Nocardia in inborn errors in immunity.

Nocardiosis is caused by the Gram-positive bacterium Nocardia spp. The most common inborn error in immunity (IEI) associated with nocardiosis is chronic granulomatous disease (CGD). This case series highlights five cases of nocardiosis with a diagnosis of IEI other than CGD. P1, nine-year-old male child, diagnosed case of IL12RB1 deficiency, presented with seizures. MRI brain showed multiple ring-enhancing lesions. He was empirically treated with AKT and steroids for tuberculomas. Newer lesions on MRI brain prompted biopsy that showed acid-fast filaments on modified-ZN stain. Culture grew Nocardia spp. P2, 10-year-old male presented with cachexia, deep jaundice, abdominal distension with right pyopneumothorax and large splenic abscess. Splenic aspirate and pleural tap revealed the presence of Nocardia spp on culture and Nocardia cyriacigeorgica on MALDI-TOF. In view of disseminated nocardiosis, NBT/DHR test was advised which was normal, WES revealed homozygous IL12RB1 pathogenic variant. P3, nine-year male with refractory atopic dermatitis since three months of age. He had eosinophilia (10,000 cells/cumm) and hyper IgE (2360 IU/ml). He was diagnosed with DOCK8 deficiency on NGS. While being evaluated for BMT he had focal seizure with ataxia, MRI brain revealed the presence of cerebellar abscess. Biopsy revealed Nocardia spp. P4 and P5 were patients with Goods syndrome and nocardia pneumonia. Thus, isolation of nocardia at any age must prompt one to look for underlying IEI other than CGD as well. Extensive and invasive tests along with radiological tests need to be undertaken in patients with IEI to isolate and appropriately treat.