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J.D. Sheppard, D.F. Sahm; National Survey of Pathogen Susceptibility After 8 Years of Exposure to Levofloxacin . Invest. Ophthalmol. Vis. Sci. 2005;46(13):4876.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Since bacterial resistance may threaten antibiotic effectiveness and public health, continuous surveillance studies are necessary to monitor shifts in pathogen susceptibility. In contrast to studies of a relatively small number of isolates from one laboratory, robust surveillance requires monitoring large numbers of isolates from many institutions over a broad geographic distribution. TRUST (Tracking Resistance in the United States Today) has monitored antimicrobial resistance among common respiratory pathogens (Streptococcus pneumoniae and Haemophilus influenzae) continuously since 1996, and is the largest longitudinal surveillance program in the US encompassing all 50 states. We report findings from TRUST data for LVX and other FQs. Methods: TRUST annually surveys antimicrobial resistance during respiratory seasons (Nov–Apr), representing the period of highest exposure with the potential for resistance development. Since 1996, more than 66,000 respiratory isolates from >200 laboratories in 9 U.S. Census Bureau regions have been analyzed. Susceptibility testing was performed in a centralized laboratory, using broth microdilution NCCLS reference method. Data are presented for S. pneumoniae and H. influenzae. Results: From November 2003 to April 2004, 4,309 strains of S. pneumoniae and 1,207 strains of H. influenzae were analyzed. A total of 98.7% of S. pneumoniae isolates were susceptible to LVX; 98.8% to gatifloxacin, and 98.9% to moxifloxacin. From 1997 to 2004, 99% of S. pneumoniae isolates were susceptible to LVX, with no increase in the MIC90 of 1 µg/mL. From 2001–2004, S. pneumoniae isolates resistant to 2–4 antibiotic classes were 97–98% susceptible to LVX. During the 2003–04 respiratory period, H. influenzae isolates showed a rare incidence of LVX resistance (<0.3%) and susceptibility for LVX has remained >99.7% since 1996. Conclusions: As demonstrated by a large longitudinal surveillance study of S. pneumoniae and H. influenzae, LVX is associated with a very low occurrence of resistance, despite >8 yrs of use.
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