Clostridium difficile (C. difficile) is a Gram-positive, anaerobic, toxin-producing germ first isolated from the stool of healthy newborns in 1935(1). It is the most common cause of antimicrobial therapy-associated diarrhea and is a common healthcare-associated pathogen (2). In recent years, there has been an increase in the incidence of community-acquired infection in subjects without known risk factors (3,4), such as previous exposure to antibiotics, patients with chronic gastrointestinal pathology or inflammatory bowel disease (IBD).

C. difficile may be considered a constituent of the normal microbiota, but under specific conditions that disrupt the normal intestinal microbiota, it colonizes the large intestine causing, through the action of its toxins, varying degrees of colonic damage, ranging from mild diarrhea to toxic megacolon (5).

In recent years, there have been substantial changes in its diagnostic and therapeutic management (6). However, there is a lack of research on C. difficile infection (CDI) in children, with much of the data being extrapolated from studies of adult patients (7).

The aim of the present review was to provide the pediatrician with up-to-date information and recommendations on CDI in pediatric patients.

The Cochrane (https://www.cochrane.org/), MEDLINE (https://www.nlm.nih.gov/) and EMBASE (https://www.embase.com/) databases were explored from January 2000 to September 2023, using the terms ‘Clostridium difficile neonates’, ‘Child, pediatric, Clostridium difficile’; a total of 112 studies containing relevant data were selected and checked. Studies were excluded if they were not published in English or French, if the pediatric population was not treated separately from the adult population or if the study did not contain original data (Fig. 1). Studies that included adult groups were also selected for the pathogenesis and epidemiology chapter.

Recognized risk factors for older children that acquire C. difficile have included the use of antibiotics and proton pump inhibitors (PPIs) for prolonged periods, immunosuppressive treatments, repeated enemas, the use of diapers, prolonged nasogastric tube insertion, gastrointestinal tract surgery, renal failure, the presence of IBD and impaired humoral immunity (1,6,22).

A previous study of pediatric C. difficile cases reported as risk factors the antibiotic treatment in 92% of children, the immunosuppressive treatment in 60%, a malignancy or organ transplant in 39%, while 13% had IBD (23). Among the antibiotics, the most commonly associated with increased risk of C. difficile infection are the combinations of antibiotics, cephalosporins, fluoroquinolones, penicillins, carbapenems and cotrimoxazole (14).

While a study conducted in 2020 found that clindamycin is associated with higher odds of community-acquired CDI in pediatrics [odds ratio (OR), 14.9; 95% confidence interval (CI), 5.2-42.3], followed by amoxicillin-clavulanate (OR, 2.2; 95% CI, 1.2-3.9) and cephalosporin (OR, 2; 95% CI, 1.1-3.6) (22), a different study reported an association between community-acquired CDI and cephalosporins (OR, 1.95; 95% CI, 0.68-4.95; P=0.16), exposure to clindamycin (OR, 2.70; 95% CI, 0.70-10.39; P=0.15) and the presence of a gastrointestinal feeding device (OR, 2.27; 95% CI, 0.92-5.60; P=0.08) (24), while a study conducted by Adams et al (25) reported an association between community-acquired CDI and clindamycin (OR, 73.00; 95% CI, 13.85-384.68) and third-generation cephalosporins (OR, 16.32; 95% CI, 9.11-29.26).

Chemotherapy is associated with an increased risk of CDI, possibly due to the antimicrobial properties of chemotherapeutic agents, the effects of immunosuppression and neutropenia, and changes in intestinal mucosa (26). Hypogammaglobulinemia is also associated with an increased risk of CDI.

While a number of studies suggest that drugs that suppress gastric acidity, particularly PPIs (27), cause the alteration of the gut microbiota, allowing pathogens including C. difficile to increase, in a previous pediatric study the H2 receptor antagonists have actually been associated with decreased colonization by C. difficile (28).

The presence of frequent and prolonged hospitalizations among children with C. difficile is highlighted by numerous studies; this is due to the exposure to an environmental reservoir of C. difficile, with the possible transmission of this pathogen, and is indirectly associated with other risk factors such as the use of antibiotics and PPIs (1).

Inflammation of the intestinal epithelium secondary to viral gastroenteritis (noroviruses and caliciviruses), may facilitate adhesion and colonization by C. difficile and the occurrence of infection (1).

Comorbidities (especially chronic gastrointestinal and neurological diseases) are associated with CDI, due to the numerous associated risk factors that trigger disturbances of the gut microbiota such as: i) Prolonged hospitalization, ii) the use of antibiotics or PPIs and iii) immunosuppression (1,29). Thus, according to studies, IBD (OR, 3.72; 95% CI, 1.52-9.12), renal failure (OR, 2.64; 95% CI, 1.23-5.68), hematologic cancer (OR, 1.75; 95% CI, 1.02-5.68) and diabetes mellitus (OR, 1.15; 95% CI, 1.05-1.27) were associated with CDI (30). A study conducted in 2018 demonstrated that other conditions identified as risk factors for CDI included coagulopathy (OR, 3.07; 95% CI, 1.34-7.06), pneumonia (OR, 2.37; 95% CI, 1.73-3.25), female pelvic infection (OR, 2.01; 95% CI 1.21-3.37), IBD (OR, 1.96; 95% CI, 1.36-2.81), irritable bowel syndrome (OR, 1.66; 95% CI, 1.23-2.24), iron deficiency anemia (OR, 1.55; 95% CI, 1.02-2.33), viral infections (OR, 1.51; 95% CI, 1.06-2.15), depression (OR, 1.45; 95% CI, 1.06-1.98) and stroke (OR 1.43, 95% CI 1.00-2.03) (31).

The incubation period from exposure to onset of symptomatic CDI (CSI) is two to three days. The reservoir for C. difficile spores is represented by toilets, furniture in the clinic, telephones and medical devices (thermometers, stethoscopes).

Important pathophysiological characteristics of C. difficile include the resistance to heat of the spore (which allows its persistence in the environment for several months), the resistance to acids, antibiotics and the production of toxins (28).

Once in the gut, bile acids play an important role in inducing the germination of C. difficile spores (1). Colonization does not necessarily mean symptomatic infection, only 25-30% of asymptomatic colonized patients develop diarrhea (32).

The microbial intestinal ecosystem, rich in the anaerobic Bacteroides and Firmicutes species, plays an important role in the regulation of host physiology, especially in the defense against pathogens, in the stimulation of angiogenesis or in the nutrition process (1).

C. difficile begins to dominate and colonize the large intestine when the balance of intestinal microorganisms is disturbed, which is the first step of infection.

C. difficile is not invasive, virulence is due mainly to enzymes such as collagenase, hyaluronidase, chondroitin sulfatase, as well as toxins A and B, which damage the cytoskeleton of epithelial cells, leading to disruption of tight junctions and loss of mucosal functionality (32). Toxin A (enterotoxin) can disrupt neuronal function and cause aberrant calcium release (33). Toxin B (cytotoxin) exerts its effect on white blood cells by altering neutrophil chemotaxis and activating mast cells and macrophages, which leads to the release of inflammatory mediators (26,33). There is also a third toxin, CDT, a binary toxin that is produced by certain C. difficile strains, including the PCR027 ribotypes, which theoretically could have clinical impact, however its role is unclear. The end result of toxin activity in the gut is fluid secretion, mucosal damage and interstitial inflammation (1).

In more severe forms, microulcerations covered with pseudo-membranes (composed of destroyed intestinal cells, neutrophils and fibrin) begin to appear on the surface of the intestinal mucosa (32).

A case definition of CDI includes the presence of symptoms (usually watery diarrhea) and either one stool test result that is positive for C. difficile toxin or colonoscopy findings demonstrating pseudomembranous colitis.

The clinical picture of CDI is very heterogeneous and ranges from asymptomatic carrier state, mild or moderate diarrhea, to fulminant life-threatening colitis (34). Although the incubation period is not precisely defined, recent studies revealed that it is longer than 3 days and is highly dependent on the individual.

