Abstract:

The use of ampicillin in the outpatient setting has traditionally been avoided due to its short half-life and instability in solution. However, recent in vitro data and two recent case series have supported the safe and effective administration of ampicillin by continuous infusion in the community. Therapeutic drug monitoring (TDM) of beta-lactam antibiotics can be used to optimise antibiotic exposure and ensure adequate clinical responses. We present a case series of patients receiving ampicillin via prolonged infusion in the outpatient setting, with TDM used to ensure adequate antibiotic levels were achieved. Three patients who received ampicillin by continuous infusion under the Outpatient Parenteral Antimicrobial Therapy (OPAT) program are described, including antibiotic dose and steady state plasma drug concentration as measured by high performance liquid chromatography. All patients had an infection with ampicillin-susceptible Enterococcus faecalis; one patient had post-partum endometritis, one had urosepsis and one a complex polymicrobial bone and joint infection. Adequate plasma drug levels were achieved in all patients. Management of the antibiotic temperature, infusion times, and appropriate timing of drug levels in the community was required. Two patients achieved clinical cure, while the third required further surgical debridement and antibiotic therapy. Therapeutic drug monitoring in this setting enabled the contemporaneous management and alteration of ampicillin dosing. Ampicillin may be a safe and effective drug when administered by continuous infusion in the community setting with appropriate TDM.

Reference:

Parsonson, D.F., Legg, M.A., Halford, M.M. and McCarthy, D.K. (2020) Contemporaneous Management of Ampicillin Infusions in the Outpatient Setting Through the use of Therapeutic Drug Monitoring. International Journal of Antimicrobial Agents. April 20th. doi: 10.1016/j.ijantimicag.2020.105975. (Epub ahead of print).