Epidemiology of Clostridium difficile infections in Australia: enhanced surveillance to evaluate time trends and severity of illness in Victoria, 2010-2014

Multi-omics analysis of hospital-acquired diarrhoeal patients reveals biomarkers of enterococcal proliferation and Clostridioides difficile infection

Hospital-acquired diarrhoea (HAD) is common, and often associated with gut microbiota and metabolome dysbiosis following antibiotic administration. Clostridioides difficile is the most significant antibiotic-associated diarrhoeal (AAD) pathogen, but less is known about the microbiota and metabolome associated with AAD and C. difficile infection (CDI) with contrasting antibiotic treatment. We characterised faecal microbiota and metabolome for 169 HAD patients (33 with CDI and 133 non-CDI) to determine dysbiosis biomarkers and gain insights into metabolic strategies C. difficile might use for gut colonisation. The specimen microbial community was analysed using 16 S rRNA gene amplicon sequencing, coupled with untargeted metabolite profiling using gas chromatography-mass spectrometry (GC-MS), and short-chain fatty acid (SCFA) profiling using GC-MS. AAD and CDI patients were associated with a spectrum of dysbiosis reflecting non-antibiotic, short-term, and extended-antibiotic treatment. Notably, extended antibiotic treatment was associated with enterococcal proliferation (mostly vancomycin-resistant Enterococcus faecium) coupled with putative biomarkers of enterococcal tyrosine decarboxylation. We also uncovered unrecognised metabolome dynamics associated with concomitant enterococcal proliferation and CDI, including biomarkers of Stickland fermentation and amino acid competition that could distinguish CDI from non-CDI patients. Here we show, candidate metabolic biomarkers for diagnostic development with possible implications for CDI and vancomycin-resistant enterococci (VRE) treatment.

Update on Commonly Used Molecular Typing Methods for Clostridioides difficile

This review aims to provide a comprehensive overview of the significant Clostridioides difficile molecular typing techniques currently employed in research and medical communities. The main objectives of this review are to describe the key molecular typing methods utilized in C. difficile studies and to highlight the epidemiological characteristics of the most prevalent strains on a global scale. Geographically distinct regions exhibit distinct strain types of C. difficile, with notable concordance observed among various typing methodologies. The advantages that next-generation sequencing (NGS) offers has changed epidemiology research, enabling high-resolution genomic analyses of this pathogen. NGS platforms offer an unprecedented opportunity to explore the genetic intricacies and evolutionary trajectories of C. difficile strains. It is relevant to acknowledge that novel routes of transmission are continually being unveiled and warrant further investigation, particularly in the context of zoonotic implications and environmental contamination.

Clostridioides difficile Infection: Clinical Practice and Health Outcomes in 6 Large Tertiary Hospitals in Eastern Australia

Background

Clostridioides difficile infection (CDI) is associated with significant morbidity and mortality in both healthcare and community settings. We aimed to define the predisposing factors, risks for severe disease, and mortality determinants of CDI in eastern Australia over a 1-year period.

Methods

This is an observational retrospective study of CDI in hospitalized patients aged ≥18 years in 6 tertiary institutions from 1 January 2016 to 31 December 2016. Patients were identified through laboratory databases and medical records of participating institutions. Clinical, imaging, and laboratory data were input into an electronic database hosted at a central site.

Results

A total of 578 patients (578 CDI episodes) were included. Median age was 65 (range, 18-99) years and 48.2% were male. Hospital-onset CDI occurred in 64.0%. Recent antimicrobial use (41.9%) and proton pump inhibitor use (35.8%) were common. Significant risk factors for severe CDI were age <65 years (P < .001), malignancy within the last 5 years (P < .001), and surgery within the previous 30 days (P < .001). Significant risk factors for first recurrence included severe CDI (P = .03) and inflammatory bowel disease (P = .04). Metronidazole was the most common regimen for first episodes of CDI with 65.2% being concordant with Australian treatment guidelines overall. Determinants for death at 60 days included age ≥65 years (P = .01), severe CDI (P < .001), and antibiotic use within the prior 30 days (P = .02). Of those who received metronidazole as first-line therapy, 10.1% died in the 60-day follow-up period, compared to 9.8% of those who received vancomycin (P = .86).

