press information / news

Infection Research
18.02.2019

Antibiotic resistances spread faster than so far thought

By studying fish raised in aquaculture, researchers from the Helmholtz Zentrum München, the University of Copenhagen and the University of Campinas in Brazil have shed new light on the mechanisms by which antibiotic resistance genes are transferred between bacteria. According to the study published in the journal ‘Microbiome’, those mechanisms are more varied than previously thought.

Piaractus mesopotamicus, a South American species known as pacu, is often raised in aquaculture. © Helmholtz Zentrum München

“In the past 70 years, the use of antibiotics in human and veterinary medicine has steadily increased, leading to a dramatic rise in resistant microorganisms,” says Prof. Dr. Michael Schloter, head of the Research Unit for Comparative Microbiome Analyses (COMI) at Helmholtz Zentrum München. It is especially alarming that many micro­organisms are resistant not just to one antibiotic, but to a whole range of different substances, states the corresponding author of the recent study. This poses particular problems in the treatment of infectious diseases. “We therefore set out to discover the mechanisms responsible for resistance development,” he says.

To this end, he and his team, together with Danish scientists led by Gisle Vestergaard (University of Copenhagen and Helmholtz Zentrum München), investigated fish raised in aquaculture. Specifically, they studied Piaractus mesopotamicus, a South American species known as pacu that is often raised in aquaculture. The fish received the antibiotic florfenicol in their food for 34 days. During this time and after the application period, the researchers took samples from the digestive tract of the fish and looked for relevant genetic changes in the gut bacteria.

Resistance genes hop around the genome

“As expected, administration of the antibiotic induced an increase in the genes responsible for resistance to that antibiotic,” explains COMI doctoral student Johan Sebastian Sáenz Medina, lead author of the paper. “One example are genes for pump proteins, which simply remove the active substance from the bacteria again. However, we were particularly surprised by the different mechanisms that we could detect by which antibiotic resistance genes are spread amongst gut bacteria of the fish” Sáenz Medina explains. “This suggests that the bacteria also exchange resistance through viruses, known as phages, and transposons.”

Further metagenomic studies confirmed that these mobile genetic elements induce a fast distribution of resistance genes among genomes of different organisms. So far it has been postulated that only plasmids (in essence, easily transferable mini-chromosomes) are mainly responsible for the exchange of resistance genes.

“The finding that resistance is also extensively transferred between bacteria without the involvement of plasmids is really quite surprising,” says Michael Schloter. “Based on this observation, relevant dissemination models should be reviewed and modified. In addition, our data certainly lead us to question whether and to what extent we should continue to use antibiotics in the world’s increasing number of aquacultures.”


Further Information

Background:
At the same time, the antibiotic also changed the composition of the bacteria in the digestive tract of the fish. Putatively pathogenic genera such as Salmonella, Plesiomonas and Citrobacter proliferated. However, once the experiment ended, the microbiome returned to its original composition.

Michael Schloter has been dedicating his research to antibiotic resistance for some time. Recently, he was involved in a study in 'Environment International' that showed how pollution from antibiotic production induces spatial and seasonal bacterial community shifts in receiving river sediments.

Original Publication:
Sáenz, J.S. et al. (2019): Oral administration of antibiotics increased the potential mobility of bacterial resistance genes in the gut of the fish Piaractus mesopotamicus. Microbiome, DOI: 10.1186/s40168-019-0632-7

As German Research Center for Environmental Health, Helmholtz Zentrum München pursues the goal of developing personalized medical approaches for the prevention and therapy of major common diseases such as diabetes mellitus, allergies and lung diseases. To achieve this, it investigates the interaction of genetics, environmental factors and lifestyle. The Helmholtz Zentrum München has about 2,300 staff members and is headquartered in Neuherberg in the north of Munich. Helmholtz Zentrum München is a member of the Helmholtz Association, a community of 19 scientific-technical and medical-biological research centers with a total of about 37,000 staff members. 

Die Abteilung für Vergleichende Mikrobiomanalysen (COMI) untersucht elementare Prinzipien der Entwicklung von Mikrobiomen und deren Funktionen in unterschiedlichen Wirten. Ein besonderer Fokus liegt hierbei auf der Erforschung von Netzwerkstrukturen und deren Rolle für Resilienz gegenüber Stressoren und sich verändernden Bedingungen. Ziel ist es generelle Mechanismen der Strukturbildung von Mikrobiomen zu identifizieren, die unabhängig vom jeweiligen Wirt beziehungsweise Umwelt ablaufen. Basierend auf den Ergebnissen sollen Möglichleiten der Stabilisierung von Mikrobiomen erarbeitet werden, die dann unmittelbaren Einfluss auf die Gesundheit der jeweiligen Wirte haben. Mit diesem Forschungsansatz steht die Abteilung an der Schnittstelle zwischen die Forschungsfelder „Umwelt“ und „menschliche Gesundheit“ am Helmholtz Zentrum München.

We use cookies to improve your experience on our Website. We need cookies to continuously improve the services, to enable certain features and when embedding services or content of third parties, such as video player. By using our website, you agree to the use of cookies. We use different types of cookies. You can personalize your cookie settings here:

Show detail settings
Please find more information in our privacy statement.

There you may also change your settings later.