Risk for Asymptomatic Household Transmission of Clostridioides difficile Infection Associated with Recently Hospitalized Family Members

Evaluating the risk of Clostridioides difficile infection from toilet flushing: a quantitative microbial risk assessment and implications for infection control

BACKGROUND

Despite stringent infection control measures, Clostridioides difficile infection (CDI) remains a challenge in healthcare settings, partly due to overlooked transmission vectors such as toilet plume bioaerosols.

AIM

To systematically quantify the risks associated with CDI transmission via toilet flushing and provide critical insights to inform CDI preventive strategies.

METHODS

Impaction sampling was used to quantify airborne C. difficile post-flush and high-contact surfaces were swabbed to assess contamination levels, in a controlled toilet environment. A quantitative microbial risk assessment (QMRA) approach was then used to estimate the risk to subsequent users from contamination by a previously colonized individual.

FINDINGS

A single flush can release C. difficile into the air, with bioaerosol concentrations up to 29.50 ± 10.52 cfu/m3 and deposit about 8-11 cfu on immediate surfaces. Despite a 4.4 log reduction in bacterial concentration within the toilet bowl post-flush, bacteria persist on its inner walls. Relative humidity increases by approximately 31.28% within the first 10 min post-flush, potentially enhancing the viability and transmission of aerosolized C. difficile. The flush button contact and inhalation-followed-by-ingestion in frequent-use hospital settings present the highest risks and exceed US EPA and WHO acceptable infection risk thresholds.

CONCLUSION

The findings of this study necessitate a review of current toilet designs, public health policies and facility management practices to mitigate the overlooked risks of CDI transmission through toilet plume bioaerosols in healthcare settings. Additionally, this study lays a foundation for developing evidence-based interventions aimed at achieving substantial behavioural and infrastructural changes in infection control practices.

Diverse Sources and Latent Reservoirs of Community-Associated Clostridioides difficile Infection

Clostridioides difficile is a spore-forming, toxin-producing, anaerobic bacterium that infects the human gastrointestinal tract, causing diarrhea and life-threatening colitis. Clostridioides difficile epidemiology continues to evolve, and it is recognized as a major community-associated (CA) pathogen in addition to its established role in causing healthcare-associated (HA) infection. While current surveillance and prevention measures mainly focus on healthcare-associated C. difficile infections (HA-CDI), much less is known about the factors that drive CA-CDI. This review highlights the potential contribution of reservoirs, including asymptomatic carriers, to CA C. difficile transmission. The reservoirs discussed in this review provide potential avenues for research to better understand and reduce CA transmission of C. difficile.

Hospitalizations among family members increase the risk of MRSA infection in a household

OBJECTIVE

Estimate the risk for household transmission of Methicillin-Resistant Staphylococcus aureus (MRSA) following exposure to infected family members or family members recently discharged from a hospital.

DESIGN

Analysis of monthly MRSA incidence from longitudinal insurance claims using the Merative MarketScan Commercial and Medicare (2001-2021) databases.

SETTING

Visits to inpatient, emergency department, and outpatient settings.

PATIENTS

Households with ≥2 family members enrolled in the same insurance plan for the entire month.

METHODS

We estimated a monthly incidence model, where enrollees were binned into monthly enrollment strata defined by demographic, patient, and exposure characteristics. Monthly incidence within each stratum was computed, and a regression analysis was used to estimate the incidence rate ratio (IRR) associated with household exposures of interest while accounting for potential confounding factors.

RESULTS

A total of 157,944,708 enrollees were included and 424,512 cases of MRSA were identified. Across all included enrollees, exposure to a family member with MRSA in the prior 30 days was associated with significantly increased risk of infection (IRR: 71.03 [95% CI, 67.73-74.50]). After removing enrollees who were hospitalized or exposed to a family member with MRSA, exposure to a family member who was recently discharged from the hospital was associated with increased risk of infection (IRR: 1.44 [95% CI, 1.39-1.49]) and the risk of infection increased with the duration of the family member's hospital stay (P value < .001).

