Clavam antibiotics

The 1-caibapenems (Fig. 5.5C) comprise a new family of fused /3-lactam antibiotics. They are analogues of penicillins or clavams, the snlphur (penicilhns) or o gen (calvams) atom being replaced by carbon. Examples are the olivanic acids (section 2.5.1) and thienamycin and imipenem (section 2.5.2). 

Lactams are a broad class of antibiotics that include penicillin derivatives, cephalosporins, monobactams, carbapenems, and clavams (/8-lactamase inhibitors). The metabolic engineering of penicillin and cephalosporins production has been summarized by several good reviews [71,72], so the focus here is clavulanic acid, which has attracted interest in recent years. 

An important group of four-membered heterocyclic compounds are the derivatives of the /i-lactam [azetidin-2-one (15)] system. Many of the compounds are biologically active, for example, the monocyclic nocardicins [e.g. (16)] and the bicyclic penicillin and cephalosporin antibiotics [e.g. (17) and (18) respectively], and the -lactamase inhibitors of the clavam group (19). 

The C. are jS-lactam antibiotics of the oxapenam type (4-oxa-l-azabicyclo[3.2.0]heptan-7-one), in contrast to the penams the sulfur atom is replaced by oxygen. The C. have antifungal properties and are isolated from culture broths of Streptomyces species. The first C. to be discovered was clavam-2-ca xylic acid important C. are also the clavamycins from S. hygroscopi-... 

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