Category Archives: C. diff. Research Community

Researchers Find Key Role of Excess Calcium In the Gut In C. difficile infections (CDI)

New research shows, it can’t make this last, crucial move without enough of a humble nutrient: calcium.

And that new knowledge about Clostridium difficile (a bacterium also known as “C. diff“) may lead to better treatment for the most vulnerable patients.

The discovery, made in research laboratories at the University of Michigan Medical School and the U.S. Food and Drug Administration, is published in the online journal PLoS Pathogens.

It helps solve a key mystery about C. diff: What triggers it to germinate, or break its dormancy, from its hard spore form when it reaches the gut.

Though the findings were made in mice, not humans, the researchers say the crucial role of calcium may help explain another mystery: Why some hospital patients and nursing home residents have a much higher risk of contracting C. diff infections and the resulting diarrhea that carries its spores out of the body.

That group includes people whose guts are flooded with extra calcium because they’re taking certain medications or supplements, have low levels of Vitamin D in their blood or have gut diseases that keep them from absorbing calcium.

The new discovery shows that C. diff can recognize this extra calcium, along with a substance called bile salt produced in the liver, to trigger its awakening and the breaking of its shell.

Previous research had suggested it couldn’t do this without another key component, an amino acid called glycine. But the new findings show calcium and the bile salt called taurochlorate alone are enough. Mouse gut contents that were depleted of gut calcium had a 90 percent lower rate of C. diff spore germination.

“These spores are like armored seeds, and they can pass through the gut’s acidic environment intact,” says Philip Hanna, Ph.D., senior author of the new paper and a professor of microbiology and immunology at U-M. “Much of the spore’s own weight is made of calcium, but we’ve shown that calcium from the gut can work with bile salts to trigger the enzyme needed to activate the spore and start the germination process.”

Ironically, the researchers say, one way to use this new knowledge in human patients might be to add even more calcium to the system.

That could awaken all the dormant C. diff spores in a patient’s gut at once, and make them vulnerable to antibiotics that can only kill the germinated form. That could also prevent the transmission of more spores through diarrhea to the patient’s room. That could slow or stop the cycle of transmission that could threaten them or other patients in the future.

Hanna’s graduate student, Travis Kochan, made a key observation that led to the discovery. He noted that the fluid “growth medium” that the researchers typically grow C. diff in for their studies had calcium in it. He realized this could artificially alter the results of their experiments about what caused C. diff spores to germinate.

So, he used a chemical to remove the calcium while leaving all the other nutrients that                  keep C. diff growing. The result: no new spore germination happened in the calcium-free growth medium.

FDA’s Center for Biologics Evaluation and Research conducted further research in laboratory dishes and in the guts of mice. FDA’s Paul Carlson, Ph.D., a former U-M research fellow, and fellow FDA scientists in his laboratory found that C. diff spores that were mutated so that glycine couldn’t act on them could still germinate and colonize mice. This suggested that calcium, and not glycine, was critical for this process.

Both mutant and regular forms of the bacteria could still activate an enzyme inside the C. diff spore that led the bacteria to start dissolving their hard shell. This released the store of calcium that the spore had been harboring inside itself, and increases the local level of the nutrient even further.

“These spores don’t want to germinate in the wrong place,” says Kochan, whose grandfather suffered from a severe C. diff infection which ultimately led to his death. “C. diff spores have specialized to germinate in the gut environment, especially in the environment of the small intestine, where calcium and the bile salt injection from the liver comes in.”

Hanna notes that the bile salt connection to C. diff spore germination was first discovered at U-M in 1982 by a team led by Ken Wilson, M.D.

Calcium and the gut

Certain ailments and treatments cause defects in calcium absorption, but are also risk factors for C. diff infections. For example, patients with vitamin D deficiency are five times more likely to get C. diff.

Medications aimed at calming acid reflux – such as proton pump inhibitors – and steroids can increase the amount of calcium in the gut. A Vitamin D deficiency can keep the body from reabsorbing calcium through the gut wall, allowing it to build up.

And people with inflammatory bowel diseases such as Crohn’s and colitis also have a harder time absorbing calcium from food through their gut walls.

Older adults are also often counseled to take calcium supplements to compensate for lower calcium levels and protect their bones from fracturing.

Hanna cautions that the new findings should not cause any patients to stop taking their medications or doctor-recommended supplements, or to start taking new ones. But he hopes to work with clinicians at U-M and beyond to test the new knowledge in a clinical setting. Meanwhile, he and Kochan and their FDA and U-M colleagues will continue to study C. diff germination in mice and look for ways to block the enzymes crucial to spore germination.

