Abstract
Keywords
Introduction
In recent years, tremendous efforts have been directed at curbing healthcare-associated CDI worldwide. The Centers for Disease Control (CDC) in the United States launched its
Community-acquired CDI
Rising incidence over the past decade
According to recent guidelines from the Society for Healthcare Epidemiology of America released in 2018, CDI cases are categorized as community associated (CA-CDI) if patients experienced diarrhea onset in the community or within 48 h after hospitalization and had not been discharged from a healthcare facility in the prior 12 weeks.
1
The population-based CA-CDI incidence was reported to be 20–40 per 100,000 people between 2005 and 2006, before more sensitive nucleic acid amplification tests for

Estimated national burden of total
The uptick of CA-CDI is consistent with previous studies in different regions in North America (Table 1).7,9 In a retrospective multicenter cohort study from 43 hospitals in Georgia, Florida, North Carolina, South Carolina, Virginia, and West Virginia, CA-CDI increased from 48.5% to 61.0% of all CDI cases.10,11 CA-CDI has also led to increasing hospitalizations in the United States, from 17.1 per 100,000 persons in 2011 to 21.7 per 100,000 persons in 2017. In contrast, healthcare-associated CDI (HA-CDI) hospitalizations have been declining (60.7 per 100,000 persons to 47.9 per 100,000 persons in 2017). 6 In Canada, CA-CDI has also increased in Quebec (from 0.51 to 0.69 per 100,000 population between 2008 and 2015) and Ontario (from 6.09 to 9.56 cases per 100,000 person-years between 2005 and 2015) during the overlapping time period while total CDI cases in the nation decreased.12–14
Comparison of total
Global CA-CDI trends vary considerably when compared with the United States and Canada. During 2006 and 2017, the reported proportion of CA-CDI varied between 10.9% and 43.0% of all CDI cases in Japan, Italy, and Australia.5,12,15–17 The global discrepancy likely lies in surveillance methods. Cases of CA-CDI tend to be lower using hospital-based surveillance while reaching nearly 50% with population-based surveillance, given that nearly 75% of patients with CA-CDI are treated as outpatients.7,17 The worldwide burden of CDI in the community warrants further investigation.
Risk factors and mortality for CA-CDI
Patients diagnosed with CA-CDI tend to be younger with a significant proportion of patients (36%) reporting no antibiotic exposure during the 12 weeks prior to diagnosis (Table 2).1,9 In a population study by Khanna
A comparison of risk factors and other characteristics in healthcare-associated
Antibiotic use has long been associated with increased risks of CDI [odds ratio (OR) 3.55, 2.56–4.94].
22
As mentioned earlier, a larger portion of patients had no prior exposure to antibiotics in CA-CDI compared with HA-CDI. In a meta-analysis in the United States and a retrospective study in Britain, the proportions of CA-CDI patients without antibiotic exposure are approximately 21%–38%, compared with 6%–20.3% in HA-CDI.11,17,23 In terms of the classes of antibiotics, Brown
Among the medications that are suspected culprits for increasing risk for CDI, proton pump inhibitors (PPIs) have drawn extensive scrutiny. However, the association of PPIs in CA-CDI specifically has not been well studied. In a large prospective study from 2009 to 2011 of 984 patients with CA-CDI in eight US states, 31% of patients without prior antibiotic exposure reported PPI use. 17 In a case-control study of CA-CDI cases in a registry in United Kingdom between 1994 and 2004, exposure to PPI during the 90 days before index date was correlated with increased risk of CA-CDI with an OR of 3.5. 28 However, while these studies suggest an association with PPI, there is a need for further, large-scale studies to better understand the relationship between PPI and CA-CDI.
Multiple chronic medical conditions have been associated with increased risk of CA-CDI, including cardiac disease (OR 4.87), chronic kidney disease (OR 12.12) and inflammatory bowel disease (IBD) (OR 5.13).
29
Among these, interest has grown in particular on exploring the relationship between IBD and development of CDI.
1
A population-based study of an IBD registry in Manitoba between 2005 and 2014 found the incidence of CDI to be 512 per 100,000 person-years for ulcerative colitis, 377 for Crohn’s Disease, and 99 for non-IBD patients.
30
Importantly, it is unclear if some of these patients may be colonized with
Community reservoirs, strain types and colonization
As the majority of patients with CA-CDI have no prior hospital or antibiotic exposure, multiple studies have attempted to elucidate possible routes of transmission. It has been proposed that many
In addition to community reservoirs, several studies have employed sequencing to determine if particular
Real-world CDI transmission rates outside of healthcare facilities remains an understudied epidemiologic question. In a study using a Markov model built with data extracted from national databases, the transmission rate from a person with CDI to an uncolonized individual in the community was estimated to be 0.1% compared with 0.05% from an asymptomatic colonized person to an uncolonized one. An uncolonized person was estimated to have a probability of 0.12% per day of acquiring CDI in the community, compared with 2.3% in the hospital and 0.37% in a long-term care facility. 49 Despite these findings, the proportion of CA-CDI is rising, and the growing pool of colonized individuals is likely contributing. Future epidemiologic studies will be crucial to understand the mechanisms of community transmission to mitigate its spread.
Recurrent C. difficile infections
CDI recurrence is defined as symptom onset and positive assay result following interim resolution of symptoms with standard of care treatment of a primary episode in the previous 2–8 weeks.
