Safety of meropenem in patients reporting penicillin allergy: lack of allergic cross reactions.

Over the years, meropenem has become the mainstay of empiric therapy for serious systemic infections in critically ill patients. Although we have had extensive clinical experience since 1996 using meropenem safely in treating hundreds of patients with reported allergic reactions to penicillin without any adverse events, we have not published our experience. This study was conducted to document our clinical practice experience. Accordingly, over a 12-month period we prospectively monitored 110 patients treated with meropenem reporting penicillin allergic reactions for that 12-month period. Since early empiric therapy in such patients is essential, there is often no time for penicillin skin testing. Penicillin skin testing was not done in this "real world" clinical study. Patients were divided into two groups, depending on the nature of their penicillin allergic reactions. During a 12-month period, 110 patients with non-anaphylactic (59) and anaphylactic (51) penicillin allergic reactions tolerated prolonged meropenem therapy (1-4 weeks) safely without any allergic reactions. Based on these data and our previous clinical experience, there appears to be little/no potential cross reactivity between meropenem and penicillins even in patients with a definite history of anaphylactic reactions to penicillins. To the best of our knowledge, this is the first prospective clinical study demonstrating that meropenem may be safely given to patients with known/unknown allergic reactions to penicillin, including those with anaphylactic reactions, without penicillin skin testing. We conclude that meropenem may be given safely to patients reporting a history of non-anaphylactic or anaphylactic allergic reactions to penicillins without penicillin skin testing.