Cell wall and membrane active antibiotics Flashcards
List the B lactams
- Penicillins
- cephalosporins
- carbapenams
- mono act and
What are the naturally occurring penicillins
Penicillin G and penicillin V
What’s penicillin G mode of administration
IV and IM
What is penicillin V mode of administration
Oral
What’s the mechanism of action of natural penicillins
Bind to penicillin binding proteins to block cross linking of peptidoglycan in cell wall
What are the uses of natural penicillins
Against gram + organisms, some gram - mainly N meningitidis and spirochete T pallium (Blactamase sensitive)
Natural penicillins adverse effects
Drug induced interstitial nephritis, hypersensitivity reactions
What is penicillin G indicated for
Erysipleas by S pyogens
Gas gangrene by C perfringes
Endocarditis by S viridans
List the antistaphylococcal penicillins
Nafcillin
Dicloxacillin
Cloxacillin
Methicillin
antistaphylococcal penicillins mechanism of action
Same as natural penicillins
Bind to penicillin binding proteins to block cross linking of peptidoglycan in cell wall
antistaphylococcal penicillins indications
Given for S aureus except MRSA
Why can’t antistaphylococcal penicillins work on MRSA
They have altered PBP
Why are antistaphylococcal penicillins resistant to B lactamase
They have Bulky R group blocking access to B lactam
antistaphylococcal penicillins adverse effects
Hypersensitivity and interstitial nephritis
List extended spectrum penicillin
Amoxicillin
Ampicillin
Amoxicillin mode of administration
Oral
Ampicillin mode of administration
I.V
What are extended spectrum penicillin sensitive to?
Penicillinase
How to protect extended spectrum penicillin against B lactamases
By combining them with B lactamases inhibitors like (Clavulanic acid and sulbactam)
What are extended spectrum penicillin given for ?
Giver for HHELPSS
- H influenza
- H pylori
- E coli
- listeria monocytogenes
- proteus mirabilis
- shigella
- salmonella
What makes augmentin
Amoxicillin + clavulanic acid
What makes Unasyn
Ampicillin + sulbactam
List antispeudomonal penicillins
Ticarcillin
Piperacillin
Which B lactamase inhibitor ticarcillin
Clavulunic acid
Which B lactamase inhibitor piperacillin
Tazobactam
Why do we add B lactamase inhibitors to antispeudomonal penicillins
They are B lactamase sensitive
Antispeudomonal penicillins clinical uses
Given for P arguenosa and gram - rods
List all B lactamase inhibitors
CAST Clavulanic acid Avibactam Sulbactam Tazobactam
Piperacillin + tazobactam gives coverage against
Bacteroides species
What also covers bacetroides species
Ampicilin and sulbactam
What does Hyper sensitivity to penicillin presents with
Skin rash
Urticaria
Anaphylactic shock
Adverse effects of penicillins
Drug induced Coombs + haemolytic anemia
Nephritis -> methicillin
Neurotoxicity
Penicillin x cephalosporins cross reactivity
Patents with penicillin allergy can be safely given cephalosporins if—>
1- allergy is not suggestive of IgE mediated
2- reaction occurred more than 10 years ago
What are cephalosporins
B lactam drugs that inhibit cell wall synthesis; but less susceptible to penicillinase
List the Bacteria not covered by 1st to 4th generation of cephalosporins
LAME Listeria monocytogenes Atypicals MRSA Enteroccoci
What are the drugs of first generation cephalosporins
Cefazolin and cephalexin
What is first generation cephalosporins used for
Gram + cocci and PEcK ( proteus mirbilis, E. coli, klebsiella)
What is cefazolin specially used for
It is used before surgery to prevent S aureus wound infection
What are the drugs of second generation cephalosporins
Cefuroxime, Cefozitin and Cefotetan
What are second generation cephalosporins used for
Gram + cocci and PEcK ( proteus mirbilis, E. coli, klebsiella) and HENS ( H influenza, Entrobacter, Neisseria and Serratia)
What does cefoxitin and cefotetan cover on their own while other second generation doesn’t cover
B. Fragilis
What are the third generation cephalosporins
Ceftriaxone and ceftazidime
What are third generation cephalosporins used for
Serious gram negative infections resistant to other B lactamas
Special characteristic of ceftriaxeone and clinical uses due to it
Can cross BBB to CSF to treat meningitis, gonorrhea and Lyme disease
What is Cefotaxime
It’s a 3rd generation cephalosporins that acts like Ceftriaxeone
Special characteristic of Ceftazidime
Works agains Pseudomonas arugenosa
What are the drugs of fourth generation cephalosporins
Cefepime
What are the 4th generation cephalosporins used for
They have increased activity against Pseudomonas
What are the drugs of 5th generation cephalosporins
Ceftaroline
What is ceftaroline 5th generation cephalosporins used against
It covers MRSA
Cephalosporins adverse effects
Disulfram like reaction, allergic reaction and nephrotoxicity
What happens in disulfram like reactions
Disulfram blocks aldehyde dehydrogenase —> build up of acetaldehyde
What drugs cause disulfram like reactions
Cephalosporins, sulfonamides and metronidazole
Why should we not take cephalosporins with aminoglycosides
Because that increases nephrotoxicity
What are the drugs of carbapenams
DIME Doripenem Imipenem Meropenem Ertapenem
When are carbapenams given
Given when there is a 10/10 life threatening infection
Carbapenams mechanism of action
Imipenem is a broad spectrum B lactamase resistant carbapenem
What are carbapenams always administered with and why
Cilastin - it inhibits dihydropeptidase to decrease metabolism of drug in renal tubules to reduce nephrotoxicity
Carbapenems adverse effects
They can cause seizures
Which drugs are monobactam
Aztreonam
What is azetreonam a monobactam active against
Aerobic gram negative bacilli, resistant to B-lactamases
Vancomycin mode of administration
IV
When is vancomycin given orally
Exclusively given orally for pseudomembranous colitis
Vancomycin mechanism of action
Inhibits cell wall peotidoglycan formation by binding to D-ala-D-ala
How can bacteria become resistant to vancomycin
By altering their D-ala-D-ala to D-ala-D-lac
Vancomycin clinical uses
Active against gram positive only —> MRSA, streptococci, entrococci and C. Difficile
Vancomycin adverse effects
Nephrotoxicity, ototoxicity and red man syndrome
Which bacteria has emerging resistance against vancomycin
Enterococcus fascium
What is bacitracin used for
Gram positive bacteria like Staph and strep
What is fosfomycin mechanism of action
Blocks cell wall synthesis by inhibiting enolpyruvate transferase
Which drug can be given to pregnant women with UTI?
Fosfomycin
Fosfomycin clinical uses
UTI by Ecoli and E. decal is and FIRST LINE for acute cystitis
Daptomycin mechanism of action
It’s a bacteriocidal, lipopeptide that disrupts cell membrane of gram + cocci by creating transmembrane channels
What is used for skin infections by MRSA
Daptomycin daily I.V
DAPTOMYCIN clinical uses
Used in MRSA, VRE - vancomycin resistant enterococci -> not used for pneumonia
Daptomycin side effects
Myopathy and rahbdomyolysis
List the polymyxin drugs
Polymyxin B and E
What is another name for polymyxin E
Colistin
Polymyxin mechanism of action
Disrupts cell membrane integrity causing leakage of cellular components
Polymyxin clinical uses
Against gram negative bacteria
- multi drug resistant gram negative bacteria !!
Polymyxins adverse effects
Nephrotoxicity, neurotoxicity and respiratory failure
