High dose antibiotic regimens

Reporting of antibiotic susceptibility from microbiology laboratories has changed in line with new European (EUCAST) recommendations. Some antibiotics are reported as I as well as the more familiar S and R. The definitions of these are listed below.

S = Susceptible at standard dose

I = Susceptible, increased exposure (= increased dose)

R = Resistant even with increased exposure/dose

Agents reported as “I” are still effective treatment options when given at the correct (higher) dose. These higher doses are listed in the table below.

Doses are for normal renal and hepatic function and may need adjusted accordingly/ discussed with pharmacy.

Drug	High dose regime
Amoxicillin oral	1g every 8 hours
Amoxicillin IV	2g every 4 hours
Aztreonam IV	2g every 6 hours
Benzylpenicillin IV^	1.2g every 4 hours
Cefotaxime IV*	2g every 8 hours
Ceftazidime IV	2g every 8 hours
Ceftriaxone IV*	2g every 12 hours or 4g once daily
Ciprofloxacin IV	400mg every 8 hours
Ciprofloxacin oral	750mg every 12 hours
Co-amoxiclav oral	Co-amoxiclav 625mg every 8 hours + Amoxicillin 500mg every 8 hours
Co-trimoxazole IV/oral	1440mg every 12 hours
Fluconazole IV/oral	800mg once daily
Levofloxacin IV/oral	500mg every 12 hours
Meropenem IV+	2g every 8 hours
Piperacillin/tazobactam IV	4.5g every 6 hours
Temocillin IV	2g every 8 hours

^For meningitis/CNS infection caused by Streptococcus pneumoniae, higher doses (2.4g every 4 hours) should be used.

*For Streptococcus pneumoniae reported as “I” to Amoxicillin, Cefotaxime or Ceftriaxone; these agents should NOT be used in meningitis/CNS infection.

+For Acinetobacter spp. and Pseudomonas spp. reported as “I” to Meropenem; this agent should NOT be used in meningitis/CNS infection.