Comparative in vitro activity of fluoroquinolones against ocular coagulase‐negative Staphylococcus species: a four‐year study

Abstract

Abstract Purpose The aim of our study was to examine the frequency of gram‐positive isolates from samples taken from patients with keratitis and endophalmitis and the in vitro susceptibility profiles of second‐ (ciprofloxacin), third‐ (levofloxacin) and fourth‐generation fluoroquinolones (moxifloxacin) against the most common of them (coagulase‐negative Staphylococcus species‐CoNs) from 2005 to 2009. Methods A retrospective audit of the medical records of patients treated for keratitis and endophalmitis in the Department of Ophthalmology, Veroia General Hospital during 2005‐2009 was carried out. Adequate specimens (cornea scrapings, and intraocular fluids) were collected prior to any antibacterial therapy. The minimum inhibitory concentrations for individual isolates were determined by Vitek 2 (Biomerieux, France). Results Out of 73 ocular isolates for all years of study, 49 (67,12%) were gram‐positive (Staphylococcus spp., Streptococcus spp., Bacillus spp.). CoNs were the most common gram‐positive isolates (n=31, 63,26%). From 2005 to 2008, 100% of CoNs isolates were susceptible to all fluoroquinolones tested. In 2009, both second‐ (ciprofloxacin) and third‐generation fluoroquinolones (levofloxacin) provided coverage for 60% of them. All CoNs ocular pathogens were susceptible to fourth‐generation fluoroquinolones (moxifloxacin) during the study period. Conclusion CoNs were the most prevalent gram‐positive pathogens identified in keratitis and endophthalmitis cases from 2005 to 2009. No significant change in the frequency of their isolation among the years was observed. The in‐vitro potency of second and third generation fluoroquinolones against CoNs was decreased during the last year of study.