Epidemiologic and Clinical Characteristics of Clostridioides difficile Infections in Hospitalized and Outpatient Pediatric Oncology and Hematopoietic Stem Cell Transplant Patients.

BACKGROUND: The epidemiology and clinical course of Clostridioides difficile infection (CDI) in children, especially with cancer, are poorly defined. We aim to describe the epidemiology, clinical features and outcomes of CDI and to identify risk factors for recurrence in a pediatric oncology center. METHODS: This is a retrospective cohort study of CDI in pediatric oncology and hematopoietic stem cell transplant (HSCT) patients in 2016 and 2017. CDI cases were identified by positive C. difficile test in symptomatic patients. CDI episodes were classified as incident, duplicate or recurrent and community-onset, hospital-onset or community-onset healthcare facility-associated. Data about clinical course and outcomes were abstracted. Risk factors for CDI recurrence were assessed by logistic regression. RESULTS: One hundred seventy-eight patients 1 year of age and older developed 291 CDI episodes; 78% were incident and 22% recurrent. Underlying diagnoses were leukemia/lymphoma (57%) and solid/brain tumors (41%); 30% were HSCT recipients. Antibiotics, chemotherapy, antacids, steroids and laxatives were received by 96%, 82%, 70%, 47% and 15%, respectively. Half of the patients were neutropenic. Twenty-two percent of outpatients with CDI required hospitalization. Chemotherapy was delayed in 25%. There were no intensive care unit admissions nor deaths due to CDI. Exposure to H2-antagonists was identified as an independent risk factor for CDI recurrence. CONCLUSIONS: Although CDI in pediatric oncology and HSCT patients was associated with chemotherapy delay and hospitalization in approximately a quarter of patients, it was not associated with morbidity or mortality because patients had no attributable intensive care unit admission nor death. H2-antagonists are independent risk factors for CDI recurrence.

Prognostic role of perioperative acid-base disturbances on the risk of Clostridioides difficile infection in patients undergoing cardiac surgery.

BACKGROUND: It is unclear whether acid-base balance disturbances during the perioperative period may impact Clostridium difficile infection (CDI), which is the third most common major infection following cardiac surgery. We hypothesized that perioperative acid-base abnormalities including lactate disturbances may predict the probability of incidence of CDI in patients after cardiac procedures. METHODS: Of the 12,235 analyzed patients following cardiac surgery, 143 (1.2%) developed CDI. The control group included 200 consecutive patients without diarrhea, who underwent cardiac procedure within the same period of observation. Pre-, intra and post-operative levels of blood gases, as well as lactate and glucose concentrations were determined. Postoperatively, arterial blood was drawn four times: immediately after surgery and successively; 4, 8 and 12 h following the procedure. RESULTS: Baseline pH was lower and PaO2 was higher in CDI patients (p < 0.001 and p = 0.001, respectively). Additionally, these patients had greater base deficiency at each of the analyzed time points (p < 0.001, p = 0.004, p = 0.012, p = 0.001, p = 0.016 and p = 0.001, respectively). Severe hyperlactatemia was also more common in CDI patients; during the cardiac procedure, 4 h and 12 h after surgery (p = 0.027, p = 0.004 and p = 0.001, respectively). Multivariate logistic regression analysis revealed that independent risk factors for CDI following cardiac surgery were as follows: intraoperative severe hyperlactatemia (OR 2.387, 95% CI 1.155-4.933, p = 0.019), decreased lactate clearance between values immediately and 12 h after procedure (OR 0.996, 95% CI 0.994-0.999, p = 0.013), increased age (OR 1.045, 95% CI 1.020-1.070, p < 0.001), emergent surgery (OR 2.755, 95% CI 1.565-4.848, p < 0.001) and use of antibiotics other than periprocedural prophylaxis (OR 2.778, 95% CI 1.690-4.565, p < 0.001). CONCLUSION: This study is the first to show that perioperative hyperlactatemia and decreased lactate clearance may be predictors for occurrence of CDI after cardiac surgery.

