Cell wall/membrane inhibitors Flashcards
Spectrum of action of vancomycin
Gram-positive
Used for drug resistant gram positive organisms
MOA of vancomycin
Inhibits cell wall synthesis
Binds to D-ala-D-ala terminal of the peptidoglycan pentapeptide side chain and prevents polymerization of the linear peptidoglycan
concentration-independent killing
Antibiotic with this MOA:
Inhibits cell wall synthesis at step 2
Binds to D-ala-D-ala terminal of the peptidoglycan pentapeptide side chain and prevents polymerization of the linear peptidoglycan
Vancomycin
Elimination of vancomycin
Excreted unchanged in urine (80%) or stool
Vancomycin half life is ~6 hours, but increases to 7-9 days in patients with this
Renal dysfunction
Hypersensitivity, Ototoxicity, Fever and chills, flushing or “red man syndrome”, hemolysis in G6PD deficiency, and nephrotoxicity are adverse effects of this antibiotic
Vancomycin
Ototoxicity is a characteristic adverse effect of this cell wall/membrane inhibitor
Vancomycin
Hemolysis in G6PD deficiency is a characteristic adverse effect of this cell wall/membrane inhibitor
Vancomycin
Histamine-induced rash of the head and upper thorax caused by vancomycin direct action on mast cells
Flushing or “Red Man Syndrome”
“Red man syndrome” is a histamine-induced rash of the head and upper thorax caused by this antibiotic direct action on mast cells
Vancomycin
Spectrum of action of Bacitracin
Narrow gram positive cocci
Severe hypersensitivity and nephrotoxicity if systemically absorbed are adverse effects of this narrow gram positive cocci antibiotic
Bacitracin
2 main adverse effects of Bacitracin
Severe hypersensitivity and nephrotoxicity if systemically absorbed
Antibiotic that inhibits incorporation of sugar-pentapeptide in to cell wall by interfering with the final dephosphorylated step in the phospholipid carrier cycle
Damages cell membrane and cell wall
Bacteriostatic at normal doses, bactericidal at higher doses
Bacitracin
MOA of bacitracin
Inhibits incorporation of sugar-pentapeptide into cell wall by interfering with the final dephosphorylated step in the phospholipid carrier cycle
Antibiotic class with this MOA:
Binds to penicillin-binding proteins (PBPs) located in membrane
Blocks the transpeptidase crosslinking of cell wall components
Activates autolysis enzymes (releases murein hydrolase) to promote cell wall dissolution
Results in weakened cell wall, aberrant morphological form, cell lysis and death
Beta-lactam antibiotics
MOA of beta-lactam antibiotics (3)
Binds PBPs in membrane
Blocks transpeptidase crosslinking of cell wall components
Activates autolytic enzymes to promote cell wall dissolution
Antibiotic with the following 2 mechanisms of resistance:
Express enzymes that inactivate antibiotic ring
Formation of aberrant PBP that does not allow effective antibiotic binding
Beta-lactam antibiotics
2 mechanisms of resistance of beta-lactam antibiotics
Express beta-lactamases that inactivate (open) beta-lactam ring
Formation of aberrant PBP that does not allow effective beta lactam binding
Why is caution needed in using penicillins with meningitis?