Conclusions

Patients who experience CDI are vulnerable and require early diagnosis, clinical surveillance, and effective therapy to prevent complications and improve outcomes.

Sex and Gender Differences in Bacterial Infections

There is a growing awareness of the importance of sex and gender in medicine and research. Women typically have stronger immune responses to self and foreign antigens than men, resulting in sex-based differences in autoimmunity and infectious diseases. In both animals and humans, males are generally more susceptible than females to bacterial infections. At the same time, gender differences in health-seeking behavior, quality of health care, and adherence to treatment recommendations have been reported. This review explores our current understanding of differences between males and females in bacterial diseases. We describe how genetic, immunological, hormonal, and anatomical factors interact to influence sex-based differences in pathophysiology, epidemiology, clinical presentation, disease severity, and prognosis, and how gender roles affect the behavior of patients and providers in the health care system.

Comparative genomic and transmission analysis of Clostridioides difficile between environmental, animal, and clinical sources in China

Clostridioides difficile is the most common pathogen causing antibiotic-associated diarrhea. Previous studies showed that diverse sources, aside from C. difficile infection (CDI) patients, played a major role in C. difficile hospital transmission. This study aimed to investigate relationships and transmission potential of C. difficile strains from different sources. A prospective study was conducted both in the intensive care unit (ICU) and six livestock farms in China in 2018–2019. Ninety-eight strains from CDI patients (10 isolates), asymptomatic hospitalized carriers (55), the ICU environment (12), animals (14), soil (4), and farmers (3) were collected. Sequence type (ST) 3/ribotype (RT) 001, ST35/RT046, and ST48/RT596 were dominant types, distributed widely in multiple sources. Core-genome single-nucleotide polymorphism (cgSNP) analysis showed that hospital and farm strains shared several common clonal groups (CGs, strains separated by ≤ 2 cgSNPs) (CG4/ST3/RT001, CG7/ST35/RT046, CG11/ST48/RT596). CDI patients, asymptomatic carriers, and the ICU environment strains also shared several common CGs. The number of virulence genes was not statistically different between strains from different sources. Multi-source strains in the same CG carried identical virulence gene sequences, including pathogenicity genes at the pathogenicity locus and adhesion-related genes at S-layer cassette. Resistance genes (ermB, tetM, etc.) were widespread in multiple sources, and multi-source strains in the same CG had similar resistance phenotypes and carried consistent transposons and plasmid types. The study indicated that interspecies and cross-regional transmission of C. difficile occurs between animals, the environment, and humans. Community-associated strains from both farms and asymptomatic hospitalized carriers were important reservoirs of CDI in hospitals.

Use of a Victorian statewide surveillance program to evaluate the burden of healthcare-associated Staphylococcus aureus bacteraemia and Clostridioides difficile infection in patients with cancer

BACKGROUND

Patients with cancer are at high risk for infection, but the epidemiology of healthcare-associated Staphylococcus aureus bacteraemia (HA-SAB) and Clostridioides difficile infection (HA-CDI) in Australian cancer patients has not previously been reported.

AIMS

To compare the cumulative aggregate incidence and time trends of HA-SAB and HA-CDI in a predefined cancer cohort with a mixed statewide patient population in Victoria, Australia.

METHODS

All SAB and CDI events in patients admitted to Victorian healthcare facilities between 1^st July 2010 and 31^st December 2018 were submitted to the Victorian Healthcare Associated Infection Surveillance System Coordinating Centre. Descriptive analyses and multilevel mixed-effects Poisson regression modelling were applied to a standardised data extract.

