Inhibitors of cell wall synthesis
Inhibitors of nucleic acid synthesis
Inhibitors of protein synthesis
Penicillins
Indications: Very useful against Gram +ve bacteria
MOA: Bactericidal → inhibit bacterial transpeptidase, an enzyme required for cell wall synthesis
SE’s: Hypersensitivity: rash, EM, anaphylaxis. GI upset, maculopapular rash in EBV, diarrhoea
CI’s: Hypersensitivity (10% cross-reactivity with cephalosporins)
Interactions: May reduce effect of OCP, increased by probenecid
Other: PenV + PenG (IV) = Strep’s N. meningitidis, syphilis
Amox + ampicillin = broad spec: pneumococcus, listeria, E.coli, enterococci
Fluclox = penicillinase-resistant, MRSA
Piperaccillin + ticarcillin = anti-pseudomonal
Coamoxiclav = severe CAP, UTI
Tazocin = Severe HAP, sepsis
Cephalosporins
Indications: Broad spec Abx - used in: septicaemia, pneumonia, meningitis, biliary tract infections, peritonitis, UTI’s
MOA: Bactericidal: inhibit bacterial transpeptidase → required for cell wall construction. Generations have increasing activity against Gram -ves
SE’s: GI upset → antibiotic associated colitis, headache, allergic reactions
CI’s: Hypersensitivity
Interactions:
Other:1st gen: cephalexin → UTI (rarely used)
2nd gen: cefuroxime → mod/severe CAP, GI sepsis, pre-op
3rd gen: cefotaximine, cefriaxone, ceftazidime, cefixime → meningitis, epiglottitis, gonorrhoea, SBP
Carbapenems
Indications: Broad spec Abx: covers Gram -ve, +ve (except MRSA), anaerobes + pseudomonas. Used for nosocomial infections (neutropenic sepsis)
MOA: Bactericidal - inhibit bacterial transpeptidase - required for cell wall construction
**SE’s: **GI upset - N/V, seizures
CI’s: Avoid if pt has Hx of immediate hypersensitivity to β-lactams. Reduce dose in renal impairment
Interactions: Reduce concentration of valproate
Other: Imipenam = rapidly inactivated by kidney, give with cilastatin → blocks it’s metabolism
Meropenam
Ertapenam
Chloramphenicol
Indications: Superficial eye infections - conjunctivitis
MOA: Bacteriostatic - inhibits the 50s subunit → prevents peptide bond formation and thus inhibits protein synthesis
SE’s: Irreversible aplastic anaemia (not used for other infections), grey baby syndrome if oral use in 3rd trimester
CI’s: Pregnancy, lactation, renal disease
**Interactions:
Other: **
Gentamicin
Amikacin
Tobramycin
Neomycin
Streptomycin
Tetracycline
Doxycyline
Linezolid
Indications: Active against gram +ve including MRSA + VRE. No action against gram -ves
MOA: Oxazolidinone → bacteriostatic - inhibit 23s component of 50s subunit (also is a MAOI)
SE’s: Diarrhoea (Abx associated colitis), N+V, blood dyscrasias
CI’s: Giving with another MAOI, SSRIs, triptans, TCAs, opioids, tyramine, uncontrolled HTN, phaeo, thyrotoxicosis, BPAD, schizo etc.
Interactions:
Other:Monitor FBC
Erythromycin
Clarithromycin
Azithromycin
Synercid
**Indications: **VRE, MRSA
**MOA: **Streptogramins - bacteriostatic: 50S subunit inhibition of protein synthesis
**SE’s: **
**CI’s:
Interactions:
Other: **Only used when other agents failed
Clindamycin
Vancomycin
Teicoplanin
Ciprofloxacin
Levofloxacin
Ofloxacin
Moxifloxacin
Metronidazole
Nitrofurantoin
Tinidazole
Rifampicin
Rifaximin
Rifabutin
Trimethoprim
Sulfamethoxazole
Sulfadiazine
Co-trimoxazole
Indications: UTI, PCP, toxoplasmosis
MOA: Folate antagonists: bacteriostatic → inhibits bacterial DNA syntheisis
SE’s: Blood dyscrasias, EM→SJS, EN, nephrotoxic, hepatotoxic
CI’s: Severe renal and liver impairment, pregnancy. Don’t use with methotrexate
Interactions:
Other:Stop immediately if rash or dyscrasias occur
Daptomycin
Colistin
Ethambutol
Indications: Anti TB
MOA: Bacteriostatic → inhibitis mycobacterial cell wall synthesis
SE’s: Optic neuritis, red/green colour blindness, peripheral neuritis
CI’s: Optic neuritis, poor vision
Interactions:
Other:Monitor vision - lose colour vision first
Pyrazinamide
Indications: Anti TB
MOA: Bactericidal: Prodrug that stops growth of TB
SE’s: Hepatotoxicity → hepatitis, jaundice, N+V etc
CI’s: Acute attack of gout, caution in DM, severe hepatic impairment
Interactions:
Other:Monitor LFTs
Isoniazid
Fusidate (Fusidic acid)