Abstract
Purpose :
Microbial keratitis is an ophthalmic emergency requiring effective treatment to avoid serious complications. Antimicrobial resistance (AMR) is a public health threat, yet poorly reported in ocular infections. This study describes the outcomes of microbial keratitis cases resistant to antimicrobials at Sydney Eye Hospital, New South Wales, Australia.
Methods :
A retrospective case review included patients with microbial keratitis who presented to the hospital from 2012 to 2016. Cases were identified from pathology and hospital coding data. Patient demographics, clinical details, management and outcomes were collated from the medical records. The most common organisms (Coagulase negative staphylococci (CoNS), methicillin sensitive S. aureus (MSSA) and Corynebacterium spp.) with resistance to either cefalotin, chloramphenicol, ciprofloxacin, gentamicin, or vancomycin were analyzed.
Results :
Of 884 organisms identified, 405 were CoNS, 95 MSSA, and 37 Corynebacterium spp. Resistance to any of the antimicrobials was found in 129 (32%) CoNS isolates; in 18 (19%) MSSA, and in 13 (37%) Corynebacterium spp.
AMR was associated with older females (69%, median age 85 years) with Corynebacterium spp. as causal organism (p <0.001). Larger epithelial defects (p=0.167) and infiltrates (p=0.162) were more likely to be associated with Corynebacterium spp., but this was not statistically significant. Initial and final visual acuities were significantly worse in resistant MSSA (2 logMAR, 1.85 logMAR) and in Corynebacterium spp. (2 logMAR, 1.7 logMAR) compared to CoNS (1 logMAR, 0.6 logMAR) (p<0.001).
Epithelial ulcer healing time was not statistically significant longer in Corynebacterium spp. infections (26 days) compared to CoNS (11 days) and MSSA (11 days) (p=0.76). Corneal perforation and grafts were more statistically significant to occur in MSSA resistant cases (p<0.001), while a non-resolving epithelial defect was more likely to occur in resistant Corynebacterium spp. (p<0.001). One evisceration was caused by Corynebacterium spp. and two by CoNS isolates.
Conclusions :
A third of CoNS, the most common causal organism of bacterial keratitis, were resistant to at least one antibiotic. Patients with resistant CoNS were younger and presented with smaller ulcers and moderate vision loss. Visual and clinical outcomes were significantly better for resistant CoNS than for those with resistant MSSA or Corynebacterium spp.
This is a 2020 ARVO Annual Meeting abstract.