Ocular surface flora and prophylactic antibiotics for cataract surgery in the age of antimicrobial resistance.

According to the World Health Organization alert about the antimicrobial resistance crisis released in 2015, clinicians should strongly reconsider the prolonged use of antimicrobials. In this review, we focus on the ocular surface flora with respect to the trend of fluoroquinolone resistance, and its upset and restoration after topical administration of antimicrobials and preservatives. Even 3 weeks of topical administration of levofloxacin (LVFX) yields a selection of fluoroquinolone-resistant isolates bearing genetic changes in the ocular surface flora. One month of topical prophylactic administration of LVFX after cataract surgery induces the loss of diversity with LVFX-resistance of the ocular surface flora. Restoration of LVFX-sensitive flora occurs 6 to 9 months after the final topical administration of LVFX. The ocular surface flora recovers earlier in patients given LVFX for 1 week after the surgical procedure. These findings suggest that shorter periods of postoperative topical antibiotics are less frequently associated with persistent antimicrobial-resistant bacteria in the ocular flora. In addition, microbiologic analysis of ocular surfaces treated with a long period of eye drops containing benzalkonium chloride (BAC) showed a higher incidence of isolates resistant to methicillin and fluoroquinolones than did ocular surfaces treated with eye drops not containing BAC. To avoid the emergence of antimicrobial-resistant bacteria on the ocular surface, an urgent discussion must be held about the appropriate use of antibiotics and preservatives in the ophthalmology field.