Relationship between Fluoroquinolone Area under the Curve:Minimum Inhibitory Concentration Ratio and the Probability of Eradication of the Infecting Pathogen, in Patients with Nosocomial Pneumonia

Our objective was to prospectively determine the factors influencing the probability of a good microbiological or clinical outcome in patients with nosocomial pneumonia treated with a fluoroquinolone. Levofloxacin was administered as an infusion of 500 mg/h for 1.5 h (total dose, 750 mg). For patients with Pseudomonas aeruginosa or methicillin-resistant Staphylococcus aureus, a second drug was added (ceftazidime or piperacillin/ tazobactam for P. aeruginosa and vancomycin for methicillin-resistant S. aureus). Population pharmacokinetic studies of 58 patients demonstrated that this population handled the drug differently from populations of volunteers. Multivariate logistic regression analysis ( patients) demonstrated that only the age of the n p 47 patient and the achievement of an area under the curve:minimum inhibitory concentration ratio of 87 had a significant effect on eradication of the pathogen ( ). Achieving the breakpoint made the patient 4 P ! .001 times more likely to achieve eradication. The effect was greatest in patients 67 years old.