Group A, scenario 1, presents the case of a 16-year-old boy who is diagnosed with strep throat. Upon discharge, he is prescribed amoxicillin to treat the infection which quickly induces an anaphylactic response after he takes his first dose. As is typical of a type 1 hypersensitivity reaction, he quickly develops facial edema, dyspnea, and audible wheezes. This scenario illustrates two common pathologies that affect adults and children, namely, strep throat (Group A Streptococcus) and anaphylaxis (Type I hypersensitivity).
Group A strep is a bacteria that affects the nose and throat of young children and can be spread to adults through respiratory droplets (Centers for Disease Control and Prevention, 2022). Anaphylaxis is an exaggerated immune response to an allergen. Many biological components are involved in what is commonly known as an allergic reaction. Anaphylaxis is the most severe and life-threatening form of an allergy.
At the cellular level, a foreign substance called an antigen – in this case, penicillin – enters the body and is immediately identified as a threat by the immune system which mounts an acute inflammatory response. Type I hypersensitivities are mediated by immunoglobulin E (IgE) antibodies and the products of mast cells (i.e., histamines and leukotrienes; Justiz-Vaillant & Zito, 2019).
According to McCance and Huether (2018), the most potent mediator of this process is histamine, which acts through H1 receptors located in the smooth muscle cells of several tissues including the airway, heart/blood vessels, and brain. The symptoms experienced by the patient in the scenario can be explained by the effects of this mediator.
Histamine causes smooth muscle contraction leading to bronchial airway constriction and, therefore, dyspnea and wheezing; increased capillary permeability, which causes edema; and vasodilation, which increases blood flow to the affected areas (erythema).
Various factors play a role in the susceptibility of individuals to atopic conditions including environment, genetics, age, and gender. Allergies have a strong genetic component according to Aldakheel (2021). 70% of identical twins and 40% of non-identical twins have reported similar allergies. Furthermore, individuals with hereditary α-tryptasemia have been identified for increased risk for severe anaphylaxis (Lyons et al., 2021).
Allergies tend to occur more frequently in children than adults as IgE levels peak in infancy and decrease with age up until about 30 years where they level off. Young boys tend to experience allergies more often than young girls due to higher sensitization rates for grass pollen, dust mites, and cat epithelium. The author also states that many of these sex and age differences tend to diminish over time.
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