ORCID Profile
0000-0001-8983-6573
Current Organisation
University of Western Australia
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Publisher: Springer Science and Business Media LLC
Date: 02-2017
DOI: 10.1038/SREP41196
Abstract: Clostridium difficile is a well-established hospital pathogen. Recently, it has been detected increasingly in patients without hospital contact. Given this rise in community associated infections with C. difficile , we hypothesized that the environment could play an important role in transmission of spores outside the hospital. Lawn s les (311) collected in public spaces in the metropolitan area of Perth, Western Australia, from February to June 2016 were cultured for C. difficile. C. difficile was isolated from the s les by direct and enrichment culture, and characterized by standard molecular methods using toxin gene PCR and ribotyping. The overall prevalence of C. difficile was 59%, new lawn (≤4 months old) was twice as likely as old lawn ( months old) to test positive (OR = 2.3 95%CI 1.16–4.57, p = 0.015) and 35 C. difficile ribotypes were identified with toxigenic ribotype 014/020 (39%) predominating. The highest viable count from lawn soil s les was 1200 CFU/g. These results show that lawns in Perth, Western Australia, harbor toxigenic C. difficile , an important finding. The source of lawn contamination is likely related to modern practice of producing “roll-out” lawn. Further work should focus on identifying specific management practices that lead to C. difficile contamination of lawn to inform prevention and control measures.
Publisher: CSIRO Publishing
Date: 2020
DOI: 10.1071/MA20007
Abstract: The One Health concept recognises that the health of humans is interconnected to the health of animals and the environment. It encourages multidisciplinary communication and collaboration with the aim of enhancing surveillance and research and developing integrative policy frameworks. Clostridium difficile (also known as Clostridioides difficile) infection (CDI) has long been viewed as a hospital-associated (HA) enteric disease mainly linked to the use of broad-spectrum antimicrobials that cause dysbiosis in the gut and loss of ‘colonisation resistance'. However, since the early 2000s, the rate of community-associated CDI (CA-CDI) has increased to ~15% in Europe, ~30% in Australia and ~40% in the USA in populations often without obvious risk factors. Since the 1990s, it has become apparent that food animals are now a major reservoir and lification host for C.difficile, including lineages of clinical importance. Cephalosporin antimicrobials, to which C. difficile is intrinsically resistant, were licensed for animal use in North America in 1990. By the second decade of the 21st century, there were reports of C. difficile contamination of food and the environment in general. Using whole-genome sequencing (WGS) and high-resolution typing, C. difficile isolates from humans, animals, food and the environment were proven to be genetically closely related and, in some cases, indistinguishable. This suggests possible zoonoses and/or anthroponoses, with contaminated food and the environment acting as the conduit for transmission between animals and humans. This paper summarises the key evidence that demonstrates the One Health importance of C. difficile.
Publisher: Elsevier BV
Date: 02-2016
DOI: 10.1016/J.ANAEROBE.2015.12.004
Abstract: Clostridium difficile is an important enteric pathogen of humans and food animals. Recently it has been isolated from retail foods with prevalences up to 42%, prompting concern that contaminated foods may be one of the reasons for increased community-acquired C. difficile infection (CA-CDI). A number of studies have examined the prevalence of C. difficile in raw meats and fresh vegetables however, fewer studies have examined the prevalence of C. difficile in ready-to-eat meat. The aim of this study was to investigate the in vitro susceptibility of 11 C. difficile isolates of food animal and retail food origins to food preservatives commonly used in ready-to-eat meats. The broth microdilution method was used to determine the minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) for sodium nitrite, sodium nitrate and sodium metabisulphite against C. difficile. Checkerboard assays were used to investigate the combined effect of sodium nitrite and sodium nitrate, commonly used in combination in meats. Modal MIC values for sodium nitrite, sodium nitrate and sodium metabisulphite were 250 μg/ml, >4000 μg/ml and 1000 μg/ml, respectively. No bactericidal activity was observed for all three food preservatives. The checkerboard assays showed indifferent interaction between sodium nitrite and sodium nitrate. This study demonstrated that C. difficile can survive in the presence of food preservatives at concentrations higher than the current maximum permitted levels allowed in ready-to-eat meats. The possibility of retail ready-to-eat meats contaminated with C. difficile acting as a source of CDI needs to be investigated.
