Dr. Stacy Kahn: Clostridioides difficile 2026

Recently, Dr. Stacy Kahn gave our group an excellent update on Clostridioides difficile. My notes below may contain errors in transcription and in omission. Along with my notes, I have included many of her slides. Dr. Kahn has been a leader on treatment and advocacy for C. difficille. In 2025, she received the Leadership Award from the Peggy Lillis Foundation recognizing her clinical, research and advocacy efforts related to C. difficile awareness and treatments.

Key points:

Diagnosis: C. diff is difficult to diagnose. The NAAT-based assays are highly sensitive but cannot readily distinguish active infection from colonization. ELISA toxin assays have higher specificity. However, there are many of these assays and their reliability in identifying active infection from colonization varies. In individuals with underlying diseases like IBD and IBS, this can create uncertainty about the diagnosis of C. diff.

Presentation: Symptoms are quite variable, from asymptomatic to bloody diarrhea to fulminant colitis (uncommon in kids). Profound urgency is a common feature.

Transmission: C. diff bacteria can survive on surfaces for 24 hrs. The spores can survive months to years. In addition, the (invisible) spores are highly resistant to heat, disinfection and antimicrobials. Thus, nursing homes and hospitals are frequent reservoirs.

Epidemiology: C diff rates in the hospital setting have improved, likely due to antibiotic stewardship. Community rates have increased; though, precise estimates are problematic as the diagnostic testing is not straightforward.

Costs: In 2016, the estimated annual costs due to C diff were $ 6.3 billion (Zhang S. et al. BMC Infect Dis. 2016).

Resources/Websites:

Severe C diff in Children: In a retrospective study of C diff in hospitalized children (2013-2019, n=17,142 children) showed that among 23,053 CDI admissions, 74 (0.3%) had a colectomy (55 in IBD patients), and 29 (0.1%) had toxic megacolon. All-cause mortality was noted in 429 (1.9%) (Reference: Edwards PT, Kahn SA, Nicholson, M et al. J Pediatr. 2023; 252:111-116.e1. Open Access! Clostridioides difficile Infection in Hospitalized Pediatric Patients: Comparisons of Epidemiology, Testing, and Treatment from 2013 to 2019).

Testing: Recommendations include avoiding testing in those taking laxatives; however, an exception to this would be patients with motility disorders. Even combination testing cannot always distinguish between colonization and active infection. In addition, there are numerous toxin tests with variable performance.

[From prior blog post: In a large adult study with 293 of 1416 hospitalized adults testing positive for C. diff, virtually all CDI-related complications and deaths occurred in patients with positive toxin immunoassay test results. Patients with a positive molecular test result and a negative toxin immunoassay test result had outcomes that were comparable to patients without C difficile by either method. (Overdiagnosis of Clostridium difficile with PCR Assays)]

Treatment:

  • 1st line treatment remains vancomycin.
  • 10-day treatment course is recommended.
  • Fidaxomicin, particularly for recurrrent C. diff could be helpful and easier to administer (2/day).
  • Prophylactic treatment (low dose vancomycin) may be appropriate in high risk individuals needing to take antibiotics.
  • FMT is no longer readily available from stool banks. Donor-directed FMT may be an option after appropriate screening. Given the lack of stool banks, urgent treatment with FMT for severe cases is not available.
  • Probiotics have not been proven effective in reducing recurrence and increase the costs for families. A diet high in fruits and veggies (‘eat the rainbow‘) could help restore a more healthy microbiome.
  • Newer treatments in adults, Vowst and Rebyota, are expensive and not readily available for children. Anecdotal reports suggest they may be beneficial in pediatric patients.

Conclusions: C diff research is difficult in pediatrics. Many of the patients who need treatment would be excluded from trials. There are very few treatment options in kids.

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Disclaimer: This blog, gutsandgrowth, assumes no responsibility for any use or operation of any method, product, instruction, concept or idea contained in the material herein or for any injury or damage to persons or property (whether products liability, negligence or otherwise) resulting from such use or operation. These blog posts are for educational purposes only. Specific dosing of medications (along with potential adverse effects) should be confirmed by prescribing physician. Because of rapid advances in the medical sciences, the gutsandgrowth blog cautions that independent verification should be made of diagnosis and drug dosages. The reader is solely responsible for the conduct of any suggested test or procedure. This content is not a substitute for medical advice, diagnosis or treatment provided by a qualified healthcare provider. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a condition.

