title: Nontuberculous mycobacterial ocular infections--comparing the clinical and microbiological characteristics between Mycobacterium abscessus and Mycobacterium massiliense.
abstract: OBJECTIVE
  To analyze the clinical characteristics of nontuberculous mycobacterial (NTM) ocular infections and the species-specific in vitro antimicrobial susceptibility.
  
  
  METHODS
  In 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.
  
  
  RESULTS
  A 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.
authors.affiliation: Department of Ophthalmology, National Taiwan University Hospital, Medical College, National Taiwan University, Taipei, Taiwan.
authors.forename: Hsiao-Sang
authors.initials: HS
authors.lastname: Chu
authors.affiliation: Division of Infectious Disease, Department of Internal Medicine, National Taiwan University Hospital, Medical College, National Taiwan University, Taipei, Taiwan.
authors.forename: Shan-Chwen
authors.initials: SC
authors.lastname: Chang
authors.affiliation: Department of Ophthalmology, National Taiwan University Hospital, Medical College, National Taiwan University, Taipei, Taiwan.
authors.forename: Elizabeth P
authors.initials: EP
authors.lastname: Shen
authors.affiliation: Department of Ophthalmology, National Taiwan University Hospital, Medical College, National Taiwan University, Taipei, Taiwan.
authors.forename: Fung-Rong
authors.initials: FR
authors.lastname: Hu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000583:Amikacin / Q000494:pharmacology / Q000627:therapeutic use; D000890:Anti-Infective Agents / Q000494:pharmacology* / Q000627:therapeutic use; D002648:Child; D017291:Clarithromycin / Q000494:pharmacology / Q000627:therapeutic use; D024881:Drug Resistance, Bacterial; D015818:Eye Infections, Bacterial / Q000188:drug therapy / Q000382:microbiology*; D006801:Humans; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D009165:Mycobacterium Infections, Nontuberculous / Q000188:drug therapy / Q000382:microbiology*; D009170:Nontuberculous Mycobacteria / Q000187:drug effects* / Q000302:isolation & purification; D055815:Young Adult
chemical_list: D000890:Anti-Infective Agents; D000583:Amikacin; D017291:Clarithromycin