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 (n = 47 patients) demonstrated that only the age of the patient and the achievement of an area under the curve:minimum inhibitory concentration ratio of greater than or equal to87 had a significant effect on eradication of the pathogen (P<.001). Achieving the breakpoint made the patient 4 times more likely to achieve eradication. The effect was greatest in patients >= 67 years old.