Drugs & Bugs- Lectures Flashcards
Bacteria and archaea are both (prokaryotes/eukaroytes) but only _ can cause disease
Bacteria and archaea are both prokaryotes but only bacteria can cause disease
* Prokaryotes are unicellular
* Like eukaryotes they have a cell membrane, cytoplasm, ribosomes, and DNA
Fungi, helminths, protozoa, and algae are all (prokaryotes/ eukaryotes)
Fungi, helminths, protozoa, and algae are all eukaryotes
* Fungi, helminths, and protozoa can cause disease
* Because they are eukaryotes they have a nucleus and membrane bound organelles
Bacteria that are vibrio have _ shape
Bacteria that are vibrio have comma-like shape
We call bacteria that are spiral-shaped _ and bacteria that are corkscrew-shaped _
We call bacteria that are spiral-shaped spirillum and bacteria that are corkscrew shaped spirochete
The cell wall provides the bacterium with rigidity and shape; also prevents osmotic shock; it contains _
The cell wall provides the bacterium with rigidity and shape; also prevents osmotic shock; it contains peptidoglycan
The outer membrane is only found in _ bacteria and its major component is _
The outer membrane is only found in gram-negative bacteria and its major component is LPS
Identify the nucleoid and cell wall
(Gram-positive/ gram-negative) has porins
Gram-negative has porins
(Gram-positive/ gram-negative) has LPS or “endotoxin”
Gram-negative has LPS or “endotoxin”
(Gram-positive/ gram-negative) has teichoic acid and lipoteichoic acid
Gram-positive has teichoic acid and lipoteichoic acid
(Gram-positive/ gram-negative) has thick peptidoglycan
Gram-positive has thick peptidoglycan
(Gram-positive/ gram-negative) has a periplasm
Gram-negative has a periplasm
(between the cytoplasmic membrane and the outer membrane)
Both gram-positive and gram-negative bacteria have a cell wall that is composed of peptidoglycan; peptidoglycan is made up of repeating units of alternating sugars, _ and _
Both gram-positive and gram-negative bacteria have a cell wall that is composed of peptidoglycan; peptidoglycan is made up of repeating units of alternating sugars, NAM and NAG
Peptide chains of amino acids get added to (NAM/NAG)
Peptide chains of amino acids get added to NAM
* Strands are cross-linked by peptide bonds
_ is the enzyme that catalyzes the bond between sugars (NAM and NAGs)
Transglycosylase is the enzyme that catalyzes the bond between sugars (NAM and NAGs)
_ is the enzyme that catalyzes the bond between peptide chains
Transpeptidase is the enzyme that catalyzes the bond between peptide chains
What are the three domains of the outer membrane?
Outer membrane:
1. Lipid A : endotoxin
2. Core of conserved sugars
3. O-antigen: polysaccharide; O serotyping
Recall that only gram-negative bacteria have an outermembrane and LPS
_ have their own outer membrane with a thick, waxy coat of mycolic acid (no LPS); they are neither gram-positive or gram-negative and have to be identified using _
Mycobacterium have their own outer membrane with a thick, waxy coat of mycolic acid (no LPS); they are neither gram-positive or gram-negative and have to be identified using acid-fast staining (aka Ziehl-Neelsen stain)
Some bacteria (both gram-positive and gram-negative) contain a capsule external to the cell wall; it functions to protect the bacteria from _
Some bacteria (both gram-positive and gram-negative) contain a capsule external to the cell wall; it functions to protect the bacteria from phagocytosis
One important example of bacteria containing a capsule is _ ; its capsule allows it to get passed the blood brain barrier and it is known to cause nuchal rigidity
One important example of bacteria containing a capsule is Neisseria meningitidis ; its capsule allows it to get passed the blood brain barrier and it is known to cause nuchal rigidity (neck pain/soreness)
* It’s capsule can also help to distinguish it from Neisseria gonorrhea, which does not have a capsule
Give four examples of bacteria with a capsule
- Streptococcus pneumoniae
- Klebsiella pneumoniae
- Neisseria meningitidis
- Haemophilus influenzae
The only spore-forming species of bacteria that are known are (gram-positive/ gram-negative)
The only spore-forming species of bacteria that are known are gram-positive
* Spores are formed during adverse environmental conditions
* They are dormant and metabolically inactive
* Internal spore stains with malachite green
Name two important spore-forming bacteria
- Clostridioidies
- Bacillus anthracis
What are the four stages of bacteria growth?
