To report a case of recurrent nontuberculous mycobacterial
endophthalmitis in the context of neurotrophic keratopathy secondary to
herpes zoster ophthalmicus that had an atypical presentation and complex course, and highlights the challenges of causative organism identification and therapeutic interventions in this condition.
METHODS: A retrospective chart review was conducted to determine the visual outcomes of the patient.
RESULTS: A 68-year-old pseudophakic male with long-standing neurotrophic keratopathy and perforated descemetocele managed with
cyanoacrylate glue and a contact
bandage lens in the left eye, began experiencing recurrent episodes of
endophthalmitis after undergoing a
penetrating keratoplasty. Several therapeutic procedures including an anterior chamber washout, two pars plana
vitrectomies, explantation of the posterior chamber
intraocular lens and capsular bag, and multiple intravitreal antimicrobial
injections, were performed to which he has ultimately responded favorably, with no signs of
infection to date and stable visual acuity. The causative organism of his
recurrent infections was initially identified as Mycobacterium abscessus through biochemical testing and 16S ribosomal
ribonucleic acid gene sequencing; however, repeat polymerase chain reaction (PCR) and sequencing of the 65 kDa
heat shock protein (hsp65) gene for experimental purposes confirmed the accurate identification of the organism to be Mycobacterium chelonae. Given the greater reliability of PCR and sequencing of the hsp65 gene over traditional biochemical tests and culture techniques, M. chelonae was likely the infectious agent all along, and the organism was originally misidentified on the basis of less accurate tests.
CONCLUSION: Recurrent atypical mycobacterial
endophthalmitis requires expedient identification and management to prevent poor visual outcomes. Standard biochemical testing can identify the causative organism but is limited by the inability to distinguish between nontuberculous species reliably. We recommend the use of PCR in conjunction with sequencing of the hsp65 gene for reliable differentiation of M. chelonae and M. abscessus in atypical mycobacterial
ocular infections. Minimum inhibitory concentration
antibiotic susceptibility tests on cultured strains are the best guide to
antibiotic selection, given the rapidly rising resistance to antimicrobials in atypical mycobacterial species.