CONCLUSIONS

Exposure to a recently hospitalized and discharged family member increased the risk of MRSA infection in a household even when the hospitalized family member was not diagnosed with MRSA.

The Increase in Household Transmission of Pertussis Associated With Diagnostic Delays

BACKGROUND

Pertussis is a highly contagious respiratory illness that can be especially dangerous to young children. Transmission of pertussis often occurs in household settings and is impacted by the timing of treatment and postexposure chemoprophylaxis. This study analyzes the risk for secondary household transmission and if delays in diagnosing pertussis increased the risk for household transmission.

METHODS

We conducted 2 population-based studies using a large nationally representative administrative claims database. The first study utilized a stratified monthly incidence model to compare the incidence of pertussis among enrollees exposed to a family member with pertussis versus those not exposed. The second study was conducted at a household level following the index case of pertussis in each household. We identified diagnostic delays in the initial household case and used a logistic regression model to evaluate if such delays were associated with a greater risk for transmission.

RESULTS

The incidence rate ratio of pertussis was 938.99 [95% confidence interval (CI): 880.19-1001.73] among enrollees exposed to a family member with pertussis relative to those not exposed. The odds of secondary household transmission in households where the index case experienced a diagnostic delay was 5.10 (CI: 4.44-5.85) times the odds of transmission when the index case was not delayed. We found that longer delays were associated with a greater risk for secondary household transmission ( P < 0.0001).

CONCLUSIONS

There is a high rate of secondary transmission of pertussis in household settings. Diagnostic delays increase the likelihood that pertussis will transmit in the household.

Molecular Epidemiology of Clostridioides difficile Colonization in Families With Infants

Background

Community-associated Clostridioides difficile infection is a major public health hazard to adults and older children. Infants frequently excrete toxigenic C difficile asymptomatically in their stool, but their importance as a community reservoir of C difficile is uncertain.

Methods

Families of healthy infants were recruited at the baby's 4-month well child visit and were followed longitudinally until the baby was approximately 9 months old. Babies and mothers submitted stool or rectal swabs every 2 weeks that were cultivated for C difficile; fathers' participation was encouraged but not required. Clostridioides difficile isolates were strain-typed by fluorescent polymerase chain reaction ribotyping and by core genome multilocus sequence typing, and the number of families in whom the same strain was cultivated from >1 family member ("strain sharing") was assessed.

Results

Thirty families were enrolled, including 33 infants (3 sets of twins) and 30 mothers; 19 fathers also participated. Clostridioides difficile was identified in 28 of these 30 families over the course of the study, and strain sharing was identified in 17 of these 28. In 3 families, 2 separate strains were shared. The infant was involved in 17 of 20 instances of strain sharing, and in 13 of these, the baby was identified first, with or without a concomitantly excreting adult. Excretion of shared strains usually was persistent.

Conclusions

Clostridioides difficile strain sharing was frequent in healthy families caring for an infant, increasing the likelihood that asymptomatically excreting babies and their families represent a reservoir of the organism in the community.

Improving Risk Prediction of Methicillin-Resistant Staphylococcus aureus Using Machine Learning Methods With Network Features: Retrospective Development Study

BACKGROUND

Health care-associated infections due to multidrug-resistant organisms (MDROs), such as methicillin-resistant Staphylococcus aureus (MRSA) and Clostridioides difficile (CDI), place a significant burden on our health care infrastructure.

OBJECTIVE

Screening for MDROs is an important mechanism for preventing spread but is resource intensive. The objective of this study was to develop automated tools that can predict colonization or infection risk using electronic health record (EHR) data, provide useful information to aid infection control, and guide empiric antibiotic coverage.

