Antibiotics

Target: cell membrane

Active against: Gram negatives

S/E: causes neuromuscular blockade in overdose

Target: cell membrane

Active against: Gram positives

S/E: reversible myotoxicity

Additional comments: requires CK monitoring

Beta-lactam

Target: cell wall

Active against: Gram positives

Route: oral/IV (good oral bioavailability)

S/E: penicillin allergy, GI upset common, rash

Additional notes:

• especially effective against S. aureus
• no use in MRSA
• good for skin and soft tissue infections (e.g. cellulitis)
• resistance growing

Beta lactam

Target: cell wall

Active against: Gram positives, some Gram negative activity

Route: oral/IV

S/E: penicillin allergy, GI upset (common), rash

Additional notes:

• broad spectrum
• resistance is growing
• can cross blood-brain barrier when meninges are inflamed
• beware in EBV (causes rash)

Beta lactam (amoxicillin) + beta lactamase inhibitor (clavulanic acid)

Target: cell wall

Active against: Gram positives, Gram negatives, anaerobes

S/E: penicillin allergy, GI upset (common), rash, deranged LFTs

Additional notes:

• good soft tissue penetration
• broad spectrum
• AKA Augmentin
• can cross blood-brain barrier when meninges are inflamed

Beta lactam (piperacillin) and beta lactamase inhibitor (tazobactam)

Target: cell wall

Active against: Gram positives, Gram negatives, antipseudomonal

S/E: penicillin allergy, GI upset (common), rash

Additional notes:

• good for hospital acquired infections
• broad spectrum
• similar sites of penetration to co-amoxiclav but can't cross blood-brain barrier
• good for necrotising fasciitis in combination with clindamycin

1st generation cephalosporin

Target: cell wall

Active against: Gram positives, Gram negatives

Route: oral (only oral cephalosporin)

S/E: GI upset, rash, some cross-reactivity with penicillin allergy

Additional notes:

• good penetration into skin and urine
• often used for UTIs

2nd generation cephalosporin

Target: cell wall

Active against: Gram positives and Gram negatives

Route: IV

S/E: GI upset, rash, some cross-reactivity with penicillin allergy

Additional notes:

• broader cover than 1st generation cephalosporins
• often used in sepsis of unknown origin in combination with metronidazole

3rd generation cephalosporins

Target: cell wall

Active against: Gram negatives, some Gram positives

Route: IV

S/E: GI upset, rash, some cross-reactivity with penicillin allergy

Additional notes:

• crosses blood-brain barrier when meninges are inflamed
• often used in meningitis

Includes meropenem and ertapenem

Target: cell wall

Active against: Gram negatives (very broad), Gram positives (broad), anaerobes, antipseudomonal (meropenem only)

S/E: GI upset, rash, some cross-reactivity with penicillin allergy

Additional notes:

• less affected by common mechanisms of resistance

Target: cytoplasm

Active against: anaerobes, protozoa

Route: oral/IV/PR

S/E: vomiting, GI upset

Additional notes:

• no activity against aerobic bacteria
• reacts with alcohol
• good at getting into abscesses

Clarithromycin, azithromycin, erythromycin

Target: ribosomes

Active against: Gram positives, Gram negatives, atypical organisms

Route: oral/IV

S/E: prolonged QT interval, GI upset, rash, hepatotoxicity

Additional notes:

• good penetration
• caution in hepatic or renal failure
• interactions: increases levels of warfarin and phenytoin

Lincosamide (same mechanism as macrolides)

Target: ribosomes

Active against: Gram positives, anaerobes, also anti-toxin

Route: oral/IV (100% oral bioavailability)

S/E: rash, GI upset, increased risk of C. difficile infection and pseudomembranous colitis

Additional notes:

• excellent skin and soft tissue penetration
• good for necrotising fasciitis in combination with tazocin

Target: ribosomes

Active against: Gram positives, atypical organisms, some Gram negatives and anaerobes

S/E: GI upset, hepatotoxicity, photosensitivity

Additional notes:

• contraindicated in children < 12, pregnancy and breastfeeding due to risk of teeth staining

Target: ribosomes

Active against: Gram positives, Gram negatives, antipseudomonal

Route: IV/topical

S/E: ototoxicity, nephrotoxicity

Additional notes:

• dose according to body weight (beware in obesity- may need to use ideal weight)
• renal excretion so reduce dose if renal impairment (don't use if severe)
• contraindications: renal failure, myasthenia gravis
• S/E related to blood concentration so monitoring required (trough levels < 1mg/L after 24hrs)

Quinolone (like moxifloxacin)

Target: DNA gyrase

Active against: Gram positives, Gram negatives, atypical organisms

Route: oral (100% oral bioavailability)

S/E: GI upset (risk of C. difficile), tendon rupture (children), reduced seizure threshold

Additional notes:

• hepatic and renal excretion so reduce dose in impairment
• avoid in children due to risk of tendon rupture
• avoid in epilepsy due to reduced seizure threshold
• very good penetration

Target: folate synthesis

Active against: Gram positives, Gram negatives

Route: oral

Additional notes:

• often used in UTI
• avoid in renal failure
• avoid in pregnancy (especially 1st trimester) - risk of neural tube defects
• avoid in patients on other antifolate drugs (e.g. methotrexate)

Unknown mechanism

Route: oral

Additional notes:

• only get a high enough concentration in urine so used for lower UTIs
• not useful in pyelonephritis
• useless in renal failure
• avoid in infants and pregnancy (especially 3rd trimester) - risk of haemolysis