New Target For Clostridioides Difficile Treatment

From Boston Children’s (10/25/23): A new approach to C. diff? Targeting the inflammation, not the bacteria

An excerpt:

A new and promising approach — which Dong, Rao, and their colleagues describe in the journal Nature — focuses on curbing intestinal inflammation rather than fighting the bacteria directly…

In response to the toxin, the sensory neurons secrete the neuropeptides substance P and calcitonin gene-related peptide (CGRP), while the pericytes, which surround blood vessels, produce pro-inflammatory cytokines. In a mouse model, this drove intense neurogenic inflammation and tissue damage —the same kind of damage that occurs in patients…

FDA-approved drugs already exist to block the triggering neuropeptides. Aprepitant, used for nausea and vomiting, blocks substance P signaling. Small molecules related to olcegepant or monoclonal antibodies such as fremanezumab, used for migraines, inhibit CGRP signaling.

In the mouse model, these drugs reduced inflammation and tissue damage. Somewhat surprisingly, they even reduced the burden of C. diff bacteria in the animals’ intestines.

My take: Clinical trials are needed to see if these therapies can improve outcomes more than current treatments.

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IBD Updates: Treat-to-Target Uptake, Long-Term Data on Ustekinumab Intensification, and Low Rates of C diff with Tofacitinib (& Clinical Pearl)

JL Yang et al. Inflamm Bowel Dis 2023; 29: 735-743. Utilization of Colonoscopy Following Treatment Initiation in U.S. Commercially Insured Patients With Inflammatory Bowel Disease, 2013-2019

In this study with 39,734 commercially-insured initiators of IBD medications (18-64 year old), 34% had a colonoscopy by 12 months and 42% at 15 months. The authors state that “it is evident that patients without any colonoscopy during this interval are not being followed under an optimal long-term T2T (treat-to-target) paradigm.”

RS Dalal et al. Inflamm Bowel Dis 2023; 29: 830-833. Long-Term Outcomes After Ustekinumab Dose Intensification for Inflammatory Bowel Diseases

This retrospective study examined 123 patients with Crohn’s disease and 40 with ulcerative colitis who had dose intensification with ustekinumab (to either every 4 weeks, n=91, or every 6 weeks, n=72). Dose escalation was effective in both achieving and maintaining corticosteroid-free clinical remission for 61% of patients with Crohn’s disease and 40% with ulcerative colitis at 24 months; endoscopic remission was noted in 43% with Crohn’s disease and 55% with ulcerative colitis.

EV Loftus et al. Inflamm Bowel Dis 2023; 29: 744-751. Open Access! Clostridium difficile Infection in Patients with Ulcerative Colitis Treated with Tofacitinib in the Ulcerative Colitis Program 

Using data from multiple studies with 1157 patients, only 9 tofacitinib patients developed Clostridioides difficile infection (CDI) which was lower than the placebo group. CDI were all mild–moderate in severity and resolved with treatment in 8 patients. Six of 9 patients continued tofacitinib treatment without interruption. The low rate of infection was likely in part due to screening for CDI prior to treatment. In addition, “it is possible than the lower rates of CDI …may be due to better-controlled disease…, thus reducing susceptibility to infection.”

One clinical pearl in the discussion: “When considering treatment [for CDI], initial therapy with oral vancomycin should be considered instead of metronidazole, and treating for at least 21 days should also be considered [in patients with IBD due to]…lower rates of CDI recurrence.”

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Disclaimer: This blog, gutsandgrowth, assumes no responsibility for any use or operation of any method, product, instruction, concept or idea contained in the material herein or for any injury or damage to persons or property (whether products liability, negligence or otherwise) resulting from such use or operation. These blog posts are for educational purposes only. Specific dosing of medications (along with potential adverse effects) should be confirmed by prescribing physician.  Because of rapid advances in the medical sciences, the gutsandgrowth blog cautions that independent verification should be made of diagnosis and drug dosages. The reader is solely responsible for the conduct of any suggested test or procedure.  This content is not a substitute for medical advice, diagnosis or treatment provided by a qualified healthcare provider. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a condition.

