Abstract
Purpose :
Microbial keratitis is an ophthalmic emergency requiring immediate anti-microbial therapy. Antimicrobial resistance is a public health threat with impact on patient outcomes. This study reports the spectrum and resistance patterns of organisms isolated from cornea scrapings in microbial keratitis at Sydney Eye Hospital, Australia over 5 years.
Methods :
A retrospective case review of clinically diagnosed microbial keratitis cases that underwent a corneal scrape was conducted. Cases were identified from pathology results and ICD-10 coding data from 1 January 2012 to 31 December 2016. All specimens were processed at the NSW Health Pathology, Department of Microbiology.
Results :
1117 corneal scrapes were performed on 1051 eyes. 933 organisms were grown on 742 of 1117 plates (66% positive culture rate), 689 (74%) were gram-positive, 200 (21%) were gram-negative, 40 (4%) fungi and 4 (0.4%) acanthamoeba.
Coagulase-negative staphy (CoNS) 59% (407/689), staph aureus 16% (107/689), including seven methicillin resistant staph aureus (MRSA), Corynebacterium spp 6% (38/689), strept pneumoniae 4% (29/689) and pseudomonas aeruginosa 55% (110/200) were the most common isolates.
Resistance for methicillin sensitive staphy aureus (MSSA) to chloramphenicol increased from 5% in 2012 to 20% in 2014 and plummeted to 0 cases in 2015 and 2016; and to gentamicin has remained at between 7 and 10%. Resistance for CoNS to cefalotin decreased from 23% in 2012 to 14% in 2013 and rose to 29% in 2014 to decrease again to 14% in 2015 and 2016. Resistance to chloramphenicol had a peak (21%) in 2013 which fell steadily to 3% in 2016. Resistances to ciprofloxacin and gentamicin declined from 14% and 19% in 2012 to 3 and 4%, respectively in 2015 but climbed to 7% and 12% in 2016.
Resistance for Corynebacterium spp. to chloramphenicol plummeted from 71% in 2012 to 0% in 2013; and was between 13% and 50% from 2014 to 2016. Resistance to cefalotin increased from 25 to 50% from 2013 to 2016; while it has decreased from 25% to 0% to ciprofloxacin.
Resistance for streptococcus pneumoniae to cefalotin was 25% in 2015 and decreased to 14% in 2016. No resistance for Pseudomonas aeruginosa was identified.
Conclusions :
Gram-positive bacteria were most commonly isolated from cases of bacterial keratitis. Emerging resistance was noted to cefalotin for CoNS while resistance has decreased to chloramphenicol.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.