Combining LC-MS/MS and hollow-fiber infection model for real-time quantitation of ampicillin to antimicrobial resistance.

Although a marked decrease in mortality associated with bacterial infections is attributed to the discovery of antibiotics, antibiotic resistance has become a global health concern due to their misuse. A dynamic in vitro hollow-fiber system was used to study antibiotic resistance in Escherichia coli using ampicillin. An LC-MS/MS assay was validated for quantitative analysis of ampicillin in Luria-Bertani broth. The assay was linear from 0.10-50.00 mu g/ml. The assay met acceptance criteria for inter-and intra-assay precisions and accuracies across three quality controls. Stability of ampicillin was confirmed at three different storage conditions. In vitro data were similar to simulated plasma PK data further confirming the appropriateness of the experimental design to quantify antibiotics and study occurrence of antimicrobial resistance in real-time. Lay abstract: Urinary tract infections are becoming untreatable with the rise of antibiotic resistance. Escherichia coli is the cause of most urinary tract infections, one of the most common infections that require treatment with antibiotics. The utility of a hollow-fiber system, which is a dynamic system mimicking human disposition of antibiotics more closely than static systems, can help design single or combination drug dosing regimens for antibiotics based on their pharmacokinetic profiles. The data generated from these studies can be utilized to help understand the time when bacteria start developing resistance and aid in adjusting the drug combinations and their doses.