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[Infectious mononucleosis and ampicillin]
Abstract:
One to 10% of the cases have cutaneous reactions caused by ampicillin. When this drug is associated to MI the percentage goes up to 90% of the cases. The physiopathogenic mechanism of the generalized exanthema in this association is unknown. The development of toxicity is postulated because these patients have no previous history of allergy to penicillin either before of after the cutaneous reaction. By a still obscure mechanism, MI predisposes or alters the patient sensibility to the drug and the cutaneous reaction appears. This picture cannot be attributed to MI because the exanthema that present is mild. Neither is this picture of allergy due to ampicillin, without relationship with the MI, because the reaction is not coincident with other descriptions of reactions by this drug. The clinic evidence, observed in patients with MI, and ampicillin, is of a strong relation between two factors and the cutaneous reaction. In our patient the eruption affected principally the sites exposed to the sun, that makes us think in a phototoxicity reaction. Despite this fact the tests done were negative. We agree with other authors that the administration of ampicillin in patients with ill-defined pharyngeal symptoms is contraindicated until infections mononucleosis is ruled out.
Insights
Ampicillin use in patients with infectious mononucleosis (IM) significantly increases the risk of cutaneous reactions, with unknown mechanisms. Ruling out IM is crucial before prescribing ampicillin for pharyngeal symptoms.
Area of Science:
- Pharmacology
- Dermatology
- Infectious Diseases
Background:
- Ampicillin commonly causes cutaneous reactions in 1-10% of patients.
- Infectious mononucleosis (IM) is frequently associated with ampicillin, leading to a dramatic increase in cutaneous reactions, up to 90% of cases.
- The underlying physiopathogenic mechanism for this ampicillin-induced exanthema in IM patients remains unclear.
Observation:
- Patients experiencing these reactions often lack a prior history of penicillin allergy.
- The observed cutaneous reactions present as mild exanthema, not solely attributable to IM.
- The reaction pattern differs from typical ampicillin-induced allergic responses, suggesting a unique interaction.
Findings:
- A strong clinical association exists between ampicillin administration and cutaneous reactions in patients with IM.
- Phototoxicity is suspected due to sun-exposed areas being primarily affected, though tests were negative.
- The data suggest IM may predispose or alter patient sensitivity to ampicillin, triggering reactions.
Implications:
- Ampicillin administration is contraindicated in patients with undiagnosed pharyngeal symptoms until infectious mononucleosis is ruled out.
- Further research is needed to elucidate the specific mechanisms behind ampicillin-induced cutaneous reactions in the context of IM.
- This finding highlights the importance of careful patient evaluation and drug selection in managing infectious mononucleosis.
