Antibiotic pharmacokinetics in infected pleural effusions

Pleural infection is usually treated with empirical broad-spectrum antibiotics but limited data exists around their penetrance into the infected pleural space. We performed a pharmacokinetic study analysing the concentration of 5 intravenous antibiotics across 146 separate timepoints in 35 patients (amoxicillin, metronidazole, piperacillin-tazobactam, clindamycin and cotrimoxazole). All antibiotics tested, apart from co-trimoxazole, reach pleural fluid levels equivalent to levels within blood, and well above the relevant minimum inhibitory concentrations. The results demonstrate that concerns around the penetration of commonly used antibiotics, apart from co-trimoxazole, into the infected pleural space are unfounded.