Comeback of the antibiotic trimethoprim

Antibiotic trimethoprim could be used successfully against streptococci in certain regions

03/20/2014

The antibiotic trimethoprim could be used increasingly again in the future. So far, experts have assumed that streptococci are resistant to the drug. However, scientists from the Helmholtz Center for Infection Research (HZI) in Braunschweig came to the conclusion with the National Reference Center for Streptococci in Aachen that this is a mistake. Especially in less developed countries, the antibiotic could be used because of its effectiveness against the bacteria.

Low resistance of streptococci to antibiotic trimethoprim
The bacterium Streptococcus pyogenes causes inflammation of the skin as well as scarlet fever. The sequelae of the infections include rheumatic fever and kidney inflammation. In Germany, doctors usually prescribe penicillin for streptococci. The antibiotic trimethoprim is not ordinarily prescribed as it has been thought by those skilled in the art that the bacteria have a resistance to the agent from the outset. In a study in which samples of infected patients from Germany and India were evaluated for their resistance to trimethoprim, Dr. Ing. Patric Nitsche-Schmitz from the HZI and his team that the level of resistance is much lower than expected. „This shows that trimethoprim is effective in many infections with Streptococcus pyogenes“, explains Nitsche-Schmitz. The wrong assumption was based on previous studies in which one „Nutrient medium was used, which mitigates the antimicrobial effect of trimethoprim“, it says in a statement of the HZI.

Antibiotic trimethoprim could be used especially in less developed countries
The Braunschweig scientists were also interested in the cases in which the antibiotic did not work. They discovered various causes of resistance. „In the gene for dihydrofolate reductase, spontaneous mutations can take place, so that trimethoprim can no longer attack the enzyme thereby altered and becomes ineffective“, reports Nitsche-Schmitz. In many of the samples, the researchers detected a mutation of this gene. In addition, bacteria are able to pass copies of altered variants of the dihydrofolate reductase gene among themselves. In this way, resistance spreads very quickly. The Braunschweiger identified two of these genes as another reason for the resistance. „We found three causes for the rapid spread of resistance“, reports Nitsche-Schmitz.

The funds could be used especially in less developed countries, as expensive penicillin is hardly available there. In addition, it does not work against the bacterium Staphylococcus aureus, which often causes co-infection. Trimethoprim, on the other hand, fights both types of bacteria. „As with all antibiotics, it is important that trimethoprim is not prescribed unnecessarily and that patients take it as prescribed“, emphasizes Nitsche-Schmitz. „It's like a sword that quickly loses its sharpness.“ Their study results published the scientists in the trade magazine „Antimicrobial Agent and Chemotherapy“. (Ag)

Image: Sebastian Karkus