The antibiotic susceptibility of water-based bacteria Ralstonia pickettii and Ralstonia insidiosa

Ralstonia pickettii and Ralstonia insidiosa are waterborne bacteria that can survive and grow in various water sources that are emerging pathogens in hospital settings. Not much is known about the antibiotic resistance of these bacteria. Previous reports of antimicrobial susceptibility have been largely limited to a few clinical stains with no accounting for genotypic or phenotypic diversity or that these species could vary from the set breakpoints. E-tests and disc diffusion tests were carried out to compare the antimicrobial susceptibilities to twelve different antibiotics of sixty-eight different isolates of R. pickettii (fifty-three) and R. insidiosa (fifteen) from varying environments, which have previously been well characterised both phenotypically and genetically. The majority of the R. pickettii and R. insidiosa isolates showed susceptibility to most of the antibiotics tested in this study. The most effective were found to be the quinolones and sulphamethoxazole/trimethoprim. Antibiotic susceptibility was also found not vary between environmental niches for R. pickettii and R. insidiosa isolates.