Good bacteria armed with antibiotic resistance protect gut microbiome

Researchers from Case Western Reserve University in Cleveland have discovered that populating the gastrointestinal (GI) tracts of mice with Bacteroides species producing a specific enzyme helps protect the good commensal bacteria from the harmful effects of antibiotics. Their research is published ahead of print in Antimicrobial Agents and Chemotherapy.

Antibiotics are powerful weapons against pathogens, but most are relatively indiscriminate, killing the , along with the bad. Thus, they may render patients vulnerable to invasion, particularly by virulent, antibiotic-resistant pathogens that frequently populate hospitals.

The novel aspect of the research is that the enzyme produced by these bacteria, beta-lactamase, is a major cause of , says first author, Usha Stiefel. Interestingly, the enzyme is not only protecting the bacteria that produce it but also the rest of the bacteria making up the intestinal microbiome.

In the study, the investigators established populations of beta-lactamase producing Bacteroides in some mice, but not others. They then gave all the mice ceftriaxone, a beta-lactam antibiotic, for three days and then oral doses of vancomycin-resistant enterococcus, or Clostridium difficile, both of which are virulent GI pathogens.

The mice that had been populated with Bacteroides maintained their diverse species of commensal gut bacteria, free of pathogens, while the control mice saw their commensals decimated by , enabling establishment of the pathogens.

"When patients in the hospital or nursing home setting receive antibiotics, it is doubly dangerous when they lose their native colonic bacteria, because healthcare settings are full of resistant or particularly , and so patients are especially vulnerable to acquiring these bacteria within their intestinal tracts," says Stiefel.

Since the Bacteroides, which comprise roughly one quarter of the intestinal microbiome, are absent elsewhere in the body, the investigators believe that the beta-lactamase will not interfere with treatment of infections in other organ systems, such as in the respiratory tract, or the blood, explains Stiefel.

"The results of our study are exciting because they show how it might be possible to take antibiotics without suffering from the loss of your colonic microbiome and then becoming colonized by virulent pathogens," says Stiefel. For example, beta-lactamase enzymes could be given orally as drugs, to protect the from systemic antibiotics. Alternatively, as with the mice, patients' GI tracts might be populated with antibiotic-degrading .

One weakness of the strategy is that while it could protect against acquiring a GI infection, C. difficile, for example, it could not be used to combat such an infection.

"The recognition of the importance of an intact and diverse microbiome has probably best been demonstrated by the successful treatment of Clostridium difficile colitis by fecal microbiota transplantation, or 'stool transplant,'" says Stiefel. "If you have an intact intestinal microbiome, you simply are going to be resistant to acquiring many types of infection."

"If we can find ways to preserve the microbiome in hospitalized patients who are receiving antibiotics, we are on our way to preventing a large proportion of hospital-acquired infections," says Stiefel.

More information: The manuscript can be found online. The final version of the article is scheduled for the August 2014 issue of Antimicrobial Agents and Chemotherapy.

add to favorites email to friend print save as pdf

Related Stories

Recommended for you

Liberia holds Senate vote amid Ebola fears

28 minutes ago

Health workers manned polling stations across Liberia on Saturday as voters cast their ballots in a twice-delayed Senate vote that has been criticized for its potential to spread the deadly Ebola disease.

Evidence-based recs issued for systemic care in psoriasis

20 hours ago

(HealthDay)—For appropriately selected patients with psoriasis, combining biologics with other systemic treatments, including phototherapy, oral medications, or other biologic, may result in greater efficacy ...

Bacteria in caramel apples kills at least four in US

20 hours ago

A listeria outbreak believed to originate from commercially packaged caramel apples has killed at least four people in the United States and sickened 28 people since November, officials said Friday.

Steroid-based treatment may answer needs of pediatric EoE patients

21 hours ago

A new formulation of oral budesonide suspension, a steroid-based treatment, is safe and effective in treating pediatric patients with eosinophilic esophagitis (EoE), according to a new study in Clinical Gastroenterology and Hepatology, the official clinical practice journal ...

Discovery of genes that predispose a severe form of COPD

23 hours ago

A study by Ramcés Falfán-Valencia, researcher at the National Institute of Respiratory Diseases (INER), found that the mestizo Mexican population has a number of variations in certain genes that predispose ...

User comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.