Variation in Risk of Hospital-Onset Clostridium difficile Infection Across β-Lactam Antibiotics in Children With New-Onset Acute Lymphoblastic Leukemia

Comparative effectiveness and safety of antibiotic prophylaxis during induction chemotherapy in children with acute leukaemia: a systematic review and meta-analysis

BACKGROUND

Bacterial infections are common during induction therapy in children and adolescents with acute leukaemia and may cause infection-related mortality.

AIM

To determine the efficacy and safety of prophylactic antibiotics in paediatric patients with acute leukaemia receiving induction chemotherapy.

METHODS

From three English databases and four Chinese databases, we searched for randomized controlled trials (RCTs) and cohort studies that compared prophylactic antibiotics to placebo, no prophylaxis, or that compared one antibiotic versus another in paediatric patients with acute leukaemia undergoing induction chemotherapy. Two reviewers independently screened the studies, extracted data, and assessed the risk of bias using Cochrane Risk of Bias 2 tool and Newcastle-Ottawa Scale, and the certainty of evidence using Grading of Recommendations Assessment, Development, and Evaluation (GRADE).

FINDINGS

Two RCTs and ten cohort studies were finally included. For children with acute lymphoblastic leukaemia, antibiotic prophylaxis, including levofloxacin, sulfamethoxazole-trimethoprim, or other antibiotics, probably reduced bacteraemia (risk ratio (RR): 0.44; 95% confidence interval (CI): 0.33-0.60; moderate certainty) without significantly increasing Clostridioides difficile infection (CDI) or invasive fungal infection. Levofloxacin reduced the CDI rate (RR: 0.08; 95% CI: 0.01-0.62; high certainty). Ciprofloxacin prophylaxis probably reduced infection-related mortality (RR: 0.12; 95% CI: 0.01-0.97; moderate certainty). In children with acute myeloid leukaemia, ciprofloxacin plus vancomycin may reduce febrile neutropenia (RR: 0.79; 95% CI: 0.66-0.94; low certainty). Individual studies indicated that prophylaxis increased antibiotic exposure but reduced non-preventive antibiotic exposure.

CONCLUSION

In children with acute leukaemia undergoing induction therapy, antibiotic prophylaxis may improve the bacterial infection and mortality.

Adverse effects of antibiotics in children with cancer: are short-course antibiotics for febrile neutropenia part of the solution?

INTRODUCTION

Febrile neutropenia is a common complication experienced by children with cancer or those undergoing hematopoietic stem cell transplantation. Repeated episodes of febrile neutropenia result in cumulative exposure to broad-spectrum antibiotics with potential for a range of serious adverse effects. Short-course antibiotics, even in patients with high-risk febrile neutropenia, may offer a solution.

AREAS COVERED

This review addresses the known broad effects of antibiotics, highlights developments in understanding the relationship between cancer, antibiotics, and the gut microbiome, and discusses emerging evidence regarding long-term adverse antibiotic effects. The authors consider available evidence to guide the duration of empiric antibiotics in pediatric febrile neutropenia and directions for future research.

EXPERT OPINION

Broad-spectrum antibiotics are associated with antimicrobial resistance, Clostridioides difficile infection, invasive candidiasis, significant disturbance of the gut microbiome and may seriously impact outcomes in children with cancer or undergoing allogenic hematopoietic stem cell transplant. Short-course empiric antibiotics are likely safe in most children with febrile neutropenia and present a valuable opportunity to reduce the risks of antibiotic exposure.

Which Type of Empiric Antibiotic Therapy is Appropriate? A 20-Year Retrospective Study of Bloodstream Infections in Childhood Cancer

INTRODUCTION

Sufficient empirical antimicrobial therapy in febrile patients with cancer is challenging, owing to the limited arsenal of available antibiotics in an era of growing resistance. Because of the emergence of gram-negative bacteria resistant to ceftazidime and piperacillin, a combination antibiotic therapy was employed that uses meropenem combined with gentamicin and/or vancomycin if the patient further deteriorates.

METHODS

A retrospective cohort analysis was performed including all patients with catheter-associated bloodstream infections (BSIs) and treated for childhood cancer in a tertiary single centre between 1 January 2000 and 31 June 2018. We calculated the prevalence and the risk for BSIs and compared the in vitro susceptibility to various antimicrobial agents.

