Methods: A retrospective study that includes all penicillin allergy history–positive/penicillin skin test–negative/oral amoxicillin challenge-non reactive individuals who had been tested in advance of need between the years 2000-2009 at one medical center (n=140). To uncover late reactions, they were offered after the test a five day course of amoxicillin. The study tool was a phone-questionnaire assessing the patients' confidence in their test results, and whether they have used penicillin since testing.
Results: 106 patients (76%) agreed to participate in the survey. Ninety nine patients (93%) chose to take the five day course of amoxicillin. From this group of patients twenty seven (27.2%) answered that they feel intermediate insecurity and fourteen (14.1%) that they feel complete insecurity to receive penicillin. Since having the test seventy two (72.7%) of the 99 needed penicillin. Sixty two (86.1%) indeed took a beta-lactam while 10 patients (13.9%) chose to receive another antibiotic class due to their or their physician's disbelief in the test. All the patients (n=7) who chose not to take the course of amoxicillin after the test stated that they feel complete insecurity to receive penicillin. Four (57.1%) of these patients had a disease that requires a beta-lactam antibiotic and actually, none of them agreed to take one (P=0.01).
Conclusions: A negative penicillin test done in advance of need even when includes an oral challenge may not be enough to convince patients that they can use beta-lactams. Our study suggests that giving a five day course of amoxicillin after the test increases the patients' confidence in the results.