Microbiological features, epidemiology, and clinical presentation of Clostridioidesdifficile strains from MLST Clade 2: A narrative review.

Clostridioides difficile is an emerging One Health pathogen and a common etiologic agent of diarrhea, both in healthcare settings and the community. This bacterial species is highly diverse, and its global population has been classified in eight clades by multilocus sequence typing (MLST). The C. difficile MLST Clade 2 includes the NAP1/RT027/ST01 strain, which is highly recognized due to its epidemicity and association with severe disease presentation and mortality. By contrast, the remaining 83 sequence types (STs) that compose this clade have received much less attention. In response to this shortcoming, we reviewed articles published in English between 1999 and 2020 and collected information for 27 Clade 2 STs, with an emphasis on STs 01, 67, 41 and 188/231/365. Our analysis provides evidence of large phenotypic differences that preclude support of the rather widespread notion that ST01 and Clade 2 strains are "hypervirulent". Moreover, it revealed a profound lack of (meta)data for nearly 70% of the Clade 2 STs that have been identified in surveillance efforts. Targeted studies aiming to relate wet-lab and bioinformatics results to patient and clinical parameters should be performed to gain a more in-depth insight into the biology of this intriguing group of C. difficile isolates.

Clostridioides difficile on dairy farms and potential risk to dairy farm workers.

Clostridioides difficile causes severe colitis in people and is a significant enteric pathogen in many species of animals, including swine, horses, and potentially cattle. C. difficile is shed in feces, and transmission occurs horizontally via the fecal-oral route. Livestock has been suggested as a potential reservoir for C. difficile, and while studies have shown that swine and farm workers can be colonized with identical clones of C. difficile, the zoonotic transmission of C. difficile from livestock to people has not been definitively demonstrated. The goal of this study was to determine whether dairy calves and dairy farm workers harbored genetically similar isolates of C. difficile. First, we validated a glove juice protocol for detecting C. difficile on farm workers' hands. We then visited 23 farms and collected 1) fecal samples from 92 dairy calves, 2) hand rinsates from 38 dairy farm workers, and 3) fecal samples from five of the dairy farm workers who were willing to submit them. All samples underwent anaerobic culture and qPCR to detect C. difficile. C. difficile was detected on 15 of the farms (65.2%, 95% confidence interval (CI) 42.7%-83.6%) and in 28 calves (30.4%, 95% CI 21.2-40.9%) but in none of the hand rinsates or human fecal samples. Thus, the zoonotic transmission of C. difficile on dairy farms could not be demonstrated, and dairy farmers did not appear to be at increased risk of acquiring C. difficile via the fecal-oral route.

Study on the interactive effect of deoxynivalenol and Clostridium perfringens on the jejunal health of broiler chickens.

With global warming and ban on antibiotics, it occurs occasionally that deoxynivalenol (DON) together with Clostridium perfringens impairs the gut health of broiler chickens. However, the interactive effect of DON and C. perfringens on intestinal health is still unknown. A total of 120 one-day-old Arbor Acres broilers were randomly distributed to 4 groups. Birds were gavaged with C. perfringens (8 × 108 CFU/d per bird) or sterile medium and fed a DON diet (0 or 5 mg of DON per kg diet) to investigate the interactive effects. The main effect analysis showed that DON diet significantly downregulated (P < 0.05) the mRNA expression of mucin-2, B-cell lymphoma-2-associated X, and cysteinyl aspartate-specific proteinase-3 of jejunal mucosa; decreased (P < 0.05) the indexes of ACE, Chao1, Shannon, and Simpson; and also decreased the relative abundance of the phylum Bacteroidete and the genera Lactococcus in jejunal contents of broilers chickens. Meanwhile, C. perfringens significantly increased (P < 0.05) crypt depth; decreased (P < 0.05) the ratio of villi height to crypt depth, the activity of jejunal diamine oxidase, and the relative abundance of Lactococcus; and upregulated (P < 0.05) the relative expression of B-cell lymphoma-2 and cysteinyl aspartate-specific proteinase-8. Furthermore, the interactions between DON and C. perfringens were most significant (P < 0.05) in the mRNA expression of lipopolysaccharide-induced TNF factor (LITAF) and TLR-4, the abundance of the genera Lactococcus in jejunal contents, and butyric acid concentrations in cecal contents of birds. Finally, Spearman correlation analysis suggested that the most negative correlations (P < 0.05) with the abundance of the genera except Lactobacillus were observed within the mRNA expression of LITAF. The abundance of Lactococcus had a positive correlation (P < 0.05) with the expression of Caspase-3. Most genera except Lactobacillus negatively correlated (P < 0.05) with acetic acid, butyric acid, and total short-chain fatty acids. In conclusion, dietary deoxynivalenol and C. perfringens challenge had a harmful effect on the jejunal health and should be carefully monitored in broiler production.

Computational modeling of the gut microbiota reveals putative metabolic mechanisms of recurrent Clostridioides difficile infection.

Approximately 30% of patients who have Clostridioides difficile infection (CDI) will suffer at least one incident of reinfection. While the underlying causes of CDI recurrence are poorly understood, interactions between C. difficile and commensal gut bacteria are thought to play an important role. In this study, an in silico pipeline was used to process 16S rRNA gene amplicon sequence data of 225 stool samples from 93 CDI patients into sample-specific models of bacterial community metabolism. Clustered metabolite production rates generated from post-diagnosis samples generated a high Enterobacteriaceae abundance cluster containing disproportionately large numbers of recurrent samples and patients. This cluster was predicted to have significantly reduced capabilities for secondary bile acid synthesis but elevated capabilities for aromatic amino acid catabolism. When applied to 16S sequence data of 40 samples from fecal microbiota transplantation (FMT) patients suffering from recurrent CDI and their stool donors, the community modeling method generated a high Enterobacteriaceae abundance cluster with a disproportionate large number of pre-FMT samples. This cluster also was predicted to exhibit reduced secondary bile acid synthesis and elevated aromatic amino acid catabolism. Collectively, these in silico predictions suggest that Enterobacteriaceae may create a gut environment favorable for C. difficile spore germination and/or toxin synthesis.

Differential expression of intestinal genes in necrotic enteritis challenged broiler chickens with 2 different Clostridium perfringens strains.

The primary cause of necrotic enteritis (NE) disease in chickens is the NetB-positive Clostridium perfringens bacterium. Many factors are known to affect the severity of NE in the challenge models of broiler chickens, and one of these factors is the virulence of C. perfringens strain. This study was conducted to evaluate the effect of 2 pathogenic C. perfringens strains in a NE challenge model on gut health and mRNA expression of genes encoding apoptosis, tight junction, immunity, and nutrient transporters in broilers. Day-old Ross-308 male broilers (n = 468) were allocated in a 2 × 3 factorial arrangement of treatments with in-feed antibiotics (no or yes) and challenge (Non, C. perfringens strain NE18, and C. perfringens strain NE36) as the factors. The birds in the challenged groups were inoculated with Eimeria species on day 9 and with a fresh suspension of C. perfringens NE18 or NE36 on day 14 and 15. Sample collection was performed on 2 birds of each pen on day 16. Necrotic enteritis challenge, impaired feed conversion ratio during day 0 to 16 compared with the control group where the effect of the NE36 challenge was more severe than that with NE18 (P < 0.001). The mRNA expression of mucin-2, immunoglobulin-G, occludin (P < 0.001), and tight junction protein-1 (P < 0.05) genes were downregulated in both challenged groups compared with the nonchallenged counterparts. Antibiotic supplementation, on the other hand, increased weight gain, and feed intake in all challenged birds (P < 0.01), but upregulated mucin-5ac and alanine, serine, cysteine, and threonine transporter-1 (P < 0.05) only in the NE18 challenged birds. The challenge with NE36 significantly upregulated caspase-8 and claudin-1 (P < 0.001), but downregulated glucose transporter-2 (P < 0.001) compared with the NE18 challenge. These results suggest that NE challenge is detrimental to the performance of broilers through compromised intestinal health, and different C. perfringens strains can affect the severity of the disease through modulating the expression of intestinal genes encoding proteins responsible for apoptosis, gut integrity, immunity, mucus production, and nutrient transporters.

