Laboratory surveillance of paediatric Clostridium difficile infections in healthcare and community settings in Australia, from 2013 to at present

Background: Clostridium difficile is a common antimicrobial-resistant bacterium in healthcare and community settings. C. difficile colonises the gastrointestinal tract and proliferates as a result of the disruption to microbiota from antimicrobial exposure. Increasing rates of hospital and community-acquired C. difficile infections (CA-CDI) in children have been recorded in many parts of the world, however, research in Australia has been limited. The C. difficile Antimicrobial Resistance Surveillance (CDARS) study is a longitudinal investigation of both the molecular epidemiology and antimicrobial resistance phenotype of C. difficile isolated in Australia since 2013. Here we report the molecular characterization of C. difficile isolated from paediatric patients during this period. Methods & Materials: C. difficile isolates (or PCR positive stool samples) were sent from 10 laboratories (one private and one public laboratory) across five states in Australia. Isolates were characterized by PCR for toxin genes and ribotyping. Results: Of the 1542 isolates recovered throughout the study period (August–September 2013–February–March 2018), 127 (8.2%) were from paediatric patients with ages ranging from <1 to 17 years. Overall, 88.2% of isolates (n = 112) were toxigenic (A+B+CDT−, n = 104; A+B+CDT+, n = 6; A−B+CDT−, n = 2). A total of 38 different RTs were identified of which two were novel. The most common RTs isolated were toxigenic RTs 014/020, 002, 046 and 056. Interestingly, RT 027 was isolated from an 11-year-old patient in a public hospital in Queensland. Conclusion: The presence of highly diverse strains in paediatric patients from both hospitals and community-based healthcare establishments suggests the possibility of patients acquiring infections from sources/reservoirs external to the hospital contributing to the rise in CA-CDIs in Australia in recent years. The presence of toxigenic strains, especially the well-established (in both humans and animals) RT 014/020, and the strain commonly found in the Asia-Pacific region, RT 017, is of interest. Additional whole genome sequencing studies will enhance our understanding of the significance of isolating C. difficile from young children (primarily toxigenic strains that are commonly found in other sources/reservoirs such as the environment, food, animals and the elderly).