RESULTS

Of 653 patients with childhood cancer, 113 patients (17.3%) were identified with a total of 139 BSIs, most of them occurring in patients with leukaemia (n = 90, 64.7%) and were associated with gram-positive bacteria (60.5%). In our cohort, all BSIs with gram-negative bacteria exhibited in vitro susceptibility against meropenem alone without any signs of resistance development. The antibiotic coverage of our meropenem-based combination therapy was also highly effective for gram-positive and non-fermenting bacteria. Thus, BSI-related mortality in all 139 BSI episodes was 1.4%. Clostridium difficile infections (CDIs), as main adverse event of carbapenem usage, occurred in only 16 (2.5%) patients.

CONCLUSION

Our meropenem-based combination therapy showed sufficient empirical antibiotic coverage in the majority of BSIs (96.4%) and did not result in an increased rate of unwanted side effects or development of antibiotic resistance.

Recurrent community-acquired Clostridium(Clostridioides)difficile infection in Serbianchildren

Information on recurrent Clostridium difficile infections (rCDI) in children is rare and limited, especially community acquired (CA-CDI).This study was designed to identify risk factors for rCA-CDI in Serbian pediatric population. The study group included 71 children (aged from 1 to 14 years) with a first episode of CDI. Data were collected from 56 (78.87%) children with only one episode of CA-CDI and from 15 (21.13%) children with rCA-CDI were mutually compared. The following parameters were found to be statistically significantly more frequent in the children with rCA-CDI group (p < 0.05); leukemia as underlying disease, treatment with immunosuppressive and-or cytostatic drugs, and treatment with antibiotics. Similarly, previously visits to outpatient facilities, daycare hospitals and hospitals were also associated with rCDI. Analysis of clinical symptoms and laboratory parameters, revealed a statistically significant association of the severity of the first episode of CDI (determined by an increase in body temperature, higher maximum WBC and higher CRP) with development of a rCDI. Ribotype (RT) 027 was more common in children with rCA-CDI (66.7%, p = 0.006). During the seven-year research period, we found a rate of rCA-CDI rate in children of 21.13%. Our study identified several parameters statistically significantly more frequently in children with rCA-CDI. The obtained results will serve as a basis for future larger studies, but new prospective, studies are necessary to build a prediction model of rCDI in children that can be used to guide the treatment to prevent rCDI.

Clostridioides difficile-Associated Diarrhea: Infection Prevention Unknowns and Evolving Risk Reduction Strategies

PURPOSE OF REVIEW

New controversies in the diagnosis and prevention of Clostridiodes difficile are challenging and at times changing infection control practice at many medical centers.

RECENT FINDINGS

Molecular epidemiologic studies are changing our understanding of C. difficile and its spectrum of disease. C. difficile as a hospital-acquired infection is likely largely overdiagnosed given overly sensitive molecular testing and widespread colonization of ill or debilitated patients. Clostridiodes difficile infection continues to challenge infection prevention programs. Shifts in our understanding of the epidemiology of this organism and its spectrum of clinical presentations are changing the approach to prevention efforts. Nevertheless, cleanliness of the healthcare environment and antimicrobial stewardship remain core risk reduction strategies. Other strategies such as screening and isolation are inciting controversy. The optimal infection prevention strategies for C. difficile remain the subject of intense study and debate.

Targeting Clostridium difficile Surface Components to Develop Immunotherapeutic Strategies Against Clostridium difficile Infection

New therapies are needed to prevent and treat Clostridium difficile infection and to limit the rise in antibiotic resistance. Besides toxins, several surface components have been characterized as colonization factors and have been shown as immunogenic. This review will focus on passive and active immunization strategies targeting C. difficile surface components to combat C. difficile. Concerning passive immunization, the first strategies used antisera raised against the entire bacterium to prevent infection in the hamster model. Then, surface components such as the flagellin and the S-layer proteins were used for immunization and the passive transfer of antibodies was protective in animal models. Passive immunotherapy with polyvalent immunoglobulins was used in humans and bovine immunoglobulin concentrates were evaluated in clinical trials. Concerning active immunization, vaccine assays targeting surface components were tested mainly in animal models, mouse models of colonization and hamster models of infection. Bacterial extracts, spore proteins and surface components of vegetative cells such as cell wall proteins, flagellar proteins, and polysaccharides were used as vaccine targets. Vaccine assays were performed by parenteral and mucosal routes of immunization. Both gave promising results and pave the way to development of new vaccines.