Faecal microbiota transplantation for Clostridioides difficile: mechanisms and pharmacology.

Faecal microbiota transplantation (FMT) has emerged as a remarkably successful treatment for recurrent Clostridioides difficile infection that cannot be cured with antibiotics alone. Understanding the complex biology and pathogenesis of C. difficile infection, which we discuss in this Perspective, is essential for understanding the potential mechanisms by which FMT cures this disease. Although FMT has already entered clinical practice, different microbiota-based products are currently in clinical trials and are vying for regulatory approval. However, all these therapeutics belong to an entirely new class of agents that require the development of a new branch of pharmacology. Characterization of microbiota therapeutics uses novel and rapidly evolving technologies and requires incorporation of microbial ecology concepts. Here, we consider FMT within a pharmacological framework, including its essential elements: formulation, pharmacokinetics and pharmacodynamics. From this viewpoint, multiple gaps in knowledge become apparent, identifying areas that require systematic research. This knowledge is needed to help clinical providers use microbiota therapeutics appropriately and to facilitate development of next-generation microbiota products with improved safety and efficacy. The discussion here is limited to FMT as a representative of microbiota therapeutics and recurrent C. difficile as the indication; however, consideration of the intrinsic basic principles is relevant to this entire class of microbiota-based therapeutics.

Patients with More Severe IBD Get Clostridioides difficile Rather than Clostridioides difficile Increasing the Severity of IBD.

BACKGROUND: Inflammatory bowel disease (IBD) patients who have Clostridioides difficile infection (CDI) have worse outcomes. AIMS: We aimed to determine whether such outcomes are the result of CDI or whether CDI occurs in patients who have more severe IBD. METHODS: This was a retrospective study of patients hospitalized for ≥ 2 IBD flares from 2010 to 2019. The primary outcome was time to IBD flare between hospitalizations. First, time to flare was compared between patients who were hospitalized for a flare complicated by CDI and subsequently for a CDI-negative flare (cohort A, denoted +/-) versus patients who were hospitalized for two CDI-negative flares (cohort B, -/-). Second, time between flares was compared within the subset of cohort A patients who had three flares (cohort C, -/+/-) before and after CDI. RESULTS: Time between flares was a median of 4 months (IQR 1-9) among 51 cohort A patients versus 12 months (IQR 6-38) among 51 cohort B patients (log-rank P < 0.01). In contrast, the median time between flares was similar within cohort C before and after CDI (log-rank P = 0.54). At time of the second IBD flare, patients in cohort A (+/-) were more likely to have moderate or severe disease compared to patients in cohort B (-/-). CONCLUSIONS: Patients with prior CDI had shorter time to subsequent IBD flare relative to their CDI-negative counterparts. This is not likely due to CDI itself because there was no difference in time between flares before versus after acquiring CDI. Rather, patients who acquire CDI may have more severe IBD.

Pharmacokinetics of CamSA, a potential prophylactic compound against Clostridioides difficile infections.