Penicillins are neurotoxic
Caution is required in this as penicillins are neurotoxic
Meningitis
Elimination of penicillins
Renal
10% filtration, 90% tubular secretion
Biotransformation or biliary (Nafcillin, Ampicillin, Piperacillin)
Nafcillin, Ampicillin, and Pipercillin are penicillins that are eliminated via these routes
Biotransformation or biliary
Natural penicillin that is unstable in acid, intramuscular and IV route of administration
Penicillin G
Natural penicillin that is acid stable, oral route of administration
Penicillin V
Penicillin G and Penicillin V are this type of penicillin
Natural penicillins
Spectrum of action of natural penicillins
Narrow gram positive
These are drugs of choice for syphilis and S. pneumoniae
Natural penicillins (Penicillin G and V)
Spectrum of action of Semisynthetic/Aminopenicillins
Broad (very extended)
“HELPS”
Haemophilus influenzae
E. coli
Listeria monocytogenes
Proteus mirabilis
Salmonella
Penicillins with broad (very extended) spectrum of action
“HELPS”
Haemophilus influenzae
E. coli
Listeria monocytogenes
Proteus mirabilis
Salmonella
Semisynthetic/Aminopenicillins
Drugs of choice for preventing endocarditis with surgical or dental procedures
Semisynthetic/Aminopenicillins
Ampicillin and Amoxicillin are vulnerable to these
Beta lactamases
Semisynthetic/Aminopenicillins are vulnerable to these
Beta lactamases
Ampicillin and Amoxicillin are this type of penicillin
Semisynthetic/Aminopenicillins
Spectrum of action of Antistaphylococcal penicillins (aka Pellicinase-resistant penicillins)
Very narrow gram positive
Staphylococcal infections
Another name for Antistaphylococcal penicillins
Penicillinase-resistant penicillins
Antistaphylococcal penicillins are penicillin analogs with bulky side chains that make them resistant to some beta lactamases, but can’t bind this
Mutated PBPs
Methicilin, Nafcillin, Oxacillin, and Dicloxacillin are this type of penicillin
Antistaphylococcal penicillins (Penicillinase-resistant penicillins)
Ticarcillin, Carbenicillin and Piperacillin are this type of penicillin
Antipseudomonal penicillins
Penicillin type with broad spectrum of action, resistant to many but not all beta lactamases expressed by gram negative bacteria
Side groups allow greater penetration into gram negative bacteria (Pseudomonas, Anaerobes)
Antipseudomonal penicillins
These are paired with agents sensitive to beta-lactamases with similar pharmacokinetics to overcome some resistance
Suicide inhibitors (irreversible beta-lactamase inhibitors)
Clavulanate is this
Suicide inhibitor (irreversible beta-lactamase inhibitor)
Paired with agents sensitive to beta-lactamase with similar pharmacokinetics to overcome some resistance
Sulbactam is this
Suicide inhibitor (irreversible beta-lactamase inhibitor)
Paired with agents sensitive to beta-lactamase with similar pharmacokinetics to overcome some resistance
Tazobactam is this
Suicide inhibitor (irreversible beta-lactamase inhibitor)
Paired with agents sensitive to beta-lactamase with similar pharmacokinetics to overcome some resistance
Clavulanate, Sulbactam and Tazobactam are this
Suicide inhibitors (irreversible beta-lactamase inhibitor)
Paired with agents sensitive to beta-lactamase with similar pharmacokinetics to overcome some resistance
These should be used when resistance by beta-lactamase is expected
Suicide inhibitors (irreversible beta-lactamase inhibitors)
Ex: Sulbactam, Tazobactam, Clavulanata
Allergic responses (~10%), Allergic cross reactions are significant (~6%), Neurotoxicity, and Vitamin K deficiency are adverse effects of this
Penicillins
Vitamin K deficiency is a characteristic adverse effect of this drug
Penicillins
Moving from first to higher generation of cephalosporins, how does the activity against gram negatives change?
Is increased
Moving from first to higher generation of cephalosporins, how does resistance to beta-lactamases change?
Is increased
Moving from first to higher generation of cephalosporins, how does distribution change?
Increased distribution to body tissues and fluids, especially during inflammation
Third and later generations can cross blood brain barrier
Moving from first to higher generation of cephalosporins, how does activity against gram positives change?
