Bacterial Ocular Surveillance System (BOSS) Sydney, Australia 2017-2018

Abstract

This study investigated antimicrobial resistance (AMR) profiles from a cohort of patients with bacterial keratitis treated at Sydney Eye Hospital, 1 January 2017 – 31 December 2018. These AMR profiles were analysed in the context of the current Australian empiric regimens for topical therapy: ciprofloxacin/ofloxacin monotherapy versus combination therapy of cefalotin/cephazolin plus gentamicin. At our Centre, combinations of (i) chloramphenicol plus gentamicin and (ii) chloramphenicol plus ciprofloxacin are alternatively used, so were also analysed. Three hundred and seventy-four isolates were cultured prospectively: 280/374 (75%) were gram positive, and 94/374 (25%) were gram negative. Coagulase-negative staphylococci comprised 173/374 (46%). Isolates included <i>Staphylococcus aureus</i> (n = 43/374) 11%; <i>Streptococcus pneumoniae</i> (n = 14/374) 3.7%; and <i>Pseudomonas aeruginosa</i> (n = 50/374) 13%. Statistical comparison was performed. There was no significant difference between cover provided either of the current Australian recommendations: ciprofloxacin/ofloxacin vs cefalotin/cephazolin plus gentamicin (5.3% vs 4.8%, respectively; <i>p</i> = 0.655). However, the combination of chloramphenicol plus an anti-pseudomonal agent (ciprofloxacin/ofloxacin or gentamicin) had significantly improved cover. Chloramphenicol plus gentamicin was superior to ciprofloxacin/ofloxacin (1.9% vs 5.3% resistance respectively; <i>p</i> = 0.007), and cefalotin/cephazolin plus gentamicin (1.9% vs 4.8%; <i>p</i> = 0.005). Chloramphenicol plus ciprofloxacin was superior to ciprofloxacin/ofloxacin monotherapy (1.3% vs 5.3%; <i>p</i> ≤ 0.001), and to cefalotin/cephazolin plus gentamicin (1.3% vs 4.8%; <i>p</i> = 0.003). Chloramphenicol plus gentamicin versus chloramphenicol plus ciprofloxacin/ofloxacin were equivalent (<i>p</i> = 0.48). There was no demonstrated in vitro superiority of either the current empiric antibiotic regimens. For our setting, for bacterial keratitis, chloramphenicol in combination offered superior in vitro cover. Broadened surveillance for ocular AMR is urgently needed across jurisdictions.

Cyclodextrins Allow the Combination of Incompatible Vancomycin and Ceftazidime into an Ophthalmic Formulation for the Treatment of Bacterial Keratitis

“…In addition, a synergistic effect of the two antibiotics as a mixture was possibly observed against the strains of S. aureus with larger diameters on average than those of the ATBs separately. This is faithful to what can be found in the literature [ 5 , 6 ] since the dual CZ/VA therapy makes it possible to target both the strains responsible for KB: Staphylococcus aureus (effect of CZ and VA) and Pseudomonas aeruginosa (effect of CZ).…”

“…To verify that the formulation adopted did not show any loss of activity, bacteriological tests on the strains most found in the context of KB ( Staphylococcus aureus and Pseudomonas aeruginosa [ 1 , 2 , 5 , 6 ]) were carried out. The antibacterial activity was also tested against Escherichia coli which has also been reported in bacterial keratitis and other ocular infections [ 58 , 59 ].…”

“…and Moraxella spp. [ 1 , 2 , 5 , 6 ]. Unfortunately, identifying the causal pathogen to be able treat it with the appropriate antibiotic takes laboratory time that the patient often does not have, which is why an empiric treatment of antibiotic eye drops covering the spectra of the most common bacteria is recommended [ 7 , 8 , 9 ].…”

Infectious keratitis: A review

“…44 On the other hand, in Australia, the Bacterial Ocular Surveillance System reported lower rates of resistance to ciprofloxacin with 16% among all isolates of S. aureus and 6% of CoNS. 8,9,14,42…”

Outcomes of Microbial Keratitis Cases Resistant to Antimicrobials in Sydney, Australia

“…In Australia, a Keratitis Antimicrobial Surveillance Program was initiated in 2016 7 which continued as the Bacterial Ocular Surveillance System in 2017 to 2018. 8 Similarly, this program monitors AMR in CoNS, S. aureus , Corynebacterium spp., P. aeruginosa , and S. pneumoniae .…”