Antibiotic classes

Protein synthesis inhibitors

Act on ribosome.  In theory, reduce toxin production as well as growth.

  • Macrolides
  • Aminoglycosides
  • Clindamycin
  • Chloramphenicol
  • Tetracyclines
  • Linezolid


Eg Gentamicin.  Broad spectrum but poor CSF penetration (but still used for Listeria meningitis!).

Some important bacteria are usually resistant to the aminoglycosides, including gentamicin:

  • most streptococcal species (including Streptococcus pneumoniae and the Group D streptococci),
  • most enterococcal species (including Enterococcus faecalis, E. faecium,  and E. durans),
  • anaerobic organisms, such as Bacteroides species and Clostridium species.
  • Salmonella and Shigella
  • Pseudomonas unless you use ones with antipseudomonal activity eg tobramicin

Hearing damage is an important side effect, known genetic marker for this but usually not done ahead of treatment.

Renal excretion.


Block DNA synthesis.  Broad spectrum but not great gram positive, excellent absorption, penetration and intracellular too.  See quinolones.