mecillinam mecillinam mecillinam (inn) or amdinocillin (usan) is an extended-spectrum penicillin antibiotic of the amidinopenicillin class that binds specifically to penicillin binding protein 2 (pbp2), and is only considered to be active against gram-negative bacteria. it is used primarily in the treatment of urinary tract infections, and has also been used to treat typhoid and paratyphoid fever. because mecillinam has very low oral bioavailability, an orally active prodrug was developed: pivmecillinam. mecillinamclinical datatrade namescoactin, leo, selexid, selexidinahfs/drugs.cominternational drug namespregnancycategory appears safe in pregnancy routes ofadministrationintravenous, intramuscularatc codej01ca11 (who) legal statuslegal status au: s4 (prescription only) uk: pom (prescription only) in general: ℞ (prescription only) pharmacokinetic databioavailabilitynegligibleprotein binding5 to 10%metabolismsome hepatic metabolismelimination half-life1 to 3 hoursexcretionrenal and biliary, mostly unchangedidentifiers iupac name (2s,5r,6r)-6--3,3-dimethyl-7-oxo-4-thia-1-azabicycloheptane-2-carboxylic acid cas number32887-01-7 ypubchem cid36273drugbankdb01163 ychemspider33357 nuniiv10579p3qzkeggd02888 nchemblchembl530 ycomptox dashboard (epa)dtxsid3022584 echa infocard100.046.601 chemical and physical dataformulac15h23n3o3smolar mass325.43 g·mol−13d model (jsmol)interactive image smiles cc1((n2(s1)(c2=o)n=cn3cccccc3)c(=o)o)c ny (what is this?) (verify) medical uses mecillinam is used in the treatment of infections due to susceptible gram-negative bacteria, especially urinary tract infections which are most commonly caused by escherichia coli. mecillinam is active against most pathogenic gram-negative bacteria, except pseudomonas aeruginosa and some species of proteus. several studies have also found it to be as effective as other antibiotics for treating staphylococcus saprophyticus infection, though it is gram-positive, possibly because mecillinam reaches very high concentrations in urine. worldwide resistance to mecillinam in bacteria causing urinary tract infection has remained very low since its introduction; a 2003 study conducted in 16 european countries and canada found resistance to range from 1.2% (escherichia coli) to 5.2% (proteus mirabilis). another large study conducted in europe and brazil obtained similar results — 95.9% of e. coli strains, for instance, were sensitive to mecillinam. adverse effects