Abstract
Purpose :
Moraxella is an ocular bacterial pathogen isolated in cases of keratitis, conjunctivitis, and endophthalmitis. Although Moraxella catarrhalis is a common clinical pathogen, other species of Moraxella appear to have a more prominent role in eye infections. It is our experience that Gram-stain (brick-shaped diplobacilli) from ocular specimens, and slow growth in culture, are early indications of Moraxella ocular infection. Identifying Moraxella to species is complex and inconsistent.
Methods :
In this study, bacteria consistent with Moraxella were identified to species using: 1) DNA sequencing, 2) MALDI-TOF MS, and 3) Biolog ID System. Study samples consisted of 9 ATCC Moraxella controls; 82 isolates from keratitis; 21 isolates from conjunctivitis; and 4 isolates from endophthalmitis.
Results :
The ATCC controls were correctly identified using the three techniques. For keratitis, 64 (78%) were identified as nonliquefaciens, 5 (6%) as osloensis, 5 (6%) as lacunata, 1 (1.6%) as bovis, 2 (2.4%) as Acinetobacter, and 5 (6%) as No ID. For conjunctivitis, 8 (38%) were identified as osloensis, 5 (24%) as nonliquefaciens, 3 (14.3%) as Roseomonas, 2 (9.5%) as Acinetobacter, 1 as M catarrhalis (4.7%), and 2 (9.5%) as No ID. From endophthalmitis, 3 of 4 of the isolates were nonliquefaciens. Overall, nonliquefaciens and osloensis were identified in 67% (72 of 107) and 12% (13 of 107) of cases, respectively, totaling 79 % (85 of 107).
Conclusions :
Our study supports that M nonliquefaciens and osloensis are key bacterial pathogens of the eye. DNA sequencing and MALDI-TOF MS can reliably identify Moraxella to species with head-to-head correlation.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.