Publisher: Elsevier BV
Date: 09-2018
DOI: 10.1016/J.IJANTIMICAG.2018.05.013
Abstract: We recently reported a high prevalence of Clostridium difficile in retail vegetables, compost and lawn in Western Australia. The objective of this study was to investigate the antimicrobial susceptibility of previously isolated food and environmental C. difficile isolates from Western Australia. A total of 274 C. difficile isolates from vegetables, compost and lawn were tested for susceptibility to a panel of 10 antimicrobial agents (fidaxomicin, vancomycin, metronidazole, rifaximin, clindamycin, erythromycin, amoxicillin/clavulanic acid, moxifloxacin, meropenem and tetracycline) using the agar incorporation method. Fidaxomicin was the most potent agent (MIC
Publisher: Cold Spring Harbor Laboratory
Date: 20-10-2022
DOI: 10.1101/2022.10.19.512806
Abstract: There is growing evidence that shows Clostridium ( Clostridioides ) difficile is a pathogen of One Health importance with a complex dissemination pathway involving animals, humans and the environment. Thus, environmental discharge and agricultural recycling of human and animal waste have been suspected as factors behind the dissemination of C. difficile in the community. Here, the presence of C. difficile in 12 wastewater treatment plants (WWTPs) in Western Australia was investigated. Overall, C. difficile was found in 90.5% (114/126) of raw sewage influent, 48.1% (50/104) of treated effluent, 40% (2/5) of reclaimed irrigation water, 100% (38/38) of untreated biosolids, 95.2% (20/21) of anaerobically digested biosolids and 72.7% (8/11) of lime-amended biosolids. Over half the isolates (55.3%, 157/284) were toxigenic and 97 C. difficile ribotypes (RTs) were identified with RT014/020 the most common (14.8%, 42/284). Thirteen C. difficile isolates with the toxin profile A+B+CDT+ were found, including the hypervirulent RT078 strain. Resistance to the antimicrobials fidaxomicin, vancomycin, metronidazole, rifaximin, amoxicillin/clavulanate, meropenem and moxifloxacin was uncommon, however, resistance to clindamycin, erythromycin and tetracycline was relatively frequent at 56.7% (161/284), 14.4% (41/284) and 13.7% (39/284), respectively. This study revealed that toxigenic C. difficile was commonly encountered in WWTPs and being released into the environment. This raises concern about the possible spill-over of C. difficile into animal and/or human populations via land receiving the treated waste. In Western Australia, stringent measures are in place to mitigate the health and environmental risk of recycling human waste, however, further studies are needed to elucidate the public health significance of C. difficile surviving the treatment processes at WWTPs. Clostridium difficile infection (CDI) is a leading cause of antimicrobial-associated diarrhoea in healthcare facilities. Extended hospital stays and recurrences increase the cost of treatment, and morbidity and mortality. Community-associated CDI (CA-CDI) cases, with no history of antimicrobial use or exposure to healthcare settings, are increasing. The isolation of clinically important C. difficile strains from animals, rivers, soil, meat, vegetables, compost, treated wastewater and biosolids has been reported. The objective of this study was to characterise C. difficile in wastewater treatment plants (WWTPs) in Australia. We found that C. difficile can persist through the treatment processes of WWTPs and toxigenic C. difficile was being released into the environment becoming a potential source/reservoir for CA-CDI.
Publisher: Oxford University Press (OUP)
Date: 22-01-2018
DOI: 10.1111/JAM.13653
Abstract: The incidence of community-associated Clostridium difficile infection (CA-CDI) in Australia has increased since mid-2011. With reports of clinically important C. difficile strains being isolated from retail foods in Europe and North America, a foodborne source of C. difficile in cases of CA-CDI is a possibility. This study represents the first to investigate the prevalence and genotypes of C. difficile in Australian retail vegetables. A total of 300 root vegetables grown in Western Australia (WA) were collected from retail stores and farmers' markets. Three vegetables of the same kind bought from the same store/market were treated as one s le. Selective enrichment culture, toxin profiling and PCR ribotyping were performed. Clostridium difficile was isolated from 30% (30/100) of pooled vegetable s les, 55·6% of organic potatoes, 50% of nonorganic potatoes, 22·2% of organic beetroots, 5·6% of organic onions and 5·3% of organic carrots. Over half (51·2%, 22/43) the isolates were toxigenic. Many of the ribotypes of C. difficile isolated were common among human and Australian animals. Clostridium difficile could be found commonly on retail root vegetables of WA. This may be potential sources for CA-CDI. This study enhances knowledge of possible sources of C. difficile in the Australian community, outside the hospital setting.
