Phage therapy reduces Campylobacter jejuni colonization in broilers Jaap A. Wagenaar a, * , Marcel A.P. Van Bergen a , Mark A. Mueller b , Trudy M. Wassenaar c , Richard M. Carlton b a Division of Infectious Diseases, Animal Sciences Group, P.O. Box 65, 8200 AB Lelystad, The Netherlands b Exponential Biotherapies Inc., Washington DC, USA c Molecular Microbiology and Genomics Consultants, Zotzenheim, Germany Received 4 March 2005; received in revised form 27 May 2005; accepted 2 June 2005 Abstract The effect of phage therapy in the control of Campylobacter jejuni colonization in young broilers, either as a preventive or a therapeutic measure, was tested. A prevention group was infected with C. jejuni at day 4 of a 10-day phage treatment. A therapeutic group was phage treated for 6 days, starting 5 days after C. jejuni colonization of the broilers had been established. Treatment was monitored by enumerating Campylobacter colony forming units (CFU) and phage plaque forming units (PFU) from caecal content. Counts were compared with control birds not receiving phage therapy. A clear 3 log decline in C. jejuni counts was initially observed in the therapeutic group, however, after 5 days bacterial counts stabilized at a level 1 log lower than that of the control group. Colonization of C. jejuni in the prevention group was delayed by the treatment and after an initial 2 log reduction, colonization stabilized within a week at levels comparable to the therapeutic group. The CFU and PFU counts displayed opposing highs and lows over time, indicative of alternating shifts in amplification of bacteria and phages. There were no adverse health effects from the phage treatment. Two different phages were combined as therapeutic treatment of Campylobacter positive chickens challenged at the age approaching broiler harvest. This again resulted in a significant decrease in Campylobacter colonization. We conclude that phage treatment is a promising alternative for reducing C. jejuni colonization in broilers. # 2005 Elsevier B.V. All rights reserved. Keywords: Campylobacter control; Bacteriophage; Phage; Chicken treatment; Poultry; Food safety 1. Introduction Campylobacter jejuni is an important human pathogen and is the most common cause of bacterial gastroenteritis worldwide (Lindqvist et al., 2001; Adak et al., 2002; Samuel et al., 2004). Poultry flocks are frequently colonized with C. jejuni without apparent symptoms (Shane, 2000) and risk assessment analyses have identified handling and consumption of poultry meat as one of the most important sources of human campylobacteriosis (Evans et al., 2003; Potter et al., 2003; Friedman et al., 2004). www.elsevier.com/locate/vetmic Veterinary Microbiology 109 (2005) 275–283 * Corresponding author. Tel.: +31 320 238157; fax: +31 320 238961. E-mail address: Jaap.Wagenaar@wur.nl (J.A. Wagenaar). 0378-1135/$ – see front matter # 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.vetmic.2005.06.002