Low levels of fluoroquinolone resistance in Escherichia coli. A five-year trend in Australia measured through the use of TSN Database Australia.

In many countries, fluoroquinolones are among the most commonly used antibacterial drugs. Concerns about bacterial resistance to these and other frequently used drugs have been raised by the medical and scientific communities. While fluoroquinolone resistance has not yet developed among many bacteria, emergence of resistance in Escherichia coli would be a problem as multiple resistances to other antibiotics is now a common problem. This paper examines trends in resistance to fluoroquinolones in Escherichia coli through analysis of data collected from Australian institutions between 1997 and 2001. During the study period, norfloxacin and ciprofloxacin were the most frequently tested fluoroquinolones in Australian laboratories. An examination of results for strains tested simultaneously against both drugs indicated that testing against either drug accurately predicted resistance or susceptibility for the other (99.7% agreement). Over 400,000 tests were performed to determine the fluoroquinolone susceptibility of E. coil. Data were analysed by the test method used (Calibrated Dichotomous Sensitivity (CDS) or National Committee for Clinical Laboratory Standards (NCCLS)). The data indicate that fluoroquinolone resistance in E. coli has not yet emerged as a significant problem in Australia, but there are some indications of low level increases in resistance rates. Norfloxacin results are likely to be a better guide to fluoroquinolone resistance in this species using this method of surveillance.