Publisher: Elsevier BV
Date: 06-2022
DOI: 10.1016/J.PATHOL.2021.10.009
Abstract: Less is understood about the epidemiology of Clostridioides difficile infection (CDI) in children compared to adults, and its impact is complicated by variations in the natural development of infection in paediatric patients. The interplay of rising CDI incidence in hospitalised paediatric patients, emergence of hypervirulent strains and community associated CDI (CA-CDI) in the past decade is a potential threat in both hospital and community settings. Research in Australia regarding paediatric CDI is limited. Here, we report the molecular characterisation of C. difficile isolated from paediatric patients at a tertiary hospital in Perth, Western Australia. A total of 427 stool s les was collected from patients aged from <1 to 17 years being investigated for diarrhoea from July 2019 to June 2020. Stool specimens were cultured and isolates of C. difficile characterised by ribotyping and toxin gene profiling. Clostridioides difficile was recovered from 84/427 (19.7%) s les tested. The most prevalent PCR ribotypes (RTs) were RT 002 (12.4%), a toxigenic strain, and RT 009 (15.7%), a non-toxigenic strain. Interestingly, C. difficile RT 078 and RT 017, strains that are not endemic in Australia, were isolated from a 1- and 4-year-old child, respectively. Clostridioides difficile RT 106, a strain of emerging importance in Australia, was recovered from two cases (5.3%). Resistance to metronidazole, fidaxomicin, amoxicillin, rifaximin and meropenem was not detected, however, 45 isolates (50.6%) showed resistance to at least one agent, and multidrug resistance was observed in 13.3% of the resistant isolates (6/45). This study provides a baseline for future surveillance of paediatric CDI in Australia. Given that young children can be asymptomatically colonised with toxigenic C. difficile strains, they represent a potential reservoir of strains causing CDI in adults.
Publisher: American Chemical Society (ACS)
Date: 04-2022
Abstract: Soft actuators that respond to external stimuli like moisture, magnetism, light, and temperature have received tremendous attention owing to their promising potential in many frontier applications, including smart switches, soft robots, sensors, and artificial muscles. However, most of the conventional actuators can only be triggered by a solo stimulus and demand advanced manufacturing techniques that utilize expensive, hazardous, and synthetic raw materials. Herein, we design and fabricate a multiple stimuli-responsive actuator using graphene oxide, Fe
Publisher: Wiley
Date: 24-10-2021
Abstract: Clostridium difficile isolates from the environment are closely related to those from humans, indicating a possible environmental transmission route for C. difficile infection (CDI). In this study, C. difficile was isolated from 47.3% (53/112) of lake ond, 23.0% (14/61) of river, 20.0% (3/15) of estuary and 0.0% (0/89) of seawater s les. The most common toxigenic strain isolated was C. difficile PCR ribotype (RT) 014/020 (10.5%, 8/76). All water isolates were susceptible to fidaxomicin, metronidazole, rifaximin, amoxicillin/clavulanic acid, moxifloxacin and tetracycline. Resistance to vancomycin, clindamycin, erythromycin and meropenem was detected in 5.3% (4/76), 26.3% (20/76), 1.3% (1/76) and 6.6% (5/76) of isolates, respectively. High‐resolution core‐genome analysis was performed on RT 014/020 isolates of water origin and 26 clinical RT 014/020 isolates from the same year and geographical location. Notably, both human and water strains were intermixed across three sequence types (STs), 2, 13 and 49. Six closely related groups with ≤10 core‐genome single nucleotide polymorphisms were identified, five of which comprised human and water strains. Overall, 19.2% (5/26) of human strains shared a recent genomic relationship with one or more water strains. This study supports the growing hypothesis that environmental contamination by C. difficile plays a role in CDI transmission.
Publisher: Springer Science and Business Media LLC
Date: 20-03-2023
DOI: 10.1007/S10096-023-04569-X
Abstract: Recurrent cases of Clostridioides difficile infection (rCDI) remain one of the most common and serious challenges faced in the management of CDI. The accurate distinction between a relapse (caused by infection with the same strain) and reinfection (caused by a new strain) has implications for infection control and prevention, and patient therapy. Here, we used whole-genome sequencing to investigate the epidemiology of 94 C. difficile isolates from 38 patients with rCDI in Western Australia. The C. difficile strain population comprised 13 sequence types (STs) led by ST2 (PCR ribotype (RT) 014, 36.2%), ST8 (RT002, 19.1%) and ST34 (RT056, 11.7%). Among 38 patients, core genome SNP (cgSNP) typing found 27 strains (71%) from initial and recurring cases differed by ≤ 2 cgSNPs, suggesting a likely relapse of infection with the initial strain, while eight strains differed by ≥ 3 cgSNPs, suggesting reinfection. Almost half of patients with CDI relapse confirmed by WGS suffered episodes that occurred outside the widely used 8-week cut-off for defining rCDI. Several putative strain transmission events between epidemiologically unrelated patients were identified. Isolates of STs 2 and 34 from rCDI cases and environmental sources shared a recent evolutionary history, suggesting a possible common community reservoir. For some rCDI episodes caused by STs 2 and 231, within-host strain ersity was observed, characterised by loss/gain of moxifloxacin resistance. Genomics improves discrimination of relapse from reinfection and identifies putative strain transmission events among patients with rCDI. Current definitions of relapse and reinfection based on the timing of recurrence need to be reconsidered.
