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. 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. 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. 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. The risks of medicolegal prosecution are always a. For example: in patients with a penicillin allergy, cefazolin, ceftriaxone, and meropenem all have dissimilar R1 side chains and have rates of adverse reactions similar to the general public. Patients were divided into two groups, depending on the nature of their penicillin allergic reactions. Cross-reactivity is exceptionally rare, and occurs only when there is similarity in R1 side chains. Penicillin skin testing was not done in this 'real world' clinical study. Since early empiric therapy in such patients is essential, there is often no time for penicillin skin testing. Accordingly, over a 12-month period we prospectively monitored 110 patients treated with meropenem reporting penicillin allergic reactions for that 12-month period. This study was conducted to document our clinical practice experience. 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. Over the years, meropenem has become the mainstay of empiric therapy for serious systemic infections in critically ill patients.

Pcn allergy cross reactivity