 

To read the article in its entirety – please click on the following link to be re-directed:

http://www.news-medical.net/news/20170713/Scientists-reveal-key-role-of-excess-gut-calcium-in-C-diffc2a0infections.aspx?utm_source=dlvr.it&utm_medium=twitter

Inquire and Consider Becoming A Candidate In a C. difficile Infection Clinical Trial To Help You – Help Them – Help Others

Every scientific research and development, every clinical trial in progress is a glimmer of hope………..HOPE for clinically safe and approved avenues to prevent and treat a
C. difficile infection
.

 

 

Listed below you will find a web link that will redirect you to obtain information that pertains to organizations who have on-going
C. difficile Prevention and Treatment clinical trials in progress.  

Click on each organization’s website link to review their research and clinical trial study opportunities — Inquire if you or your loved one qualify to participate in a study. Please direct all clinical trial questions to the companies offering the clinical trials.  Thank you.

To Learn More About Clinical Trials —

ClinicalTrials.gov is a registry and results database of publicly and privately supported clinical studies of human participants conducted around the world. Learn more About Clinical Studies and About This Site, including relevant History, Policies, and Laws.  Click on the link below to be redirected to the clinicaltrials.gov website:

https://clinicaltrials.gov/

 

Clinical Studies In Progress To

Help You — Help Them — Help Others  ♥

 

 

Here is a list of Clinical Trial Phases:

Clinical trials are conducted in a series of steps, called phases – each phase is designed to answer a separate research question.

  • Phase I: Researchers test a new drug or treatment in a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
  • Phase II: The drug or treatment is given to a larger group of people to see if it is effective and to further evaluate its safety.
  • Phase III: The drug or treatment is given to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
  • Phase IV: Studies are done after the drug or treatment has been marketed to gather information on the drug’s effect in various populations and any side effects associated with long-term use.

Additional Resource Information on clinical trials can be found at http://clinicaltrials.gov/info/resources

 

To review C. difficile Clinical Trials Available Today, please click on the following link to be redirected:

https://cdifffoundation.org/clinical-trials-2/

 

 

 

 

DISCLAIMER
“The C Diff Foundation’s mission is to educate and advocate for Clostridium difficile infection prevention, treatments, support, and environmental safety worldwide.
The C Diff Foundation’s organization is comprised of 100% volunteering members who are dedicated to our mission and adhere to the Foundation’s Code of Ethics
which prohibits paid endorsements and/or paid promotion of products, services, medications, or clinical studies in progress.   All website postings are strictly for
information purposes.
All website entries, public presentations, and workshops are to raise C. diff. infection awareness in all areas of the C Diff Foundation’s mission statement, including infection prevention, diagnostics, sepsis, healthcare-associated infections, antimicrobial resistance, antibiotic stewardship and provide education on all the above.”

C diff Infection Compared Control in 6 United Kingdom Hospitals With Whole-Genome Sequencing (WGS)

David W. Eyre
Warren N. Fawley
Anu Rajgopal
Christopher Settle
Kalani Mortimer
Simon D. Goldenberg
Susan Dawson
Derrick W. Crook
Tim E. A. Peto
A. Sarah Walker

.

Clin Infect Dis cix338.
Published:
29 May 2017 

Abstract

Background Variation in Clostridium difficile infection (CDI) rates between healthcare institutions suggests overall incidence could be reduced if the lowest rates could be achieved more widely.
Methods.

We used whole-genome sequencing (WGS) of consecutive C. difficile isolates from 6 English hospitals over 1 year (2013–14) to compare infection control performance. Fecal samples with a positive initial screen for C. difficile were sequenced. Within each hospital, we estimated the proportion of cases plausibly acquired from previous cases.

Results.

Overall, 851/971 (87.6%) sequenced samples contained toxin genes, and 451 (46.4%) were fecal-toxin-positive. Of 652 potentially toxigenic isolates >90-days after the study started, 128 (20%, 95% confidence interval [CI] 17–23%) were genetically linked (within ≤2 single nucleotide polymorphisms) to a prior patient’s isolate from the previous 90 days. Hospital 2 had the fewest linked isolates, 7/105 (7%, 3–13%), hospital 1, 9/70 (13%, 6–23%), and hospitals 3–6 had similar proportions of linked isolates (22–26%) (P ≤ .002 comparing hospital-2 vs 3–6). Results were similar adjusting for locally circulating ribotypes. Adjusting for hospital, ribotype-027 had the highest proportion of linked isolates (57%, 95% CI 29–81%). Fecal-toxin-positive and toxin-negative patients were similarly likely to be a potential transmission donor, OR = 1.01 (0.68–1.49). There was no association between the estimated proportion of linked cases and testing rates.

