Antibiotic resistances spread faster than so far thought

February 18, 2019, Helmholtz Association of German Research Centres
Piaractus mesopotamicus, a South American species known as pacu, is often raised in aquaculture. Credit: Helmholtz Zentrum München

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.

"In the past 70 years, the use of in human and 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 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 .

Resistance genes hop around the genome

"As expected, administration of the antibiotic induced an increase in the 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 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 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."

Explore further: Supermarket produce harbors antibiotic-resistance genes

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

Related Stories

Supermarket produce harbors antibiotic-resistance genes

November 6, 2018

Researchers from the Julius Kühn Institut, Germany have found that produce is a reservoir for transferable antibiotic resistance genes that often escape traditional molecular detection methods. These antibiotic resistance ...

New strategy may curtail spread of antibiotic resistance

January 10, 2019

Spotless surfaces in hospitals can hide bacteria that rarely cause problems for healthy people but pose a serious threat to people with weakened immune systems. Acinetobacter baumannii causes life-threatening lung and bloodstream ...

Fish food for marine farms harbor antibiotic resistance genes

August 30, 2017

From isolated caves to ancient permafrost, antibiotic-resistant bacteria and genes for resistance have been showing up in unexpected places. As scientists puzzle over how genes for antibiotic resistance arise in various environments ...

Recommended for you

A decade on, smartphone-like software finally heads to space

March 20, 2019

Once a traditional satellite is launched into space, its physical hardware and computer software stay mostly immutable for the rest of its existence as it orbits the Earth, even as the technology it serves on the ground continues ...

Tiny 'water bears' can teach us about survival

March 20, 2019

Earth's ultimate survivors can weather extreme heat, cold, radiation and even the vacuum of space. Now the U.S. military hopes these tiny critters called tardigrades can teach us about true toughness.

Researchers find hidden proteins in bacteria

March 20, 2019

Scientists at the University of Illinois at Chicago have developed a way to identify the beginning of every gene—known as a translation start site or a start codon—in bacterial cell DNA with a single experiment and, through ...

Turn off a light, save a life, says new study

March 20, 2019

We all know that turning off lights and buying energy-efficient appliances affects our financial bottom line. Now, according to a new study by University of Wisconsin-Madison researchers, we know that saving energy also saves ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.