Penicillins can be metabolized to penicilloic acids in man, the extent being dependent on the penicillin structure. In the phenoxy penicillin series, phenoxymethyl penicillin was found to be particularly unstable, but the higher homologues were more stable. In the isoxazolyl series, oxacillin was unstable, and progressive insertion of halogen in the phenyl ring increased stability. Ampicillin a...

The susceptibilities of 36 recent isolates of Staphylococcus aureus and 35 recent isolates of Staphylococcus epidermidis were determined against each of 65 antimicrobial agents and against two of them in combination. Rifampin was the most active of all the agents tested against both S. aureus and S. epidermidis. Among the penicillins, cloxacillin, dicloxacillin, and nafcillin were most active, ...

background and objective: methicillin resistance in staphylococcus aureus is an increasingly important clinical problem. a chromosomal gene, meca, mediates resistance to penicillinase-resistant penicillins such as methicillin and oxacillin in staphylococcus aureus. we evaluated the validity of disk diffusion test by using oxacillin, methicillin and cefoxitin disks with consideration of the pres...

Enterococci are isolated from 10–20% of cases of bacterial endocarditis and therapy generally consists of a combination of a penicillin or vancomycin plus an aminoglycoside. For the penicillins, data suggest that serum concentrations should be maintained above the MIC throughout the dosing interval to prevent the loss of efficacy, since no post-antibiotic effect has been observed for these agen...

Rotational use of antimicrobials is one of the strategies that have been suggested to reduce the development of drug-resistant bacteria. Cycling of homogeneous antimicrobial exposure is, however, unlikely to control the emergence of antimicrobial resistance. Penicillins and cephalosporins have been extensively used for therapeutic and prophylactic management of oral infection. The aim of the st...