Piperacillin. A review of its antibacterial activity, pharmacokinetic properties and therapeutic use.

Piperacillin is one of the new generation of semisynthetic penicillins which can be administered intravenously or intramuscularly. It has a broad spectrum of activity against Gram-positive and Gram-negative aerobic and anaerobic bacteria. Although piperacillin has shown greater activity against beta-lactamase-producing organisms than the other penicillins, it is hydrolysed by the plasmid-mediated beta-lactamases (TEM-1). Activity against Pseudomonas aeruginosa is better than that of ticarcillin, carbenicillin and mezlocillin. Although only limited controlled studies have been reported, in those which have been conducted and in a larger number of open studies piperacillin was effective in the treatment of complicated urinary tract infections and lower respiratory tract infections, particularly pneumonia, caused by Gram-negative bacilli. Favourable clinical results have been obtained in patients with infections caused by mixed aerobic/anaerobic organisms (such as intra-abdominal infections) but the relatively average in vitro activity of piperacillin against Bacteroides fragilis may not indicate its usage in situations where this organism is the suspected or proven pathogen. Piperacillin in combination with an aminoglycoside or a 'third generation' cephalosporin gave encouraging results in the treatment of infections in immunocompromised patients, whilst its penetration into the diseased central nervous system and lack of toxicity indicate a potential value in the treatment of neonatal Gram-negative bacillary meningitis, particularly where the causative organism is Pseudomonas aeruginosa. Whether piperacillin alone is appropriate therapy for conditions usually treated with aminoglycosides (other than pseudomonal infections) needs additional clarification, but if established as equally effective in such conditions it has the advantages of its apparent lack of serious adverse effects and freedom from the need to undertake plasma concentration monitoring. These advantages would not, however, apply when considering one of the new (third generation) cephalosporins as alternative therapy in non-pseudomonal infections. Generally, however, it is still considered necessary to treat serious and complicated infections with combination therapy, either a cephalosporin, or in cases of resistance to P. aeruginosa an aminoglycoside.