Antibiotics Flashcards
Amoxicillin, ampicillin
Class + MoA
which bacteria they work against
Broad spectrum penicillin
MoA: beta lactam
(for all bacteria)
Flucloxacillin, methicillin
Class + MoA
which bacteria they work against
Beta lactamase resistant penicillin
MoA: beta lactam
(only for Gram POSITIVE bacteria)
Piperacillin
Class + MoA
which bacteria they work against
Extended spectrum penicillin
MoA: beta lactam
(most effective against pseudomonas,
effective against most Gram NEGATIVE except Klebsiella)
Mecillinam, Temocillin
Class + MoA
which bacteria they work against
Reverse spectrum penicillin
MoA: beta lactam
(more for gram POSITIVE bacteria)
Vancomycin
Class + MoA
which bacteria they work against
Glycopeptide
MoA: inhibits cell wall integrity by preventing transglycosylation (binds to D-ala at end of peptidoglycan chain)
(for serious Gram POSITIVE infx e.g. MRSA, C diff)
Name the MoA of the following TB drugs: Isoniazid Ethambutol Rifampin Pyrazinamide
ISONIAZID
-inhibits formation of mycolic acid in mycobacteria
ETHAMBUTOL
-inhibits arabinosyl transferase (which synthesizes mycobacteria cell wall)
RIFAMPIN
-blocks initiation of transcription by interacting with beta subunit of RNA polymerase
PYRAZINAMIDE
-unknown MoA
Carbapenems
Class + MoA
which bacteria they work against
Beta lactam
for all bacteria
Aztreonam
Class + MoA +
which bacteria they work against
Monobactam (beta lactam)
(for gram NEGATIVE bacteria, especially Enterobacteria & Pseudomonas)
Enterobacteria incude Salmonella, E Coli, Yersinia, Klebsiella, Shigella
Cefuroxime
Class + MoA +
which bacteria they work against
2nd gen cephalosporin
(beta lactam)
(broader specificity against Gram -ve e.g. Hib, Neisseria)
Can be used for all UTI
Ceftriaxone, Cefotaxime, Ceftazidime
Class + MoA +
which bacteria they work against
3rd gen cephalosporin
(beta lactam)
passes through CSF so can be used to treat meningitis bacteria
Gram NEGATIVE: Neisseria, Hib, E Coli
Gram POSITIVE: Strep pneumo (most common), Listeria (if young/old/immunocompromised)
Metronidazole
Class + MoA +
which bacteria they work against
Inhibits nucleic acid synthesis
used against C diff
Ciprofloxacin
Class + MoA +
which bacteria they work against
Quinolone
Inhibits DNA gyrase (involved in removing DNA supercoiling)
Used for UTI
Trimethoprim
MoA +
which bacteria they work against
Blocks dihydrofolate reductase
Used for UTI
Sulfonamides
MoA +
which bacteria they work against
Blocks dihydrofolate synthase
Sulphasalazine used for ulcerative colitis as active in gut
Polymyxins
MoA +
which bacteria they work against
Disrupt inner and outer membranes
Used for gram NEGATIVE bacteria
Erythromycin, Clarithromycin, Azithromycin
Class + MoA +
which bacteria they work against
Macrolides
Bind reversibly to 50S subunit, blocks P site
(Work against Gram POSITIVE e.g. Strep + Gram NEGATIVE e.g. Hib, pertussis)
Clindamycin
MoA +
which bacteria they work against
Bind reversibly to 50S subunit, blocks P site (similar action to macrolides)
(Work against MRSA, Staph, Strep)
Note:
Most aerobic gram negative bacteria (Pseudomonas, Legionella, Hib) are resistant
Doxycycline
Class + MoA +
which bacteria they work against
Tetracyclines
Bind reversibly to 30S subunit, interferes with binding of tRNA to mRNA
(broad spectrum action, for all)
Gentamycin
Class + MoA +
which bacteria they work against
Aminoglycoside
Binds IRREVERSIBLY to 30S subunit, ribosome not fitted properly, mRNA slips out
(works against gram NEGATIVE bacteria)
If someone is allergic to penicillins, what other types of a/b should not be given to them
Cephalosporins
Carbapenams
(monobactams are ok. usually dont have cross reactivity with other beta lactams)
Which a/b is Hib resistant to
Amoxycillin/ampicillin
Clindamycin
Enterobacteria are gram negative. What do they consist of?
- E Coli
- Salmonella
- Klebsiella
- Shigella
- Yersinia
Is Neisseria gram positive or gram negative
Neisseria = gram negative
Is Streptococcus gram positive or gram negative
Strep = gram positive
What bacteria can cause meningitis in immunocompromised/ >55yo patients?
What a/b should be added to cover this?
Listeria.
Add amoxicillin/ gentamycin to cover
Alcohol can induce vomiting if consumed within 48 hours of taking what antibiotic
Metronidazole
What a/b(s) are used to treat MRSA
- vancomycin
- teicoplanin
(prontoderm to get off skin)
What a/b(s) are used to treat anaerobic bacteria
Metronidazole
add to broad spectrum cephalosporin
What a/b to give asymptomatic contacts of syphilis patient
Doxycycline
14 days
What a/b to give purulent conjunctivitis
Chlormaphenicol eye drops
What a/b to give otitis externa
Topical tx (see BNF)
Flucloxacillin if spreading cellulitis
What a/b to give otitis media
NOTE: usually viral, no need a/b
Ampicillin/Amoxicillin if no improvement after 72h
What a/b to give sinusitis
NOTE: only give if persistent symptoms + purulent discharge for 7 days
Ampicillin/Amoxicillin
7 days
Which classes are beta lactams?
- penicillins
- cephalosporins
- carbapenems
- monobactams
How do beta lactams work as a/b?
Disrupt cell wall synthesis
Name example(s) of beta lactamase resistant a/b
- flucoxacillin
- methylcillin
Define bacteriocidal vs bacteriostatic
Bacteriocidal = kills bacteria
Bacteriostatic = stops replication of bacteria
Examples of classes of bacteriocidal a/b
- penicillins
- cephalosporins
- carbapenams
- monobactams
- glycopeptides eg vancomycin
- metronidazole
- nitrofurantoin
Examples of classes of bacteriostatic a/b
INHIBIT FOLATE SYNTHESIS
- trimethoprim
- sulfonamides
INHIBIT PROTEIN SYNTHESIS
- clindamycin
- macrolides
- tetracyclines
- aminoglycosides
Which a/b might cause Steven Johnson syndrome
Vancomycin
Which a/b might cause Red Man syndrome
Vancomycin
and other glycopeptides
Describe Steven Johnson syndrome
Type 4 hypersensitivity reaction
Fever + flu-like symptoms then skin blisters and peels
Describe Red Man syndrome
Red rash
Severe complications of Steven Johnson syndrome
- Multiple organ failure
- scar tissue inside eyelids leading to impaired vision
How to avoid Red Man syndrome
Infuse vancomycin slowly (over >60min interval)
Main side effects of gentamycin
- ototoxic
2. nephrotoxic
Main side effects of co-trimoxazole (trimethoprim + sulfamethoxazole)
- Nausea
- Nephrotoxic, hepatotoxic
- Steven Johnson syndrome
- Bone marrow suppression
Generally, what a/b should be given as replacement in penicillin allergy
Macrolide (erythromyin/ clindamycin)
Which antibiotics are hepatotoxic
- Tetracycline
- Nitrofurantoin
- Anti TB drugs
- Chloramphenicol
- Erythromycin
Which a/b causes cholestasis
Erythromycin
Which a/b may cause BM suppression
Chloramphenicol
