Pharmacodynamic effects of amikacin, ciprofloxacin and imipenem on growing and non-growing Escherichia coli and Pseudomonas aeruginosa.
OBJECTIVE: To compare control-related effective regrowth times (CERTs) and postantibiotic effects (PAEs) of amikacin, ciprofloxacin and imipenem on growing and non-growing Escherichia coli and Pseudomonas aeruginosa. METHODS: CERTs and PAEs of amikacin, ciprofloxacin and imipenem were determined with bioluminescence assay of bacterial ATP and viable counts. RESULTS: Negative viable count PAEs of amikacin and imipenem occurred on growing bacteria, but bioluminescence PAEs were positive. CERTs were equal with both methods. Amikacin and ciprofloxacin induced long, concentration-dependent CERTs on growing and non-growing cultures. Amikacin (32 mg/L) prevented regrowth of E. coli and induced a CERT of 6.0 h on P. aeruginosa; corresponding CERTs on non-growing bacteria were 3.4 h and 3.3 h, respectively. Ciprofloxacin (8 mg/L) prevented regrowth of both strains in growing cultures and induced CERTs of 5.1 h on non-growing E. coli and 13.3 h on P. aeruginosa. Imipenem induced a concentration-dependent CERT on growing bacteria and no CERT on non-growing cultures. Imipenem (16 mg/L) induced a CERT of 5.3 h on growing P. aeruginosa and 3.2 h on E. coli. CONCLUSION: Amikacin and ciprofloxacin induced strong pharmacodynamic effects on growing and non-growing E. coli and P. aeruginosa, while imipenem was only effective on growing cultures.
Svensson
Erik
E
Departments of Clinical Microbiology and.
Hanberger
H>>kan
H
Nilsson
Maud
M
Nilsson
Lennart E.
LE