Exam One Flashcards
Gram positive bacteria stain color
purple
Gram negative bacteria stain color
red/pink
Cell wall of gram positive bacteria
thick peptidoglycan cell wall
Cell wall of gram negative bacteria
thin peptidoglycan cell wall
Atypical bacteria gram stain color
Do not stain using gram stain
Acid fast bacilli (AFB) characteristic overview
resistant to acids/ethanol based decolorization procedures
Which gram positive bacteria is an anaerobic cocci?
peptococcus peptostreptococcus
Which type of gram positive bacteria are catalase postive?
- aerobic cocci clusters
- staphylococcus spp
Which gram positive bacteria are aerobic catalase (+) coagulase (+) ?
staphylococcus aureus
Which gram positive bacteria are aerobic catalase (+) coagulase (-) ?
CoNS (staphylococcus epidermidis)
Which type of gram positive bacteria are catalase negative?
- aerobic pairs/chains
- streptococcus spp.
- enterococcus spp.
- viridans streptococci
How are pairs/chains further differentiated?
alpha/beta/gamma hemolysis
Alpha hemolysis culture
partial hemolysis
Beta hemolysis culture
full hemolysis
Gamma hemolysis culture
non-hemolytic
Which type of bacteria are characterized as gram positive, aerobic, catalase (-), alpha hemolysis?
- streptococcus pneumoniae
- viridans streptococci
Which type of bacteria are characterized as gram positive, aerobic, catalase (-), beta hemolysis?
- streptococcus pyogenes (GAS)
- streptococcus agalactiae (GBS)
- think fire and GAS
Which type of bacteria are characterized as gram positive, aerobic, catalase (-), gamma hemolysis?
- enterococcus faecium
- enterococcus faaecalis
Which type of gram positive bacteria are anaerobic bacilli?
- clostridium spp.
- clostridioides difficile
- cutibacterium
- actinomyces
Which type of bacteria are characterized as gram positive, anaerobic and spore forming?
- clostridium spp.
- clostridioides difficile
Which type of bacteria are characterized as gram positive, anaerobic and non-spore forming?
- cutibacterium
- actinomyces
Which type of gram positive bacteria are aerobic bacilli?
- bacillus spp.
- corynebacterium
- lactobacillus spp.
- listeria monocytogenes
Which type of gram bacteria are characterized as aerobic and spore forming?
bacillus spp.
Which type of gram positive bacteria are characterized as aerobic and non-spore forming?
- corynebacterium
- lactobacillus spp.
- Listeria monocytogenes
Most medically important gram positive pathogens are ____ rather than ______.
cocci, bacilli
Which colony forms clusters?
gram positive staphylococcus
Which bacteria appear in pairs or chains?
gram positive streptococci and enterococci
Where in the body can you find alpha hemolytic pathogens?
oral cavity
Where in the body can you find beta hemolytic pathogens?
skin, pharynx, genitourinary
Where in the body can you find gamma hemolytic pathogens?
gastrointestinal system
Which type of bacteria are characterized as gram negative aerobic cocci?
- Neisseria spp.
- Moraxella catarrhalis
Which type of bacteria are characterized as gram negative aerobic coccobacilli?
- Haemophilus spp.
Which type of bacteria are characterized as gram negative anaerobic cocci?
- veillonella spp.
Which type of bacteria are characterized as gram negative anaerobic bacilli?
- bacteroides spp.
- fusobacterium spp.
- prevotella spp.
Which type of bacteria are considered gram negative aerobic bacilli enterobacterales and are lactose-fermenters (oxidase negative)?
- citrobacter spp.
- enterobacter spp.
- E. coli
- Klebsiella spp.
- think CEEK out lactose
Which type of bacteria are considered gram negative aerobic bacilli enterobacterales and are nonlactose-fermenters?
- morganella morganii
- proteus spp.
- providencia spp.
- salmonella spp.
- serratia marcescens
- shigella spp.