RESULTS

In total, 10,608 and 13,118 SAB and CDI events were reported across 139 Victorian healthcare facilities, respectively. Of these, 89 (85%) and 279 (88%) were healthcare-associated in the cancer cohort compared to 34% (3,561/10,503) and 66% (8,403/12,802) in the statewide cohort. The aggregate incidence was more than two-fold higher in the cancer compared to the statewide cohort for HA-SAB (2.25 [95% CI: 1.74-2.77] vs. 1.11 [95% CI: 1.07-1.15] HA-SABs/10,000 OBDs) and three-fold higher for HA-CDI (6.26 [95% CI: 5.12-7.41] vs. 2.31 [95% CI: 2.21-2.42] HA-CDIs/10,000 OBDs). Higher quarterly diminishing rates were observed in the cancer cohort than the statewide data for both infections.

CONCLUSIONS

Our findings demonstrate a higher burden of HA-SAB and HA-CDI in a cancer cohort when compared with state data and highlight the need for cancer-specific targets and benchmarks to meaningfully support quality improvement. This article is protected by copyright. All rights reserved.

Clostridioides difficile Infection in a Rural New Zealand Secondary Care Centre: An Incidence Case-Control Study

BACKGROUND

Clostridioides difficile Infection (CDI) is a form of antibiotic associated infectious diarrhoea resulting in significant morbidity and mortality. Community acquired disease in low risk individuals is increasingly recognised. There are limited New Zealand data published.

AIM

To determine the incidence and location of onset of CDI cases in the Manawatu region, and further describe the demographics, risk factors and prevalent C. difficile ribotypes of the population.

METHODS

We performed an incidence case-control study of CDI in the Manawatu region between September 2018 and September 2019. Cases were matched to controls with a negative test for C. difficile. Demographic and comorbidity data, location of onset, drug exposure, disease recurrence and 30-day mortality were collected. Ribotype analysis was performed on C. difficile isolates.

RESULTS

32 specimens tested toxin positive over twelve months, yielding an incidence of 18.3 cases per 100,000 person-years. 25% of cases had community onset disease. Cases were more likely to have had amoxicillin/clavulanate or ceftriaxone prescribed. Elevated blood white cell count and lower HbA1c were significantly associated with CDI. The dominant ribotype was 014/020, 2 cases were RT 023.

CONCLUSION

Our data are similar to previous national data. RT 023 has not been previously reported in New Zealand and has been associated with severe colitis. We demonstrated a significant proportion of community acquired cases and the true incidence may be higher. Vigilance for community onset disease is required. This data may allow observation of temporal changes in incidence and infection patterns of CDI in New Zealand. This article is protected by copyright. All rights reserved.

Healthcare-associated infections and antimicrobial resistance in Canadian acute care hospitals, 2014-2018

Background

Healthcare-associated infections (HAIs) and antimicrobial resistance (AMR) pose serious threats to the health of Canadians due to increased morbidity, mortality and healthcare costs. Epidemiologic and laboratory surveillance data, collected through the Canadian Nosocomial Infection Surveillance Program, are used to inform infection prevention and control and antimicrobial stewardship programs and policies. The objective of this study was to describe the epidemiologic and laboratory characteristics and trends of HAIs and AMR from 2014 to 2018 using surveillance data provided by Canadian hospitals participating in the Canadian Nosocomial Infection Surveillance Program.

Methods

Data were collected from 70 Canadian sentinel hospitals between January 1, 2014 and December 31, 2018 for Clostridioides difficile infection (CDI), methicillin-resistant Staphylococcus aureus bloodstream infections, vancomycin-resistant Enterococci bloodstream infections and carbapenemase-producing Enterobacteriaceae. Case counts, rates, outcome data, molecular characterization and antimicrobial resistance profiles are presented. Additionally, hospital-level Escherichia coli antibiogram data were collected and are described.

