Changes

* They are active against gram-negative rods, including enterobacteriaceae.

* They are active against gram-negative rods, including enterobacteriaceae.

* They are active against the anaerobes, ''Actinomyces'' and ''Fusobacterium'', but inactive against clostridial species and anaerobic cocci.

* They are active against the anaerobes, ''Actinomyces'' and ''Fusobacterium'', but inactive against clostridial species and anaerobic cocci.

* Reistance is now widespread.

* Resistance is now widespread.

* Drugs which contain a PABA nuclear core, such as procaine, antagonise their actions.

* Drugs which contain a PABA nuclear core, such as procaine, antagonise their actions.

==Pharmacokinetic Considerations==

==Pharmacokinetic Considerations==