Laboratory-Based Surveillance of Clostridium difficile Infection in Australian Health Care and Community Settings, 2013 to 2018.

In the early 2000s, a binary toxin (CDT)-producing strain of , ribotype 027 (RT027), caused extensive outbreaks of diarrheal disease in North America and Europe. This strain has not become established in Australia, and there is a markedly different repertoire of circulating strains there compared to other regions of the world. The Antimicrobial Resistance Surveillance (CDARS) study is a nationwide longitudinal surveillance study of infection (CDI) in Australia. Here, we describe the molecular epidemiology of CDI in Australian health care and community settings over the first 5 years of the study, 2013 to 2018. Between 2013 and 2018, 10 diagnostic microbiology laboratories from five states in Australia participated in the CDARS study. From each of five states, one private (representing community) and one public (representing hospitals) laboratory submitted isolates of or PCR-positive stool samples during two collection periods per year, February-March (summer/autumn) and August-September (winter/spring). was characterized by toxin gene profiling and ribotyping. A total of 1,523 isolates of were studied. PCR ribotyping yielded 203 different RTs, the most prevalent being RT014/020 ( = 449; 29.5%). The epidemic CDT RT027 ( = 2) and RT078 ( = 6), and the recently described RT251 ( = 10) and RT244 ( = 6) were not common, while RT126 ( = 17) was the most prevalent CDT type. A heterogeneous population was identified. RT014/020 was the most prevalent type found in humans with CDI. Continued surveillance of CDI in Australia remains critical for the detection of emerging strain lineages.