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Please note that microbial sensitivities vary between regions & countries, as well as over time. Individual hospital guidelines very widely, and this is just an overview of general sensitivies. Please check your local hospital guidelines for specific advice when prescribing.

Gram positive

Cocci

Catalase positive – Staphylococcus
  • S. aureus – flucloxacillin
  • S. saprophyticus – Penicillin
  • S. epidermidis – Vancomycin
Catalase negative – Streptococcus
  • Group A B-haemolytic strep: S. pyogenes
  • GBS – agalactiae
  • Alpha-haemolytic – S. viridians and S. pneumoniae
  • Gamma-haemolytic – enteroccus
  • Treat all above with penicillin

Rods

  • Clostridium – metronidazole, vancomycin
  • Listeria – ampicillin, ceftriaxone, cotrimoxazole
  • Bacillus: anthracis – penicillin, doxycycline, ciprofloxacin, levofloxacin
  • Bacillus: cereus – no antibiotics
  • Corynebacterium diptheriae – penicillin, erythromycin

Gram Negatives

Cocco-bacilli

  • Haemophilus influenza – serious (cefotaxime/ceftriaxone) less serious (ampicillin/amoxicillin)
  • Brucella – tetracyclines, rifampicin, aminoglycosides
  • Legionella – erythromycin + rifampicin
  • Pertussis – erythromycin in early stage
  • Diplococci
  • Neisseria meningitidis – ceftriaxone/penicillin G (close contacts Rifampicin)
  • Neisseria gonorrhoeae – ceftriaxone

Rods

Lactose positive
  • E. coli – avoid abx
  • Enterobacter
  • Klebsiella –3rd generation cephalosporin
Lactose negative
  • Bacteriodes fragilis – ceftriaxone
Lactose negative oxidase positive
  • Vibrio cholera
  • Pseudomonas – Pitazobactam or ciprofloxacin + gentamycin
  • Campylobacter – fluoroquinolones/erythromycin
Lactose negative oxidase negative
  • H. pylori – PPI + amoxicillin + clarythromycin
  • Shigella – fluoroquinolones
  • Salmonella – ciprofloxacin/ceftriaxone
  • Yersinia – no antibiotics

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