Discovered soil microbes with antibiotic resistance

Discovered soil microbes with antibiotic-resistant hospital germs

08/31/2012

Antibiotic resistance is usually associated with hospital germs. They represent a high health risk for patients with bacterial infections. Because when antibiotics are no longer effective, bacteria can spread in the body and in the worst case cause the death of the patient. Now, an international research team has discovered antibiotic resistance in soil microbes. Presumably, the resistance-conferring genes enter the soil via liquid manure, manure and wastewater and spread further from there.

Antibiotic resistance-mediating genes enter the soil via sewage, manure and manure
For medical care or in livestock - antibiotics are used too often and too carelessly. Experts have long agreed on this. The result of the mass supply are antibiotic-resistant germs, bacteria in which penicillin and Co. are no longer effective. Especially in hospitals so-called multi-resistant germs are a big problem.

Anyone can transmit (multi-) resistant bacteria, even if the antibiotic treatment has been around for some time. In healthy people, the pathogens usually have no serious health consequences. However, if the germs enter the body of a seriously ill person with a weak immune system, such as patients in an intensive care unit, they can cause serious damage and even death. Typical complications of multidrug-resistant infection include severe inflammation of surgical wounds, toxemia and pneumonia. Special hygiene regulations and dressings are designed to help prevent the spread of such germs in hospitals. Nevertheless, they enter the environment through residues in wastewater, for example, and pass on their resistance via certain genes to other bacteria.

Now antibiotic-resistant soil microbes have been discovered. Like an international research group in the current issue of the trade magazine „Science“ reports, "it was the first evidence of a transfer of resistance-mediating genes between pathogenic germs and harmless soil microbes".

Pathogens have transferred genes into direct contact with soil microbes
Kevin Forsberg of the Washington University School of Medicine and his colleagues found that harmless soil bacteria could contribute to the spread of antibiotic resistance. When analyzing soil samples from crops, scientists discovered microbes that were resistant to five common classes of antibiotics. As the researchers report, the resistance-mediating genes of the harmless bacteria are those of germs that can trigger serious infections and are difficult to combat. This suggests that the pathogens have transmitted their genes in direct contact with the soil microbes. The microbes could in turn pass on their resistance to other germs, which could then also develop antibiotic resistance, the scientists write.

Presumably, the resistant germs on manure and manure of livestock, which were treated with antibiotics, arrived at the fields. In addition, "residues in the wastewater could be responsible for the spread in the environment," the researchers speculate. It has been suspected for some time that harmless germs are also involved in the transmission and spread of antibiotic resistance. „Now we know that this could be the case, at least on the ground“, write Forsberg and his colleagues.

Also discovered multi-resistant soil microbes
The scientists analyzed soil samples from eleven different sites in the US. A total of 95 bacterial cultures were isolated and tested for susceptibility to 18 different antibiotics. The resistance genes of the microbes were also examined.

Researchers identified seven antibiotic-resistant genes in soil bacteria that were identical to those of resistant strains of hospital germs. This indicates that the transmission of resistance has taken place recently, the scientists report. The resistance genes protect the bacteria against five common antibiotic classes, which included beta-lactams, aminoglycosides, amphenicols, sulfonamides and tetracyclines. „These genes thus encompass all major types and strategies of antibiotic resistance“, explain the researchers. In two of the bacterial species from farmland, six genes were discovered at once. Thus, these are considered multi-resistant. For other bacteria, only one or a few genes appeared. „This is the first evidence of such a gene transfer between pathogenic germs and harmless soil microbes“, write the scientists. The soil is therefore a crucial reservoir for antibiotic resistance, which can be transmitted both from disease-causing germs to the soil microbes and vice versa. However, the exact processes of the exchange are not yet known and should now be investigated. (Ag)

Read about:
Hospital germs: Staphylococci prefer blood
Every year 30,000 deaths from hospital infections
Multi-resistant germs at the meat counter
Multi-resistant germs in the pigsty
Resistant germs due to antibiotic animal husbandry
Multi-resistant germs on frozen chicken
Resistant bacteria in German hospitals
Risk of infection in the hospital
WHO warns of antibiotic resistance

Picture: Gerd Altmann