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-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.