Clostridioides difficile infections (CDI) are the leading cause of nosocomial antibiotic-associated diarrhea. C. difficile produces dormant spores that serve as infectious agents. Bile salts in the gastrointestinal tract signal spores to germinate into toxin-producing cells. As spore germination is required for CDI onset, anti-germination compounds may serve as prophylactics. CamSA, a synthetic bile salt, was previously shown to inhibit C. difficile spore germination in vitro and in vivo. Unexpectedly, a single dose of CamSA was sufficient to offer multi-day protection from CDI in mice without any observable toxicity. To study this intriguing protection pattern, we examined the pharmacokinetic parameters of CamSA. CamSA was stable to the gut of antibiotic-treated mice but was extensively degraded by the microbiota of non-antibiotic-treated animals. Our data also suggest that CamSA's systemic absorption is minimal since it is retained primarily in the intestinal lumen and liver. CamSA shows weak interactions with CYP3A4, a P450 hepatic isozyme involved in drug metabolism and bile salt modification. Like other bile salts, CamSA seems to undergo enterohepatic circulation. We hypothesize that the cycling of CamSA between the liver and intestines serves as a slow-release mechanism that allows CamSA to be retained in the gastrointestinal tract for days. This model explains how a single CamSA dose can prevent murine CDI even though spores are present in the animal's intestine for up to four days post-challenge.

Impact of Clostridioides difficile infection on the outcome of patients receiving a hematopoietic stem cell transplantation.

OBJECTIVES: Clostridioides difficile infections (CDI) are common in autologous (auto-HSCT) or allogenic hematopoietic stem cell transplant (allo-HSCT) recipients. However, the impact of CDI on patient outcomes is controversial. We conducted this study to examine the impact of CDI on patient outcomes. METHODS: We performed a retrospective single-center study, including 191 lymphoma patients receiving an auto-HSCT and 276 acute myeloid leukemia (AML) patients receiving an allo-HSCT. The primary endpoint was overall survival (OS). Secondary endpoints were causes of death and, for the allo-HSCT cohort, GvHD- and relapse-free survival (GRFS). RESULTS: The prevalence of CDI was 17.6% in the AML allo-HSCT and 7.3% in the lymphoma auto-HSCT cohort. A higher prevalence of bloodstream infections, but no differences concerning OS or cause of death were found for patients with CDI in the auto-HSCT cohort. [AU] In the allo-HSCT cohort, OS and GRFS were similar between CDI and non-CDI patients. However, the leading cause of death was relapse among non-CDI patients, but it was infectious diseases in the CDI group with fewer deaths due to relapse. CONCLUSIONS: CDI was not associated with worse survival in patients receiving a hematopoietic stem cell transplantation, and there were even fewer relapse-related deaths in the AML allo-HSCT cohort.

Risk factors and intestinal microbiota: Clostridioides difficile infection in patients receiving enteral nutrition at Intensive Care Units.

BACKGROUND: Clostridioides difficile infection (CDI) is a leading cause of nosocomial diarrhea. Patients receiving enteral nutrition (EN) in the intensive care unit (ICU) are potentially at high risk of CDI. In the present study, we assessed the risk factors and intestinal microbiome of patients to better understand the occurrence and development of CDI. METHODS: Patients were screened for C. difficile every week after starting EN, and their clinical records were collected for risk factor identification. Fecal samples were analyzed using 16S rRNA sequencing to evaluate the intestinal microbiota. RESULTS: Overall incidence of CDI was 10.7% (18/168 patients). History of cerebral infarction was significantly associated with CDI occurrence (OR, 9.759; 95% CI, 2.140-44.498), and treatment with metronidazole was identified to be protective (OR, 0.287; 95% CI, 0.091-0.902). Patients with EN had lower bacterial richness and diversity, accompanied by a remarkable decrease in the abundance of Bacteroides, Prevotella_9, Ruminococcaceae, and Lachnospiraceae. Of these patients, acquisition of C. difficile resulted in a transient increase in microbial diversity, along with consistent alterations in the proportion of some bacterial taxa, especially Ruminococcaceae and Lachnospiraceae. Upon initiation of EN, patients who were positive for C. difficile later showed an enhanced load of Bacteroides, which was negatively correlated with the abundance of C. difficile when CDI developed. CONCLUSION: ICU patients receiving EN have a high prevalence of CDI and a fragile intestinal microbial environment. History of cerebral infarction and prior treatment with metronidazole are considered as vital risk and protective factors, respectively. We propose that the emergence of CDI could cause a protective alteration of the intestinal microbiota. Additionally, Bacteroides loads seem to be closely related to the occurrence and development of CDI.