Hospital-Level Variability in Broad-Spectrum Antibiotic Use for Children With Acute Leukemia Undergoing Hematopoietic Cell Transplantation

OBJECTIVETo explore the prevalence and drivers of hospital-level variability in antibiotic utilization among hematopoietic cell transplant (HCT) recipients to inform antimicrobial stewardship initiatives.DESIGNRetrospective cohort study using data merged from the Pediatric Health Information System and the Center for International Blood and Marrow Transplant Research.SETTINGThe study included 27 transplant centers in freestanding children's hospitals.METHODSThe primary outcome was days of broad-spectrum antibiotic use in the interval from day of HCT through neutrophil engraftment. Hospital antibiotic utilization rates were reported as days of therapy (DOTs) per 1,000 neutropenic days. Negative binomial regression was used to estimate hospital utilization rates, adjusting for patient covariates including demographics, transplant characteristics, and severity of illness. To better quantify the magnitude of hospital variation and to explore hospital-level drivers in addition to patient-level drivers of variation, mixed-effects negative binomial models were also constructed.RESULTSAdjusted hospital rates of antipseudomonal antibiotic use varied from 436 to 1121 DOTs per 1,000 neutropenic days, and rates of broad-spectrum, gram-positive antibiotic use varied from 153 to 728 DOTs per 1,000 neutropenic days. We detected variability by hospital in choice of antipseudomonal agent (ie, cephalosporins, penicillins, and carbapenems), but gram-positive coverage was primarily driven by vancomycin use. Considerable center-level variability remained even after controlling for additional hospital-level factors. Antibiotic use was not strongly associated with days of significant illness or mortality.CONCLUSIONAmong a homogenous population of children undergoing HCT for acute leukemia, both the quantity and spectrum of antibiotic exposure in the immediate posttransplant period varied widely. Antimicrobial stewardship initiatives can apply these data to optimize the use of antibiotics in transplant patients.Infect Control Hosp Epidemiol 2018;797-805.

Investigation of Clostridium difficile ribotypes in symptomatic patients of a German pediatric oncology center

In a German pediatric oncology unit, the attending physicians diagnosed 27 cases of Clostridium difficile-associated disease (CDI) from January 01, 2010 to October 31, 2013. This refers to a CDI incidence density of 2.0/1000 inpatient days. According to the hospital hygiene standard, symptomatic patients with CDI were kept in contact isolation. Most patients (median age 8.2 years) suffered from acute lymphoblastic leukemia; 88.9% were treated with broad-spectrum antibiotics during the preceding 4 weeks. 29.6% received intravenous morphine/metamizole and parenteral nutrition due to severe chemotherapy-induced mucositis. None of the patients experienced severe complications such as lower gastrointestinal tract bleeding, sepsis, or toxic megacolon. Genotyping of the isolates derived from symptomatic patients revealed many different ribotypes without detection of the hypervirulent 027 strain and did not point at hospital transmission as an important promoter of CDI in our unit.

CONCLUSION

Under strict standard hygiene and contact isolation for symptomatic patients, genotyping of clinical isolates revealed that in pediatric cancer patients, CDI is not necessarily based on nosocomial transmission. The rate of CDI-related severe complications was low. What is Known: • Pediatric cancer patients face an increased risk of Clostridium difficile-associated disease due to immunosuppression, cancer chemotherapy, mucositis, and dysbiosis following intravenous broad-spectrum antimicrobial treatment. • C. difficile may be transmitted from patient to patient. What is New: • Under strict standard hygiene and contact isolation for symptomatic patients, genotyping of clinical isolates revealed that in pediatric cancer patients, CDI is not necessarily based on nosocomial transmission. • The rate of CDI-related severe complications was low.