Lag: adapt to new environment
Log: exponential growth (binary fission)
Stationary: nutrients begin to deplete; death rate = production rate
Death: population decreases
What equation represents exponential bacteria growth by binary fission?
If oxygen is present and aerobic respiration can be carried out, _ serves as the final electron carrier and _ ATP will be produced
If oxygen is present and aerobic respiration can be carried out, oxygen serves as the final electron carrier and 38 ATP will be produced (glycolysis + TCA + oxidative phosphorylation)
Under anaerobic conditions, _ occurs and only _ ATP are produced (from glycolysis)
Under anaerobic conditions, fermentation occurs and only 2 ATP are produced (from glycolysis)
(True/ False) Oxygen kills obligate anaerobes
False; oxygen does not kill obligate anaerobes, radicals (ROS) kill obligate anaerobes
Obligate aerobes and facultative anaerobes will settle at the (top/bottom) of the test tube
Obligate aerobes and facultative anaerobes will settle at the top of the test tube –> more O2 there = more ATP
Facultative anaerobes vs. aerotolerant anaerobes
Facultative anaerobes can grow with or without O2 but will prefer O2 conditions because they can generate more ATP
Aerotolerant anaerobes are unaffected by the presense of O2 because they will not use it even if it is available; they only use fermentation
_ require lower levels of O2 (5-10%) for respiration
Microaerophiles require lower levels of O2 (5-10%) for respiration
All bacterial genetic material, whether chromosomal or plasmid, will be _ , _ , and _
All bacterial genetic material, whether chromosomal or plasmid, will be closed , circular , and double-stranded
_ are extrachromosomal and replicate independently of the chromosome; they often carry virulence factors or antibiotic resistance genes
Plasmids are extrachromosomal and replicate independently of the chromosome; they often carry virulence factors or antibiotic resistance genes
Bacterial chromosomal dsDNA replicates at a single origin of replication and requires _ enzyme
Bacterial chromosomal dsDNA replicates at a single origin of replication and requires DNA-dependent DNA polymerase
There is only one mechanism of vertical gene transmission and that is _
There is only one mechanism of vertical gene transmission and that is binary fission –> yields identical progeny
Horizontal gene transfer between bacteria can occur by one of three mechanisms:
Horizontal gene transfer between bacteria can occur by one of three mechanisms:
1. Transformation
2. Transduction
3. Conjugation
The purpose is to generate diversity (also spread resistance)
If a bacteria is described as competent, you should think (transformation/ transduction/ conjugation)
If a bacteria is described as competent, you should think transformation!
What is transformation?
Bacteria lyses –>
Releases naked DNA –>
Naked DNA gets integrated into bacterial chromosome by homologous recombination
naked DNA can be either in fragments or plasmids
Bacteriophage = (transformation/ transduction/ conjugation)
Bacteriophage = transduction!
