Antibiotic (Extended-Spectrum Penicillin + Beta-Lactamase Inhibitor) Pregnancy: B — safe

Piperacillin-Tazobactam

Brand names: Tazocin

Adult dose

Dose: 4.5g three to four times daily IV

Route: IV

Frequency: Three to four times daily

Severe infections: 4.5g QDS. Continuous infusion: 13.5g/24h (pharmacokinetically superior for resistant organisms). Infuse over 30 min.

Paediatric dose

Dose: 90 mg/kg

Route: IV infusion

Frequency: every 8 hours (every 6 hours for severe infection)

Max: 4.5 g per dose

Concentration: 2.25 g/50 mL or 4.5 g/100 mL vials mg/ml

BNF: 90 mg/kg (max 4.5 g) every 8h (approx 270 mg/kg/day); severe infection: every 6h (approx 360 mg/kg/day); neonates >7 days: 90 mg/kg every 8h; neonates <7 days: 90 mg/kg every 12h (per dose)

Paediatric weight-based calculator

Patient weight (kg)

BNF: 90 mg/kg (max 4.5 g) every 8h (approx 270 mg/kg/day); severe infection: every 6h (approx 360 mg/kg/day); neonates >7 days: 90 mg/kg every 8h; neonates <7 days: 90 mg/kg every 12h (per dose)

Clinical pearls

Broad-spectrum: covers most Gram-positive, Gram-negative, and anaerobes including Pseudomonas
MERINO trial: not inferior to meropenem for E. coli/Klebsiella bacteraemia — use Tazocin when susceptible
Reserve carbapenems — do not reflexively escalate to meropenem
Hypokalaemia common — check electrolytes daily in ICU patients

Contraindications

Penicillin allergy
Cholestasis (relative — associated with hepatotoxicity)

Side effects

Hypokalaemia
Hepatitis/cholestasis
Rash
Clostridium difficile
Thrombophlebitis (IV)
Neurotoxicity at high doses

Interactions

Methotrexate — reduced excretion
Tobramycin — synergistic for Pseudomonas
Vecuronium — prolonged neuromuscular blockade

Monitoring

U&E daily (hypokalaemia risk)
LFTs (prolonged use)
Renal function

Reference: BNFc; MERINO trial (JAMA 2018); BNF; PHE Guidelines. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways