Clostridium Difficile Colonization in Hematopoietic Stem Cell Transplant Recipients: A Prospective Study of the Epidemiology and Outcomes Involving Toxigenic and Nontoxigenic Strains

Multiplexed Gastrointestinal PCR Panels for the Evaluation of Diarrhea in Hematopoietic Stem Cell Transplantation Recipients

Multiplexed gastrointestinal PCR panels (MGPPs) are frequently used to aid the diagnosis and management of diarrhea in hematopoietic stem cell transplantation (HCT) recipients. Many issues related to the optimal use of MGPPs in HCT patients remain to be clarified. We aimed to better define MGPP diagnostic and therapeutic stewardship in HCT recipients, including indications for and benefits of testing, optimal timing of tests, and interpretation of results. We retrieved 463 consecutive MGPPs ordered on 651 consecutive first HCT (312 allogeneic, 339 autologous) performed at our institution between June 2015 and June 2023. One hundred and sixteen of the 463 MGPPs (25%) identified at least 1 diarrheagenic pathogen, and 12 (3%) identified more than 1 diarrheagenic pathogen. A positive result was more likely if the test was ordered within 48 hours of a hospital admission (41%; 32 of 78) or as an outpatient (41%; 46 of 111) compared with evaluation of hospital-onset diarrhea (14%; 38 of 274). Among the positive results, the most frequent pathogens identified included Clostridioides difficile (64%), diarrheagenic Escherichia coli (20%), norovirus (9%), and adenovirus 40/41 (5%). Thirty-eight percent of the positive C. difficile MGPP determinations were associated with a positive test for toxin. In our allogeneic HCT cohort, 3% of MGPPs for hospital-onset diarrhea yielded an organism other than C. difficile. Fifty-six percent of positive and 14% of all submitted tests resulted in a change in treatment. For organisms other than C. difficile, only 1% of all tests and 5% of positive tests resulted in initiation of therapy. For patients at risk for acute graft-versus-host disease (aGVHD), a positive or negative MGPP result was not predictive of a new diagnosis of aGVHD in proximity to diarrhea onset. These results suggest that MGPP testing is most useful when performed at hospital admission or on an outpatient basis. Because MGPPs are sensitive and do not distinguish between colonization and causes of diarrhea, caution is needed when interpreting results, especially for toxin-negative C. difficile and diarrheagenic gram-negative organisms.

Clostridioides difficile infection: history, epidemiology, risk factors, prevention, clinical manifestations, treatment, and future options

SUMMARYClostridioides difficile infection (CDI) is one of the major issues in nosocomial infections. This bacterium is constantly evolving and poses complex challenges for clinicians, often encountered in real-life scenarios. In the face of CDI, we are increasingly equipped with new therapeutic strategies, such as monoclonal antibodies and live biotherapeutic products, which need to be thoroughly understood to fully harness their benefits. Moreover, interesting options are currently under study for the future, including bacteriophages, vaccines, and antibiotic inhibitors. Surveillance and prevention strategies continue to play a pivotal role in limiting the spread of the infection. In this review, we aim to provide the reader with a comprehensive overview of epidemiological aspects, predisposing factors, clinical manifestations, diagnostic tools, and current and future prophylactic and therapeutic options for C. difficile infection.

Genomic surveillance of Clostridioides difficile transmission and virulence in a healthcare setting

Clostridioides difficile infection (CDI) is a major cause of healthcare-associated diarrhea, despite the widespread implementation of contact precautions for patients with CDI. Here, we investigate strain contamination in a hospital setting and the genomic determinants of disease outcomes. Across two wards over 6 months, we selectively cultured C. difficile from patients (n = 384) and their environments. Whole-genome sequencing (WGS) of 146 isolates revealed that most C. difficile isolates were from clade 1 (131/146, 89.7%), while only one isolate of the hypervirulent ST1 was recovered. Of culture-positive admissions (n = 79), 19 (24%) patients were colonized with toxigenic C. difficile on admission to the hospital. We defined 25 strain networks at ≤2 core gene single nucleotide polymorphisms; two of these networks contain strains from different patients. Strain networks were temporally linked (P < 0.0001). To understand the genomic correlates of the disease, we conducted WGS on an additional cohort of C. difficile (n = 102 isolates) from the same hospital and confirmed that clade 1 isolates are responsible for most CDI cases. We found that while toxigenic C. difficile isolates are associated with the presence of cdtR, nontoxigenic isolates have an increased abundance of prophages. Our pangenomic analysis of clade 1 isolates suggests that while toxin genes (tcdABER and cdtR) were associated with CDI symptoms, they are dispensable for patient colonization. These data indicate that toxigenic and nontoxigenic C. difficile contamination persist in a hospital setting and highlight further investigation into how accessory genomic repertoires contribute to C. difficile colonization and disease.

IMPORTANCE

Clostridioides difficile infection remains a leading cause of hospital-associated diarrhea, despite increased antibiotic stewardship and transmission prevention strategies. This suggests a changing genomic landscape of C. difficile. Our study provides insight into the nature of prevalent C. difficile strains in a hospital setting and transmission patterns among carriers. Longitudinal sampling of surfaces and patient stool revealed that both toxigenic and nontoxigenic strains of C. difficile clade 1 dominate these two wards. Moreover, quantification of transmission in carriers of these clade 1 isolates underscores the need to revisit infection prevention measures in this patient group. We identified unique genetic signatures associated with virulence in this clade. Our data highlight the complexities of preventing transmission of this pathogen in a hospital setting and the need to investigate the mechanisms of in vivo persistence and virulence of prevalent lineages in the host gut microbiome.

A Systematic Literature Review on Risk Factors for and Timing of Clostridioides difficile Infection in the United States

INTRODUCTION

Clostridioides difficile infection (CDI) is a major public health threat. Up to 40% of patients with CDI experience recurrent CDI (rCDI), which is associated with increased morbidity. This study aimed to define an at-risk population by obtaining a detailed understanding of the different factors leading to CDI, rCDI, and CDI-related morbidity and of time to CDI.

METHODS

We conducted a systematic literature review (SLR) of MEDLINE (using PubMed) and EMBASE for relevant articles published between January 1, 2016, and November 11, 2022, covering the US population.

RESULTS

Of the 1324 articles identified, 151 met prespecified inclusion criteria. Advanced patient age was a likely risk factor for primary CDI within a general population, with significant risk estimates identified in nine of 10 studies. Older age was less important in specific populations with comorbidities usually diagnosed at earlier age, such as bowel disease and cancer. In terms of comorbidities, the established factors of infection, kidney disease, liver disease, cardiovascular disease, and bowel disease along with several new factors (including anemia, fluid and electrolyte disorders, and coagulation disorders) were likely risk factors for primary CDI. Data on diabetes, cancer, and obesity were mixed. Other primary CDI risk factors were antibiotics, proton pump inhibitors, female sex, prior hospitalization, and the length of stay in hospital. Similar factors were identified for rCDI, but evidence was limited. Older age was a likely risk factor for mortality. Timing of primary CDI varied depending on the population: 2-3 weeks in patients receiving stem cell transplants, within 3 weeks for patients undergoing surgery, and generally more than 3 weeks following solid organ transplant.

CONCLUSION

This SLR uses recent evidence to define the most important factors associated with CDI, confirming those that are well established and highlighting new ones that could help to identify patient populations at high risk.

