Plasmid mediated resistance to penicillins and cephalosporins is almost universally associated with the elaboration of a β lactamase. Two general classes of drug resistance (R) factor mediated β lactamase are now recognized. The so called TEM type β lactamase (TEM) has a high absolute activity of 60 to 1700 mU of β lactamase per 109 R+ bacteria against benzyl penicillin. Relative to its activity of benzyl penicillin, TEM has high activity on ampicillin and cephaloridine substrates but low activity against isoazolyl penicillins such as oxacillin and methacillin.
ASJC Scopus subject areas
- Molecular Biology