Conclusions.

WGS can be used as a novel surveillance tool to identify varying rates of C. difficile transmission between institutions and therefore to allow targeted efforts to reduce CDI incidence.

To view the article in its entirety please click on the following link:

Preventing Clostridium difficile infection (CDI) is a priority for infection control teams, as it remains a major healthcare-associated infection; although the incidence of healthcare-associated CDI in the United Kingdom has fallen to 1.5 per 10000 inpatient bed-days [1], rates across Europe range from 0.7 to 28.7/10000 bed-days [2], and there were an estimated 293000 healthcare-associated cases in the United States in 2011 [3].

Variation in CDI incidence across countries and between healthcare institutions [4] suggests overall incidence could be reduced if the lowest rates could be achieved more widely. Surveillance programs [5] and penalties for healthcare institutions [6] have been implemented to promote reductions. However, robustly identifying the best performing institutions is challenging.

Variations in true incidence can arise from differences in patient risk factors or locally circulating strains. However, testing strategy also influences reported incidence; reported CDI incidence is associated with testing rates [2]. With low testing rates, CDI ascertainment is likely to be suboptimal. Conversely, high testing rates may lead to overdiagnosis, for example, from testing C. difficile colonized patients, who do not have CDI but may have diarrhea of another cause.

The lack of a universally accepted objective CDI case definition means that robust comparisons of infection rates between institutions should ideally also consider independent measures of which patients are being tested to assess the comparability of differing testing strategies [7].

Additionally, assessing potential sources of healthcare- attributed CDI cases [8] is complex, requiring differentiation between lapses in infection control around symptomatic cases or more generally, deviation from optimal antimicrobial stewardship, and external factors, for example, the food chain. Healthcare exposure increases the risk of C. difficile acquisition; both CDI and colonization increase during hospital stay [9]. However, despite this strong association, studies using whole-genome sequencing (WGS) [10–12] and other genotyping schemes [13–15] have shown that, in endemic settings with standard infection control, only the minority of infections are likely to have been acquired from other hospitalized CDI cases. However, the extent to which this proportion of linked cases varies between hospitals is unknown. Furthermore, such potential variance in linkage rates could identify a potentially preventable group of CDIs.

We investigated variation in the proportion of linked cases using WGS of consecutive C. difficile isolates from 6 hospitals in England and explored whether this could be used to assess their infection control effectiveness, by assessing the proportion of cases plausibly acquired from (linked to) previous cases.

METHODS

Samples and Settings

Hospitals in England are recommended to store frozen aliquots of C. difficile–positive fecal samples for 12 months [16]. Stored consecutive hospital and community diarrheal samples submitted for routine C. difficile testing at 6 hospital laboratories were studied, including a tertiary referral center and teaching hospital, and 5 district general hospitals serving a mix of urban and rural populations (see Supplement). Samples were obtained for a one-year period at each hospital between January 2013 and October 2014. Results were anonymized by assigning a computer-generated random identifier, hospital 1 to hospital 6.

Each hospital used the United Kingdom-recommended 2-stage C. difficile testing algorithm [17]. Hospital 1 used toxin gene polymerase chain reaction (PCR) as a screening test, hospital 2 both glutamate dehydrogenase (GDH) enzyme immunoassay (EIA) and toxin gene PCR as a combined screening test, and hospitals 3–6 a GDH screen. Screen-positive samples underwent confirmatory fecal-toxin EIA testing. Screen-positive, fecal-toxin-positive patients were regarded as having CDI. Toxin gene PCR was also performed as a third-line test on all GDH-positive samples at hospitals 3 and 6, and on samples from inpatients at hospital 5. PCR-positive, fecal-toxin-negative patients, with a clinical syndrome in keeping with CDI, were regarded as potential cases for treatment and infection control purposes.

All screen-positive fecal samples were sent to Leeds General Infirmary microbiology laboratory, United Kingdom (except hospital 2, which submitted isolates and excluded toxin EIA-negative/PCR-negative samples), where they underwent selective culture for C. difficile [18] and capillary electrophoresis ribotyping [19]. Individual patient consent for use of anonymized bacterial isolates was not required.

