Strategies to prevent adverse outcomes following Clostridioides difficile infection in the elderly

Multimodal vaccination targeting the receptor binding domains of Clostridioides difficile toxins A and B with an attenuated Salmonella Typhimurium vector (YS1646) protects mice from lethal challenge

Developing a vaccine against Clostridioides difficile is a key strategy to protect the elderly. Two candidate vaccines using a traditional approach of intramuscular (IM) delivery of recombinant antigens targeting C. difficile toxins A (TcdA) and B (TcdB) failed to meet their primary endpoints in large phase 3 trials. To elicit a mucosal response against C. difficile, we repurposed an attenuated strain of Salmonella Typhimurium (YS1646) to deliver the receptor binding domains (rbd) of TcdA and TcdB to the gut-associated lymphoid tissues, to elicit a mucosal response against C. difficile. In this study, YS1646 candidates with either rbdA or rbdB expression cassettes integrated into the bacterial chromosome at the attTn7 site were generated and used in a short-course multimodal vaccination strategy that combined oral delivery of the YS1646 candidate(s) on days 0, 2, and 4 and IM delivery of recombinant antigen(s) on day 0. Five weeks after vaccination, mice had high serum IgG titers and increased intestinal antigen-specific IgA titers. Multimodal vaccination increased the IgG avidity compared to the IM-only control. In the mesenteric lymph nodes, we observed increased IL-5 secretion and increased IgA+ plasma cells. Oral vaccination skewed the IgG response toward IgG2c dominance (vs IgG1 dominance in the IM-only group). Both oral alone and multimodal vaccination against TcdA protected mice from lethal C. difficile challenge (100% survival vs 30% in controls). Given the established safety profile of YS1646, we hope to move this vaccine candidate forward into a phase I clinical trial.IMPORTANCEClostridioides difficile remains a major public health threat, and new approaches are needed to develop an effective vaccine. To date, the industry has focused on intramuscular vaccination targeting the C. difficile toxins. Multiple disappointing results in phase III trials have largely confirmed that this may not be the best strategy. As C. difficile is a pathogen that remains in the intestine, we believe that targeting mucosal immune responses in the gut will be a more successful strategy. We have repurposed a highly attenuated Salmonella Typhimurium (YS1646), originally pursued as a cancer therapeutic, as a vaccine vector. Using a multimodal vaccination strategy (both recombinant protein delivered intramuscularly and YS1646 expressing antigen delivered orally), we elicited both systemic and local immune responses. Oral vaccination alone completely protected mice from lethal challenge. Given the established safety profile of YS1646, we hope to move these vaccine candidates forward into a phase I clinical trial.

Costs Attributable to Clostridioides difficile Infection Based on the Setting of Onset

BACKGROUND

Although hospital-onset Clostridioides difficile infection (CDI) is associated with significant healthcare costs, the economic burden of CDI with onset in other facilities or the community has not been well studied.

METHODS

Incident CDI cases were identified using 2011-2017 Medicare fee-for-service data. Controls were randomly selected in a 4:1 ratio matching to the CDI case surveillance definition. Inverse probability of exposure weights were used to balance on measured confounders. One-, 3-, and 5-year cumulative costs attributable to CDI were computed using a 3-part estimator (parametric survival model and pair of 2-part models predicting costs separately in intervals where death did and did not occur).

RESULTS

A total of 60 492 CDI cases were frequency-matched to 241 968 controls. One-, 3-, and 5-year adjusted attributable costs were highest for hospital-onset CDI at $14 257, $18 953, and $21 792, respectively, compared with hospitalized controls and lowest for community-associated CDI compared with community controls at $1013, $3161, and $6454, respectively. Adjusted 1-, 3-, and 5-year costs attributable to community-onset healthcare facility-associated CDI were $8222, $13 066, and $16 329 and for other healthcare facility-onset CDI were $5345, $6764, and $7125, respectively.

CONCLUSIONS

Economic costs attributable to CDI in elderly persons were highest for hospital-onset and community-onset healthcare facility-associated CDI. Although lower, attributable costs due to CDI were significantly higher in cases with CDI onset in the community or other healthcare facility than for comparable persons without CDI. Additional strategies to prevent CDI in the elderly are needed to reduce morbidity and healthcare expenditures.

Clinical burden of recurrent Clostridioides difficile infection in the medicare population: A real-world claims analysis

OBJECTIVE

To describe 12-month outcomes for beneficiaries in the 100% Medicare Fee-for-Service (FFS) population with primary and recurrent Clostridioides difficile infection (CDI).

DESIGN

A retrospective, descriptive, cohort study of CDI claims from the 100% Medicare FFS population, with a first CDI diagnosis between January 1, 2010, and December 31, 2016.

SETTING

Any US-based provider that submitted inpatient or outpatient CDI diagnosis claims to Medicare FFS.

PATIENTS

The study included patients aged ≥65 years with continuous enrollment in Medicare Parts A, B, and D during 12 months before and 12 months after the index period.

METHODS

The number of CDI and recurrent (rCDI) episodes, healthcare resource utilization, treatments, complications, and procedures were calculated for pre-index and follow-up periods. The data were stratified by number of rCDI episodes (ie, no rCDI, 1 rCDI, 2 rCDI, and ≥3 rCDI).

RESULTS

Of 268,762 patients with an index CDI, 34.7% had at least 1 recurrence. Of those who had 1 recurrence, 59.1% had a second recurrence and of those who had 2 recurrences, 58.4% had ≥3 recurrences. Incident psychiatric conditions occurred in 11.3%-18.2% of each rCDI cohort; 6.0% of patients with rCDI underwent subtotal colectomy, and 1.1% of patients underwent diverting loop ileostomy. After each CDI episode, ∼1 in 5 patients had a documented sepsis event. Over the 12-month follow-up, 30% of patients experienced sepsis, and sepsis occurred in 27.0% of the cohort with no rCDI, compared to 35.5% of patients in the rCDI cohorts.

CONCLUSIONS

Elderly patients with CDI and rCDI experienced a significant clinical burden and complications.