Abstract
Purpose :
In patients undergoing intraocular surgery, fluoroquinolones are commonly used as an endophthalmitis prophylaxis in the pre-operative, perioperative, and/or post-operative setting. However, emerging fluoroquinolone resistance has been reported in several clinical settings, including eye surgery. The purpose of this study is to determine fluoroquinolone resistance patterns of bacterial isolates from vitreous biopsy specimens obtained from 2000-2015 at a Midwestern tertiary care hospital.
Methods :
A retrospective review of all culture-positive vitreous biopsy specimens obtained from 2000-2014 at the University of Nebraska Medical Center was conducted. Data collected included biopsy date, species, antibacterial resistance, and minimum inhibitory concentration (MIC). The specimens were divided into 5-year groups. Resistance to ciprofloxacin, moxifloxacin, levofloxacin, and gatifloxacin were compared between the three groups. Fisher Exact test was used to determine the significant difference of resistance rates between the time intervals. Changes in MIC were determined using linear regression over the 15-year study period.
Results :
There were 92 culture-positive cases of endophthalmitis from 2000-2014. Coagulase negative staphylococcus represented the most commonly isolated organism (n=49), followed by viridans group streptococcus (n=13), enterococcus faecalis (n=7), staphylococcus aureus (n=9), and other gram-negative organisms (n=9). There was a statistically significant decline in sensitivity to levofloxacin (79% in 2000-2005 down to 46% in 2010-2014, p=.005) and ciprofloxacin (63.6% in 2000-2005 down to 25% in 2010-2014, p=.006) for all bacterial species. There were trends toward declining susceptibility to moxifloxacin and gatifloxicin over the same period (figure 1). For staphylococcal species, the MIC of levofloxacin increased over the 15-year period (r=0.39, p=0.028). Staphylococcal species also showed a trend toward increased MIC for ciprofloxacin over the same period.
Conclusions :
This study demonstrates increasing resistance to second (ciprofloxacin) and third (levofloxacin) generation fluoroquinolones over a 15 year period in vitreous samples from patients with endophthalmitis. Consideration should be given to alternative antibiotic prophylaxis for intraocular surgery. Further studies into the mechanism to fluoroquinolone resistance in endophthalmitis are needed.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.