Effectiveness of Fluoroquinolones Against Mycobacterium abscessus In Vivo

Abstract

Purpose: To determine the effectiveness of fluoroquinolones against Mycobacterium abscessus in vivo. Methods: M. abscessus growth was determined quantitatively in rabbit corneas after intrastromal bacterial injection (104 CFU/cornea; n ≥ 4 corneas per group). Eyes were treated topically with 0.3% ciprofloxacin, 0.5% levofloxacin, or 0.5% moxifloxacin by three protocols: (1) 1 drop of antibiotic applied hourly for 10 hr on day 3 postinfection (PI); (2) 1 drop applied every 2 hr for 10 hr on days 2 and 3 PI; or (3) 1 drop applied every 2 hr for 10 hr on days 1, 2, and 3 PI. Corneas were cultured 1 hr after the last topical drop. Results are expressed as the log CFU. Results: Bacteria in control group reached maximal numbers in vivo by day 3 PI (∼6 logs CFU/cornea). Treatment of infected eyes on day 3 with moxifloxacin or levofloxacin resulted in ∼2.0 log decrease in CFU/cornea relative to the untreated control. Treatment on days 2 and 3 with moxifloxacin or levofloxacin resulted in ∼3.0 and 2.5 log CFU/cornea decrease, respectively. Ciprofloxacin had no effect on bacterial load. Treatment on days 1, 2, and 3 with moxifloxacin resulted in a 5.5 log CFU decrease, whereas treatment with levofloxacin or ciprofloxacin resulted in a ∼4.0 log CFU decrease. Conclusions: Moxifloxacin, and to a lesser extent levofloxacin and ciprofloxacin, demonstrated significant effectiveness for reducing the number of M. abscessus in vivo, suggesting the potential usage of these agents in prevention of M. abscessus keratitis.