Serum bactericidal activity of piperacillin/tazobactam against Staphylococcus aureus, piperacillin-susceptible and piperacillin-resistant Escherichia coli and Pseudomonas aeruginosa.
BACKGROUND
The serum bactericidal test measures the highest level of an antibiotic-containing serum dilution at which 99.9% of bacteria are killed. In this study the serum bactericidal activity of piperacillin/tazobactam was determined for bacteria often involved in severe infections. In earlier studies titres >/=1:8 in the serum bactericidal tests correlated well with clinical success in the treatment of endocarditis and osteomyelitis as well as bacterial eradication.


METHODS
Blood samples of 6 healthy volunteers were taken before and 1 and 4 h after piperacillin/tazobactam (4.5 g) administration. Serum concentrations and serum bactericidal activity were determined for 10 strains each of Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli, both piperacillin-resistant and piperacillin-susceptible according to NCCLS guidelines.


RESULTS
100% of S. aureus and piperacillin-susceptible E. coli, 90% of piperacillin-resistant E. coli and 80% of P. aeruginosa were killed 1 h after drug administration. 4 h after drug administration serum bactericidal activity decreased to 60% for S. aureus, 90% for piperacillin-susceptible E. coli, 80% for piperacillin-resistant E. coli and 30% for P. aeruginosa.


CONCLUSIONS
Excellent serum bactericidal activity of piperacillin/tazobactam was recorded 1 h after drug administration for S. aureus, E. coli and P. aeruginosa. After 4 h limited killing rates for P. aeruginosa could be detected, which supports the idea of a combination therapy.
Lemmen
S W
SW
Department of Infection Control, University Hospital Aachen, Aachen, Germany. slemmen@ukaachen.de
Zolldann
D
D
Klik
S
S
Lütticken
R
R
Kümmerer
K
K
Häfner
H
H
D000328:Adult; D000900:Anti-Bacterial Agents / Q000097:blood / Q000494:pharmacology*; D004359:Drug Therapy, Combination; D004926:Escherichia coli / Q000187:drug effects*; D005260:Female; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D010397:Penicillanic Acid / Q000031:analogs & derivatives* / Q000097:blood / Q000494:pharmacology*; D010403:Penicillin Resistance; D010878:Piperacillin / Q000097:blood / Q000494:pharmacology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects*; D013211:Staphylococcus aureus / Q000187:drug effects*; D000078142:Tazobactam
D000900:Anti-Bacterial Agents; D010397:Penicillanic Acid; D000078142:Tazobactam; D010878:Piperacillin