Multidrug-resistant germs: the rat as a possible source

Multidrug-resistant germs are considered a global threat. Many antibiotics are no longer effective for many people. Doctors fear that if multidrug-resistant germs spread, resistance becomes even stronger, the world could be rejected medically for centuries. This development could be accelerated by the rats. As a recent study shows, many rats living in Vienna carry dangerous multidrug-resistant bacteria. Therefore, all seven rats caught in the city center of Vienna between 2016 and 2017 were carriers of multidrug-resistant enterobacteria. Their most important representatives are also known as coliforms. This corresponds to a share of 14.5%. One seventh of all Viennese rats were carriers of multidrug-resistant pathogens.

"Frequency of concern" of multidrug-resistant bacteria

"Although the exact interaction between rats infected with multidrug-resistant bacteria and the risk to human health is unclear, the incidence of multidrug-resistant bacteria is of concern," explain the authors. "One of the rats we studied, for example, was captured in a green area used by homeless people in the summer to sleep, and this particular situation increases the risk of transmission of the resistant bacteria." Basically, the researchers write, various scenarios are possible for a transfer. The fight against rats, but also other rodents such as mice, is and will remain an important public health priority in cities.

Rats – vector of dangerous disease

The spread of the brown rat is particularly relevant according to the scientists. Rats are therefore considered to be the most productive and widespread urban pest species. "They feed on human waste and feed the sewer system, allowing them to interact with human feces and ingest and spread multidrug-resistant bacteria," veterinarians write.

Climate change and rural exodus can aggravate the problem

The finding adds to the high risk of distribution for another explosive reason. More and more people live in cities. Already half of the world's population lives in urban areas and by 2030 this proportion is expected to increase further to 60%. "The density of the human population, the increasing interaction with urban wildlife, and the warmer microclimate of the city are promoting the development of diseases that are transmitted from wildlife to humans," the researchers explain. Cities could be places where pathogens are introduced and spread.

Figures comparable to other major cities

The work is the result of cooperation between the University of Vienna (Vetmeduni Vienna), the Austrian Agency for Food Safety (AGES), the Free University of Berlin and the University of Vienna. Leibniz Institute for Photonic Technologies in Jena. According to the researchers, the incidence in Vienna is also comparable to previous studies. As a result, 13.6% of the rats examined in Berlin had multidrug-resistant pathogens and 13.9% in Hong Kong. In Vienna, more than half of the rats (59.7%) had previously been diagnosed with multidrug-resistant staphylococci.

The study "Urban brown rats (Rattus norvegicus) as a possible source of multidrug-resistant enterobacteria and methicillin-resistant Staphylococcus, Vienna, Austria, 2016 and 2017" was published in the Journal of Infectious Diseases "Eurosurveillance".