Statins as a possible factor affecting fluoroquinolone resistance of coagulase-negative Staphylococcus in the conjunctiva: a case-control study

Abstract

Background: Conjunctival bacterial flora is a common cause of endophthalmitis after ophthalmic procedures. This study investigated the conjunctival bacterial flora, especially coagulase-negative Staphylococcus (CoNS), and their antibiotic sensitivity in patients who underwent ophthalmic procedures. Factors related to fluoroquinolone resistance were also investigated.Methods: In total, 167 samples were analyzed from 135 patients who underwent cataract surgery or intravitreal injection at Kosin University Gospel Hospital between April 14, 2014, and September 29, 2016. Bacterial identification was performed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry or VITEK 2 equipment. Antibiotic sensitivity tests were performed using an AST-P600 card with VITEK 2 equipment. Clinical information was extracted from patients’ medical records. Sixty-eight individuals with conjunctival flora containing CoNS were classified into the fluoroquinolone-sensitive and fluoroquinolone-resistant CoNS groups, and their characteristics were compared. Results: A total of 192 isolates of Gram-positive bacteria were identified, including Staphylococcus epidermidis (33.3%), Corynebacterium spp. (18.8%), and CoNS other than S. epidermidis (9.2%). Of the 106 CoNS isolates, 68.9%, 69.8%, and 58.5% were sensitive to ciprofloxacin, levofloxacin, and norfloxacin, respectively. In patients with CoNS, statin use within 3 months before sample collection was significantly associated with fluoroquinolone resistance (p=0.016). Statin use was a significant risk factor for fluoroquinolone resistance in multivariate logistic regression analysis (odds ratio, 4.86; 95% confidence interval, 1.25–18.91; p=0.022).Conclusions: CoNS, including S. epidermidis, was the most common conjunctival bacterial flora, with a fluoroquinolone sensitivity rate ranging from 58.5% to 69.8% in patients undergoing ophthalmic procedures. Statin use was a significant risk factor for fluoroquinolone resistance.