Characteristic features of infants with pneumonia testing positive for specific immunoglobulin E

ObjectiveTo analyse the characteristic features of infants with pneumonia who test positive for serum milk-specific immunoglobulin E (sIgE) and to provide a reference for the diagnosis, management and prevention of the condition.MethodsWe retrospectively analysed data from 284 infants admitted to our hospital with pneumonia between January 2017 and December 2020 who underwent serum allergen testing. Based on the results, patients were categorised into three groups: pure milk sIgE-positive; mixed milk sIgE-positive; and allergen sIgE-negative. We then compared the general conditions, clinical characteristics, laboratory tests, imaging results and pathogenic data across these groups.ResultsAmong the patient population, 16.20% (46/284) tested positive for pure milk sIgE, 32.75% (93/284) tested positive for mixed milk sIgE and 51.06% (145/284) were negative for any allergen sIgE. Statistically significant differences were observed among the three groups in terms of general conditions, breastfeeding status, pre-existing respiratory infections and history of respiratory infections (>3 times) (p < 0.05 for each). The median length of hospital stay was longer in the pure milk sIgE-positive group and the mixed milk sIgE-positive group (8 [range 7-10] days) compared with the allergen sIgE-negative group (8 [range 6-9] days) (p < 0.05). The eosinophil counts of the mixed milk sIgE-positive group were significantly higher than in the other two groups (p < 0.05). Haemophilus influenzae of the pure milk sIgE-positive group was significantly higher than in the other two groups (p < 0.05).ConclusionThe presence of mixed milk sIgE allergens does not exacerbate clinical symptoms. However, infants who test positive solely for milk sIgE and have pneumonia require longer hospitalisation. This suggests that extra attention is necessary for infants with milk allergies when they develop pneumonia.