Results

Increases in rates per 10,000 patient-days were observed for methicillin-resistant S. aureus bloodstream infections (59%; 0.66-1.05, p=0.023) and vancomycin-resistant Enterococci bloodstream infections (143%; 0.14-0.34, p=0.023). However, CDI rates decreased by 12.5% between 2015 and 2018 (from 6.16-5.39, p=0.042). Carbapenemase-producing Enterobacteriaceae infection rates remained low and stable whereas colonization increased by 375% (0.04-0.19; p=0.014).

Conclusion

Ongoing efforts to prevent HAIs and reduce AMR in Canada require consistent, standardized surveillance data from acute care hospitals. Increased collaboration with provincial, territorial and international partners in infection prevention and control, as well as antimicrobial stewardship, will be essential in reducing the burden of observed HAIs (including antimicrobial resistant organisms).

Spatial clusters of Clostridium difficile infection and an association with neighbourhood socio-economic disadvantage in the Australian Capital Territory, 2004-2014

BACKGROUND

In Australia, rates of Clostridium difficile infection (CDI) in all States and Territories have increased significantly since mid-2011, with rates of infection increasing faster in the community setting than within hospitals. Knowledge about the risk factors for CDI is essential to determine the risk of community outbreaks of CDI and to design interventions that reduce those risks.

METHODS

We examine the role of neighbourhood socio-economic disadvantage, demography and testing practices on spatial patterns in CDI incidence in the Australian Capital Territory (ACT). Data on all tests conducted for CDI, including postcode of residence, were obtained from January 2004-December 2014. Distribution of age groups and the neighbourhood Index of Relative Socio-economic Advantage Disadvantage (IRSAD) were obtained from the Australian Bureau of Statistics 2011 National Census data. A Bayesian spatial conditional autoregressive model was fitted at the postcode level to quantify the relationship between CDI and socio-demographic factors. To identify CDI hotspots, exceedance probabilities were set at a threshold of twice the estimated relative risk.

RESULTS

After controlling for spatial patterns in testing practices, area-level socio-economic advantage (IRSAD) (RR = 0.74, 95% CI 0.57, 0.94) was inversely associated with CDI. Three postcodes had a high probability (0.8-1.0) of excess risk of diagnosed CDI.

CONCLUSION

We demonstrate geographic variations in CDI in the ACT with a positive association of CDI with neighbourhood socioeconomic disadvantage and identify areas with a high probability of elevated risk compared with surrounding communities. These findings provide further evidence to inform a targeted response to reduce CDI risk.

Seasonality of Clostridium difficile in the natural environment

Clostridium difficile is considered the leading cause of antibiotic-associated disease worldwide. In the past decade, a large number of studies have focused on identifying the main sources of contamination in order to elucidate the complete life cycle of the infection. Hospitals, animals and retail foods have been considered as potential vectors. However, the prevalence of C. difficile in these types of samples was found to be rather low, suggesting that other contamination routes must exist. This study explores the presence of C. difficile in the natural environment and the seasonal dynamics of the bacterium. C. difficile was isolated from a total of 45 samples out of 112 collected (40.2%) on 56 sampling points. A total of 17 points were positive only during the winter sampling (30.4%), 10 were positive only during the summer sampling (17.9%) and 9 sampling points (16.1%) were positive in both summer sampling and winter sampling. Spore counts in soil samples ranged between 50 and 250 cfu/g for 24.4% of the positive samples, with the highest concentrations detected in samples collected in the forest during winter campaign (200-250 cfu/g). A total of 17 different PCR ribotypes were identified, and 15 of them had the genes coding for toxins A and B. Most of those ribotypes had not previously been found or had been isolated only sporadically (<1% of samples) from hospitals in Belgium. Regarding antimicrobial susceptibility, most of the resistant strains were found during the summer campaign. These findings bear out that C. difficile is present in the natural environment, where the bacterium undergoes seasonal variations.