Recurrent Clostridioides difficile infection: Recognition, management, prevention.

Clostridioides difficile infection (CDI) is the most common cause of diarrhea in hospitalized patients and results in substantial morbidity, mortality, and costs. Its clinical management, primarily with antibiotics, is often complicated by recurrent episodes. These recurrent CDI episodes are thought to be caused by antibiotic disruption of colonic microbiota and usually occur within 4 weeks of completing antibiotic therapy. The risk of recurrent CDI increases after the first episode, creating a need for management strategies to diagnose, treat, and prevent these complications.

Effects of Eimeria maxima and Clostridium perfringens infections on cecal microbial composition and the possible correlation with body weight gain in broiler chickens.

With the voluntary and regulatory withdrawal of antibiotic growth promoters from animal feed, coccidiosis and necrotic enteritis (NE) emerge as the top two enteric poultry infectious diseases responsible for major economic loss worldwide. The objective of this study was to investigate the correlation between the cecal microbiota compositions with the growth trait after coccidiosis and NE. In this study, the effects of Eimeria maxima and/or Clostridium perfringens infections on the microbial composition and potential correlation with the body weight gain were investigated in broiler chickens using 16S rRNA gene sequencing. E. maxima and C. perfringens coinfection successfully induced NE with its typical gut lesions and significant reductions in the percentage of relative body weight gain (RBWG%). The NE challenge model did not affect cecal microbial diversity, but influenced the cecal microbial composition. KEGG enzymes in microbiota were significantly altered in abundance following dual infections. Furthermore, significant correlations between cecal microbiota modules and RBWG% were identified in the sham control, E. maxima or C. perfringens infected groups. Understanding of host-microbiota interaction in NE would enhance the development of antibiotics-independent strategies to reduce the harmful effect of NE on the gut microbiota structure, and improve the gut health and poultry production.

[Updated review of Clostridium difficile infection in elderly]. / Actualización sobre infección por Clostridium difficile en el paciente mayor.

Clostridium difficile infection is the most common cause of health care-associated diarrhoea, and its incidence increases with age. Clinical challenges, risk of resistance to treatment, risk of recurrence, and treatment responses are different in elderly. The aim of this review is to discuss the updated epidemiology, pathophysiology, diagnosis, and therapeutic management of C. difficile infection in elderly with the available data.

The effect of different dietary ratios of lysine and arginine in diets with high or low methionine levels on oxidative and epigenetic DNA damage, the gene expression of tight junction proteins and selected metabolic parameters in Clostridium perfringens-challenged turkeys.

Two experiments were performed to investigate the effect of different ratios of arginine (Arg) to lysine (Lys) in diets with low (30% Lys; Experiment 1) and high (45% Lys; Experiment 2) methionine (Met) levels on selected metabolic parameters, oxidative and epigenetic DNA damage, and the mechanisms underlying intestinal barrier integrity in turkeys challenged with Clostridium perfringens. In each experiment, 108 one-day-old Hybrid Converter female turkeys were placed in 6 pens (18 birds per pen) and reared for 42 days. At 34, 36 and 37 days of age, half of the birds were subjected to C. perfringens challenge. A 3 × 2 factorial design with three levels of Arg relative to Lys (90, 100 and 110%; Arg90, Arg100 and Arg110, respectively) and C. perfringens infection (-, +) was employed. Challenging birds with C. perfringens increased lipid oxidation and the oxidation and methylation of DNA of intestinal mucosa, and down-regulated the activities of DNA-repairing enzymes. Neither the dietary treatment nor the challenge affected the markers of liver function or metabolism. Arg110 diets with the high Met level induced DNA oxidation and methylation whereas these processes were downregulated in birds fed Arg90 diets. The results indicate that Arg90 diets with high Met levels have a beneficial influence on the indicators of intestinal barrier integrity in turkeys with necrotic enteritis (NE). Despite the analyzed amino acid ratios interacted with the systems responsible for the maintenance of gut integrity in the host organism, this dietary intervention probably enabled birds to cope with NE.

