Nontuberculous mycobacterial ocular infections--comparing the clinical and microbiological characteristics between Mycobacterium abscessus and Mycobacterium massiliense.

Hsiao-Sang Chu,Elizabeth P Shen,Shan-Chwen Chang,Fung-Rong Hu,Andres R Floto

doi:10.1371/journal.pone.0116236

Hsiao-Sang Chu, Elizabeth P Shen + Show 3 more

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https://doi.org/10.1371/journal.pone.0116236

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Journal: PloS one	Publication Date: Jan 12, 2015
Citations: 16	License type: CC BY 4.0

Affiliation: National Taiwan University Hospital

Abstract

PurposeTo analyze the clinical characteristics of nontuberculous mycobacterial (NTM) ocular infections and the species-specific in vitro antimicrobial susceptibility.Material and MethodsIn 2000 to 2011 at the National Taiwan University Hospital, multilocus sequencing of rpoB, hsp65 and secA was used to identify NTM isolates from ocular infections. The clinical presentation and treatment outcomes were retrospectively compared between species. Broth microdilution method was used to determine the minimum inhibitory concentrations of amikacin (AMK), clarithromycin (CLA), ciprofloxacin (CPF), levofloxacin (LVF), moxifloxacin (MXF) and gatifloxacin (GAF) against all strains. The activities of antimicrobial combinations were assessed by the checkerboard titration method.ResultsA total of 24 NTM strains (13 Mycobacterium abscessus and 11 Mycobacterium massiliense) were isolated from 13 keratitis, 10 buckle infections, and 1 canaliculitis cases. Clinically, manifestations and outcomes caused by these two species were similar and surgical intervention was necessary for medically unresponsive NTM infection. Microbiologically, 100% of M. abscessus and 90.9% of M. massiliense ocular isolates were susceptible to amikacin but all were resistant to fluoroquinolones. Inducible clarithromycin resistance existed in 69.3% of M. abscessus but not in M. massiliense isolates. None of the AMK-CLA, AMK-MXF, AMK-GAF, CLA-MXF and CLA-GAF combinations showed synergistic or antagonistic effect against both species in vitro.Conclusions M. abscessus and M. massiliense are the most commonly identified species for NTM ocular infections in Taiwan. Both species were resistant to fluoroquinolones, susceptible to amikacin, and differ in clarithromycin resistance. Combined antimicrobial treatments showed no interaction in vitro but could be considered in combination with surgical interventions for eradication of this devastating ocular infection.

Highlights

Nontuberculous mycobacteria (NTM), known as atypical mycobacteria, are opportunistic pathogens that live in natural environments including water, soil, food, and air.[1]
100% of M. abscessus and 90.9% of M. massiliense ocular isolates were susceptible to amikacin but all were resistant to fluoroquinolones
M. abscessus and M. massiliense are the most commonly identified species for NTM ocular infections in Taiwan. Both species were resistant to fluoroquinolones, susceptible to amikacin, and differ in clarithromycin resistance

Summary

Introduction

Nontuberculous mycobacteria (NTM), known as atypical mycobacteria, are opportunistic pathogens that live in natural environments including water, soil, food, and air.[1] In the past twenty years, the number of NTM ocular infections has gradually increased and the majority of the infections was caused by the rapidly growing mycobacteria (RGM).[2,3] Penetrating ocular trauma or surgery can introduce NTM from the environment into ocular tissues.[4] The coexistence of foreign body or biomaterial, exposure to contaminated water, and local or systemic immunosuppression of host are other risk factors of NTM eye infections.[5,6] After the1990s’ with the growing popularity of laser refractive surgery or keratoplasty, NTM keratitis has been more widely recognized and commonly reported.[3,7] Other sporadic NTM ocular infections include buckle infections, conjunctivitis, canaliculitis, scleritis, choroiditis, endophthalmitis and external adnexal infections.[8]

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