Status of vaccine research and development for Clostridium difficile

Clostridium difficile associated disease is fundamentally associated with dysbiosis of the gut microbiome as a consequence of antibiotic use. This is because this sporulating, obligate anaerobe germinates and proliferates rapidly in the dysbiotic gut, which is an indirect consequence of their use. During its growth, C. difficile produces two toxins, toxin A (TcdA) and toxin B (TcdB), which are responsible for the majority of clinical symptoms associated with the disease. Three parenterally delivered vaccines, based on detoxified or recombinant forms of these toxins, have undergone or are undergoing clinical trials. Each offers the opportunity to generate high titres of toxin neutralising antibodies. Whilst these data suggest these vaccines may reduce primary symptomatic disease, they do not in their current form reduce the capacity of the organism to persist and shed from the vaccinated host. The current progress of vaccine development is considered with advantages and limitations of each highlighted. In addition, several alternative approaches are described that seek to limit C. difficile germination, colonisation and persistence. It may yet prove that the most effective treatments to limit infection, disease and spread of the organism will require a combination of therapeutic approaches. The potential use and efficacy of these vaccines in low and middle income countries will be depend on the development of a cost effective vaccine and greater understanding of the distribution and extent of disease in these countries.

ASID/ACIPC position statement - Infection control for patients with Clostridium difficile infection in healthcare facilities

BACKGROUND

In 2011, the Australasian Society for Infectious Diseases (ASID) and the Australian Infection Control Association (AICA), now known as the Australasian College of Infection Prevention and Control (ACIPC), produced a position statement on infection control requirements for preventing and controlling Clostridium difficile infection (CDI) in healthcare settings.

METHODS

The statement updated in 2017 to reflect new literature available .The authors reviewed the 2011 position statement and critically appraised new literature published between 2011 and 2017 and relevant current infection control guidelines to identify where new evidence had become available or best practice had changed.

RESULTS

The position statement was updated incorporating the new findings. A draft version of the updated position statement was circulated for consultation to members of ASID and ACIPC. The authors responded to all comments received and updated the position statement.

CONCLUSIONS

This updated position statement emphasizes the importance of health service organizations having evidence-based infection prevention and control programs and comprehensive antimicrobial stewardship programs, to ensure the risk of C. difficile acquisition, transmission and infection is minimised.

Clostridium difficile-related hospitalizations and risk factors for in-hospital mortality in Spain between 2001 and 2015

AIMS

To examine trends in the incidence, characteristics and in-hospital outcomes of Clostridium difficile infection (CDI) hospitalizations from 2001 to 2015, to compare clinical variables among patients according to the diagnosis position (primary or secondary) of CDI, and to identify factors associated with in-hospital mortality (IHM).

METHODS

A retrospective study was performed using the Spanish National Hospital Discharge Database, 2001-2015. The study population included patients who had CDI as the primary or secondary diagnosis in their discharge report. Annual hospitalization rates were calculated and trends were assessed using Poisson regression models and Jointpoint analysis. Multi-variate logistic regression models were performed to identify variables associated with IHM.

FINDINGS

In total, 49,347 hospital discharges were identified (52.31% females, 33.69% with CDI as the primary diagnosis). The rate of hospitalization increased from 3.9 cases per 100,000 inhabitants in 2001-2003 to 12.97 cases per 100,000 inhabitants in 2013-2015. Severity of CDI and mean cost per patient increased from 6.36% and 3750.11€ to 11.19% and 4340.91€, respectively, while IHM decreased from 12.66% to 10.66%. Age, Charlson Comorbidity Index, severity, length of hospital stay and mean cost were significantly higher in patients with a primary diagnosis of CDI. Irrespective of the CDI diagnosis position, IHM was associated with male sex, older age, comorbidities, readmission and severity of CDI. Primary diagnosis of CDI was associated with lower IHM (odds ratio 0.60; 95% confidence interval 0.56-0.65).

CONCLUSION

CDI-related hospitalization rates are increasing, leading to a high cost burden, although IHM has decreased in recent years. Factors associated with IHM should be considered in strategies for the prevention and management of CDI.

