A 7 year old boy living in a low socio-economic background presenting with ocular complaints, was found to have nodules on the bulbar conjunctiva near the limbus. Phlyctenular conjunctivitis is diagnosed. Regarding phlyctenular conjunctivitis TRUE is:

Phlyctenular keratoconjunctivitis is a Type IV delayed hypersensitivity response to microbial proteins, including the proteins of the tubercle bacillus, Staphylococcus species (most common), C albicans, Coccidioides immitis, H aegyptius, and C trachomatis serovars L1, L2, and L3. The conjunctival phlyctenule begins as a small lesion (usually 1-3 mm in diameter) that is hard, red, elevated, and surrounded by a zone of hyperemia. Conjunctival phlyctenules usually produce only irritation and tearing. Ref: Nijm L.M., Garcia-Ferrer F.J., Schwab I.R., Augsburger J.J., Correa Z.M. (2011). Chapter 5. Conjunctiva & Tears. In P. Riordan-Eva, E.T. Cunningham, Jr. (Eds), Vaughan & Asbury's General Ophthalmology, 18e.