antibiotics and pneumonia Flashcards
Penicillin types
natural penicillin
aminopenicillin
antistaphylococcal penicillin
extended spectrum/ antipseudomonal penicillin
Natural penicillin
- gram pos, susceptible to beta lactamase
- penicillin V used for oral due to resistant to acid hydrolysis
Aminopenicillin
- gram pos and neg, due to more hydrophilic, enter via porins, but not the pseudomonas
- susceptible to beta lactamase
- acid stable: amoxicillin, ampicillin
Antistaphylococcal penicillin
methicillin, oxacillin, cloxacillin, flucloxacillin
acid stable: oral
bulky side chain make them resistant to staphylococcal beta lactamase
difficult to diffuse across cell membrane, may be less effective
antipseudomonal penicillin
- effective against gram neg and pseudomonas
acid labile (except carbenicillin)
carboxypenicillin: ticarcillin and carbenicillin
ureidopenicillin: piperacillin
beta lactamase susceptible
UTI, bacteremia, skin infections
cephalosporin
resistant to beta-lactamase
interstitial nephritis, hypersensitivity, neurotoxicity, coagulopathy
1st gen cephalosporin
Gram pos, community acquired enterobacter
cefadroxil
2nd gen cephalosporin
gram pos, some gram neg
cefuroxime
3rd gen cephalosporin
mainly gram neg, less effective against gram pos
ceftriaxone, cefotaxime
4th gen cephalosporin
broad spectrum and increase beta lactamase resistance
cefepime
5th gen cephalosporin
borad spectrum
ceftaroline
Macrolide- MOA
- bacteriostatic, prototype: erythromycin
- inhibit the peptidyl tRNA to transfer from acceptor site to donor site (P site) catalysed by peptidyl transferase, by binding to 50s subunit of ribosome
- next amino-acyl tRNA cannot bind to the A site
- inhibit protein synthesis
Macrolide- side effects
- GI disturbances due to motilin receptor stimulation
- high dose erythromycin causes deafness
- liver toxicity: estolate salt causes cholestatic hepatitis
- CYP3A4 interaction except azithromycin
- prolonged QT interval (arrthymia)
erythromycin
same as penicillin G, use for allergic patient
clarithromycin
similar to erythromycinn
intracellular bacteria: legionella and chlamydia
M. leprae, H. pylori, T. gondii
azithromycin
less effective against gram, pos, more against gram neg
telithromycin (ketolide)
same as azithromycin, but can be against macrolide resistant strains
Tetracycline- MOA
- broad spectrum antibiotics
- bacteriostatic
- binds to 30s subunit, block the binding of amino acyl tRNA to the A site, no amino acid added to the peptide chain and no transfer of peptide chain to A site, protein synthesis inhibited
Doxycycline
- semisynthetic
- biliary excretion, therefore suitable for renal impaired patients
- oral, absorption decreases when taken with food or milk
Glycylcycline
- derived from tigecycline, IV infusion
- biliary excretion again
- multiresistant gram pos, gram neg and anaerobes
- not against proteus and pseudomonas
- complicated skin and soft tissue infection and complicated intra-abdominal infections
Eravacycline
- fully synthetic, similar to tigecycline (IV)
- gram pos cocci, gram neg bacilli, anaerobes
- high extravascular distribution, especially in the lungs
- low durg-drug interactions
- complicated intra-abdominal infections, UTI
Tetracycline- side effects
- teeth discolouration (preganant, <8)
- hepatotoxicity (pregnant)
- photosensitivity
- local irritation (avoid IM)
fluoroquinolones- MOA
- bactericidal, inhibit DNA replication
DUAL action - topoisomerase II/ DNA gyrase: DNA transcription and replications
- topoisomerase IV: separation of interlocked and replicated DNA
- oral and parenteral both ok
fluoroquinolone- side effect
- peripheral neuropathy
- tenndon rupture
- hypersensitivity
fluoroquinolone- excretion
- mostly via urine, moxifloxacin via biliary excretio
fluoroquiolone- use
- reserve for resistant respiratory tract infections and UTI
- high tissue penetration including the CNS
1st gen- nalidixic acid
- UTI, urinary antiseptics, gram neg
2nd gen- ciprofloxacin and ofloxacin
- some gram pos and atypical organism
- broad spectrum gram neg
3rd gen- levofloxacin
- gram neg, some (expanded) gram pos and atypical organism
4th gen- moxifloxacin
- gram neg, gram pos, anaerobe
recommended treatment for CAP
beta lactam with or without macrolide