Comparison of Clostridioides difficile nucleic acid amplification test (NAAT) results using fresh and frozen stool specimens and rectal swabs

IMPORTANCE

Nucleic acid amplification tests (NAATs) are frequently used in Clostridioides difficile research and diagnostic testing, but the effect of freezing specimens on C. difficile NAAT performance is not well characterized. This study evaluated the concordance of NAAT results between fresh and frozen specimens (fecal and rectal swabs) and found it to be very good to excellent. The results indicate that frozen fecal and rectal swab specimens may be used for C. difficile NAAT testing in research when fresh specimens are not available.

Genomic surveillance of Clostridioides difficile transmission and virulence in a healthcare setting

Clostridioides difficile infection (CDI) is a major cause of healthcare-associated diarrhea, despite the widespread implementation of contact precautions for patients with CDI. Here, we investigate strain contamination in a hospital setting and genomic determinants of disease outcomes. Across two wards over six months, we selectively cultured C. difficile from patients (n=384) and their environments. Whole-genome sequencing (WGS) of 146 isolates revealed that most C. difficile isolates were from clade 1 (131/146, 89.7%), while only one isolate of the hypervirulent ST1 was recovered. Of culture-positive admissions (n=79), 19 (24%) of patients were colonized with toxigenic C. difficile on admission to the hospital. We defined 25 strain networks at ≤ 2 core gene SNPs; 2 of these networks contain strains from different patients. Strain networks were temporally linked (p<0.0001). To understand genomic correlates of disease, we conducted WGS on an additional cohort of C. difficile (n=102 isolates) from the same hospital and confirmed that clade 1 isolates are responsible for most CDI cases. We found that while toxigenic C. difficile isolates are associated with the presence of cdtR , nontoxigenic isolates have an increased abundance of prophages. Our pangenomic analysis of clade 1 isolates suggests that while toxin genes ( tcdABER and cdtR ) were associated with CDI symptoms, they are dispensable for patient colonization. These data indicate toxigenic and nontoxigenic C. difficile contamination persists in a hospital setting and highlight further investigation into how accessory genomic repertoires contribute to C. difficile colonization and disease.

Prevention and treatment of C. difficile in cancer patients

PURPOSE OF REVIEW

We provide an update on the recent literature on Clostridioides difficile infection (CDI) in cancer patients.

RECENT FINDINGS

Distinguishing between colonization and infection remains challenging in cancer patients. Many patients with negative toxin analysis are still treated for CDI, and some meet criteria for severe cases. The incidence of CDI is high in cancer patients, especially those with haematological malignancies. Disruption of the gut microbiome due to antibiotic consumption, chemotherapy and radiotherapy is the primary factor contributing to CDI development. The severity of CDI in cancer patients is often unclear due to the absence of well-defined severity criteria. Certain microbiome species predominance and specific ribotypes have been associated with worse outcomes. Whole genome sequencing could be helpful for differentiating recurrence from reinfection and exploring potential nosocomial transmission. While certain new drugs such as fidaxomicin or bezlotoxumab show promise, the optimal treatment and prevention strategies for CDI in cancer patients remain uncertain. Faecal microbiota transplantation (FMT) holds potential for reducing CDI recurrence rates.

SUMMARY

Further studies are needed to provide robust recommendations for diagnosis, grading severity, and therapeutic management of CDI in cancer patients. Recurrences are particularly concerning due to subsequent exposition to CDI risk factors.

Clostridioides difficile infection in the allogeneic hematopoietic cell transplant recipient

Clostridioides difficile (CD) is one of the most important causes of diarrhea in hospitalized patients, in particular those who undergo an allogeneic hematopoietic cell transplant (allo-HCT) and who are more at risk of developing a CD infection (CDI) due to frequent hospitalizations, iatrogenic immunosuppression, and prolonged antibiotic cycles. CDI may represent a severe condition in allo-HCT patients, increasing the length of hospitalization, influencing the intestinal microbiome with a bidirectional association with graft-versus-host disease, and leading to unfavorable outcomes, including death. The diagnosis of CDI requires the exclusion of other probable causes of diarrhea in HCT patients and is based on highly sensitive and highly specific tests to distinguish colonization from infection. In adult patients, fidaxomicin is recommended as first-line, with oral vancomycin as an alternative agent. Bezlotoxumab may be used to reduce the risk of recurrence. In pediatric patients, vancomycin and metronidazole are still suggested as first-line therapy, but fidaxomicin will probably become standard in pediatrics in the near future. Because of insufficient safety data, fecal microbiota transplantation is not routinely recommended in HCT in spite of promising results for the management of recurrences in other populations.

How I approach diarrhea in hematological transplant patients: A practical tool

Diarrhea in hematopoietic stem-cell transplantation (HSCT) remains a multifactorial challenge that demands a nuanced diagnostic approach. The causes of infectious diarrhea in HSCT recipients are diverse and influenced by patient-specific risk factors, the post-transplant timeline, and local epidemiology. During the past decade, our understanding of diarrhea in HSCT has witnessed a transformative shift through the incorporation of gastrointestinal (GI) multiplex polymerase chain reaction (PCR) panels. However, the judicious application of these panels is imperative to avoid overtesting and prevent adverse outcomes. The challenge lies in distinguishing between the diverse causes of diarrhea, ascertaining the clinical significance of detected pathogens, and navigating the diagnostic uncertainty presented by several non-infectious conditions such as mucositis, intestinal dysbiosis, and acute graft-versus-host disease (aGvHD), all of which mimic infection. This review examines the landscape of infectious diarrhea in the HSCT population, encompassing both established (e.g., Cytomegalovirus, Clostridioides difficile, and norovirus) and emerging pathogens (e.g., sapoviruses, astroviruses). We propose a multifaceted diagnostic algorithm that combines clinical assessment, risk stratification, and tailored utilization of molecular platforms. While multiplex GI panels present invaluable opportunities for rapid and comprehensive pathogen detection, their judicious use is pivotal in preserving diagnostic stewardship. Customization of diagnostic algorithms tailored to local epidemiology ensures optimal patient care and resource utilization.

An Algorithm Addressing the Problem of Overdiagnoses of Clostridioides difficile Infections in Hematopoietic Stem-Cell Transplant Recipients: Effects on CDI Rates and Patient Outcomes

BACKGROUND

Diarrhea of other causes and Clostridioides difficile colonization are common in patients hospitalized for hematopoietic stem-cell transplants (HSCT). It has been well recognized that these issues tend to decrease the specificity of stool testing for C. difficile infection (CDI). The best way to address this problem is uncertain.

OBJECTIVE

In September 2018, we initiated a project with the goal of addressing the apparent problem of overdiagnosis of CDIs in our HSCT population. Using the quality improvement tool Model for Improvement we introduced a C. difficile stool testing and CDI diagnosis algorithm with the aim of decreasing unnecessary inpatient CDI diagnoses and treatments. In this study we examine the effects of the algorithm.

STUDY DESIGN

We reviewed all HSCT admissions for the 2 years before the algorithm introduction and the 3 years following recording all stool submissions for C. difficile determination and CDI. At the close of the study, we recruited our advanced practice providers (APPs) to review all CDI following algorithm initiation and provide feedback on the ease of use of the algorithm and potential improvements to the overall process.

