Rifampicin in collections of pus--a kinetic study in human abscesses

Most of the successful non-surgical management of abdominal abscesses is based upon the presence of therapeutic amounts of effective antibiotics within the collection. However few data are currently available concerning antimicrobial levels in human purulent lesions. To study the relationship between serum and pus concentrations of rifampicin, 11 patients with deep-seated abscesses were given 900 mg intravenously of rifampicin daily; after 3, 8 and 20 h from injection, an ultrasound-guided percutaneous aspiration of the collection was performed. Samples were obtained on the first day of therapy in six cases, while in other six the aspiration took place on the third day. Rifampicin levels of therapeutic value were present after 8 h from the first injection. From this time antibiotic amounts in pus, ranging from 1.6 to 5.8 mg/l, were consistent with a long persistence of rifampicin in abscesses, without any evidence of accumulation.