Explanation: Ampicillin is the large spectrum anti-biotic most commonly used. Ampicillin is a beta-lactam antibiotic that is part of the amino- penicillin family and is roughly equivalent to its successor, amoxicillin in terms of spectrum and level of activity. It can sometimes result in reactions that range in severity from a rash (in the case of patients that may unwittingly have mononucleosis) to potentially lethal allergic reactions such as anaphylaxis.