Clostridium difficile and idiopathic neonatal diarrhoea in Australian piglets

Michele Mary Squire

    Research output: ThesisDoctoral Thesis

    361 Downloads (Pure)

    Abstract

    [Truncated] Clostridium difficile has emerged in pork producing countries worldwide as a leading cause of enteric disease in piglets less than 7 days of age. Outside Australia this is primarily due to a single ribotype, RT 078. While this association has been well studied elsewhere, nothing is known about porcine CDI in Australia despite reports of idiopathic scour. It was hypothesised that C. difficile would be present in Australian pig herds but the epidemiology would be different due to our geographic isolation, rigorous import restrictions on live animals and low pig stocking density, limiting the applicability of available data to the local setting.

    To understand this organism in the Australian context, epidemiologic approaches were used to evaluate C. difficile in Australian farrowing units, including prevalence and risk factors such as environmental contamination. Genetic analyses were employed to characterize the unique Australian strains isolated in these studies and determine the most reliable diagnostic tools for a genetically diverse and heterogeneous population. The relationship between Australian porcine C. difficile strains and enteric disease was assessed in a mouse and piglet model of infection.

    Prevalence studies revealed C. difficile was commonly found in Australian piggeries, with 60% prevalence in a retrospective analysis of diagnostic samples and 67% in a period prevalence study of scouring and non-scouring neonatal herds. These rates are higher than that reported in diagnostic and period prevalence studies from major pork producing countries. Key aspects of CDI were confirmed, including age-dependent colonisation of piglets ≤ 7 d of age and asymptomatic carriage in affected herds, similar to other porcine enteropathogens. RT 078 was not isolated from Australian piglets. Instead there was a heterogeneous mix of RTs, the majority of which (71 and 61%, respectively) had not been previously described in animals or humans either locally or outside Australia. Strains were overwhelmingly toxigenic (87%) and A-B+ variant strains were common. There was overlap between PCR ribotypes isolated from humans, piglets and other animals but an epidemiological link was not obvious.

    Original languageEnglish
    QualificationDoctor of Philosophy
    Publication statusUnpublished - 26 Mar 2015

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