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How Effective and Safe is Fecal Microbiota Transplantation in Immunocompromised Pediatric Patients with Clostridioides difficile?

KR Conover et al. JPGN 2023; 76: 440-446. Fecal Microbiota Transplantation for Clostridioides difficile Infection in Immunocompromised Pediatric Patients

In this multicenter retrospective cohort (n=42), the authors examined the efficacy and safety of fecal microbiota transplantation (FMT) in immunocompromised (IC) children with Clostridioides difficile infection (CDI).  Etiology of IC included: solid organ transplantation (18, 43%), malignancy (12, 28%), primary immunodeficiency (10, 24%), or other chronic conditions (2, 5%)

Key findings:

  • 23 (55%) of FMT was delivered via colonoscopy, 17 (40%) were delivered via enteric tube, and 2 (5%) via capsule
  • Success rate was 79% after first FMT and 86% after 1 or more FMT.
  • There were serious adverse events (SAEs) in 13 out of 42 (31%) patients; 4 (9.5%) of which were likely treatment-related (all patients recovered). These events included cecal perforation, aspiration pneumonitis, diarrhea and fever. Given retrospective design of study, AEs were likely underreported

My take: Though there are the potential for significant adverse effects, FMT is effective in a high percentage of immunocompromised children with CDI.

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Favorite Posts of 2021

I am happy to say that this is the last nightcall that I will have this year!

Today, I’ve compiled some of my favorite posts from the past year. I started this blog a little more than 10 years ago. I am grateful for the encouragement/suggestions from many people to help make this blog better. Also, I want to wish everyone a Happy New Year.

GI:

IBD:

LIVER:

Nutrition:

Other Topics:

Thanks to Jennifer

Why Stool Hoarding Might Be A Good Idea

SK Hourigan et al. JPGN 2021; 73: 430-432. Updates and Challenges in Fecal Microbiota Transplantation for Clostridioides difficile Infection in Children

This good update provides a lot of useful information regarding fecal microbiota transplantation (FMT) and a word of caution regarding its future availability.

Key points regarding FMT:

  • Long-term safety remains unknown. FMT may lead to susceptibility to chronic inflammatory, allergic, and autoimmune diseases. “FMT has been associated with durable transmission of pro-carcinogenic bacteria from adult donors to pediatric recipients…although the long-term consequences…are unknown.”
  • Due to transfer of extended spectrum beta-lactamase (ESBL) E coli to 2 immunocompromised adult recipients, further screening of FMT was implemented.
  • Though there is no published evidence of SARS-CoV-2 fecal transmission, the FDA “advised additional precautions and testing in March 2020; “however, there are no molecular tests with stool…which have received emergency use authorization.” Hence, most FMT programs were on hold as of January 2021.
  • After 2021, OpenBiome, whose product was recently available again, is expected to stop distribution of FMT donor product due to increased costs of screening and the “promising biotherapeutics” that are in phase III trials.
  • Biotherapeutic is “loosely defined as drug therapy products where the active substance is extracted from a biological specimen.” The new products are likely to have “increased standardization, safety and practicality.”
  • The problem in pediatrics: none of these biotherapeutic products have started trials in children. This will lead to treatment problems. Even if one wanted to set up donor-directed FMT, it will be difficult to complete all of the screening recommended by the FDA. It could lead to self-administration by families with uncertain risks.

My take: My first reaction to this article: ‘Oh crap!’ It is sad and ironic that I will miss having available commercial stool for FMT.

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Secondary Prophylaxis of Clostridiodes difficile Infection

H Bao et al. Pediatrics 2021; 148: e2020031807. Oral Vancomycin as Secondary Prophylaxis for Clostridioides difficile Infection. Thanks to Ben Gold for sharing this reference.