The bacteriophage is a virus that infects bacteria
During lytic growth some bacteriophage accidentally packaged up some of the bacterial DNA into the phage head; now they can inject that bacterial DNA into the next host; this is called _
During lytic growth some bacteriophage accidentally packaged up some of the bacterial DNA into the phage head; now they can inject that bacterial DNA into the next host; this is called generalized transduction
Recall that a bacteriphage head contains viral DNA –> When the bacteriphage infects the bacteria we get incorporation of the viral DNA into the bacterial DNA –> forms a prophage –> when the prophage is excised sometimes the adjacent bacterial chromosome gets removed too and now will go into the next host; this is called _
Recall that a bacteriphage head contains viral DNA –> When the bacteriphage infects the bacteria we get incorporation of the viral DNA into the bacterial DNA –> forms a prophage –> when the prophage is excised sometimes the adjacent bacterial chromosome gets removed too and now will go into the next host; this is called specialized transduction
_ requires direct bacterium-to-bacterium contact so that F+ plasmid can transfer 1 strand of the plasmid to the F-
Conjugation requires direct bacterium-to-bacterium contact so that F+ plasmid can transfer 1 strand of the plasmid to the F- –> both donor and recipient need to complete the second strand –> now both are F+
Antibiotic resistant genes that are encoded on F plasmids are called _
Antibiotic resistant genes that are encoded on F plasmids are called R plasmids
If the F plasmid is incorporated into the chromosome it is called a _ cell; importantly, when these bacterial cells undergo conjugation they do not transfer the entire chromosome so the recipient remains _
If the F plasmid is incorporated into the chromosome it is called a Hfr (high frequency recombinant) cell; importantly, when these bacterial cells undergo conjugation they do not transfer the entire chromosome so the recipient remains F-
Both gram-negative and gram-positive bacterium can have exotoxins but only _ can have endotoxins
Both gram-negative and gram-positive bacterium can have exotoxins but only gram-negative can have endotoxins (they contain outer membranes)
Endotoxins are the _ portion of the LPS/ outer membrane
Endotoxins are the lipid A portion of the LPS/ outer membrane)
* Triggers inflammatory shock
* Can induce endotoxic septic shock
Explain the steps of endotoxin signal transduction (that leads to endotoxic septic shock)
- LPS binds to LPS-binding protein
- The LPS-LBP complex binds to host cell receptor, CD14
- Co-receptors MD2 and TLR4 come in
- TLR4 has an transmembrane domain –> induces intracellular signaling
- Activates transcription factors which promote transcription and translation of pro-inflammatory cytokines
What are the three mechanisms that are induced by endotoxins?
Endotoxin release –>
1. Macrophage activation (TLR4) –> produces pro-inflammatory cytokines
2. Complement activation: releases C3a and C5a
3. Tissue factor activation: activates clotting cascade (DIC)
Macrophage activation (TLR4) via endotoxins will manifest as _ and _
Macrophage activation (TLR4) via endotoxins will manifest as fever (IL-1, IL-6, TNF-a) and hypotension (TNF-a, NO)
Complement activation via endotoxins will manifest with _ and _
Complement activation via endotoxins will manifest with histamine release (hypotension and edema) and neutrophil chemotaxis (via C5a)
Tissue factor activation via endotoxins will manifest with _
Tissue factor activation via endotoxins will manifest with DIC (disseminated intravascular coagulation) aka abnormal clotting
Exotoxins can act (locally/ systemically/ both)
Exotoxins can act both locally and systemically
* Three different classes based on interaction with the host cell
What are type I exotoxins?
Type I exotoxins bind on the surface of the host cell and activate intracellular pathways
What are type II exotoxins?
Type II exotoxins are membrane-damaging toxins
What are type III exotoxins?