Publisher: Elsevier BV
Date: 07-2020
DOI: 10.1016/J.CMI.2019.10.023
Abstract: For over four decades, Clostridium difficile has been a significant enteric pathogen of humans. It is associated with the use of antimicrobials that generally disrupt the microbiota of the gastrointestinal tract. Previously, it was thought that C. difficile was primarily a hospital-acquired infection however, with the emergence of community-associated cases, and whole-genome sequencing suggesting the majority of the hospital C. difficile infection (CDI) cases are genetically distinct from one another, there is compelling evidence that sources/reservoirs of C. difficile outside hospitals play a significant role in the transmission of CDI. To review the 'One Health' aspects of CDI, focusing on how community sources/reservoirs might be acting as a conduit in the transfer of C. difficile between animals and humans. The importance of a One Health approach in managing CDI is discussed. A literature search was performed on PubMed and Web of Science for relevant papers published from 1 January 2000 to 10 July 2019. We present evidence that demonstrates transmission of C. difficile in hospitals from asymptomatic carriers to symptomatic CDI patients. The source of colonization is most probably community reservoirs, such as foods and the environment, where toxigenic C. difficile strains have frequently been isolated. With high-resolution genomic sequencing, the transmission of C. difficile between animals and humans can be demonstrated, despite a clear epidemiological link often being absent. The ways in which C. difficile from animals and humans can disseminate through foods and the environment are discussed, and an interconnected transmission pathway for C. difficile involving food animals, humans and the environment is presented. Clostridium difficile is a well-established pathogen of both humans and animals that contaminates foods and the environment. To manage CDI, a One Health approach with the collaboration of clinicians, veterinarians, environmentalists and policy-makers is paramount.
Publisher: Oxford University Press (OUP)
Date: 09-2022
DOI: 10.1111/JAM.15408
Abstract: To investigate if Clostridium (Clostridioides) difficile infection (CDI), traditionally thought of as hospital-acquired, can be genomically linked to hospital or community environmental sources, and to define possible importation routes from the community to the hospital. In 2019, C. difficile was isolated from 89/300 (29.7%) floor and 96/300 (32.0%) shoe sole s les at a tertiary hospital in Western Australia. Non-toxigenic C. difficile ribotype (RT) 010 predominated among floor (96.6%) and shoe sole (73.2%) isolates, while toxigenic RT 014/020 was most prevalent among contemporaneous clinical cases (33.0%) at the hospital. Whole-genome sequencing and high-resolution core genome single nucleotide polymorphism (cgSNP) analysis on C. difficile strains from hospital and community sources showed no clinical C. difficile RT 014/020 strains were genetically related, and evidence of frequent long-distance, multi-directional spread between humans, animals and the environment. In addition, cgSNP analysis of environmental RT 010 strains suggested transportation of C. difficile via shoe soles. While C. difficile RT 014/020 appears to spread via routes outside the healthcare system, RT 010 displayed a pattern of possible importation from the community into the hospital. These findings suggest developing community-based infection prevention and control strategies could significantly lower rates of CDI in the hospital setting.
Publisher: Elsevier BV
Date: 12-2018
DOI: 10.1016/J.ANAEROBE.2018.07.007
Abstract: Antimicrobial resistance (AMR) is commonly found in Clostridium difficile strains and plays a major role in strain evolution. We have previously reported the isolation of large clostridial toxin-negative, binary toxin-producing (A
Publisher: American Society for Microbiology
Date: 14-02-2023
DOI: 10.1128/SPECTRUM.03582-22
Abstract: Clostridium difficile infection (CDI) is a leading cause of antimicrobial-associated diarrhea in health care facilities. Extended hospital stays and recurrences increase the cost of treatment and morbidity and mortality.
Publisher: Wiley
Date: 07-10-2020
Publisher: American Society for Microbiology
Date: 10-10-2023
No related grants have been discovered for Su Chen Lim.