title: Serum bactericidal activity of piperacillin/tazobactam against Staphylococcus aureus, piperacillin-susceptible and piperacillin-resistant Escherichia coli and Pseudomonas aeruginosa.
abstract: 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.
authors.affiliation: Department of Infection Control, University Hospital Aachen, Aachen, Germany. slemmen@ukaachen.de
authors.forename: S W
authors.initials: SW
authors.lastname: Lemmen
authors.forename: D
authors.initials: D
authors.lastname: Zolldann
authors.forename: S
authors.initials: S
authors.lastname: Klik
authors.forename: R
authors.initials: R
authors.lastname: Lütticken
authors.forename: K
authors.initials: K
authors.lastname: Kümmerer
authors.forename: H
authors.initials: H
authors.lastname: Häfner
mesh_terms: 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
chemical_list: D000900:Anti-Bacterial Agents; D010397:Penicillanic Acid; D000078142:Tazobactam; D010878:Piperacillin