Open Access Highly Accessed Study protocol

A multicentre randomised controlled trial evaluating lactobacilli and bifidobacteria in the prevention of antibiotic-associated diarrhoea in older people admitted to hospital: the PLACIDE study protocol

Stephen J Allen16*, Kathie Wareham2, Caroline Bradley3, Wyn Harris4, Anjan Dhar3, Helga Brown3, Alwyn Foden3, Way Yee Cheung1, Michael B Gravenor1, Sue Plummer5, Ceri J Phillips1 and Dietrich Mack1

Author Affiliations

1 Swansea University, Singleton Park, Swansea, SA2 8PP, UK

2 Clinical Research Unit, Morriston Hospital, Swansea SA6 6NL, UK

3 County Durham and Darlington NHS Foundation Trust, Darlington Memorial Hospital, Hollyhurst Road, Darlington, County Durham DL3 6HX, UK

4 Abertawe Bro Morgannwg University Hospital Board, One Talbot Gateway, Baglan Energy Park, Baglan, Port Talbot SA12 7BR, UK

5 Obsidian Research Limited, Unit 2 Christchurch Road, Baglan Industrial Park, Port Talbot, West Glamorgan SA12 7BZ, UK

6 The College of Medicine, Swansea University, Room 314, Grove Building, Singleton Park, Swansea SA2 8PP, UK

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BMC Infectious Diseases 2012, 12:108  doi:10.1186/1471-2334-12-108

Published: 6 May 2012



Antibiotic associated diarrhoea complicates 5–39% of courses of antibiotic treatment. Major risk factors are increased age and admission to hospital. Of particular importance is C. difficile associated diarrhoea which occurs in about 4% of antibiotic courses and may result in severe illness, death and high healthcare costs. The emergence of the more virulent 027 strain of C. difficile has further heightened concerns. Probiotics may prevent antibiotic associated diarrhoea by several mechanisms including colonization resistance through maintaining a healthy gut flora.


This study aims to test the hypothesis that administration of a probiotic comprising two strains of lactobacilli and two strains of bifidobacteria alongside antibiotic treatment prevents antibiotic associated diarrhoea. We have designed a prospective, parallel group trial where people aged 65 years or more admitted to hospital and receiving one or more antibiotics are randomly allocated to receive either one capsule of the probiotic or a matching placebo daily for 21 days. The primary outcomes are the frequency of antibiotic associated and C. difficile diarrhoea during 8–12 weeks follow-up. To directly inform routine clinical practice, we will recruit a sufficient number of patients to demonstrate a 50% reduction in the frequency of C. difficile diarrhoea with a power of 80%. To maximize the generalizability of our findings and in view of the well-established safety record of probiotics, we will recruit a broad range of medical and surgical in-patients from two different health regions within the UK.


Antibiotic associated diarrhoea constitutes a significant health burden. In particular, current measures to prevent and control C. difficile diarrhoea are expensive and disrupt clinical care. This trial may have considerable significance for the prevention of antibiotic associated diarrhoea in hospitals.

Trial registration

International Standard Randomised Controlled Trial Number Register ISRCTN70017204.

Probiotic; Lactobacilli; Bifidobacteria; Antibiotic; Antibiotic associated diarrhoea; Clostridium difficile diarrhoea; Elderly; Hospital in-patient