Adverse Effects of Intravenous Vancomycin-Based Prophylaxis during Therapy for Pediatric Acute Myeloid Leukemia

Children and adolescents with acute myeloid leukemia (AML) are at risk of life-threatening bacterial infections, especially with viridans group streptococci. Primary antibacterial prophylaxis with vancomycin-based regimens reduces this risk but might increase the risks of renal or liver toxicity or Clostridium difficile infection (CDI). A retrospective review of data for patients treated for newly diagnosed AML at St. Jude Children's Research Hospital between 2002 and 2008 was conducted. Nephrotoxicity was classified according to pediatric risk, injury, failure, loss, and end-stage renal disease (pRIFLE) criteria and hepatotoxicity according to Common Terminology Criteria for Adverse Events (CTCAE) criteria. The risks of nephrotoxicity, hepatotoxicity, and CDI were compared between patients receiving vancomycin-based prophylaxis, no intravenous prophylaxis, or other prophylaxis. Generalized linear mixed models were used to address potential confounding. A total of 392 chemotherapy courses (108 with no intravenous prophylaxis, 218 with vancomycin-based prophylaxis, and 66 with other prophylaxis) for 111 patients were included. Development of pRIFLE risk, injury, and failure occurred in 190, 44, and 2 courses, respectively. Increases of at least one, two, and three grades for hepatotoxicity occurred in 189, 52, and 19 courses, respectively. After adjustment for confounders, vancomycin-based prophylaxis was not associated with nephrotoxicity or hepatotoxicity and reduced the risk of CDI, compared to no intravenous prophylaxis (0.9% versus 6.5%; P = 0.007) or other prophylactic regimens (0.9% versus 3.0%; P = 0.23). Despite concerns about vancomycin toxicity, vancomycin-based prophylaxis in pediatric patients with AML did not increase the risk of nephrotoxicity or hepatotoxicity and reduced the risk of CDI. Caution is advised to avoid contributing to antibiotic resistance.

Levofloxacin Prophylaxis During Induction Therapy for Pediatric Acute Lymphoblastic Leukemia

BACKGROUND

Infection is the most important cause of treatment-related morbidity and mortality in pediatric patients treated for acute lymphoblastic leukemia (ALL). Although routine in adults with leukemia, antibacterial prophylaxis is controversial in pediatrics because of insufficient evidence for its efficacy or antibiotic choice and concerns about promoting antibiotic resistance and Clostridium difficile infection.

METHODS

This was a single-center, observational cohort study of patients with newly diagnosed ALL, comparing prospectively collected infection-related outcomes in patients who received no prophylaxis, levofloxacin prophylaxis, or other prophylaxis during induction therapy on the total XVI study. A propensity score-weighted logistic regression model was used to adjust for confounders.

RESULTS

Of 344 included patients, 173 received no prophylaxis, 69 received levofloxacin prophylaxis, and 102 received other prophylaxis regimens. Patients receiving prophylaxis had longer duration of neutropenia. Prophylaxis reduced the odds of febrile neutropenia, likely bacterial infection, and bloodstream infection by ≥70%. Levofloxacin prophylaxis alone reduced these infections, but it also reduced cephalosporin, aminoglycoside, and vancomycin exposure and reduced the odds of C. difficile infection by >95%. No increase in breakthrough infections with antibiotic-resistant organisms was seen, but this cannot be excluded.

CONCLUSIONS

This is the largest study to date of antibacterial prophylaxis during induction therapy for pediatric ALL and the first to include a broad-spectrum fluoroquinolone. Prophylaxis prevented febrile neutropenia and systemic infection. Levofloxacin prophylaxis also minimized the use of treatment antibiotics and drastically reduced C. difficile infection. Although long-term antibiotic-resistance monitoring is needed, these data support using targeted prophylaxis with levofloxacin in children undergoing induction chemotherapy for ALL.

CLINICAL TRIALS REGISTRATION

NCT00549848.

Risk Factors for Hospital-acquired Clostridium difficile Infection Among Pediatric Patients With Cancer

Hospital-acquired Clostridium difficile infection (CDI) may cause life-threatening colitis for children with cancer, making identification of risk factors important. We described characteristics of pediatric cancer patients with primary and recurring CDI, and evaluated potential risk factors. Among 189 cancer patients, 51 cases (27%) of CDI and 94 matched controls of cancer patients without CDI were analyzed. Multivariable logistic regression was used to evaluate the association between CDI and several potential risk factors. Median age of CDI cases was lower (3.3 y; 0.60 to 16.2) than controls (7.7 y; 0.4 to 20.5). Median duration of neutropenia before CDI was longer for CDI cases (10.0 d; 0.0 to 30.0) compared with duration calculated from reference date in controls (6.0 d; 0.0 to 29.0). Multivariable analysis showed that older age was associated with reduced risk (≥7 vs. 0 to 3 y, odds ratio=0.11; 95% confidence interval, 0.02-0.54), and prolonged neutropenia was associated with increased risk (odds ratio=1.11; 95% confidence interval, 1.01-1.22). CDI recurred in 26% of cases. Younger age and prolonged neutropenia were risk factors for CDI in children with cancer. Increasing awareness to these risk factors will help to identify opportunities for CDI prevention in cancer patients.

[Pathogens of infections in the induction period of childhood acute lymphoblastic leukemia and drug resistance of isolated strains]

OBJECTIVE

To investigate the infections occurring in the induction period of childhood acute lymphoblastic leukemia (ALL), the pathogens of the infections, and drug resistance of isolated strains.

METHODS

A retrospective analysis was performed for the clinical data of 130 children with newly-diagnosed childhood ALL. Infections occurring during the induction chemotherapy, pathogenic strains, and drug-resistance spectrum were analyzed.

RESULTS

The incidence rate of clinical infection and/or microbial infection reached 76.2%. The lungs were the most common infection site (46.2%). The children with severe infection accounted for 52.3%, among whom 60 had pulmonary infection and/or 21 had sepsis. A total of 50 pathogenic strains were detected, which consisted of 29 bacterial strains and 21 fungal strains. Of all the children, 28.5% experienced infections caused by at least one microbe. Among the 29 bacterial strains, there were 19 (65.5%) Gram-negative bacteria and 10 (34.5%) Gram-positive bacteria. The most common Gram-negative bacteria were Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa, which were 100% sensitive to imipenem. The most common Gram-positive bacterium was Streptococcus viridans, which was 100% sensitive to vancomycin. The infections caused by fungi accounted for 16.2%, with Candida albicans as the most common fungus. Compared with those with non-severe infections, the children with severe infections had a significantly shorter time to the occurrence of agranulocytosis, a significantly longer duration of agranulocytosis, significantly higher incidence of fever and C-reactive protein (CRP) level, and a significantly longer length of hospital stay (P<0.05).

CONCLUSIONS

Pulmonary infections are common in the induction period of childhood ALL. Gram-negative bacteria are the most common pathogenic bacteria. Severe infections can be controlled by carbapenems combined with vancomycin and antifungal agents.

[Pathogens of infections in the induction period of childhood acute lymphoblastic leukemia and drug resistance of isolated strains]

OBJECTIVE

To investigate the infections occurring in the induction period of childhood acute lymphoblastic leukemia (ALL), the pathogens of the infections, and drug resistance of isolated strains.

METHODS

A retrospective analysis was performed for the clinical data of 130 children with newly-diagnosed childhood ALL. Infections occurring during the induction chemotherapy, pathogenic strains, and drug-resistance spectrum were analyzed.

RESULTS

The incidence rate of clinical infection and/or microbial infection reached 76.2%. The lungs were the most common infection site (46.2%). The children with severe infection accounted for 52.3%, among whom 60 had pulmonary infection and/or 21 had sepsis. A total of 50 pathogenic strains were detected, which consisted of 29 bacterial strains and 21 fungal strains. Of all the children, 28.5% experienced infections caused by at least one microbe. Among the 29 bacterial strains, there were 19 (65.5%) Gram-negative bacteria and 10 (34.5%) Gram-positive bacteria. The most common Gram-negative bacteria were Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa, which were 100% sensitive to imipenem. The most common Gram-positive bacterium was Streptococcus viridans, which was 100% sensitive to vancomycin. The infections caused by fungi accounted for 16.2%, with Candida albicans as the most common fungus. Compared with those with non-severe infections, the children with severe infections had a significantly shorter time to the occurrence of agranulocytosis, a significantly longer duration of agranulocytosis, significantly higher incidence of fever and C-reactive protein (CRP) level, and a significantly longer length of hospital stay (P<0.05).

CONCLUSIONS

Pulmonary infections are common in the induction period of childhood ALL. Gram-negative bacteria are the most common pathogenic bacteria. Severe infections can be controlled by carbapenems combined with vancomycin and antifungal agents.

Gastrointestinal and liver infections in children undergoing antineoplastic chemotherapy in the years 2000

AIM: To review gastrointestinal and liver infections in children undergoing antineoplastic chemotherapy. To look at gut microflora features in oncology children.

METHODS: We selected studies published after year 2000, excluding trials on transplanted pediatric patients. We searched English language publications in MEDLINE using the keywords: “gastrointestinal infection AND antineoplastic chemotherapy AND children”, “gastrointestinal infection AND oncology AND children”, “liver infection AND antineoplastic chemotherapy AND children”, “liver abscess AND chemotherapy AND child”, “neutropenic enterocolitis AND chemotherapy AND children”, “thyphlitis AND chemotherapy AND children”, “infectious diarrhea AND children AND oncology”, “abdominal pain AND infection AND children AND oncology”, “perianal sepsis AND children AND oncology”, “colonic pseudo-obstruction AND oncology AND child AND chemotherapy”, “microflora AND children AND malignancy”, “microbiota AND children AND malignancy”, “fungal flora AND children AND malignancy”. We also analysed evidence from several articles and book references.

RESULTS: Gastrointestinal and liver infections represent a major cause of morbidity and mortality in children undergoing antineoplastic chemotherapy. Antineoplastic drugs cause immunosuppression in addition to direct toxicity, predisposing to infections, although the specific risk is variable according to disease and host features. Common pathogens potentially induce severe diseases whereas opportunistic microorganisms may attack vulnerable hosts. Clinical manifestations can be subtle and not specific. In addition, several conditions are rare and diagnostic process and treatments are not standardized. Diagnosis may be challenging, however early diagnosis is needed for quick and appropriate interventions. Interestingly, the source of infection in those children can be exogenous or endogenous. Indeed, mucosal damage may allow the penetrance of endogenous microbes towards the bowel wall and their translocation into the bloodstream. However, only limited knowledge of intestinal dysbiosis in oncology children is available.

CONCLUSION: The diagnostic work-up requires a multimodal approach and should be implemented (also by further studies on new biomarkers) for a prompt and individualized therapy.

Use of Concomitant Antibiotics During Treatment for Clostridium difficile Infection (CDI) in Pediatric Inpatients: An Observational Cohort Study

Concomitant antibiotic use during treatment for Clostridium difficile infection (CDI) increases the risk of recurrence. Across a network of children’s hospitals, 46% of patients treated for CDI received concomitant antibiotics for a median of 7 days. Concomitant antibiotic use was more common among patients with malignancies, and solid organ or bone marrow transplant. Unnecessary concomitant antibiotic use in CDI patients is a potential target for pediatric antimicrobial stewardship.

Risk Factors for Recurrent Clostridium difficile Infection in Children: A Nested Case-Control Study

OBJECTIVE

To identify risk factors for recurrent Clostridium difficile infection (RCDI) in children.

STUDY DESIGN

A nested case-control study was performed to identify RCDI risk factors using a pediatric cohort of inpatients and outpatients diagnosed with Clostridium difficile infection by tcdB polymerase chain reaction (PCR) at an academic children's hospital between December 9, 2012, and June 30, 2014. Strict inclusion criteria were adopted to limit selection bias related to inappropriate inclusion of patients with probable C difficile colonization.

RESULTS

Thirty children with RCDI were compared with 94 children with non-RCDI. Statistically significant associations were identified between RCDI and malignancy (OR 2.8, 95% CI 1.0-7.4, P = .044), tracheostomy tube dependence (OR 5.2, 95% CI 1.1-24.7, P = .037), and tcdB PCR cycle threshold (OR 0.87, 95% CI 0.78-0.97, P = .01) using multivariable logistic regression modeling. The receiver operator characteristic curve for PCR cycle threshold as a predictor of RCDI demonstrated area under the curve = 0.67. The highest predictive rate (75%) for RCDI was demonstrated at cycle threshold cutpoint ≤ 20. The difference between sensitivity (64%) and specificity (68%) was minimized at cycle threshold cutpoint ≤ 23. Compared with controls with non-RCDI, children excluded because of probable C difficile colonization had a similar cycle threshold value (27.5 vs 27.2, P = .77).

CONCLUSIONS

Malignancy and tracheostomy tube dependence were identified as RCDI risk factors. Although RCDI was associated with positivity at a lower tcdB PCR cycle threshold, the clinical utility of cycle threshold as a tool to predict recurrence was limited. Better methods to predict RCDI are needed to prioritize pediatric populations to target for RCDI prevention efforts.