Find in Library

<b>Background and Objectives:</b> The advent of new fluoroquinolones has drawn the attention for reliable methods on the in-vitro susceptibility testing of <i>Streptococccus pneumoniae</i>. This study attempts to determine the minimum inhibitory concentration (MIC) of second-generation (ciprofloxacin and ofloxacin), third-generation (levofloxacin) and the fourth-generation (moxifloxacin and gatifloxacin) fluoroquinolones against <i>S. pneumoniae</i> recovered from bacterial keratitis. <b>Materials and Methods:</b> In retrospect, the MICs of 50 strains of <i>S. pneumoniae</i> isolated from the corneal scrapes of patients with bacterial keratitis were determined against ciprofloxacin, ofloxacin, levofloxacin, gatifloxacin and moxifloxacin using E-tests. The National Committee of Clinical Laboratory Standards (NCCLS) susceptibility patterns and the potencies of the MICs were statistically compared. <b>Results:</b> The median MIC of ciprofloxacin (0.25&#956;g/ml) was found to be lower than the median MICs of ofloxacin (0.5&#956;g/ml) (<i>P</i> &lt; 0.449) and levofloxacin (1.0&#956;g/ml) (<i>P</i> &lt; 0.001). The median MICs of gatifloxacin (0.1&#956;g/ml) was lower than the median MICs of ciprofloxacin (0.25&#956;g/ml) (<i>P</i> &lt; 0.001), ofloxacin (0.5&#956;g/ml) (<i>P</i> &lt; 0.001) and levofloxacin (1.0&#956;g/ml) (<i>P</i> &lt; 0.001). Moxifloxacin (0.06&#956;g/ml) had showed lower median MICs than gatifloxacin (0.1&#956;g/ml) (<i>P</i> &lt; 0.001) levofloxacin (1.0&#956;g/ml) (<i>P</i> &lt; 0.001), ofloxacin (0.5&#956;g/ml) (<i>P</i> &lt; 0.001) and ciprofloxacin (0.25&#956;g/ml) (<i>P</i> &lt; 0.001). Moxifloxacin (0.06&#956;g/ml) had a lower MIC50 (&#956;g/ml) than gatifloxacin (0.1&#956;g/ml), levofloxacin (1.0&#956;g/ml), ciprofloxacin (0.25&#956;g/ml) and ofloxacin (0.5&#956;g/ml). MIC90 (&#956;g/ml) of moxifloxacin (0.06&#956;g/ml) was found to be lower than the MIC90 (&#956;g/ml) of gatifloxacin (0.5&#956;g/ml), levofloxacin (1.0&#956;g/ml), ofloxacin (0.5&#956;g/ml) and ciprofloxacin (0.5&#956;g/ml). <b>Conclusion:</b> Based on in-vitro testing, the five portrayed fluoroquinolones 100&#x0025; sensitivity to <i>S. pneumoniae</i>. However, the fourth-generation fluoroquinolone, moxifloxacin appeared to be more effective against <i>S. pneumoniae</i> than gatifloxacin, levofloxacin, ofloxacin and ciprofloxacin.