RESULTS

Stool submissions for C. difficile determination decreased from 38.0 to 20.6/1000 inpatient days (p=<0.001) and CDI from 5.5 to 2.4/1000 days (p=0.007). Patients admitted for a first allogeneic-HSCT, a first autologous-HSCT, or an HSCT readmission showed similar proportionate reductions. No detrimental effects on length of stay, overall survival, progression free survival, rates of readmission following transplant, incidence of acute graft vs. host disease, or incidence of recurrent CDI were noted following algorithm introduction. A strategy of education, monitoring/feedback, and ease of algorithm access proved effective in inducing provider compliance. APPs rated the algorithm high on ease of use.

CONCLUSIONS

Use of an algorithm defining criteria for C. difficile testing, diagnosis, and treatment was associated with significantly decreased CDI diagnoses on a HSCT inpatient unit without apparent adverse effects.

American Society for Transplantation and Cellular Therapy Series: #5-Management of Clostridioides difficile Infection in Hematopoietic Cell Transplant Recipients

The Practice Guidelines Committee of the American Society for Transplantation and Cellular Therapy partnered with its Transplant Infectious Disease Special Interest Group to update its 2009 compendium-style infectious disease guidelines for hematopoietic cell transplantation (HCT). A completely new approach was taken with the goal of better serving clinical providers by publishing each standalone topic in the infectious disease series as a concise format of frequently asked questions (FAQ), tables, and figures. Adult and pediatric infectious disease and HCT content experts developed and then answered FAQs and finalized topics with harmonized recommendations that were made by assigning an A through E strength of recommendation paired with a level of supporting evidence graded I through III. This fifth guideline in the series focuses on Clostridioides difficile infection with FAQs that address the prevalence, incidence, clinical features, colonization versus infection, clinical complications, diagnostic considerations, pharmacological therapies for episodic or recurrent infection, and the roles of prophylactic antibiotics, probiotics, and fecal microbiota transplantation.

Prevalence of Clostridium difficile Infection in the Hematopoietic Transplantation Setting: Update of Systematic Review and Meta-Analysis

Hematopoietic stem cell transplant (HSCT) recipients are vulnerable to Clostridium difficile infection (CDI) due to risk factors such as immunosuppression, antimicrobial use, and frequent hospitalization. We systematically searched PubMed and Embase to screen relevant studies from April 2014 to November 2021. A meta-analysis was performed to identify the association between CDI and hematopoietic transplantation based on the standard mean difference and 95% confidence intervals (CIs). Among the 431 retrieved citations, we obtained 43 eligible articles, which included 15,911 HSCT patients at risk. The overall estimated prevalence of CDI was 13.2%. The prevalence of CDI among the 10,685 allogeneic transplantation patients (15.3%) was significantly higher than that among the 3,840 autologous HSCT recipients (9.2%). Different incidence rates of CDI diagnosis over the last 7 years were found worldwide, of which North America (14.1%) was significantly higher than Europe (10.7%) but not significantly different from the prevalence among Asia (11.6%). Notably, we found that the estimated prevalence of CDI diagnosed by polymerase chain reaction (PCR) (17.7%) was significantly higher than that diagnosed by enzyme immunoassay (11.5%), indicating a significant discrepancy in the incidence rate of CDI owing to differences in the sensibility and specificity of the detection methods. Recurrence of CDI was found in approximately 15% of the initial patients with CDI. Furthermore, 20.3% of CDI cases were severe. CDI was found to be a common complication among HSCT recipients, displaying an evident increase in the morbidity of infection.

Infectious Gastroenteritis in Transplant Patients

Infectious gastroenteritis is common after transplantation and can lead to increased morbidity and mortality. A wide range of organisms can lead to gastroenteritis in this patient population. Clostridioides difficile, cytomegalovirus, and norovirus are the most common pathogens. Newer diagnostic methods, especially multiplex polymerase chain reaction, have increased the diagnostic yield of infectious etiologies. In this review, we describe the epidemiology and risk factors for common infectious pathogens leading to gastroenteritis.

Colonization with Gastrointestinal Pathogens Prior to Hematopoietic Cell Transplantation and Associated Clinical Implications

Infectious diarrhea following hematopoietic cell transplantation (HCT) significantly contributes to morbidity and mortality. Most HCT recipients experience diarrhea in the post-transplantation period, and infectious pathogens are frequently detected during diarrheal episodes. However, little is known about how frequently these patients are colonized with gastrointestinal (GI) pathogens before their transplantation and whether colonization predicts future diarrheal illness. We sought to determine how frequently HCT recipients are colonized with GI pathogens before HCT and the degree to which pre-HCT colonization predicts post-transplantation infectious diarrheal illness. We conducted a prospective cohort study of allogeneic and autologous HCT recipients at a single center between December 2016 and January 2019. Stool samples were collected during the week before HCT, and formed samples were evaluated for the presence of 22 diarrheal pathogens using the BioFire FilmArray GI panel. We determined the frequency with which participants were colonized with each pathogen and identified factors associated with colonization. We then determined how frequently pretransplantation colonization led to post-transplantation diarrheal infections due to the colonizing pathogen and whether colonization was associated with increased number of days of post-transplantation diarrhea during the transplant hospitalization. We enrolled 112 asymptomatic patients (allogeneic, 61%; autologous, 39%) who had a formed stool specimen before HCT, of whom 41 (37%) had a GI pathogen detected. The most commonly detected organisms were Clostridioides difficile (n = 21; 19%), Yersinia enterocolitica (n = 9; 8%), enteropathogenic Escherichia coli (EPEC) (n = 6; 6%), and norovirus (n = 5; 4%). Female sex and previous C. difficile infection were associated with C. difficile colonization, and having non-Hodgkin lymphoma was associated with being colonized with a diarrheal pathogen other than C. difficile. Thirteen of 21 patients (62%) with pretransplantation C. difficile colonization developed a clinical C. difficile infection post-transplantation, and 8 of 10 patients (80%) colonized with EPEC or enteroaggregative E. coli developed post-transplantation infections due to their colonizing pathogen. Pretransplantation C. difficile colonization was also associated with an increased duration of post-transplantation diarrhea (P = .048). Conversely, none of the 9 patients with pretransplantation Yersinia enterocolitica colonization developed a post-transplantation Y. enterocolitica infection. Patients admitted for HCT are frequently colonized with a diverse range of GI pathogens. Colonization with C. difficile colonization and diarrheagenic E. coli is frequently associated with post-transplantation diarrheal infections caused by these organisms, but the clinical significance of colonization with other GI pathogens is not clear.

Risk Factors and Outcome of C. difficile Infection after Hematopoietic Stem Cell Transplantation

Patients who undergo hematopoietic stem cell transplants (HSCT) are at major risk of C. difficile (CD) infection (CDI), the most common cause of nosocomial diarrhea. We conducted a retrospective study, which enrolled 481 patients who underwent autologous (220) or allogeneic HSCT (261) in a 5-year period, with the aim of identifying the incidence, risk factors and outcome of CDI between the start of conditioning and 100 days after HSCT. The overall cumulative incidence of CDI based upon clinical evidence was 5.4% (95% CI, 3.7% to 7.8%), without any significant difference between the two types of procedures. The median time between HSCT and CDI diagnosis was 12 days. Out of 26 patients, 19 (73%) with clinical and symptomatic evidence of CDI were positive also for enzymatic or molecular detection of toxigenic CD; in particular, in 5 out of 26 patients (19%) CD binary toxin was also detected. CDI diagnoses significantly increased in the period 2018-2019, since the introduction in the microbiology lab unit of the two-step diagnostic test based on GDH immunoenzymatic detection and toxin B/binary toxin/027 ribotype detection by real-time PCR. Via multivariate analysis, abdominal surgery within 10 years before HSCT (p = 0.002), antibiotic therapy within two months before HSCT (p = 0.000), HCV infection (p = 0.023) and occurrence of bacterial or fungal infections up to 100 days after HSCT (p = 0.003) were significantly associated with a higher risk of CDI development. The 26 patients were treated with first-line vancomycin (24) or fidaxomicine (2) and only 2 patients needed a second-line treatment, due to the persistence of stool positivity. No significant relationship was identified between CDI and the development of acute graft versus host disease (GVHD) after allogeneic HSCT. At a median follow-up of 25 months (range 1-65), the cumulative incidence of transplant related mortality (TRM) was 16.6% (95% CI 11.7% to 22.4%) and the 3-year overall survival (OS) was 67.0% (95% CI 61.9% to 71.6%). The development of CDI had no significant impact on TRM and OS, which were significantly impaired in the multivariate analysis by gastrointestinal and urogenital comorbidities, severe GVHD, previous infections or hospitalization within two months before HSCT, active disease at transplant and occurrence of infections after HSCT. We conclude that 20% of all episodes of diarrhea occurring up to 100 days after HSCT were related to toxigenic CD infection. Patients with a history of previous abdominal surgery or HCV infection, or those who had received broad spectrum parenteral antibacterial therapy were at major risk for CDI development. CDIs were successfully treated with vancomycin or fidaxomicin after auto-HSCT as well as after allo-HSCT.

Impact of a Clostridioides Difficile Testing Computerized Clinical Decision Support Tool on an Adult Stem Cell Transplantation and Hematologic Malignancies Unit

Clostridioides difficile infection rates are higher in hospitalized hematopoietic stem cell transplantation (HSCT) recipients and patients with hematologic malignancy (HM) compared with the general population. This is related both to extensive exposure to antibiotics as well as to frequent and often prolonged hospitalization. In this population, with numerous potential causes of diarrhea, a subset of C difficile detected is presumed to represent colonization rather than clinical infection. The use of decision support tools to guide ordering in hospitalized patients has been reported to decrease both C difficile testing and detection rates. Following implementation of a computerized decision support tool on our HSCT/HM unit, we observed a >2-fold decrease in C difficile testing volume and National Healthcare Safety Network-defined laboratory identifications of C difficile. Furthermore, the rate of oral vancomycin use, as well as the incidence of vancomycin-resistant enterococci colonization and bloodstream infection, decreased in the postintervention period.

Infectious Causes of Acute Gastroenteritis in US Children Undergoing Allogeneic Hematopoietic Cell Transplant: A Longitudinal, Multicenter Study

BACKGROUND

Acute gastroenteritis (AGE) in hematopoietic cell transplant (HCT) patients causes significant morbidity and mortality. Data regarding the longitudinal assessment of infectious pathogens during symptomatic AGE and asymptomatic periods, particularly in children, are limited. We investigated the prevalence of AGE-associated infectious pathogens in children undergoing allogeneic HCT.

METHODS

From March 2015 through May 2016, 31 pediatric patients at 4 US children's hospitals were enrolled and had stool collected weekly from pre-HCT through 100 days post-HCT for infectious AGE pathogens by molecular testing. Demographics, clinical symptoms, antimicrobials, vaccination history, and outcomes were manually abstracted from the medical record into a standardized case report form.

RESULTS

We identified a pathogen in 18% (38/206) of samples, with many detections occurring during asymptomatic periods. Clostridioides difficile was the most commonly detected pathogen in 39% (15/38) of positive specimens, although only 20% (3/15) of C. difficile-positive specimens were obtained from children with diarrhea. Detection of sapovirus, in 21% (8/38) of pathogen-positive specimens, was commonly associated with AGE, with 87.5% of specimens obtained during symptomatic periods. Norovirus was not detected, and rotavirus was detected infrequently. Prolonged shedding of infectious pathogens was rare.

CONCLUSIONS

This multicenter, prospective, longitudinal study suggests that the epidemiology of AGE pathogens identified from allogeneic HCT patients may be changing. Previously reported viruses, such as rotavirus and norovirus, may be less common due to widespread vaccination and institution of infection control precautions, and emerging viruses such as sapoviruses may be increasingly recognized due to the use of molecular diagnostics.

Toxigenic Clostridioides difficile colonization as a risk factor for development of C. difficile infection in solid-organ transplant patients

BACKGROUND

The association between Clostridioides difficile colonization and C. difficile infection (CDI) is unknown in solid-organ transplant (SOT) patients. We examined C. difficile colonization and healthcare-associated exposures as risk factors for development of CDI in SOT patients.

METHODS

The retrospective study cohort included all consecutive SOT patients with at least 1 screening test between May 2017 and April 2018. CDI was defined as the presence of diarrhea (without laxatives), a positive C. difficile clinical test, and the use of C. difficile-directed antimicrobial therapy as ordered by managing clinicians. In addition to demographic variables, exposures to antimicrobials, immunosuppressants, and gastric acid suppressants were evaluated from the time of first screening test to the time of CDI, death, or final discharge.

RESULTS

Of the 348 SOT patients included in our study, 33 (9.5%) were colonized with toxigenic C. difficile. In total, 11 patients (3.2%) developed CDI. Only C. difficile colonization (odds ratio [OR], 13.52; 95% CI, 3.46-52.83; P = .0002), age (OR, 1.09; CI, 1.02-1.17; P = .0135), and hospital days (OR, 1.05; 95% CI, 1.02-1.08; P = .0017) were independently associated with CDI.

CONCLUSIONS

Although CDI was more frequent in C. difficile colonized SOT patients, the overall incidence of CDI was low in this cohort.

Multi-organism gastrointestinal polymerase chain reaction positivity among pediatric transplant vs non-transplant populations: A single-center experience

BACKGROUND

Diarrhea is a common problem in the pediatric post-solid organ transplant and post-hematopoietic stem cell transplant populations. Infectious etiology incidences are poorly defined, and the possibility of multi-organism positivity is often uninvestigated. The aim of this study is to utilize stool multiplex GIP assays to compare the PTP and NTP regarding the incidence and profiles of single-organism and multi-organism infectious diarrhea.

METHODS

A single-center retrospective review was conducted, investigating stool multiplex GIP panel results over a more than 3-year period, for pediatric patients. Assays test for 23 viral, bacterial, and protozoal organisms.

RESULTS

Positive assays in the PTP and NTP were 70/101 (69.3%) and 962/1716 (56.1%), respectively (P = .009). Thirty-two percent (32/101) of assays within the PTP were multi-organism positive, significantly more than 14.8% (254/1716) in the NTP (P < .00001). There was no significant difference in the incidence of single-organism positives, 37.6% (38/101) in PTP and 41.3% (708/1716) in the NTP. The PTP demonstrated a statistically significantly higher incidence of the following organisms within multi-agent positive GIPs (P < .05 for each): Clostridioides difficile, Cryptosporidium, EPEC, norovirus, and sapovirus.