Increasing rates of Clostridium difficile infection in Mexican hospitals

Introduction

The epidemiology of Clostridium difficile infection (CDI) has changed in the last two decades. There is a lack of information regarding incidence and severity of CDI, especially in the developing world.

Methods

This was a retrospective and observational study from four hospitals of three Mexican cities. Patients were diagnosed with CDI when presented with loose stools and had at least one of the following tests positive: toxins assay, real-time PCR, or an endoscopic image compatible with pseudomembranous colitis. CDI was classified according to international guidelines. Demographic and clinical data as well as information regarding total hospital admissions, total length-of-hospital stay, and other variables related to hospitalization were gathered from the epidemiology and administration departments of each hospital.

Results

A total of 2050 hospital beds were analyzed with 288,171 patients hospitalized accumulating 1,576,446 days of hospitalization during the study period. The average rate of CDI per 1000 hospital-days was lower than the rates reported in the US and Europe, although in 2015 CDI rates were almost persistently above the mean rate for the study period. More than half of PCR positive patients were ribotype 027.

Conclusion

Hospital rates of CDI are increasing in Mexican hospitals with a predominance of infections caused by ribotype 027.

Use of antibiotics and the prevalence of antibiotic-associated diarrhoea in patients with spinal cord injuries: an international, multi-centre study

BACKGROUND

Little is known about the use of antibiotics and the extent of antibiotic-associated diarrhoea (AAD) in patients with spinal cord injuries (SCIs).

AIMS

To record the use of antibiotics, establish the prevalence of AAD and Clostridium difficile infection (CDI), and assess if there was any seasonal variation in antibiotic use and incidence of AAD in patients with SCIs.

METHODS

A retrospective study was conducted in six European SCI centres between October 2014 and June 2015. AAD was defined as two or more watery stools (Bristol Stool Scale type 5, 6 or 7) over 24 h.

FINDINGS

In total, 1267 adults (median age 54 years, 30.7% female) with SCIs (52.7% tetraplegia, 59% complete SCI) were included in this study. Among the 215 (17%) patients on antibiotics, the top three indications for antibiotics were urinary tract infections (UTIs), infected pressure ulcers and other skin infections. Thirty-two of these 215 (14.9%) patients developed AAD and two patients out of the total study population (2/1267; 0.16%) developed CDI. AAD was more common in summer than in spring, autumn or winter (30.3% vs 3.8%, 7.4% and 16.9%, respectively; P<0.01). AAD was associated with age ≥65 years, tetraplegia, higher body mass index, hypoalbuminaemia, polypharmacy, multiple antibiotic use and high-risk antibiotic use. Summer and winter seasons and male sex were identified as independent predictors for the development of AAD.

CONCLUSION

This survey found that AAD is common in patients with SCIs, and UTI is the most common cause of infection. Summer and winter seasons and male sex are unique predictors for AAD. Both AAD and UTIs are potentially preventable; therefore, further work should focus on preventing the over-use of antibiotics, and developing strategies to improve hospital infection control measures.

Risks factors and outcomes of Clostridium difficile infection in patients with cancer: a matched case-control study

PURPOSE

Clostridium difficile infection (CDI) is the leading cause of diarrhoea in hospitalised patients. Cancer populations are at high-risk for infection, but comprehensive evaluation in the current era of cancer care has not been performed. The objective of this study was to describe characteristics, risk factors, and outcomes of CDI in cancer patients.

METHODS

Fifty consecutive patients with CDI at a large Australian cancer centre (2013-2015) were identified from the hospital pathology database. Each case was matched by ward and hospital admission date to three controls without toxigenic CDI. Treatment and outcomes of infection were evaluated and potential risk factors were analysed using conditional logistic regression.

