Challenging the concept of bacteria subsisting on antibiotics

Abstract

a b s t r a c tAntibiotic resistance concerns have been compounded by a report that soil bacteria can catabolise antibiotics, i.e. break down and use them as a sole carbon source. To date this has not been verified or reproduced, therefore in this study soil bacteria were screened to verify and reproduce this hypothesis. Survival in high concentrations of antibiotics was initially observed; however, on further analysis these bacteria either did not degrade the antibiotics or they used an intrinsic resistance mechanism (␤-lactamases) to degrade the ␤-lactams, as demonstrated by high-performance liquid chromatography. These results did not verify or reproduce the hypothesis that bacteria subsist on antibiotics or catabolise antibiotics as previously reported. This study identified that bacteria with a catabolising phenotype did not degrade streptomycin or trimethoprim and therefore could not utilise the antibiotics as a nutrient source. Therefore, we conclude that soil bacteria do not catabolise antibiotics.

Interplay between gut microbiota and antibiotics

“…Previously, Walsh et al (2013) tried to reproduce and verify the hypothesis that soil bacteria are capable to subsist on antibiotics that was brought forwards by Dantas et al (2008). Similar to our results, Walsh and coworkers found that soil bacteria were not able to degrade antibiotics and as a consequence, it is unlikely to be used as a carbon source.…”

“…Alternatively, Walsh et al (2013) proposed that bacteria possibly use a well characterized resistance mechanism that has not been previously linked to antibiotic subsistence.…”

“…elevated antibiotic concentrations or the use of antibiotics as the sole carbon source. In disagreement with the accumulating body of literature supporting the possibility of bacterial subsistence on antibiotics, Walsh et al (2013) tested whether soil bacteria could subsist on antibiotics. As no degradation of antibiotics occurred, Walsh et al (2013) concluded that soil bacteria could not utilise antibiotics (including streptomycin, trimethoprim, penicillin and carbapenicillin) as a carbon source.…”

“…Controversially, Walsh et al (2013) showed that soil bacteria could not utilize antibiotics as a carbon source since no degradation of antibiotics occurred. The fact that multidrug resistance elements participate in other processes such as detoxification of metabolic intermediates, signal trafficking and virulence, could perhaps explain why genes could not only play a role in resistance but also evolved into other functions.…”

Mining into interspecific bacterial interactions

“…Although antimicrobial compounds can inhibit or kill other strains competing for the same ecological niche, in rare cases it has been shown that antibiotics can act also as a source of nutrients promoting the growth of bacteria under nutrient deprived conditions (D'Costa et al, 2006;Dantas et al, 2008). However, contrary to the findings by Dantas a study done by Walsh and co-workers was not able to confirm the previous findings, thus it is still questionable if antibiotics can act as a source of nutrients (Walsh et al, 2013). Hence, there is so far no scientific consensus on the ecological role of antimicrobial compounds in nature (Figure 1.1).…”