Avian intestinal spirochaetosis (AIS) is primarily a disease of layer and broiler breeder chickens exhibited by delayed and/or reduced egg production, increased mortality, weight loss, and chronic diarrhoea. This disease is of concern to the egg industry because of the economic impact of reduced production and down grading of eggs due to faecal-stained shells. Avian intestinal spirochaetosis is caused by pathogenic Brachyspira spp. This review summarises the species of Brachyspira that have been associated with AIS and provides an overview of epidemiological studies that have investigated prevalence, risk factors, and preventive measures for Brachyspira spp.

Large amounts of antimicrobial agents are still being used in modern swine production in many countries around the world. This facilitates the emergence and development of antimicrobial resistance. Bacteria causing infections in swine have in several cases acquired resistance to a number of the agents most commonly used for treatment, making it difficult to predict the efficacy of different antimicrobial agents without prior susceptibility testing. This review gives an overview of recent susceptibility data from different parts of the world and discusses the importance of the development of resistance not only in the treatment of infections in swine but also taking into account the human health implications of antimicrobial resistance.