RESULTS

Patients with CDI had a mean age of 59.7 years and 74% had an underlying solid tumour. Healthcare-associated infection comprised 80% of cases. Recurrence occurred in 10, and 12% of cases were admitted to ICU within 30 days. Severe or severe-complicated infection was observed in 32%. Independent risk factors for infection included chemotherapy (odds ratio (OR) 3.82, 95% CI 1.67-8.75; p = 0.002), gastro-intestinal/abdominal surgery (OR 4.64, 95% CI 1.20-17.91; p = 0.03), proton pump inhibitor (PPI) therapy (OR 2.47, 95% CI 1.05-5.80; p = 0.04), and days of antibiotic therapy (OR 1.04, 95% CI 1.01-1.08; p = 0.02).

CONCLUSIONS

Severe or complicated infections are frequent in patients with cancer who develop CDI. Receipt of chemotherapy, gastro-intestinal/abdominal surgery, PPI therapy, and antibiotic exposure contribute to infection risk. More effective CDI therapy for cancer patients is required and dedicated antibiotic stewardship programs in high-risk cancer populations are needed to ameliorate infection risk.

The epidemiology of Clostridium difficile infection in patients with cancer

INTRODUCTION

Clostridium difficile infection (CDI) is a significant cause of healthcare-associated diarrhoea, and the emergence of endemic strains resulting in poorer outcomes is recognised worldwide. Patients with cancer are a specific high-risk group for development of infection. Areas covered: In this review, modifiable and non-modifiable risk factors for CDI in adult patients with haematological malignancy or solid tumours are evaluated. In particular, the contribution of antimicrobial exposure, hospitalisation and gastric acid suppression to risk of CDI are discussed. Recent advances in CDI treatment are outlined, namely faecal microbiota transplantation and fidaxomicin therapy for severe/refractory infection in cancer populations. Outcomes of CDI, including mortality are presented, together with the need for valid severity rating tools customised for cancer populations. Expert commentary: Future areas for research include the prognostic value of C. difficile colonisation in cancer patients and the potential impact of dedicated antimicrobial stewardship programs in reducing the burden of CDI in cancer units.

Asymptomatic Clostridium difficile colonization in two Australian tertiary hospitals, 2012-2014: prospective, repeated cross-sectional study

OBJECTIVES

To investigate the prevalence and risk factors for asymptomatic toxigenic (TCD) and nontoxigenic Clostridium difficile (NTCD) colonization in a broad cross section of the general hospital population over a 3-year period.

METHODS

Patients without diarrhoea admitted to two Australian tertiary hospitals were randomly selected through six repeated cross-sectional surveys conducted between 2012 and 2014. Stool specimens were cultured under anaerobic conditions, and C. difficile isolates were tested for the presence of toxin genes and ribotyped. Patients were then grouped into noncolonized, TCD colonized or NTCD colonized for identifying risk factors using multinomial logistic regression models.

RESULTS

A total of 1380 asymptomatic patients were enrolled; 76 patients (5.5%) were TCD colonized and 28 (2.0%) were NTCD colonized. There was a decreasing annual trend in TCD colonization, and asymptomatic colonization was more prevalent during the summer than winter months. TCD colonization was associated with gastro-oesophageal reflux disease (relative risk ratio (RRR) = 2.20; 95% confidence interval (CI) 1.17-4.14), higher number of admissions in the previous year (RRR = 1.24; 95% CI 1.10-1.39) and antimicrobial exposure during the current admission (RRR = 2.78; 95% CI 1.23-6.28). NTCD colonization was associated with chronic obstructive pulmonary disease (RRR = 3.88; 95% CI 1.66-9.07) and chronic kidney failure (RRR = 5.78; 95% CI 2.29-14.59). Forty-eight different ribotypes were identified, with 014/020 (n = 23), 018 (n = 10) and 056 (n = 6) being the most commonly isolated.

CONCLUSIONS

Risk factors differ between patients with asymptomatic colonization by toxigenic and nontoxigenic strains. Given that morbidity is largely driven by toxigenic strains, this novel finding has important implications for disease control and prevention.