The Cambridge Probiotic/Antibiotic Trial 2

Effects of probiotics on the composition of the intestinal microbiota following antibiotic therapy


This randomised, double blind, placebo controlled study investigated the effect of Lab4 probiotic supplementation on antibiotic resistance in the re-growth gut microbiota population following antibiotic therapy.


  • The study was carried out at Addenbrooke’s Hospital in Cambridge.
  • 155 patients requiring antibiotic therapy were divided into two groups.
  • The first group received 25 billion Lab4 probiotics daily for 21 days in conjunction with antibiotics.
  • The second group receiving a placebo with antibiotics.
  • Stool samples were collected at day 1 (before antibiotics), day 7 (the end of antibiotic treatment) and day 35 (4 weeks post antibiotic treatment).
  • Antibiotic resistance was evaluated in the microbiota.

The results

1. The number of Candida albicans in the placebo at the end of antibiotic therapy was significantly higher compared to the Lab4 probiotic group. (*P<0.05).

Candida albicans at the end of antibiotic therapy
Candida albicans at the end of antibiotic therapy

2. The numbers of facultative anaerobes and enterobacteria were significantly lower in the Lab4 probiotic group than in the placebo group 4 weeks post antibiotic treatment (*P=0.031 and *P=0.014, respectively)

3. Numbers of patients harbouring antibiotic resistant enterococci increased significantly post antibiotic therapy in the placebo group (P= 0.012).

4. There was no change in the incidence rate of antibiotic resistance among the patients in the Lab4 probiotic group post antibiotic therapy.

Microbial population 4 weeks post antibiotic therapy
Microbial population 4 weeks post antibiotic therapy


The supplementation of Lab4 probiotics alongside antibiotic therapy has been shown to reduce the extent of gut microbiota disruption AND to reduce the level of antibiotic resistance within the ‘re-growth’ microbiota.


Plummer S et al 2005.
Effects of probiotics on the composition of the intestinal microbiota following antibiotic therapy.
Int J of Antimicrobial Agents 26:69-74​

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