Identification of Mycobacteriophages That Infect Nontuberculous Mycobacteria Associated With Post-LASIK Keratitis

Abstract

Purpose:: To study the effect of fifteen mycobacteriophages in nontuberculous mycobacteria implicated in post-LASIK keratitis.

Methods:: Fifteen mycobacteriophages were tested for infection in Mycobacterium chelonae, abscessus and fortuitum species. Volumes of various mycobacteriophage concentrations, were pipetted onto a lawn containing 10⁸ colony forming units (c.f.u.) of the mycobacterial species. Bxz2 phage showed infection of an ATCC strain of M. chelonae.A high titer of Bxz2 was propagated from this strain. All bacteriophages were also tested on the two other ATCC strains of nontuberculous mycobacteria as well as clinical isolates of all three strains.

Results:: A titer of 10¹⁰ plaque forming units (p.f.u.)/ml of Bxz2 phage propagated in the ATCC M. chelonae was achieved. Bxz2 mycobacteriophage showed greater than 99% infection and lysis of the ATCC M. chelonae. However, Bxz2 phage did not infect the ATCC strains of M. abscessus or M. fortuitum. PG2 mycobacteriophage showed infection in several clinical isolates of M. chelonae.

Conclusions:: Bxz2 mycobacteriophage showed efficient infection and lysis of ATCC M. chelonae, and PG2 showed infection in clinical isolates of M. chelonae. This was demonstrated by increasing levels of clearing on the M. chelonae lawns corresponding to increasing concentrations of phage. These findings show the possibility of phage therapy as an alternative treatment to antibiotics for ocular infections. The abundant number and incredible genetic diversity of phages show the tremendous potential of finding more phages for infection of these nontuberculous mycobacteria implicated in post-LASIK keratits.

Keywords: keratitis • refractive surgery: LASIK • clinical laboratory testing