positive bacteira
what is the purpose of teichoic and lipoteichoic acids
they are slightly immunogenic
LPS is a characterisitc of
gram negative bacteria
porin proteins are unique characteristics of
gram negative bacteria
what are the three components of LPS (endotoxin)
O antigen, Core and Lipid A
O antigen
linear polysaccharide with 50-100 repeating units with 407 sugars/unit used in serotyping
Core
no associated activites, contains usual sugars, space between O antigen and Lipid A
Lipid A
toxic portion, part that causes sepsis
which type of bacteria has a thick or thin PPG
gram pos-thick
gram neg-thin
characteristics of gram negative peptidoglycan
hydrophilic outer membrane, lipids add hydrophobic properties too
outer membrane of gram neg
channels for passive diffusion-porins
attachment site for bacteriophages
porins
permits entry of hydrophilic molecules, may restrict some antiseptics or disinfectants that act on cell membrane, restrict entry by size
periplasmic space of gram neg
contains degradative enzymes, binding proteins, enzymes that inactivate antibiotics (beta lactamase)
examples of enzymes that cleaves the beta lactam ring
penicillinases, cephalosporinases, ESBL’s
what is the purpose of a capsule
protects from phagocytosis, buffers environment, protects from dehydration and adherence
flagella
for motility and chemotaxis, are antigenic, long hollow helical filaments
pili
mostly gram -
organisms with pilli
escherichia coli and N gonorrhoea
what species have spores
bacillus and clostridum (gram pos rod)
what are two drugs that enhibit cell wall syntheiss
beta lactams and glycopeptides
drugs that inhibit protein synthesis
aminoglycosides, tetraclycines, chloramphenicol and macrolides
________ and _______are inhibitors of nucleic acid synthesis
quinolones, and rifamycins
___________are antimetabolites
sulfonamides and trimethoprim