The symptomatic illness can be mild, moderate or severe. The mild and moderate form is usually characterized by watery diarrhea (<4 stools/day in the mild form and more in the moderate form), low-grade fever and mild abdominal pain, without phenomena of systemic toxicity. Other clinical manifestations include nausea, weakness and loss of appetite. Fecal occult blood testing is often positive, although active bleeding is rarely present (32). The severe form involves high fever, intense abdominal pain, abdominal distension, vomiting food, numerous watery stools with mucus and blood leading to significant dehydration, hypoalbuminemia with peripheral edema and subsequent circulatory shock (32).

Other severe complications of CDI include toxic megacolon, intestinal paralysis, small bowel infiltration, colonic perforation, reactive arthritis, renal failure, systemic inflammatory response syndrome, sepsis and death (35).

Complications are more likely to occur among children with hematological malignancies or those treated with hematopoietic stem cell transplantation, infants with Hirschsprung's disease or patients with IBD (1).

The mortality rate due directly to CDI is estimated at 5%, while mortality associated with complications reaches 15-25% and up to 34% in intensive care units (32).

The diagnosis of CDI is based on the association between medical history, clinical presence of >3 semi-consistent stools/24 h or bloody stools and laboratory tests (9). Because of the slow turnaround time, isolation of the organism from stool is not a clinically useful diagnostic test, nor is stool testing of asymptomatic patients.

Cell culture cytotoxicity neutralization assay (CCCA) has been replaced by more sensitive diagnostics, the most common test method used today for C. difficile toxins is the enzyme immunoassay (EIA), which detects toxins A and/or B. It is preferred due to the rapid turnaround time, the ease of testing and the high specificity (1).

Detection of glutamine dehydrogenase, an antigen present on C. difficile, although very sensitive, only indicates the presence of the pathogen. It should only be used as part of a 2-step algorithm, with confirmation of positive results using either an EIA for toxin A/B or a CCCA.

Molecular tests using nucleic acid amplification tests (NAATs) are now preferred by numerous laboratories because they have high sensitivity and specificity, comparable turnaround times to EIA and do not need to be part of a 2- or 3-step algorithm (14). In a previous study, the sensitivities of PCR tests with high sensitivity and specificity for toxins A and B compared with the EIA test were higher (95 vs. 35%, respectively), and the specificity was equal to 100% (36). Using PCR tests, positivity rates for stool samples doubled, from 7.9 to 8.3% with EIA and from 14.9 to 18.1% with PCR (9).

Stool testing in newborns and infants <1 year of age is not recommended except in the presence of risk factors such as Hirschsprung-associated enterocolitis or primary immunodeficiency, surgery on the gastrointestinal tract or the presence of an infectious outbreak; the presence of C. difficile is considered colonization (1). In children aged 1 to 2 years presenting with diarrhea, testing for C. difficile may be considered after testing for other causes of diarrhea, especially viral infection. In children >2 years of age, testing is similar to adult testing and is recommended for patients with prolonged or worsening diarrhea, especially if combined with relevant risk factors or exposures.

The presence of pseudo-membranes and hyperemic, friable rectal mucosa on colonoscopy suggests pseudomembranous colitis and establishes the diagnosis of CDI, regardless of the age of the child (1,14).

The treatment of CDI in children is based on clinical data from adults and is determined by the number and severity of episodes (37). The therapeutic recommendations in CDI are the following: i) General principles, ii) etiological treatment, iii) surgery, iv) supportive treatment, v) fecal microbiota transplantation, vi) upcoming treatment and vii) prevention.

Although the incidence of CDI is not really known, all data in the literature indicated an increase in community cases. Clinicians should be more responsible for recommending outpatient antibiotic therapy.

The diagnosis must take into account both the presence of risk factors and the presence of clinical signs and follow specific diagnostic testing algorithms. Further studies are needed to evaluate different treatment strategies for children with a poor response to classic treatment.