Type III exotoxins are intracellular-acting toxins
All heat-stable enterotoxins are type _ exotoxins
All heat-stable enterotoxins are Type I exotoxins
* E.coli and Yersinia
E.coli and Yersinia bind and activate _ –> which increases _ –> and leads to electrolyte and fluid loss (diarrhea)
E.coli and Yersinia bind and activate guanylate cyclase –> which increases cGMP –> and leads to electrolyte and fluid loss (diarrhea)
All superantigens are _ type exotoxins
All superantigens are Type I exotoxins
* Ex: S. aureus and S. pyogenes
* Causes toxic shock syndrome
Superantigens work by binding the “pocket” between _ and _ , locking them together, and producing a massive cytokine storm
Superantigens work by binding the “pocket” between TCR and MHC II , locking them together, and producing a massive cytokine storm
Type II exotoxins work by damaging cell membranes; this either occurs via enzymes that degrade the membranes directly or by forming _ in the membrane
Type II exotoxins work by damaging cell membranes; this either occurs via enzymes that degrade the membranes directly or by forming pores in the membrane
_ is an example of a bacteria with type II exotoxin activity; its alpha toxin oligomerizes to form pores in the cell membrane
S. aureus is an example of a bacteria with type II exotoxin activity; its alpha toxin oligomerizes to form pores in the cell membrane
_ has an alpha toxin that has phospholipase activity –> this enzyme degrades the cell membrane and releases gas that builds up under the skin
C. perfringens has an alpha toxin that has phospholipase activity –> this enzyme degrades the cell membrane and releases gas that builds up under the skin
* This is gas gangrene!
Type III exotoxins are AB toxins that act intracellularly;
The A subunit does _
The B subunit does _
Type III exotoxins are AB toxins that act intracellularly;
The A subunit has enzymatic activity
The B subunit binds to the host cell (“B for binds”)
Diphtheriae toxin is a type III exotoxin; how does it function inside the cell?
Diphtheriae toxin ADP-ribosylates EF-2 –> inhibits protein synthesis
* If you block an elongation factor, you block protein synthesis
Cholerae toxin is a type III exotoxin; how does it function inside the cell?
Cholerae toxin ADP-ribosylates GTP-binding protein –> increases cAMP –> watery diarrhea
“Rice water stools” =
“Rice water stools” = V. cholerae
Why would WBC be normal with V. cholerae?
The bacteria itself is no problem for the body; it is the toxin that is doing all of the damage
Multiple gram negative bacteria carry the cytolethal distending toxin (ex: E.coli, C. jejuni, S. dysenteriae); how does this work?
Multiple gram negative bacteria carry the cytolethal distending toxin (ex: E.coli, C. jejuni, S. dysenteriae) –> triggers DNase activity –> chops up DNA –> cell cycle arrest
Cytotoxin necrotizing factor (E.coli and Yersinia) works how?
Cytotoxin necrotizing factor (E.coli and Yersinia) activates Rho GTPases –> alters cytoskeletal arrangements —> induces stress fibers
Dermonecrotic toxin (Bordetella) works by activating _
Dermonecrotic toxin (Bordetella) works by activating Rho GTPases (same as cytotoxin necrotizing factor)
Biofilms are microbial communities that adhere to surfaces like central lines and indwelling catheters; bacteria secrete _ that causes the encasing
Biofilms are microbial communities that adhere to surfaces like central lines and indwelling catheters; bacteria secrete extracellular polysaccharide (EPS) that causes the encasing
* Can cause persistant infections (ear, dental plaque) that are hard to treat
What does bacillus look like on a slide?