Fecal Microbiota Transplantation for Clostridioides difficile in High-Risk Older Adults Is Associated with Early Recurrence.

BACKGROUND: Fecal microbiota transplantation (FMT) is highly effective for treating recurrent Clostridioides difficile infection (CDI). CDI disproportionately affects the elderly; however, there is a paucity of data on FMT effectiveness in older adults, especially subpopulations at highest risk for CDI-related morbidity and mortality. AIM: To assess the efficacy and safety of FMT for CDI in older adults. METHODS: A retrospective, long-term follow-up study was performed. The high-risk subpopulation included patients who were immunocompromised, patients with inflammatory bowel disease, and patients presenting with severe or fulminant colitis. Outcome measures included primary cure rates, early (< 12 weeks) and late (> 12 weeks) recurrence rates, adverse events, and subgroup analysis of higher-risk populations. RESULTS: Our cohort included 75 patients (72% female) with a mean age of 76.4 and Charlson comorbidity index score of 5.4. There were 34 patients in our higher-risk subpopulation as defined above with an adjusted recurrence rate of 32.1%. FMT was performed for severe or fulminant disease in 30.6% of patients with a 3-month survival rate of 73.9%. Overall, the adjusted primary cure rate was 67.2% and the adjusted CDI recurrence was 29.9% in our cohort (90% of recurrences occurred early). Most adverse events in our study were rehospitalizations for recurrent CDI. CONCLUSION: Compared with previous studies of FMT efficacy, our cohort had a lower primary cure rate and higher CDI recurrence rate than previously reported, likely driven by our higher-risk subpopulations. Nevertheless, FMT should be considered early to prevent progression of CDI severity and recurrence, especially in patients who present with severe and fulminant disease.

Clostridioides difficile Infection: Update on Management.

Guidelines for the diagnosis and treatment of Clostridioides difficile infection have recently been updated. Risk factors include recent exposure to health care facilities or antibiotics, especially clindamycin. C. difficile infection is characterized by a wide range of symptoms, from mild or moderate diarrhea to severe disease with pseudomembranous colitis, colonic ileus, toxic megacolon, sepsis, or death. C. difficile infection should be considered in patients who are not taking laxatives and have three or more episodes of unexplained, unformed stools in 24 hours. Testing in these patients should start with enzyme immunoassays for glutamate dehydrogenase and toxins A and B or nucleic acid amplification testing. In children older than 12 months, testing is recommended only for those with prolonged diarrhea and risk factors. Treatment depends on whether the episode is an initial vs. recurrent infection and on the severity of the infection based on white blood cell count, serum creatinine level, and other clinical signs and symptoms. For an initial episode of nonsevere C. difficile infection, oral vancomycin or oral fidaxomicin is recommended. Metronidazole is no longer recommended as first-line therapy for adults. Fecal microbiota transplantation is a reasonable treatment option with high cure rates in patients who have had multiple recurrent episodes and have received appropriate antibiotic therapy for at least three of the episodes. Good antibiotic stewardship is a key strategy to decrease rates of C. difficile infection. In routine or endemic settings, hands should be cleaned with either soap and water or an alcohol-based product, but during outbreaks soap and water is superior. The Infectious Diseases Society of America does not recommend the use of probiotics for prevention of C. difficile infection.