Application of polymerase chain reaction-based restriction fragment length polymorphism in typing ocular rapid-growing nontuberculous mycobacterial isolates from three patients with postoperative endophthalmitis

Abstract

Purpose: We describe postoperative endophthalmitis caused by rapid-growing nontuberculous mycobacteria (RGNTM) in 3 patients after small-incision cataract surgery with intraocular lens (IOL) implantation performed elsewhere and referred to us for management. Subsequent identification and confirmation was carried out with biochemical tests and polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP).

Materials and methods: The corneal scraping and eviscerated material of the first patient, the corneal button and the IOL of the second patient, and the corneal scraping of the third patient were processed for routine bacteriologic studies including acid-fast bacilli (AFB) by smear (excepting the IOL) and culture. Subsequent identification of the RGNTM was carried out by using biochemical tests and PCR-RFLP by using primers targeting the heat shock protein 65 region of mycobacteria.

Results: AFB smear was positive in all 3 patients. The corneal scraping of the first patient, the corneal button and IOL of the second patient, and the corneal scraping of the third patient were culture positive for RGNTM and were identified as Mycobacterium abscessus in the first and second patients and M. fortuitum sorbitol-positive third biovariant in the third patient.

Conclusions: A clinical suspicion of infection by RGNTM in delayed-onset postoperative endophthalmitis should be considered when resistance to standard therapy is encountered.