Bacillus is gram-positive, spore-forming
* Green- because of the spores
* Boxcar- rods are lined up in chains
Name three drugs (one is a drug class) that target the bacterial cell wall
Cell wall:
1. Beta-lactams
2. Vancomycin
3. Bacitracin
The two classes of antibacterials that target the 30S ribosome are _ and _
The two classes of antibacterials that target the 30S ribosome are Aminoglycosides and Tetracyclines
_ antibiotics require active transport into bacteria, meaning they need oxidative metabolism, meaning they are only active against aerobes
Aminoglycosides antibiotics require active transport into bacteria, meaning they need oxidative metabolism, meaning they are only active against aerobes
Name two of the classes that target 50S ribosomes: _ and _
Name two of the classes that target 50S ribosomes: Macrolides and Streptogramins
Aside from the macrolides and the streptogramins, _, _, _ also target 50S ribosome
Aside from the macrolides and the streptogramins, Linezolid, Clinadmycin, Chloramphenicol also target 50S ribosome
Macrolides and streptogramins are mostly active against (gram-positive/ gram-negative)
Macrolides and streptogramins are mostly active against gram-positive
* Macrolides are huge hydrophobic molecuels that can’t get through the outer membrane
The main antibiotics that target folic acid synthesis are _ and _
The main antibiotics that target folic acid synthesis are sulfonamides (class) and trimethoprim
* Often combined, ex: TMP-SMX
The major antibiotic class that targets DNA gyrase/ topoisomerase is _ and they are active against (gram-positive/ gram-negative/ both)
The major antibiotic class that targets DNA gyrase/ topoisomerase is fluoroquinolones and they are active against both gram-positive & gram-negative
Metronidazole targets _
Metronidazole targets DNA integrity (via free radicals)
Rifampin targets _
Rifampin targets RNA pol
What are 4 mechanisms of antibacterial resistance?
- Drug inactivating enzymes (beta-lactamase)
- Alteration of target molecule (MRSA & PBP2a)
- Decreased drug uptake (decrease porins)
- Increased drug elimination (efflux pumps)
MRSA has gained resistance by altering the target molecule _ –> _
* Methicillin can no longer bind
* Comes from _ gene
MRSA has gained resistance by altering the target molecule PBP2 –> PBP2a
* Methicillin can no longer bind
* Comes from mecA gene
Normally beta-lactam drugs bind to penicillin binding proteins (PBP) to inhibit transpeptidation
E.coli and P. aeruginosa can become resistant to tetracyclines or aminoglycosides via _ mechanism
E.coli and P. aeruginosa can become resistant to tetracyclines or aminoglycosides via increasing drug elimination (increasing efflux pumps)
Kirby-Bauer Disc diffusion and the E-test are two tests that measure _
Kirby-Bauer Disc diffusion and the E-test are two tests that measure antibiotic susceptibility
Beta-lactam antibiotics target _
Beta-lactam antibiotics target PBP (penicillin binding protein) otherwise known as transpeptidase
If patients have hypersensitivity to penicillins, a good alternative is _
If patients have hypersensitivity to penicillins, a good alternative is monobactams (no hypersensitivity)
* Cephalosporins are another option with low hypersensitivity risk
_ is a drug that inhibits the transport of peptidoglycan subunits to the bacterial periplasm
Bacitracin is a drug that inhibits the transport of peptidoglycan subunits to the bacterial periplasm
* Normally, peptidoglycan subunits get synthesized in the cytoplasm
* They must get flipped into the periplasm
* They then get incorporated into the cell wall (transpeptidase)
When administered, bacitracin prevents PG monomers from leaving the cytoplasm, so they never get to the cell wall
The specific target for bacitracin is _
The specific target for bacitracin is C55 isoprenyl pyrophosphate (related to bactoprenol)
Vancomycin blocks peptidoglycan cross-linking (transpeptidation) by physically blocking _
Vancomycin blocks peptidoglycan cross-linking (transpeptidation) by physically blocking D-Ala-D-Ala
* It blocks transpeptidation but not by blocking transpeptidase
* Instead, it blocks by binding to the peptides D-Ala-D-Ala
* Can only be given IV because it is too big to be absorbed
* First line of defense against MRSA
Two unique side effects of vancomycin are _ and _
Two unique side effects of vancomycin are injection site thrombophlebitis and Red Man syndrome
