Delayed-type oxacillin-related fever: not a rare event in hospitalized adult patients

Drug fever is a clinical event difficult to diagnose but easy to manage. To assess the characteristics, prevalence and risk factors of oxacillin-related fever, we conducted a retrospective study in a university hospital in a one-year period. Inpatients who had received more than seven days of oxacillin therapy were screened for oxacillin-related fever. Applying the elements of the criteria assessed fever patterns of 89 subjects, 5 patients (5.6 %) experienced oxacillin-related fever. Wilcoxon Rank Sum test was employed to investigate the difference between patients with and without oxacillin-related fever. Accumulative dose, average daily dose and total duration of oxacillin usage in the patients with oxacillin-related fever were significantly higher than those in the patients without oxacillin-related fever. Oxacillin-related fever was dose-independent, often present between two and three weeks of usage, and occasionally accompanied by eosinophilia, while relative bradycardia may offer another clue in diagnosis. It is important to consider its probability and to be familiar with the characteristics of oxacillin-related fever to avoid costly, inappropriate and potentially harmful investigations and therapies.