Probiotics and antibiotics, a killer combination

In the fight against drug-resistant bacteria, MIT researchers have enlisted the help of beneficial bacteria known as probiotics.

Probiotics and antibiotics

In a new study, the researchers showed that by delivering a combination of probiotics and antibiotics, they could eradicate two strains of drug-resistant bacteria that often infect wounds. To achieve this, they encapsulated the probiotic bacteria in a protective shell of alginate, a biocompatible material that prevents the probiotics from being killed by the antibiotic.

A lot of bacteria are resistant to antibiotics, which is a serious problem for human health. One way to treat them is by encapsulating a live probiotic and to let it do its job,

If shown to be successful in future tests in animals and humans, the probiotic/antibiotic combination could be incorporated into dressings for wounds, where it could help heal infected chronic wounds.

The human body contains trillions of bacterial cells and a lot of them are beneficial. Sometimes these bacteria help fend off infection by secreting antimicrobial peptides and other compounds..

Scientists have previously tested the idea of applying probiotics to chronic wounds, and they’ve had some success in studies of patients with burns, however, the probiotic strains usually can’t combat all the bacteria in an infected wound. Combining these strains with traditional antibiotics would help to kill more of the pathogenic bacteria, but the antibiotic would likely also kill off the probiotic bacteria.

Researchers at MIT encapsulated the probiotic bacteria so that they would not be affected by the antibiotic. They chose alignate as it is a component of the biofilms that clusters of bacteria form to protect themselves from antibiotics.

For this study, the researchers chose to encapsulate a type of commercially available probiotic known as Bio-K+, which consists of three strains of Lactobacillus bacteria. These strains are known to kill methicillin-resistant Staphylococcus aureus (MRSA). The exact mechanism by which they do this is not known, but one possibility is that the pathogens are susceptible to lactic acid produced by the probiotics. Another possibility is that the probiotics secrete antimicrobial peptides or other proteins that kill the pathogens or disrupt their ability to form biofilms.

The researchers delivered the encapsulated probiotics along with an antibiotic called tobramycin, which they chose among other tested antibiotics because it effectively kills Pseudomonas aeruginosa, another strain commonly found in wound infections. When MRSA and Pseudomonas aeruginosa growing in a lab dish were exposed to the combination of encapsulated Bio-K+ and tobramycin, all of the pathogenic bacteria were wiped out.

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The same experiment with non-encapsulated probiotics was conducted, where teh antibiotics killed all the probiotics, causing the bacteria to survive.

One component, either antibiotics or probiotics, can’t eradicate all the pathogens. That’s something which can be very important in clinical settings where you have wounds with different bacteria, and antibiotics are not enough to kill all the bacteria,

This approach could be used to develop new types of bandages or other wound dressings embedded with antibiotics and alginate-encapsulated probiotics. Plans to further test the approach in animals and possibly in humans are already in discussions.

This study has helped to expand the possibilities of probiotics.