CONCLUSIONS

The pediatric PTP demonstrates higher incidence of positive GIPs, higher rate of multi-organism positivity, and unique infectious organism incidence profiles. These data can provide a framework for understanding organism-specific pathogenicity factors, assessing the clinical impact of enteric co-infection, and understanding the utility of this testing modality in this unique population.

Prospective assessment of Clostridioides (formerly Clostridium) difficile colonization and acquisition in hematopoietic stem cell transplant patients

BACKGROUND

Patients undergoing hematopoietic stem cell transplant (HSCT) possess numerous risk factors for Clostridioides (formerly Clostridium) difficile infection (CDI) and experience a high rate of diarrhea. Colonization rates of Clostridium difficile vary greatly among subgroup analyses with recent studies demonstrating colonization rates in the blood and marrow transplant units up to nine times that of the general population.

METHODS

The primary objectives of this study were to identify the rate of C difficile colonization and acquisition in HSCT patients admitted to the blood and marrow transplant unit. This was a prospective study that included all adult patients admitted for hematopoietic stem cell transplantation. Stool specimens were routinely collected on admission and weekly thereafter for a maximum of six samples per patient.

RESULTS

Forty-two patients met inclusion criteria and had baseline samples available for analysis. The rate of C difficile colonization on admission was 24%, and an additional 9% of patients acquired the organism during admission. Twelve percent of patients developed CDI that was diagnosed clinically. Univariate analysis showed an increased risk of colonization for patients with three or more prior chemotherapy cycles.

CONCLUSIONS

Given high colonization rates coupled with high risk of CDI in this population, providers must be judicious when testing for CDI and interpreting test results for HSCT patients.

Clostridium difficile in Immunocompromised Hosts: A Review of Epidemiology, Risk Factors, Treatment, and Prevention

Clostridium difficile is a significant pathogen in healthcare today, impacting both hospitalized and community-based patients. Immunocompromised patients experience a high incidence of C. difficile infection, ranging from 6% to 33% in the hematology-oncology population and up to 23% among lung transplant recipients, and have a rate of 7.1-8.3 cases per 1000 patient-years in patients with human immunodeficiency virus (HIV). Recurrence of C. difficile infections among immunocompromised patients is also high, with rates up to 40% in both the hematology-oncology population and solid organ transplant recipients. This higher incidence of C. difficile infection and recurrence is believed to be secondary to frequent antimicrobial use, suppressed immune function, increased exposure to healthcare settings, and higher prevalence of C. difficile colonization. This review summarizes published data describing the epidemiology, risk factors for acquisition and infection, treatment, and prevention of C. difficile in hematology-oncology, solid organ transplant, and HIV-infected patients.

Are Clostridioides difficile infections being overdiagnosed in hematopoietic stem cell transplant recipients?

BACKGROUND

Because both diarrhea due to other causes and gastrointestinal colonization with toxigenic Clostridioides difficile are common in HSCT, there is a possibility of false-positive diagnoses of C difficile infections (CDI).

METHODS

We estimated the probability of a patient being colonized by toxigenic C difficile by testing non-diarrheal surveillance stools from 223 HSCT recipients and the probability that a specimen submitted for C difficile testing was not CDI by determining the number of clinical tests that returned negative from this cohort. The number of expected false-positive CDI was estimated using these probabilities and compared with observed clinical test results.

RESULTS

The expected false-positive and the observed numbers of positive clinical results were similar. The 20 patients diagnosed with CDI were also similar to 142 patients with diarrhea and C difficile-negative stools in number of stools on day of testing, associated symptoms, and the recorded number of days to formed stools. C difficile colonization was most commonly detected during the first week and CDI during the second. Retrospective analysis of 837 patients showed that 18 stools were submitted for each diagnosis of CDI. Ribotyping of the surveillance samples showed 17 ribotypes.

CONCLUSIONS

Although several assumptions could impact the accuracy of our false-positive CDI estimates, it appears that many HSCT recipients diagnosed with CDI may actually represent colonized status and an alternative cause of diarrhea. Diagnostic stewardship, including limiting CDI diagnoses to patients with positive toxin and restricting stool submissions to patients with more severe symptoms, may decrease the number of false-positive diagnoses.

Make Sure You Have a Safety Net: Updates in the Prevention and Management of Infectious Complications in Stem Cell Transplant Recipients

Hematopoietic stem cell transplant recipients are at increased risk of infection and immune dysregulation due to reception of cytotoxic chemotherapy; development of graft versus host disease, which necessitates treatment with immunosuppressive medications; and placement of invasive catheters. The prevention and management of infections in these vulnerable hosts is of utmost importance and a key “safety net” in stem cell transplantation. In this review, we provide updates on the prevention and management of CMV infection; invasive fungal infections; bacterial infections; Clostridium difficile infection; and EBV, HHV-6, adenovirus and BK infections. We discuss novel drugs, such as letermovir, isavuconazole, meropenem-vaborbactam and bezlotoxumab; weigh the pros and cons of using fluoroquinolone prophylaxis during neutropenia after stem cell transplantation; and provide updates on important viral infections after hematopoietic stem cell transplant (HSCT). Optimizing the prevention and management of infectious diseases by using the best available evidence will contribute to better outcomes for stem cell transplant recipients, and provide the best possible “safety net” for these immunocompromised hosts.

Detection of toxigenic Clostridium difficile colonization in patients admitted to the hospital for chemotherapy or haematopoietic cell transplantation

Increasing evidence suggests that asymptomatic carriers are an important source of healthcare-associated Clostridium difficile infection. However, it is not known which test for the detection of C. difficile colonization is most sensitive in patients with haematological malignancies. We performed a prospective cohort study of 101 patients with haematological malignancies who had been admitted to the hospital for scheduled chemotherapy or haematopoietic cell transplantation. Each patient provided a formed stool sample. We compared the performance of five different commercially available assays, using toxigenic culture as the reference method. The prevalence of toxigenic C. difficile colonization as determined by toxigenic culture was 14/101 (14 %). The Cepheid Xpert PCR C. difficile/Epi was the most sensitive test for the detection of toxigenic C. difficile colonization, with 93 % sensitivity and 99 % negative predictive value. Our findings suggest that the Xpert PCR C. difficile/Epi could be used to rule out toxigenic C. difficile colonization in this population.

Clostridioides difficile colonization and infection in patients admitted for a first autologous transplantation: Incidence, risk factors, and patient outcomes

BACKGROUND

More data are needed regarding the incidence, risk factors, and outcomes for Clostridioides difficile infection (CDI) and colonization in patients undergoing an autologous hematopoietic stem cell transplantation (AHSCT).

METHODS

We studied 472 consecutive patients admitted for a first AHSCT and conducted a prospective C difficile stool surveillance and ribotyping analysis in a subset of 94 patients.

RESULTS

Clostridioides difficile infection was diagnosed in 7% of patients for an incidence of 3.4 CDI/1000 inpatient days, recurrent/reinfection CDI was rare. CDI was increased in patients who were colonized on admission, had required a recent pre-admission inpatient stay for fever and/or serious infection, or received empiric therapy with a carbapenem or extended-spectrum penicillin. CDI was associated with a longer length of stay and higher hospital costs. Twelve of 94 patients (13%) were found to have colonization on admission; CDI was diagnosed in 27% of these vs 1% in those with initial negative stools. Colonization in the hospital for those negative on admission was infrequent. C difficile ribotyping showed a predominance of 014/020.