METHODS

We retrospectively developed a machine learning model to detect MRSA colonization and infection in undifferentiated patients at the time of sample collection from hospitalized patients at the University of Virginia Hospital. We used clinical and nonclinical features derived from on-admission and throughout-stay information from the patient's EHR data to build the model. In addition, we used a class of features derived from contact networks in EHR data; these network features can capture patients' contacts with providers and other patients, improving model interpretability and accuracy for predicting the outcome of surveillance tests for MRSA. Finally, we explored heterogeneous models for different patient subpopulations, for example, those admitted to an intensive care unit or emergency department or those with specific testing histories, which perform better.

RESULTS

We found that the penalized logistic regression performs better than other methods, and this model's performance measured in terms of its receiver operating characteristics-area under the curve score improves by nearly 11% when we use polynomial (second-degree) transformation of the features. Some significant features in predicting MDRO risk include antibiotic use, surgery, use of devices, dialysis, patient's comorbidity conditions, and network features. Among these, network features add the most value and improve the model's performance by at least 15%. The penalized logistic regression model with the same transformation of features also performs better than other models for specific patient subpopulations.

CONCLUSIONS

Our study shows that MRSA risk prediction can be conducted quite effectively by machine learning methods using clinical and nonclinical features derived from EHR data. Network features are the most predictive and provide significant improvement over prior methods. Furthermore, heterogeneous prediction models for different patient subpopulations enhance the model's performance.

Prevalence and risk factors of toxigenic Clostridioides difficile asymptomatic carriage in 11 French hospitals

Clostridioides difficile infection (CDI) incidence has increased over the last 20 years. Studies suggest that asymptomatic carriers may be an important reservoir of C. difficile in healthcare settings. We conducted a point prevalence study to estimate the toxigenic C. difficile asymptomatic carriage rate and the associated risk factors in patients >3 years old. Between September 16, 2019 and January 15, 2020, all patients hospitalized in 11 healthcare facilities in the Paris urban area were included in the study. They were screened on the day of the survey for toxigenic C. difficile carriage by rectal swab and interviewed. Isolates were characterized by PCR ribotyping and multiplex PCR targeting toxin genes. A logistic regression model was used to determine the risk factors associated with toxigenic C. difficile asymptomatic carriage using uni- and multivariate analysis in the subpopulation of patients >3 years old. During the study period, 2,389 patients were included and screened. The median age was 62 years (interquartile range 35-78 years) and 1,153 were male (48.3%). Nineteen patients had a previous CDI (0.9%). Overall, 185/2389 patients were positive for C. difficile (7.7%), including 93 toxigenic strains (3.9%): 77 (82.8%) were asymptomatic (prevalence 3.2%) whereas 12 (12.9%) were diarrheic. Prevalences of toxigenic C. difficile were 3.5% in patients >3 years old and 7.0% in ≤3 years old subjects, respectively. Toxigenic strains mainly belonged to PCR ribotypes 106 (n = 14, 15.0%), 014 (n = 12, 12.9%), and 020 (n = 10, 10.8%). Among toxigenic strains, 6 (6.4%) produced the binary toxin. In multivariate analysis, two factors were positively associated with toxigenic C. difficile asymptomatic carriage in patients >3 years old: multidrug-resistant organisms co-carriage [adjusted Odd Ratio (aOR) 2.3, CI 95% 1.2-4.7, p = 0.02] and previous CDI (aOR 5.8, CI 95% 1.2-28.6, p = 0.03). Conversely, consumption of raw milk products were associated with reduced risk of toxigenic C. difficile colonization (aOR 0.5, CI 95% 0.2-0.9, p = 0.01). We showed that there was a low prevalence of asymptomatic toxigenic C. difficile carriage in hospitalized patients. Consumption of raw milk prevents toxigenic C. difficile colonization, probably due to the barrier effect of milk-associated bacteria.