Is decreased
Fourth and fifth generation agents have more gram positive activity than third generation
Cefazolin and Cephalexin are this type of agents
1st generation cephalosporins
Spectrum of action of 1st generation cephalosporins
Extended gram positive
Cefotetan, Cefuroxime and Cefoxitin are this type of agents
2nd generation cephalosporins
Cefotaxime, Ceftazidime, Cefpodoxime proxetil and Ceftriaxone are this type of agents
3rd generation cephalosporins
Drug of choice for treatment of gonorrhea
Ceftriaxone (3rd generation cephalosporin)
Ceftriaxone is the drug of choice for this
Gonorrhea
These are the drugs of choice for syphilis and S. pneumoniae
Natural penicillins
Natural penicillins are the drugs of choice for these
Syphilis and S. pneumoniae
Semisynthetic/Aminopenicillins are drugs of choice for preventing this
Endocarditis with surgical or dental procedures
Cefepime is this type of agent
4th generation cephalosporin
Ceftaroline is this type of agent
5th generation cephalosporin
Cefepime has more or less gram positive activity than a given 3rd generation cephalosporin?
More
Spectrum of action of Ceftaroline (5th generation cephalosporin)
Broad
Active against many resistant gram positive agents (MRSA, VRSA, VISA, hVISA)
Disulfiram-like reaction with alcohol is noted for this cephalosporin
Cefotetan (2nd generation cephalosporin)
Cephalosporins adverse reactions are similar to those of this drug
Penicillins
Characteristic adverse effect noted for Cefotetan (2nd gen cephalosporin)
Disulfiram-like reaction with alcohol
Broadest spectrum of beta lactams, highly resistant to most beta-lactamases, reserved for treating bacteria with MDR
Includes Imipenem
Carbapenems
Imipenem is this type of drug
Carbapenem (beta lactam)
Spectrum of activity of Aztreoname (Monobactam)
Gram negative
Resistant to beta lactamases
Aztreonam (Monobactam) are resistant to these
Beta lactamases
Aztreoname is this type of agent
Monobactam
Aztreoname (monobactam) has low cross reactivity noted in patients sensitive to either of these
Penicillins or cephalosporins
Is there cross reactivity in Aztreoname (monobactam) with patients sensitive to penicillins or cephalosporins?
Low cross reactivity
This is the preferred agent for penicillin-sensitive patients
Aztreonam (monobactam)
Drug that binds to phospholipids in membrane to disrupt membrane integrity
Polymyxins
MOA of polymyxins
Membrane disruption
Spectrum of action of polymyxins
Aerobic gram negative
Colistin is this type of agent
Polymyxin
Cell membrane inhibitor with the following adverse effects:
Hypersensitivity
High toxicity limits systemic use to “must use” only indications
Black box: Nephrotoxicity, Neurotoxicity, Not safe in pregnancy
Polymyxins
High toxicity of polymyxins limits systemic use to this
“must use” only indications
High toxicity of this cell membrane inhibitor limits systemic use to “must use” only indications
Polymyxins
Antibiotic that at higher concentrations, binds membranes of gram positive bacteria to cause rapid depolarization leading to cell death and inhibition of intracellular synthesis of DNA, RNA and proteins
Daptomycin
Antibiotic that lethally depolarizes bacteria
Daptomycin
MOA of Daptomycin
Lethally depolarizes bacteria
At higher concentrations, binds membranes of gram positive bacteria to cause rapid depolarization leading to cell death and inhibition of intracellular synthesis of DNA, RNA and proteins
Spectrum of action of Daptomycin
Narrow gram positive
Antibiotic that is degraded by pulmonary surfactants so cannot be used in pneumonia
Daptomycin
Daptomycin is degraded by these, so cannot be used in pneumonia
Pulmonary surfactants
Daptomycin is degraded by pulmonary surfactants, so cannot be used in this
Pneumonia
Hypersensitivity, GI distress, superinfections, Myopathy, and peripheral neuropathy are adverse effects of this antibiotic
Daptomycin
Myopathy and Peripheral neuropathy are characteristic adverse effects of this antibiotic
Daptomycin