Nontuberculous Mycobacterial Keratitis Responds Favorably to Medical Therapy

Medical therapy may be able to resolve a majority of nontuberculous mycobacterial (NTM) keratitis infections without the need for surgery, according to a study published in the Journal of Ophthalmic and Vision Research.

Researchers collected study data from 16 patients with NTM (70.6% men, mean age 43.56 years). The median time from onset of infection to initial presentation was 2.23 months. A total of 65% (n=11) of patients had a history of trauma or surgery. Among these participants, 7 experienced trauma with mineral or vegatitive matter. Twelve eyes (75%) had received treatment prior to presentation. Among these patients, 6 (37.5%) were prescribed both antifungals and antibiotics, 5 (31.3%) used antibiotics, and 1 (6%) used antivirals. Investigators noted steroid use (topical or systemic) in almost half of the cohort. 

Researchers found that the most common NTM keratitis risk factor was injury with organic material (43.7%), followed by ocular surgery (25%). The team observed M. abscessus, M. fortuitum, and M. chelonae in 87.6%, 6.2%, and 6.2% of cases, respectively. 

Using in vitro sensitivity, the team determined that NTM keratitis showed the greatest sensitivity to Amikacin (AMK, 100%) followed by Azithromycin (AZM, 85.7%), and Clarithromycin (CLR, 85.7%). Among the cohort, 12 participants (75%) experienced complete corneal scarring with no active corneal inflammation after 1 month of ceasing topical antibiotic treatment with medical therapy.  A total of 4 (25%) participants required surgery. 

“[T]his study emphasizes that NTM must be kept as a differential diagnosis of infectious keratitis developing post-surgery or after injury by a foreign body injury, especially when an ulcer fails to respond adequately to the common antimicrobial drugs,” according to the researchers.  The team cautions that the prevalence of NTM is expected to rise due to an increase in the number of refractive procedures like LASIK and endothelial keratoplasties. 

Study limitations include the small sample size and retrospective nature.

Reference

Dhiman R, Lakshmipathy M, Lakshmipathy D, Lily TK. Clinico-microbiological profile of nontuberculous mycobacterial keratitis. J Ophthalmic Vis Res. 2022;17(2):160–169. doi:10.18502/jovr.v17i2.10786