1
However, given that several testing methods are used for clinical detection, reported incidences may not accurately reflect true infections (Supplemental Table 1). PCR tests do not differentiate
Relapse and reinfection
Recurrent CDI cases can be subdivided into relapse and reinfection. A relapse originates from the same strain as the initial infection, while reinfection is caused by a new strain (Table 2). Accurate classification between the two allows for rigorous evaluation of risk factors and treatment effectiveness. Several studies have sought to characterize the epidemiology of relapse
Early versus delayed recurrence
There are limited data comparing the rates of early
Risk factors for CDI recurrence
Several risk factors have been identified for rCDI including host factors such as demographics, comorbidities, previous episodes of CDI, as well as medications and environmental factors. In general, older age and female gender have been associated with increased risk for recurrent infections.20,21,54 A meta-analysis showed that age >65 years is an independent risk factor for rCDI (relative risk 1.63). 56 Multiple retrospective studies and cohort studies in North America have shown that women are at increased risk for rCDI compared with men.20,53 Medical conditions such as chronic renal insufficiency (OR 1.59), immunosuppression (OR 9.64) and IBD (HR 1.63) increase the risk of recurrence as well.15,20,57,58 The potential mechanisms of how each of these conditions and others increase risk of rCDI is beyond the scope of this review. A prior history of CDI also increases risk of rCDI episodes, with studies showing that 20% of patients recur after a single episode, 40% after two episodes and 65% after three episodes.52,56,59
Certain medications are associated with increased risk of rCDI. Conflicting data exist on the role of PPI in rCDI. A strong association between PPIs and rCDI was observed in a retrospective study of 45,341 patients with CDI in the United States (OR 1.14). 20 A similar correlation was found in a prospective study (OR 3.75). 60 However, a 6-year retrospective study in Italy did not find a significant correlation between PPI use and increased risk for recurrence (OR 0.94, CI 0.23–3.85). 15 Corticosteroids (OR 1.15) and antibiotics other than those used for CDI treatment (OR 1.79) have also been associated with recurrent infections. 20
Apart from host factors, many studies have examined if specific strains are associated with increased recurrence. Ribotype 027 has been associated with recurrent infections in cohort studies in the United States and the Netherlands.21,54 Infection with other ribotypes, such as F014-020, were more commonly seen in patients with a single episode of CDI. 61 Several other ribotypes are associated with recurrent diseases in other regions (such as ribotype 001 in Sweden and ribotype 014/020 in West Australia).18,62 The presence of multiple strains during the first CDI episode may also be a risk factor for recurrence. 61
Mortality in CDI recurrence
There are conflicting reports regarding mortality associated with rCDI. In a study of inpatient hospitalizations between 2003 and 2009 at one academic tertiary care center, rCDI was associated with a 33% increased risk of mortality at 180 days compared with patients who do not experience a recurrence.
63
However, more recent studies have shown a lower mortality rate in rCDI compared with the initial infection. In a retrospective study of the US veteran population from 2003 to 2014, 30-, 60- and 90-day mortality rates were significantly lower in first CDI recurrence as well as in second recurrence compared with the primary episode (
Treatment for rCDI
Treatment regimens for rCDI vary depending on the number of recurrences and severity of the current episode. For nonfulminant recurrent episodes, vancomycin pulsed taper or fidaxomicin are the recommended antibiotic therapies. Crook
FMT has garnered strong interest for its potential in prevention of CDI recurrence. In a recent small randomized study comparing FMT, fidaxomicin and vancomycin for the treatment of rCDI, significantly more patients who underwent FMT remained symptom-free at 8 weeks post-treatment (
Bezlotoxumab, a monoclonal antibody against
COVID-19 and CDI
Lastly, there have been ongoing efforts to monitor the trend of CDI during the COVID-19 pandemic. The published data so far showed that there has not been an increase in the rate of CDI despite rising high-risk antibiotic exposures because of COVID-19.72,73 In some centers, there has been a reduction in HA-CDI cases.74,75 Multiple factors potentially contributed to the decrease. Among them, one important aspect has been improved infection prevention measures such as higher compliance in hand hygiene and isolation precautions.74,76 Only one small study specifically commented on CA-CDI
Conclusion
Despite an overall decrease in CDI rates worldwide in the last decade, community-associated cases are increasing while the rates of recurrence of CDI are steady. CA-CDI accounts for almost 48% of annual cases in the United States and ranges from 10% to 43% of total cases across global regions. Continued efforts directed at improving disease detection and tracking are needed to help identify community reservoirs and understand patterns of transmission. While rCDI cases have decreased in the United States, rCDI remains a leading cause of significant healthcare morbidity and global economic burden. Importantly, the risk factors and disease characteristics of CA-CDI and rCDI differ regionally, calling for rigorous future investigations of various host factors, pathogen ribotypes, local reservoirs and transmission vectors specific to each region. Standardization of laboratory testing for the detection of CDI is critical to accurately characterize true infections
Supplemental Material
sj-docx-1-tag-10.1177_17562848211016248 – Supplemental material for Epidemiology of community-acquired and recurrent Clostridioides difficile infection
Supplemental material, sj-docx-1-tag-10.1177_17562848211016248 for Epidemiology of community-acquired and recurrent
Footnotes
Conflict of interest statements
Funding
Supplemental material
References
Supplementary Material
Please find the following supplemental material available below.
For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.
For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.
