It takes much higher doses of antibiotics to eliminate a bacterial multi-infection.
- Antibiotic resistance is a phenomenon in which a bacterium becomes resistant to antibiotics.
- The main reason for this phenomenon is the excessive use of antibiotics, which cancels their action to fight against these bacteria.
“People with chronic infections often have multiple infections with multiple pathogens, but the problem is that we don’t take that into account when deciding how much antibiotic to treat them with, explains Thomas O’Brien, one of the authors of a study published in the journal The ISME Journal. Our findings could help explain why, in these people, antibiotics just don’t work as well as they should.”
Better take into account the different species of microbes to treat a disease
During their work, the scientists discovered that it took much higher doses of antibiotics to eliminate a bacterial multi-infection of the respiratory tract. Thus, this finding helps explain why respiratory infections often persist in people with lung disease despite treatment who often have a mixture of different bacteria and/or microbes in their airways. Finally, according to the authors, when prescribing drugs, doctors should take greater account of the interaction between the different species of microbes in order to better adjust the dosage.
The antibiotic created to fight against a microbe does not work for a multi infection
To reach these conclusions, the scientists modeled human airways that they made sick. Thus, they were able to cultivate three types of microbes for several weeks and thus see their reaction to the treatments and how they evolved. These were mainly bacteria Pseudomonas aeruginosa and Staphylococcus aureus as well as mushroom Candida albicans. They started by treating this multi-infection using an antibiotic usually delivered to kill the bacteria Pseudomonas aeruginosa. Result: with the other two microbes in addition, this treatment did not work. This balance was also reproduced when the scientists used antibiotics which respectively targeted the Staphylococcus aureus and the Candida albicans : they did not treat the multi-infection.
Increase doses to kill bacteria
“The three species-specific antibiotics were less effective against their target when three pathogens were present together“, develops Martin Welch, one of the authors. Thus, the scientists estimate that it takes much higher doses to kill the bacteria when they are part of a multimicrobial infection, compared to a situation where there is no there is only one pathogen.
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