Inclusion Criteria:  Adult healthy volunteers (>18 years old). Previously taken penicillin-based antibiotics without allergic response. Estimated Glomerular Filtration Rate (eGFR) > 90.  Exclusion Criteria:  Lacking capacity to consent. Documented allergy to penicillin, other beta-lactam antibiotics, or probenecid. History of G6PD Deficiency. Known blood dyscrasias. Anaemia (Hb < 12g/dL female, 13g/dL males). Abnormal liver function (ALT, AST, ALP or bilirubin > ULN). eGFR < 90. Pregnant or likely to become pregnant during study period. Breastfeeding women. Symptoms consistent with active infection. History of gout or uric acid kidney stones. Taking regular medication that may interact with probenecid including, but not limited to methotrexate, lorazepam, acetaminophen, oral hypoglycaemic medication, sulfa containing drugs, non-steroidal anti-inflammatory drugs. History of evidence of any medical, neurological, or psychological condition that would expose the subject to an undue risk of a significant adverse event or interfere with study assessments during the course of the trial as determined by the clinical judgement of the investigator. Recent involvement in other research (within prior 3 months).