CONCLUSIONS

Clostridioides difficile infection is a significant infection in patients receiving a first AHSCT. The risk factors identified may be useful in designing preventive interventions.

Clostridioides difficile infection in immunocompromised hospitalized patients is associated with a high recurrence rate

OBJECTIVE

Clostridioides difficile infection (CDI) may pose a serious threat to immunocompromised patients (IMC). Herein, we evaluated the clinical outcomes of IMC patients with CDI.

METHODS

All consecutive hospitalized patients between January 1, 2013 and December 31, 2018 with laboratory confirmed CDI were included in the study. Subjects were divided into two groups: IMC patients and controls. Primary outcome was the recurrence rate of CDI (rCDI) at 30 and 90 days after the first CDI episode. Secondary outcomes included 30 and 90 day all-cause mortality, length of hospital stay (LOS) and readmission rates. A multivariate analysis adjusted other risk factors for recurrence. An analysis of IMC patient subgroups (based on type of IMC conditions) was also performed. Results are reported as odds ratios (OR) with a 95% confidence interval (95% CI).

RESULTS

A total of 573 patients were included, amongst them 149 IMC patients (36 solid organ transplants, 38 undergoing chemotherapy, 62 haematological conditions, 13 receiving high dose prednisone) and 424 controls. IMC patients were younger, independent and exhibited less significant comorbidities. On multivariable analysis, the rate of rCDI was significantly higher in IMC patients (OR 2.7, 95% CI 1.6-5). rCDI was also associated with vancomycin therapy, haemodialysis and previous hospitalizations. Mortality, LOS, CDI complications and rehospitalization rates were similar in both.

CONCLUSIONS

IMC patients with CDI have an increased risk of 90 days rCDI. Vancomycin treatment for CDI endangers recurrence in IMC patients. Further research should explore other therapies for IMC patients with CDI with alternative agents such as Fidaxomicin and Bezlotoxumab.

Clostridium Difficile infections in patients with AML or MDS undergoing allogeneic hematopoietic stem cell transplantation identify high risk for adverse outcome

Clostridium difficile (CD) infection is the main cause of nosocomial enterocolitis in western countries and in patients undergoing allogeneic hematopoietic stem cell transplantation (alloHCT). Recipients of alloHCT are at high risk for CD infection but large studies in this population are rare and conflicting results have been reported. We analyzed 727 patients with AML or MDS undergoing alloHCT in our center from 2004 to 2015. Ninety-six patients (13%) had CD infection and 103 patients (14%) were identified as asymptomatic carriers by screening at admission and once a week during aplasia. Patients with CD infection had a shorter median overall survival of 8 months (95% CI, 6-36 months) compared with 25 months (95% CI, 17-35 months) for patients without CD infection, (HR 1.4, p = 0.04). CD positive patients were less likely to develop acute graft-versus-host disease (aGvHD; HR 0.6, p = 0.004) compared with CD-negative patients, but did not show differences in gastrointestinal aGvHD (HR 0.9, p = 0.5). Symptomatic patients developed gastrointestinal aGvHD (HR 2.5, p = 0.02) more often compared with asymptomatic CD positive patients. This analysis demonstrates a high prevalence for CD infection in patients undergoing alloHCT. A significant lower overall survival for patients with CD infection could be demonstrated.

Management of Clostridioides (formerly Clostridium) difficile infection (CDI) in solid organ transplant recipients: Guidelines from the American Society of Transplantation Community of Practice

These updated guidelines from the American Society of Transplantation Infectious Diseases Community of Practice address the prevention and management of Clostridium difficile infection in solid organ transplant (SOT) recipients. Clostridioides (formerly Clostridium) difficile infection (CDI) is among the most common hospital acquired infections. In SOT recipients, the incidence of CDI varies by type and number or organs transplanted. While a meta-analysis of published literature found the prevalence of postoperative CDI in the general surgical population to be approximately 0.51%, the prevalence of CDI that is seen in the solid organ transplant population ranges from a low of 3.2% in the pancreatic transplant population to 12.7% in those receiving multiple organ transplants. There are no randomized, controlled trials evaluating the management of CDI in the SOT population. Herein is a review and summary of the currently available literature that has been synthesized into updated treatment guidelines for the management of CDI in the SOT population.

Are Many Patients Diagnosed With Healthcare-associated Clostridioides difficile Infections Colonized With the Infecting Strain on Admission?

In a cohort of 480 patients admitted to an acute care hospital, 68 (14%) had positive perirectal cultures for toxigenic Clostridioides difficile on admission. Of the 11 patients (2%) diagnosed with healthcare-associated C. difficile infections, 3 (27%) had genetically related admission and infection isolates, based on whole-genome sequencing.

Febrile Neutropenia in Transplant Recipients

Febrile neutropenic patients are at increased risk of developing infections. During the initial stages of neutropenia, most of these infections are bacterial. The spectrum of bacterial infections depends to some extent on whether or not patients receive antimicrobial prophylaxis when neutropenic. Since most transplant recipients do, Gram-positive organisms predominate, due to the fact prophylaxis is directed primarily against Gram-negative organisms. Staphylococcus species (often methicillin-resistant), Streptococcus species (viridans group streptococci, beta-hemolytic streptococci), and Enterococcus species (including vancomycin-resistant strains) are isolated most often. Therefore, potent empiric Gram-positive coverage is recommended by many in this setting. Escherichia coli, Pseudomonas aeruginosa, and Klebsiella species are the most common Gram-negative pathogens isolated. Non-fermentative Gram-negative bacilli (Stenotrophomonas maltophilia, Acinetobacter species) are emerging as important pathogens. Many of these organisms acquire multiple mechanisms of resistance that render them multidrug resistant. The administration of prompt, broad-spectrum, empiric, antimicrobial therapy is essential and is generally based on local epidemiology and susceptibility/resistance patterns. Response rate to the initial regimen is generally in the range of 75–85%. Fungal infections develop in patients with prolonged neutropenia (greater than 7–10 days). Candida species and Aspergillus species are the predominant fungal pathogens, although many other fungi are opportunistic pathogens in this setting. Fungal infections are seldom documented microbiologically or on histopathology, and the administration of empiric antifungal therapy, when such infections are suspected, is the norm. Therapy is often prolonged, and outcomes are still suboptimal. The importance of infection control and antimicrobial stewardship cannot be overemphasized.

Immediate impact of healthcare-facility-onset Clostridium difficile laboratory-identified events reporting methodology change on standardized infection ratios

In 2018, the Clostridium difficile LabID event methodology changed so that hospitals doing 2-step tests, nucleic acid amplification test (NAAT) plus enzyme immunofluorescence assay (EIA), had their adjustment modified to EIA-based tests, and only positive final tests (eg, EIA) were counted in the numerator. We report the immediate impact of this methodological change at 3 Milwaukee hospitals.

