Abstract
Purpose :
Antimicrobial resistance (AMR) is a global health threat. The World Health Organisation has recommended to address the knowledge gap on geographical patters of AMR to guide the treatment of patients and inform local, national and regional actions. Surveillance data for AMR from ocular infections is scarce relative to other infectious diseases globally. The Bacterial Ocular Surveillance Program (BOSS) was initiated at Sydney Eye Hospital in Sydney, Australia in 2016 and has expanded nationwide. We aim to report the spectrum and antibiotic non-susceptibility of bacteria isolated from corneal scrapings in bacterial keratitis from 2019 to 2022.
Methods :
A retrospective analysis of bacteria isolated from cornea scrapings from 12 centres in Sydney, Melbourne, Adelaide, and Perth from January 1, 2019 to December 31, 2022 was conducted. Bacteria were identified by MALDI-TOF mass spectrometry. Antibiotic susceptibilities were determined using standard methodology.
Results :
There were 1791 organisms isolated. Of these, 1311 (73%) were Gram-positive and 480 (27%) Gram-negative organisms.
Coagulase-negative staphylococci (CoNS) 32% (569/1791), Staphylococcus aureus 22% (398/1791), including 26 methicillin-resistant S. aureus (MRSA), Corynebacterium spp. 5% (83/1791); and Pseudomonas aeruginosa 14% (252/1791) were the most common organisms.
Antimicrobial non-susceptibility was found for CoNS to cefalotin 25%, chloramphenicol 12%, ciprofloxacin 7% and gentamicin 5%; methicillin-sensitive S. aureus (MSSA) to ciprofloxacin 6%, chloramphenicol 5%, gentamicin 1%; MRSA to ciprofloxacin 42% and gentamicin 8% and chloramphenicol 6%; Corynebacterium spp. to cefalotin 29%, ciprofloxacin 12%, chloramphenicol 9%; Pseudomonas aeruginosa to ciprofloxacin 2%, gentamicin 1.2%, and tobramycin 1%. All Gram-positive isolates were susceptible to vancomycin.
Conclusions :
CoNS were the main causal organisms of bacterial keratitis. One-quarter of CoNS and about a third of Corynebacterium spp. were resistant to cefalotin. Resistance to ciprofloxacin was low for CoNS, MSSA and Corynebacterium spp. isolates but moderate for MRSA. An emerging number of Pseudomonas aeruginosa isolates were found with resistance to antibiotics. An ongoing AMR surveillance in ocular infections across Australia is needed to provide evidence-base therapy recommendations according to geographic locations.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.