Antibiotics, while essential in many cases, can disrupt the indigenous gut microbiota and leave a patient susceptible to antibiotic-resistant bacterial infections. In this study, researchers wanted to find out the potential benefit of proactive treatment with probiotics before the administration of antibiotics.


To do that, mice with a previously abolished microbiota were given either a β-lactamase-producing anaerobe (i.e. the probiotic) or a saline solution. The β-lactamase enzymes, produced by some bacteria, inactivate β-lactam antibiotics, which are among the most widely used worldwide. After the treatment (with the probiotic strain, or the saline solution), the animals received 3 days of the antibiotic ceftriaxone, and were subsequently exposed to pathogens (vancomycin-resistant Enterococcus, in vivo, and Clostridium difficile, in vitro). Stool concentrations of Enterococcus and C. difficile were measured, and 16S rRNA analyses performed to evaluate the antibiotic effect. The results obtained showed that advance colonization with the β-lactamase-producing anaerobe rendered the ceftriaxone inactive in the gut, which allowed recovery of the normal microbiota and prevented growth of the pathogens.


The authors concluded that this colonization strategy could potentially prevent dangerous infections in hospitalized patients.



Stiefel U et al. (2014) Gastrointestinal Colonization with a Cephalosporinase-Producing Bacteroides Species Preserves Colonization Resistance against Vancomycin-Resistant Enterococcus and Clostridium difficile in Cephalosporin-Treated Mice Antimicrobial Agents and Chemotherapy 58(8) pp. 4535-4542. doi:10.1128/AAC.02782-14