Cancer stem cell populations in lymphoma in dogs and impact of cytotoxic chemotherapy

Cancer relapse following chemotherapy has been attributed in part to the presence of cancer stem cells (CSC), which drive tumour growth and metastasis and are highly resistant to the effects of cytotoxic chemotherapy. As a result, treatment with cytotoxic chemotherapy selects for drug-resistant CSC populations that eventually drive tumour recurrence. Little is known currently regarding the role of CSC in dogs with lymphoma, nor the impact of chemotherapy on CSC populations. Therefore, we prospectively quantitated CSC populations in dogs with B-cell (BCL) and T-cell lymphoma (TCL), using tumour aspirates and flow cytometric analysis with a panel of CSC markers. In addition, in vitro studies were carried out to determine the impact of chemotherapy resistance on the stem cell phenotype and stem cell properties of lymphoma cells. We found that the percentages of tumour cells expressing CSC markers were significantly increased in dogs with BCL, compared with B cells from normal lymph nodes. Similar findings were observed in dogs with TCL. In vitro studies revealed that lymphoma cells selected for resistance to CHOP chemotherapy had significantly upregulated expression of CSC markers, formed spheroids in culture more readily, and expressed significantly greater aldehyde dehydrogenase activity compared with chemotherapy-sensitive tumour cells. Similar results were observed in tumour samples dogs with relapsed BCL. These findings suggest that cytotoxic chemotherapy can lead to a relative enrichment of tumour cells with CSC properties, which may be associated with lymphoma recurrence.

Clinical Characteristics and Outcomes of Hematologic Malignancy Patients With Positive Clostridium difficile Toxin Immunoassay Versus Polymerase Chain Reaction Test Results

In a cohort of inpatients with hematologic malignancy and positive enzyme immunoassay (EIA) or polymerase chain reaction (PCR) Clostridium difficile tests, we found that clinical characteristics and outcomes were similar between these groups. The method of testing is unlikely to predict infection in this population, and PCR-positive results should be treated with concern.Infect Control Hosp Epidemiol 2018;863-866.

Screening for Clostridium difficile colonization on admission to a hematopoietic stem cell transplant unit may reduce hospital-acquired C difficile infection

Clostridium difficile infection rates are higher in patients undergoing hematopoietic stem cell transplants. In our study, patients undergoing hematopoietic stem cell transplants or chemotherapy were screened for C difficile colonization at admission and placed on contact precautions if they were positive. Patient's colonized with C difficile contribute to the overall burden of C difficile infection in hospitals.

Host genetic susceptibility to Clostridium difficile infections in patients undergoing autologous stem cell transplantation: a genome-wide association study

BACKGROUND

Clostridium difficile infection (CDI) is the most common hospital-acquired infection. Unfortunately, genes that identify CDI-susceptible patients have not been well described. We performed a genome-wide association study (GWAS) to determine genetic variants associated with the development of CDI.

METHODS

A cohort study of Caucasian patients undergoing autologous stem cell transplantation for multiple myeloma was performed. Patients were genotyped using Illumina® Whole Genome Genotyping Infinium chemistry. We then compared CDI-positive to CDI-negative patients using logistic regression for baseline clinical factors and false discovery rate (FDR) for genetic factors [single nucleotide polymorphisms (SNPs)]. SNPs associated with CDI at FDR of p < 0.01 were then incorporated into a logistic regression model combining clinical and genetic factors.

RESULTS

Of the 646 patients analyzed (59.7% male), 57 patients were tested CDI positive (cases) and were compared to 589 patients who were tested negative (controls). Hemoglobin, albumin, and hematocrit were lower for cases (p < 0.05). Eight SNPs on five genes (FLJ16171, GORASP2, RLBP1L1, ASPH, ATP7B) were associated with CDI at FDR p < 0.01. In the combined clinical and genetic model, low albumin and three genes RLBP1L1, ASPH, and ATP7B were associated with CDI.

CONCLUSION

Low serum albumin and genes RLBP1L1 and ASPH located on chromosome 8 and ATP7B on chromosome 13 were associated with CDI. Of particular interest is ATP7B given its copper modulatory role and the sporicidal properties of copper against Clostridium difficile.

Clostridium difficile Exposures, Colonization, and the Microbiome: Implications for Prevention

New studies have been published regarding the epidemiology of Clostridium difficile in topics such as asymptomatic C. difficile colonization, community-associated C. difficile infection, environmental contamination outside healthcare settings, animal colonization, and the interactions between C. difficile and the gut microbiome. In addition to summarizing these findings, this review offers a perspective on the potential impact of high-throughput sequencing and other potential techniques on the prevention of C. difficile.Infect Control Hosp Epidemiol 2018;39:596-602.

Changes in intestinal microbiota and their effects on allogeneic stem cell transplantation

The human intestinal microbiota is essential for microbial homeostasis, regulation of metabolism, and intestinal immune tolerance. Rapidly evolving understanding of the importance of the microbiota implicates changes in the composition and function of intestinal microbial communities in an assortment of systemic conditions. Complications following allogeneic stem cell transplant now join the ever-expanding list of pathologic states regulated by intestinal microbiota. Dysbiosis, or disruption of the normal ecology of this microbiome, has been directly implicated in the pathogenesis of entities such as Clostridium difficile infections, graft-versus-host disease (GVHD), and most recently disease relapse, all of which are major causes of morbidity and mortality in patients undergoing allogeneic stem cell transplant. In this review, we elucidate the key origins of microbiotic alterations and discuss how dysbiosis influences complications following allogeneic stem cell transplant. Our emerging understanding of the importance of a balanced and diverse intestinal microbiota is prompting investigation into the appropriate treatment of dysbiosis, reliable and early detection of such, and ultimately its prevention in patients to improve the outcome following allogeneic hematopoietic stem cell transplant.

Clostridium difficile colonization in preoperative colorectal cancer patients

The entire process of Clostridium difficile colonization to infection develops in large intestine. However, the real colonization pattern of C. difficile in preoperative colorectal cancer patients has not been studied. In this study, 33 C. difficile strains (16.1%) were isolated from stool samples of 205 preoperative colorectal cancer patients. C. difficile colonization rates in lymph node metastasis patients (22.3%) were significantly higher than lymph node negative patients (10.8%) (OR=2.314, 95%CI=1.023-5.235, P =0.025). Meanwhile, patients positive for stool occult blood had lower C. difficile colonization rates than negative patients (11.5% vs. 24.0%, OR=0.300, 95%CI=0.131-0.685, P =0.019). A total of 16 sequence types were revealed by multilocus sequence typing. Minimum spanning tree and time-space cluster analysis indicated that all C. difficile isolates were epidemiologically unrelated. Antibiotic susceptibility testing showed all isolates were susceptible to vancomycin and metronidazole. The results suggested that the prevalence of C. difficile colonization is high in preoperative colorectal cancer patients, and the colonization is not acquired in the hospital. Since lymph node metastasis colorectal cancer patients inevitably require adjuvant chemotherapy and C. difficile infection may halt the ongoing treatment, the call for sustained monitoring of C. difficile in those patients is apparently urgent.

Risk factors and epidemiology of Clostridium difficile infection in hematopoietic stem cell transplant recipients during the peritransplant period

BACKGROUND

Hematopoietic stem cell transplant (HSCT) recipients represent a high-risk group for developing Clostridium difficile (CD) infection (CDI). We aimed to identify specific risk factors for CDI in an HSCT patient population during the peritransplant period.

METHODS

We performed a case-control study within a cohort of HSCT patients who received a transplant from November 2010 to March 2013. Cases had a clinical presentation compatible with CDI and a positive stool sample Xpert^® C. difficile test. Controls were CDI negative and matched on age, gender, and transplant type. Peritransplant period was defined as -30 days or time of stem cell mobilization maneuver to 30 days post transplant in autologous SCT or 90 days post transplant in allogeneic SCT.

