Last reviewed 01/2018

Mecillinam and pivmecillinam both have significant activity against Gram negative bacteria including salmonellae but not pseudomonas. aeruginosa.

Pivmecillinam is administered orally and is hydrolysed to mecillinam, which is given by i.m. or slow i.v. injection or infusion.

Indications for mecillinam ('Selexidin'):-

  • severe infections due to Gram negative enteric bacteria

Indications for pivmecillinam ('Selexid'):-

  • acute uncomplicated cystitis, chronic or recurrent bacteruria and salmonellosis.

For both mecillinam and pivmecillinam; Cautions:-

  • history of allergy & renal impairment
  • liver and renal function tests on long term use


  • penicillin hypersensitivity.


  • see 'penicillins (general side-effects)'