Antibiotic-resistant bacteria in seawater

Dangerous germs: Antibiotic-resistant bacteria in seawater

22.03.2012

The discussion about antibiotic-resistant bacteria does not stop. Increasingly, the dangerous germs are being discovered outside hospitals and even on foods such as factory-made chicken. Swiss researchers have now traced the pathogens in Lake Geneva. As the original source, they identified the wastewater of a university hospital. There may be a number of lakes affected by water from clarified sewage from hospitals.

How do the multidrug-resistant germs get into the hospitals??
The multidrug-resistant bacteria (MRSA = methicillin-resistant Staphylococcus aureus) are generally called bacteria of the strain Staphylococcus aureus, which have developed resistance to almost all antibiotics. These include penicillin.

If an antibiotic is taken, the bacteria are usually killed by it. However, mutations of some pathogens can make them resistant to the antibiotic. The resistant germs can multiply and the resistance-mediating genes also other types of bacteria „infect“. The resistances are favored by the use of certain cleaning agents, whose ingredients include so-called quaternary ammonium compounds with a disinfecting effect. Because the same genes of the bacteria, which are resistant to the quaternary ammonium compounds, also transmit the antibiotic resistance to the bacteria.

Anyone can transmit multidrug-resistant bacteria, even if antibiotics have been used for a long time. For healthy people, the pathogens usually pose no danger. However, if the germs reach a seriously ill body with a severely weakened immune system, they can cause serious damage that can even lead to the death of the patient. Typical consequences of MRSA infection include, for example, severe inflammation of surgical wounds, septicemia and pneumonia.

Seawater contaminated with antibiotic-resistant germs from hospital wastewater
That urban wastewater contains a variety of bacteria is known. The sewage from hospitals is particularly heavily polluted. Due to a steady increase in MRSA in the clinics, the wastewater is also under pressure. Normally, the bacteria are rendered harmless in the sewage treatment plant. Especially the most dangerous pathogens would survive the treatment undamaged and in some cases even benefit from it, writes the Swiss Federal Institute for Water, Wastewater Treatment and Water Protection (Eawag) in Switzerland.

Nadine Czekalski, who carried out the essential research in the context of her dissertation, wanted to work with her colleagues to find out how the multidrug-resistant germs pass through the sewage treatment plant into Lake Geneva. The purified waste water comes from Lausanne. About 700 meters from the shore, it is directed in the Bay of Vidy in Lake Geneva. Since there are no pharmaceutical industry or large-scale farms in the area, these sources for the pathogens eliminated. The researchers quickly came across the University Hospital of Vaud, a large hospital attached to the Lausanne wastewater treatment plant.

Bacteria pass on resistance to each other
According to Eawag, analyzes of municipal sewage, seawater and sediment revealed „unexpected pattern“. Particularly alarming was the high number of multidrug-resistant germs in the wastewater of the hospital. In total, 75 percent of the bacteria were eliminated by the treatment plant. However, the proportion of antibiotic-resistant pathogens in the treated wastewater had been increased. According to microbiologist Helmut Bürgmann, the treatment plant could be a breeding ground for the replacement of multi-resistant gene sequences among the bacteria.

The exchange of gene sequences takes place here between germs that are normally found in the human body and bacteria that have already adapted to the environment. „The fact that bacteria incorporate resistance is nothing special or dangerous“, Bürgmann explains to Eawag. However, the frequency of multi-resistances in the vicinity of sewers, especially in Lake Geneva sediment, has only recently been revealed. This also increases the risk that multi-drug resistant genes from hospital germs would be incorporated.

According to Czekalski, the results are nonetheless „no reason to panic“. Three kilometers away from the entrance to the treatment plant there is a drinking water intake. The researchers were able to detect the multidrug-resistant bacteria in the sediment, but not in the seawater. Before it is fed into the network, it is also processed. Since 15 percent of Swiss wastewater is discharged into lakes after cleaning, scientists nevertheless call for caution. In addition, they recommend a separate treatment of wastewater from hospitals in the study as these are the source of multi-drug resistant germs.

In Germany pilot project started
In Germany, a pilot project of the AOK and the Red Cross Hospital in Bremen is currently being implemented to prevent the spread of multidrug-resistant bacteria and to reduce the risk of infection during hospitalization.

Patients are already being examined for corresponding germs in the course of a planned operation. If a multidrug-resistant pathogen is detected, patients will receive treatment in addition to the treatment to prevent the transmission of the germs to other patients and to reduce the risk of infection. (Ag)

Read on:
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Resistant bacteria in German hospitals
Risk of infection in the hospital
Hospital germs: Staphylococci prefer blood
WHO warns of antibiotic resistance

Picture: Dr. Herrmann, Pixelio.de