RESULTS

Of 781 HSCTs performed during the study period, 650 (83.2%) had a stool sample submitted for CD testing. Eight-six (13.2%) cases with CDI were identified. Most of the cases were diagnosed within a week after transplantation (median of 5 days). In adjusted analysis, prior hospitalization (odds ratio [OR]: 2.01, 95% confidence interval [CI] 1.2-3.36), prior cephalosporin administration (OR 2.72, 95% CI: 1.54-4.83), and prior chemotherapy (OR: 3.26, 95% CI: 1.92-5.5) were significantly associated with CDI.

CONCLUSIONS

Hospitalization, and prior antibiotic and chemotherapy use are risk factors that are not easily modifiable, which emphasizes the need to start investigating preventive or prophylactic strategies in this high-risk population.

Protective Factors in the Intestinal Microbiome Against Clostridium difficile Infection in Recipients of Allogeneic Hematopoietic Stem Cell Transplantation

Background

Clostridium difficile infection (CDI) is a frequent complication in recipients of allogeneic hematopoietic stem cell transplantation (allo-HSCT), who receive intensive treatments that significantly disrupt the intestinal microbiota. In this study, we examined the microbiota composition of allo-HSCT recipients to identify bacterial colonizers that confer protection against CDI after engraftment.

Methods

Feces collected from adult recipients allo-HSCT at engraftment were analyzed; 16S ribosomal RNA genes were sequenced and analyzed from each sample. Bacterial taxa with protective effects against development of CDI were identified by means of linear discriminant analysis effect size analysis and then further assessed with clinical predictors of CDI using survival analysis.

Results

A total of 234 allo-HSCT recipients were studied; postengraftment CDI developed in 53 (22.6%). Within the composition of the microbiota, the presence of 3 distinct bacterial taxa was correlated with protection against CDI: Bacteroidetes, Lachnospiraceae, and Ruminococcaceae. Colonization with these groups at engraftment was associated with a 60% lower risk of CDI, independent of clinical factors.

Conclusions

Colonization with these 3 bacterial groups is associated with a lower risk of CDI. These groups have been shown to be vital components of the intestinal microbiota. Targeted efforts to maintain them may help minimize the risk of CDI in this at-risk population.

Risk of Clostridium difficile Infection in Hematology-Oncology Patients Colonized With Toxigenic C. difficile

The prevalence of colonization with toxigenic Clostridium difficile among patients with hematological malignancies and/or bone marrow transplant at admission to a 566-bed academic medical care center was 9.3%, and 13.3% of colonized patients developed symptomatic disease during hospitalization. This population may benefit from targeted C. difficile infection control interventions. Infect Control Hosp Epidemiol 2017;38:718-720.

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.

Toward revision of antimicrobial therapies in hematopoietic stem cell transplantation: target the pathogens, but protect the indigenous microbiota

Host microbiota plays important roles in providing colonization resistance to pathogens and instructing development and function of the immune system. Antibiotic treatments intended to target pathogens further weaken the host defenses and may paradoxically increase the risk of systemic infections. This consequence is especially problematic in patients undergoing hematopoietic stem cell transplantation, where the mucosal defenses are already weakened by the conditioning regimens. This review discusses the roles that indigenous microbiota plays in protecting the host and maintaining immune homeostasis. In addition, we highlight possible strategies that are being developed to allow targeted antimicrobial therapy against pathogens, while minimizing the harm to indigenous microbiota.

Intestinal dysbiosis and allogeneic hematopoietic progenitor cell transplantation

The intestinal microbiota is a diverse and dynamic ecosystem that is increasingly understood to play a vital role in human health. Hematopoietic stem cell transplant recipients undergo prolonged exposure to antimicrobials, chemotherapeutic agents, and immunosuppressants, resulting in profound shifts in the gut microbiome. A growing body of research has revealed the ways in which these microbiologic shifts shape immune modulation, affecting susceptibility to infections and graft-versus-host disease, the two major post-transplant complications in this population. As transplant medicine becomes increasingly personalized, the potential for microbiome-modulating treatments holds immense potential. Strategies to preserve the intestinal microbiota, including targeted antibiotics, prebiotics and probiotics, and fecal microbiota transplant could mitigate some of the microbiologic shifts in stem cell transplant recipients, and reduce the incidence of peri-transplant morbidity and mortality.

[Infectious diseases in immunocompromised patients]

Immunkompromittierung birgt immer ein erhöhtes Risiko für die Entwicklung infektiöser Komplikationen. Patienten nach solider Organtransplantation sind besonders gefährdet – in dieser Patientengruppe bilden Infektionen die zweithäufigste Todesursache. Prophylaxe und Impfungen sollten daher konsequent eingesetzt werden. Infektionen bei Immunsupprimierten können mit atypischen klinischen Symptomen einhergehen, was die Diagnose und Therapie für den behandelnden Arzt erschwert. Vor allem virale und opportunistische Infektionen stellen dabei eine Herausforderung dar. Umso mehr ist eine Überwachung der Patienten hinsichtlich Infektionserkrankungen notwendig, um frühzeitig die erforderlichen Maßnahmen einleiten zu können.

High prevalence of nontoxigenic Clostridium difficile isolated from hospitalized and non-hospitalized individuals in rural Ghana

Since data about Clostridium difficile infection in sub-Saharan Africa are scarce, we determined its epidemiology and risk factors in a cross-sectional study in Eikwe, a rural community in Ghana. We tested stool samples from 176 hospitalized patients with diarrhoea and from 131 asymptomatic non-hospitalized individuals for C. difficile and some other enteric pathogens. The overall prevalence rate of C. difficile was 4.9% with ribotype 084 being predominant. With 75% of the isolates, a high rate of nontoxigenic strains was present in symptomatic patients, most of whom had no other identified enteric pathogens. All strains were susceptible against metronidazole and vancomycin, respectively. Data on lifestyle and medical history showed that age <5years (p=0.004), and use of ceftriaxone (p=0.023) were the most important risk factors for C. difficile carriage status. Although our data suggest that C. difficile is currently not a major cause of diarrhoea in this setting, the epidemiology of C. difficile in sub-Saharan Africa awaits further investigation.

Epidemiology, Diagnosis, and Management of Clostridium difficile Infection in Patients with Inflammatory Bowel Disease

Clostridium difficile infection (CDI) is a major source of morbidity and mortality for the U.S. health care system and frequently complicates the course of inflammatory bowel disease (IBD). Patients with IBD are more likely to be colonized with C. difficile and develop active infection than the general population. They are also more likely to have severe CDI and develop subsequent complications such as IBD flare, colectomy, or death. Even after successful initial treatment and recovery, recurrent CDI is common. Management of CDI in IBD is fraught with diagnostic and therapeutic challenges because the clinical presentations of CDI and IBD flare have considerable overlap. Fecal microbiota transplantation can be successful in curing recurrent CDI when other treatments have failed, but may also trigger IBD flare and this warrants caution. New experimental treatments including vaccines, monoclonal antibodies, and nontoxigenic strains of C. difficile offer promise but are not yet available for clinicians. A better understanding of the complex relationship between the gut microbiota, CDI, and IBD is needed.