* Red Man syndrome is a nonspecific histamine release
* Both can generally be avoided by slowing down IV administration
One way that vancomycin can become resistant is to mutate the peptidoglycan peptide from _ to _
One way that vancomycin can become resistant is to mutate the peptidoglycan peptide from D-Ala-D-Ala to D-Ala-D-Lac
Most of the FQs are effective against respiratory illnesses/pneumoniae; the exception is that _ is not effective against Streptococcus pneumoniae
Most of the FQs are effective against respiratory illnesses/pneumoniae; the exception is that Ciprofloxacin is not effective against Streptococcus pneumoniae
Most of the FQs are effective against UTIs; the exception is _ because it is not cleared renally
Most of the FQs are effective against UTIs; the exception is Moxifloxacin because it is not cleared renally
Which of the FQs are effective against Pseudomonas aeruginosa
Ciprofloxacin and Ofloxacin are effective agaisnt Pseudomonas aeruginosa
Only one of the FQs, _ is effective against MRSA
Only one of the FQs, Levofloxacin is effective against MRSA
A rash, otherwise called a type _ hypersensitivity can result from FQ use
A rash, otherwise called a Type IV hypersensitivity can result from FQ use
In very rare cases, FQ use can result in an autoimmune skin condition called _
In very rare cases, FQ use can result in an autoimmune skin condition called Stevens-Johnson syndrome
Trimethoprim is a competitive antagonist of _
Trimethoprim (folic acid synthesis diruptor) is a competitive antagonist of dihydrofolic acid –> blocks its binding to DHFR
Sulfonamides are competitive antagonists of _
Sulfonamides are competitive antagonists of PABA –> block the binding of PABA to dihydropteroate synthase
Sulfonamides block the step in folic acid synthesis that is catalyzed by the enzyme _
Sulfonamides block the step in folic acid synthesis that is catalyzed by the enzyme dihydropteroate synthase
Trimethoprim blocks the step in folic acid synthesis that is catalyzed by the enzyme _
Trimethoprim blocks the step in folic acid synthesis that is catalyzed by the enzyme dihydrofolate reductase
Sulfonamides are contraindicated for patients taking _ medications because they increase the patient’s bleeding risk
Sulfonamides are contraindicated for patients taking warfarin medications because they increase the patient’s bleeding risk
* They inhibit CYP2CP –> therefore inhibit the metabolism of warfarin
* Warfarin is an anti-coagulation drug
Permanent tooth discoloration can occur in children from _ use
Permanent tooth discoloration can occur in children from tetracycline use
* Avoid in pregnancy and kids under 8
_ is a macrolide that stimulates neurons in the GI tract and triggers excess smooth muscle contraction –> cramping and diarrhea
Erythromycin is a macrolide that stimulates neurons in the GI tract and triggers excess smooth muscle contraction –> cramping and diarrhea
What are the four steps of gram staining?
- Gram violet (primary stain)
- Iodine (mordant)
- Ethanol (decolorization)
- Safranin (counterstain)
Gram negative will be blue/ purple
Gram positive will be red/pink
Gram positive, cocci in clusters
Staphylococci
Gram positive rods in chains
Streptobacilli
Mycoplasma are unique because they do not have a _ ; therefore they can not be gram stained
Mycoplasma are unique because they do not have a cell wall ; therefore they can not be gram stained
Plating on sheep blood agar is useful to test for _
Plating on sheep blood agar is useful to test for hemolysis
* Alpha hemolysis: partial RBC breakdown (green)
* Beta hemolysis: complete RBC breakdown (clearing)
* Gamma hemolysis: no RBC breakdown (no change)
Only species that can tolerate high salt conditions can be grown on mannitol salt agar; specifically, it differentiates pathogenic and non-pathogenic strains of _
Only species that can tolerate high salt conditions can be grown on mannitol salt agar; specifically, it differentiates pathogenic and non-pathogenic strains of Staphylococci
What does S. epidermidis look like on MSA?
S. epidermidis is a non-fermenter (it is non-pathogenic); it does not ferment mannitol –> medium stays pink
What does S. auerus look like on MSA?
S. aureus is pathogenic; it does ferment mannitol –> produces an acid that turns the medium yellow
Bacteria that can ferment lactose cause a drop in pH that makes the MAC test _ color
Bacteria that can ferment lactose cause a drop in pH that makes the MAC test pink
