An atypical presentation of non-IgE-mediated cow’s milk allergy associated with Staphylococcus aureus: A case study

Cow’s milk allergy (CMA) is one of the most common food allergies in the first years of life. CMA is classified as immunoglobulin E (IgE) or non-IgE-mediated reactions. IgE-mediated reactions are typically of immediate onset, with symptoms manifesting within 2 hours after ingestion. However, non-IgE-mediated reactions are delayed and mostly occur between 2 and 48 hours post exposure. This report describes a 17-year-old who presented with a long-standing history of pustular lesions immediately after cow’s milk ingestion. Allergy tests, which included skin-prick test (SPT); specific IgE to cow’s milk; cow’s milk IgE components; and Cellular antigen stimulation test (CAST) yielded insignificant results. However, an oral food challenge resulted in pustular lesions and abdominal pain within 30 and 120 minutes, respectively. A swab from a pustule cultured Staphylococcus aureus. CMA was confirmed and managed with dietary restriction. It is uncommon for non-IgE reactions to occur with immediate symptoms. S. aureus may be associated with atypical skin manifestation of CMA.