Abstract
Abstract: :
Purpose:The fluoroquinolones have been used to treat gram-negative bacteria and methicillin sensitive S. aureus keratitis and conjunctivitis pathogens. We investigate the emergence of fluoroquinolone resistance among methicillin sensitive Staphylococcus aureus keratoconjunctivitis isolates Methods:MIC susceptibility profiles for 1182 culture positive patients with S. aureus keratitis and conjunctivitis were analyzed. Historical and current prevalence of emerging quinolone (ciprofloxacin and levofloxacin) resistance for methicillin resistant (MRSA) and methicillin sensitive isolates (MSSA) were monitored. Isolates were further stratified by source. Results:Ciprofloxacin resistance among keratitis and conjunctivitis S aureus isolates during the first six years after its introduction (1990-1995) was 8% and ranged from 3%-11%. Incidence for the most recent 5.5 years (1996-June 2001) was 19.4 %. This represented a 166% increase in ciprofloxacin resistance among keratitis and conjunctivitis S. aureus isolates. Initial baseline prevalence for MSSA isolates was 2% vs 55.8% for MRSA. The current incidence rate for MSSA is 4% vs 82% for MRSA. This represented a 100% increase in resistance for MSSA and 47% for the MRSA. General resistant rate for levofloxacin (2000-June 2001) was 22.9% vs 32.3% for ciprofloxacin during the same time period (p = 0.12). Levofloxacin resistant rate for MSSA was 4.3% vs 11.1% for ciprofloxacin (p = 0.11). Increased resistant among MSSA from baseline for ciprofloxacin was 400%. In MRSA isolates, a higher resistant rate was found for ciprofloxacin (94%) vs levofloxacin (73%), p = 0.024. When both intermediate and resistant isolates were considered, there was no difference (p =0.58.). A higher rate of quinolone resistance was found in keratitis isolates versus those from the conjunctivitis. Conclusion:Quinolone resistance among methicillin sensitive S. aureus keratitis and conjunctivitis isolates is increasing.
Keywords: 587 Staphylococcus • 358 clinical laboratory testing • 449 keratitis