Which type of bacteria are characterized as gram negative non enteric aerobic bacilli, lactose-fermenters (oxidase positive)?
- aeromonas hydrophila
- pasteurella multocida
- vibrio cholerae
Which type of bacteria are characterized as gram negative non enteric aerobic bacilli, nonlactose-fermenters?
- pseudomonas spp.
- acinetobacter spp.
- alcaligenes spp.
- burkholderia cepacia
- stenotrophomas maltophilia
Which type of bacteria are characterized as gram negative non enteric aerobic bacilli, fastidious
- campylobacter
- helicobacter
- bartonella
- HACEK organisms (haemophilus, actinobacilius, cardiobacterium, eikenella, kingella)
Which bacteria are considered atypical?
-chlamydia pneumoniae
- chlamydia trachomatis
- legionella pneumophila
- mycoplasma pneumoniae
Which bacteria are characterized as spirochetes?
- treponema pallidum
- borrelia burgdorferi
Which type of gram negative bacteria are the predominate pathogen?
gram negative bacilli
How is lactose fermentation important?
helps identify enterobacterales from non-fermenting rods
What is special about fastidious organisms?
slow growers, require special supplemental media
What are penicillin binding proteins?
enzymes vital for cell wall synthesis, cell shape, and structural integrity
What are the different types of penicillin biding proteins?
- transpeptidases
- carboxypeptidases
- endopeptidases
What is the relationship between the PBPs of graam positive and gram negative bacteria?
no relationship, differ from bacterial species to another
Binding to which PBPs induce a bactericidal effect?
1A, 1B, 2, and 3
Which PBP is the most important?
Transpeptidase (catalyzes the final cross linking in the peptidoglycan structure)
Cytoplasmic Membrane
- acts as selective barrier
- certain drugs must pass through to reach target site
Peptidoglycan Layer (cell wall)
- Gram Positive: thick
- Gram negative: thin
- Permeability barrier for large molecules
- PBPs are essential for cell-wall synthesis
Outer membrane
- gram negative bacteria only
- LOPS is the mediator of immune response and sepsis
- porins are hydrophilic channels that permit diffusion of essential nutrients and small hydrophilic molecules
Periplasmic Space
- Compartment between cell membrane and cell wall (gram positive)
- between cell membrane and outer membrane (gram negative)
What is the periplasmic space vital for?
- Vital for bacterial protein secretion, folding, quality control
- acts as reservoir for virulence factors
What is the definition of intrinsic resistance
always resistant to given antibiotic
What is the mechanism of intrinsic resistance?
- absence of target site
- bacterial cell impermeability
What are examples of intrinsic resistance?
- cephalosporins vs enterococci
- beta lactams vs mycoplasma
What is the definition of acquired resistance?
initially susceptible but develop resistance due to some mechanism
What is the mechanism of aquired resistance?
- mutation in bacterial DNA (spontaneously vs selective pressure)
- Acquisition of new DNA (chromosomal or extrachromosomal plasmid)
What are examples of aquired resistance?
- stable derepression of AmpC
- acquisition of KPC gene in GNRs
Plasmid Acquired Resistance
- self-replicating, extrachromosomal DNA
- transferable between organisms
- one plasmid can encode resistance to multiple antibiotics (resistance genes)
Transposons Acquired Resistance
- jumping genes
- genetic elements capable of translocating from one location to another
- move from plasmid to chromosome or vice versa
- single transposon may encode multiple resistance determinants
Phages Acquired Resistance
- viruses that can transfer DNA from organism to organism
Conjugation Acquired Resistance
- direct contact or mating via sex pili
- most common
- DNA shared via mobile genetic elements (MGE) such as plasmids or transposons
Transduction Acquired Resistance
- transfer of genes between bacteria by bacteriophage (virus)
Transformation Acquired Resistance
- transfer or uptake of free floating DNA from the environment
- DNA is integrated into host DNA