Methods: A multicampus, retrospective cohort evaluation was conducted among patients aged ≤18 years with any history of clinical CDI and receiving systemic antibiotics in a subsequent encounter from 2013–2019. This study identified 30 and 44 patients received oral vancomycin prophylaxis (OVP) and no OVP, respectively. Eligible patients had to be >12 months of age and having at 3 unformed stools everyday.

OVP dosing: “vancomycin doses of 10 mg/kg (up to 125 mg per dose) every 12 hours during concomitant antibiotic use. OVP duration was intended to continue while on systemic antimicrobial agents and for 5 days after completion of antimicrobial agents (extended prophylaxis tail), but practice varied, and duration was ultimately left to the discretion of the provider.”

Key finding:

The incidence of CDI recurrence within 8 weeks of antibiotic exposure was significantly lower in patients who received OVP (3% vs 25%P = .02) despite this group having notably more risk factors for recurrence.   After adjustment in a multivariable analysis, secondary OVP was associated with less risk of recurrence (odds ratio, 0.10; 95% confidence interval, 0.01–0.86; P = .04).

This study is in agreement with studies in adults (Brown CC, et al. Oral Vancomycin for Secondary Prophylaxis of Clostridium difficile Infection. Ann Pharmacother. 2019 Apr;53(4):396-401). In this review, the authors state: “Variable dosing regimens and lack of safety data are limitations.. clinicians can consider vancomycin 125 mg orally once or twice daily in high-risk patients receiving broad-spectrum antibacterial agents.”

My take: In patients at high risk of recurrent CDI, OVP should be considered as secondary prophylaxis when receiving systemic antibiotics.

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Looking at the Mycobiome to Distinguish Clostridium difficile Infection vs. Carriage

Y Cao et al. Gastroenterol 2021; 160: 2328-2339. Fecal Mycobiota Combined With Host Immune Factors Distinguish Clostridioides difficile Infection From Asymptomatic Carriage

Key findings:

  • The ratio of Ascomycota to Basidiomycota was dramatically higher in patients with CDI than in Carrier and Control (P < .05).
  • Using 4 fungal operational taxonomic units combined with 6 host immune markers in the random forest classifier can achieve very high performance (area under the curve ∼92.38%) in distinguishing patients with CDI from Carrier.

My take: It is interesting that fecal fungal diversity (mycobiome), in addition to bacterial diversity, is reduced in those with Clostridium difficile infection (CDI) compared to both control groups and those with Clostridium difficile asymptomatic carriage.

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Long-term Safety of Fecal Microbiota Transplantations

S Saha et al. Gastroenterol 2021; 160: 1961-1969. Full text PDF: Long-term Safety of Fecal Microbiota Transplantation for Recurrent Clostridioides difficile Infection

In this prospective study (2012-2018) with 609 patients (median age 56 years), the authors studied long-term outcomes. Key findings:

  • At 1 year, 9.5% reported additional CDI episodes. Diarrhea occured in more than half of all patients, although it lasted for than a week in most patients.
  • Among 477 with long-term data, 188 patients post-FMT developed new medical conditions/symptoms.
  • Weight gain was reported by 46 patients (10.3%) post-FMT. In these patients, the median weight gained was 30 pounds (range, 10–70). Of these patients, 11 (23%) had
    preexisting obesity.
  • Approximately 3% of patients each reported new-onset diabetes mellitus and dyslipidemia,
    whereas 2.3% reported thyroid disease.
  • Gastrointestinal symptoms were the second most frequently reported (13.4%). New-onset IBS was reported by 4%, IBD by 0.3%, chronic diarrhea by 5.0%, and chronic constipation by 1.6% of patients.
  • Serious infections were reported by 11.8% of patients: CDI in 5.7%, Pneumonia in 4.5%, UTI in 1.8% and Sepsis in 1.2%. Median time to the infections was 29 months (range, 0–73) following FMT; only 1 patient reported an infection (CDI) within the first month after FMT.
  • No deaths were considered related to FMT
  • Limitation: no control group

My take (borrowed from authors): “FMT appears safe and effective, both in the
short-term and long-term. Several new medical conditions were reported post-FMT, in particular, weight gain and IBS.”

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