Microbiome-Related and Infection Control Approaches to Primary and Secondary Prevention of Clostridioides difficile Infections

Clostridioides difficile infections (CDIs) have decreased in the past years, but since 2021, some hospitals have reported an increase in CDI rates. CDI remains a global concern and has been identified as an urgent threat to healthcare. Although multiple treatment options are available, prevention strategies are more limited. As CDI is an opportunistic infection that arises after the normally protective microbiome has been disrupted, preventive measures aimed at restoring the microbiome have been tested. Our aim is to update the present knowledge on these various preventive strategies published in the past five years (2018-2023) to guide clinicians and healthcare systems on how to best prevent CDI. A literature search was conducted using databases (PubMed, Google Scholar, and clinicaltrials.gov) for phase 2-3 clinical trials for the primary or secondary prevention of CDI and microbiome and probiotics. As the main factor for Clostridium difficile infections is the disruption of the normally protective intestinal microbiome, strategies aimed at restoring the microbiome seem most rational. Some strains of probiotics, the use of fecal microbial therapy, and live biotherapeutic products offer promise to fill this niche; although, more large randomized controlled trials are needed that document the shifts in the microbiome population.

Infrequent intrahousehold transmission of Clostridioides difficile between pet owners and their pets

Companion animals have been shown to carry Clostridioides difficile strains that are similar or identical to strains found in people, and a small number of studies have shown that pets carry genetically identical C. difficile isolates as their owners, suggesting inter-species transmission. However, the directionality of transmission is ultimately unknown, and the frequency with which animals acquire C. difficile following their owners' infection is unclear. The goal of this study was to assess how often pets belonging to people with C. difficile infection carry genetically related C. difficile isolates. We enrolled pet owners from two medical institutions (University of Pennsylvania Health System (UPHS) and The Ohio State University Wexner Medical Center (OSUWMC)) who had diarrhoea with or without positive C. difficile assays and tested their faeces and their pets' faeces for C. difficile using both anaerobic culture and PCR assays. When microorganisms were obtained from both the owner and pet and had the same toxin profile or ribotype, isolates underwent genomic sequencing. Faecal samples were obtained from a total of 59 humans, 72 dogs and 9 cats, representing 47 complete households (i.e. where a sample was available from the owner and at least one pet). Of these, C. difficile was detected in 30 humans, 10 dogs and 0 cats. There were only two households where C. difficile was detected in both the owner and pet. In one of these households, the C. difficile isolates were of different toxin profiles/ribotypes (A+/B+ / RT 499 from the owner, A-/B- / RT PR22386 from the dog). In the other household, the isolates were genetically identical (one SNP difference). Interestingly, the dog from this household had recently received a course of antibiotics (cefpodoxime and metronidazole). Our findings suggest that inter-species transmission of C. difficile occurs infrequently in households with human C. difficile infections.

Molecular epidemiology of community- and hospital-associated Clostridioides difficile infections in Jönköping, Sweden, October 2017 - March 2018

Clostridioides difficile infections (CDIs) in Sweden are mostly hospital-associated (HA) with limited knowledge regarding community-associated (CA) infections. Here, we investigated the molecular epidemiology of clinical isolates of CA-CDI and HA-CDI in a Swedish county. Data and isolates (n = 156) of CDI patients (n = 122) from Jönköping county, October 2017-March 2018, were collected and classified as CA (without previous hospital care or onset ≤2 days after admission or >12 weeks after discharge from hospital) or HA (onset >3 days after hospital admission or within 4 weeks after discharge). Molecular characterization of isolates included PCR ribotyping (n = 156 isolates) and whole genome sequencing with single nucleotide polymorphisms (SNP) analysis (n = 53 isolates). We classified 47 patients (39%) as CA-CDI and 75 (61%) as HA-CDI. Between CA-CDI and HA-CDI patients, we observed no statistically significant differences regarding gender, age, 30-day mortality or recurrence. Ribotype 005 (RR 3.1; 95% CI: 1.79-5.24) and 020 (RR 2.5; 95% CI: 1.31-4.63) were significantly associated with CA-CDI. SNP analysis identified seven clusters (0-2 SNP difference) involving 17/53 isolates of both CA-CDI and HA-CDI. Molecular epidemiology differed between CA-CDI and HA-CDI and WGS analysis suggests transmission of CDI within and between hospitals and communities.