drug allergy인지 non allergic ampicillin rash인지 감별하는 것이 매우 중요함)
J.D. was in his usual state of good health until three days ago when he awoke in the morning with a sore throat and fever. He did not document the height of his fever. He went to school as usual that day but was sent home late morning by the school nurse because he was noted to have an oral temperature of 103° F and complained of headache and stomach ache. He described his abdominal pain as diffusely tender, constant pain that did not change with position. His stools had been normal prior to feeling ill, and he continued to have normal stooling despite the abdominal pain. Neither eating nor Pepto Bismol seemed to improve his pain. Although he had no vomiting, he stated that he felt as if he was going to "throw up." Throughout the day, his sore throat progressed to the point where he found it difficult to swallow because of pain, and therefore, his fluid intake along with solid food intake diminished considerably. His mother noted that he had not voided in more than eight hours and became concerned about dehydration, and thus he was taken to his primary care physician for evaluation.
At the time his physician saw him, he was noted to be febrile to 102.5° F with a normal blood pressure. His physical exam was significant for enlarged beefy red tonsils with exudate. His anterior cervical lymph nodes were enlarged and tender to palpation. The remainder of his exam was unremarkable. A throat culture was obtained, and he was prescribed a ten day course of amoxicillin and told that he most likely had strep throat.
The patient took the medication as it was prescribed. He remained febrile with fever ranging from 100° F to 103.5° F. He continued to have headache and stomach ache that would wax and wane; however, his sore throat continued to be the main source of his complaints. He was able to sip fluids, approximately 8 - 10 ounces every two hours, but refused to eat solids. His urine output remained decreased, voiding only 3 - 4 times in 24 hours. Upon awakening this morning, he noticed several red spots developing on his chest and arms. These spots were flat, not itchy, and progressed down to his lower extremities over the next several hours. The patient and his mother came into clinic today because of concern of a new rash and continued fever and sore throat despite taking amoxicillin.
He denies any shaking/chills, dysuria, diarrhea, vomiting, URI symptoms, ear pain, changes in his vision, arthralgias, myalgias, cough, or difficulty breathing. There is no recent history of travel, and he has not been exposed to anyone ill. The family owns a golden retriever who is reportedly healthy.
Hypersensitivity: The MOST common side effect! If the physician performs antigen skin testing,he/she must test both major and minor determinants (minor determinants available at few centers). If a patient has any questionable history of a hypersensitivity reaction to any penicillin, most physicians would not risk administering a penicillin or cephalosporin. In contrast to the classic hypersensitivity reaction,
ampicillin produces a nonallergic rash in patients who have a viral illness (especially mononucleosis!). This is NOT a hypersensitivity reaction.
Erythematous macular rash(nonallergic rash)
The timing and appearance of this rash along with the clinical suspicion that the patient has infectious mononucleosis make it likely that the rash is secondary to amoxicillin in the presence of EBV. Likewise, an erythematous maculopapular rash may also occur in individuals with EBV who are not exposed to amoxicillin/ampicillin, and thus the rash may simply be due to his underlying illness alone. Other viruses (enterovirus, adenovirus, parvovirus, herpes virus type 6) can also cause the appearance of a similar rash but seem less likely in this clinical setting for the reasons that were elaborated above. It is possible that the rash is an allergic reaction to amoxicillin since the patient does have an allergic history (i.e., allergies to shellfish and to sulfa medications). The presence of itching or hives would have made an allergy seem more likely. The fact that the patient had strep throat last year and was treated with penicillin without incident lends support to this being a nonallergic reaction.
