University of Bristol | July 2018 | Stop antibiotics before resistance ‘tipping point’
New research involving scientists at the University of Bristol shows that rather than completing a course of antibiotics, patients should stop taking antibiotics as soon as possible.
The scientists examined how microbial communities – groups of microorganisms that share a common living space in the body – reacted to different antibiotic cycling patterns, which involves the medication being restricted or increased.
The team used sugars alongside the drugs to reflect variable sugars in human patients, which led to the discovery that changes both in the duration and dose of antibiotics used and in sugar level had an impact on resistance. They found that while the introduction of an antimicrobial reduced the microbial communities they started to thrive once the antimicrobial was withdrawn, this is because, unwittingly, a critical point was passed during treatment.
The team’s findings suggest that resistant species can increase within the body even after an antibiotic is withdrawn, this could lead to the microbials becoming resistant to the treatment (Source: University of Bristol).
The findings have just been published in the journal Nature Ecology & Evolution
Microbes rarely exist in isolation, rather, they form intricate multi-species communities that colonize our bodies and inserted medical devices. However, the efficacy of antimicrobials is measured in clinical laboratories exclusively using microbial monocultures. Here, to determine how multi-species interactions mediate selection for resistance during antibiotic treatment, particularly following drug withdrawal, we study a laboratory community consisting of two microbial pathogens. Single-species dose responses are a poor predictor of community dynamics during treatment so, to better understand those dynamics, we introduce the concept of a dose-response mosaic, a multi-dimensional map that indicates how species’ abundance is affected by changes in abiotic conditions. We study the dose-response mosaic of a two-species community with a ‘Gene × Gene × Environment × Environment’ ecological interaction whereby Candida glabrata, which is resistant to the antifungal drug fluconazole, competes for survival with Candida albicans, which is susceptible to fluconazole. The mosaic comprises several zones that delineate abiotic conditions where each species dominates. Zones are separated by loci of bifurcations and tipping points that identify what environmental changes can trigger the loss of either species. Observations of the laboratory communities corroborated theory, showing that changes in both antibiotic concentration and nutrient availability can push populations beyond tipping points, thus creating irreversible shifts in community composition from drug-sensitive to drug-resistant species. This has an important consequence: resistant species can increase in frequency even if an antibiotic is withdrawn because, unwittingly, a tipping point was passed during treatment.
Beardmore, R.E. et al |2018| Drug-mediated metabolic tipping between antibiotic resistant states in a mixed-species community | Nature Ecology & Evolution | ePub | https://doi.org/10.1038/s41559-018-0582-7