Sequencing

DNA was extracted from subculture of a single colony from each culture-positive sample and sequenced using Illumina HiSeq2500. Sequence data were processed as previously (see Supplement) [10, 20], mapping sequenced reads to the C. difficile 630 reference genome [21]. Sequences were compared using single-nucleotide polymorphisms (SNPs) between sequences obtained from maximum-likelihood phylogenies [22], corrected for recombination [23]. Potentially toxigenic strains were identified as those containing toxin genes using BLAST searches of de novo [24] assemblies.

Analysis

For each sample, only the hospital, collection date, and fecal-toxin EIA result were known; no further epidemiological data were available. Within each hospital, sequences were compared with all sequences from samples obtained in the prior 90 days. Samples from the community and hospital were included to increase the chance of identifying transmission events occurring in hospital but leading to CDI onset after discharge. From previous estimates of C. difficile evolution and within-host diversity [10, 25, 26], ≤2 SNPs are expected between isolates linked by transmission within 90 days. Therefore, where ≥1 prior sequences within ≤2 SNPs were identified, a case was considered to have been potentially acquired from another case. A 90 day threshold for linking cases was chosen assuming that cases were rapidly treated and infectiousness declined, and that subsequent cases related by direct transmission occurred within incubation periods implied by surveillance definitions [8] and previous studies [13]. As the sources of cases occurring at the start of the study may themselves have been sampled before the study started, the proportion of cases linked to a prior case was only calculated for cases occurring after the first 90 days, with cases in the first 90 days included only as potential sources for subsequent cases.

Two differing case definitions were considered. Initially, all patients with culture-positive potentially toxigenic C. difficile were considered “cases” to capture possible transmission events involving potentially toxigenic C. difficile irrespective of fecal-toxin status. The analysis was then repeated restricted only to fecal-toxin-positive CDI cases. For comparisons with previously published data, the same definition and analysis approach was applied to fecal-toxin-positive CDI cases occurring within 90 days in Oxford (September 2007 to December 2010, split by calendar year) [10] and Leeds (August 2010 to April 2012) [11].

Risk Factor Analysis

Univariate logistic regression was used to determine whether a case’s toxin status affected the risk of it being genetically related to a prior case, that is, potentially acquired from another case. Similarly, logistic regression was used to determine whether a case’s fecal-toxin status affected the risk of it being genetically linked to a subsequent case, that is, to assess the relative infectiousness of fecal-toxin-positive and toxin-negative patients.

To assess whether the locally circulating strain mix affected transmission estimates, hospital-specific estimates were adjusted for ribotype using multivariate logistic regression (see Supplement).

Simulations

To estimate the impact of missing data (as not all sampled cases were sequenced at some hospitals), we simulated transmission at a theoretical hospital. We subsampled simulated cases and calculated the change in the percentage of cases linked to a prior case as the proportion of missing samples increases (details in Supplement).

METHODS

Samples and Settings

Hospitals in England are recommended to store frozen aliquots of C. difficile–positive fecal samples for 12 months [16]. Stored consecutive hospital and community diarrheal samples submitted for routine C. difficile testing at 6 hospital laboratories were studied, including a tertiary referral center and teaching hospital, and 5 district general hospitals serving a mix of urban and rural populations (see Supplement).

Samples were obtained for a one-year period at each hospital between January 2013 and October 2014. Results were anonymized by assigning a computer-generated random identifier, hospital 1 to hospital 6.

Each hospital used the United Kingdom-recommended 2-stage C. difficile testing algorithm [17].

Hospital 1 used toxin gene polymerase chain reaction (PCR) as a screening test,

Hospital 2 both glutamate dehydrogenase (GDH) enzyme immunoassay (EIA) and toxin gene PCR as a combined screening test, and hospitals 3–6 a GDH screen.

Screen-positive samples underwent confirmatory fecal-toxin EIA testing. Screen-positive, fecal-toxin-positive patients were regarded as having CDI. Toxin gene PCR was also performed as a third-line test on all GDH-positive samples at hospitals 3 and 6, and on samples from inpatients at hospital 5. PCR-positive, fecal-toxin-negative patients, with a clinical syndrome in keeping with CDI, were regarded as potential cases for treatment and infection control purposes.

All screen-positive fecal samples were sent to Leeds General Infirmary microbiology laboratory, United Kingdom (except hospital 2, which submitted isolates and excluded toxin EIA-negative/PCR-negative samples), where they underwent selective culture for C. difficile [18] and capillary electrophoresis ribotyping [19]. Individual patient consent for use of anonymized bacterial isolates was not required.

Sequencing

DNA was extracted from subculture of a single colony from each culture-positive sample and sequenced using Illumina HiSeq2500. Sequence data were processed as previously (see Supplement) [10, 20], mapping sequenced reads to the C. difficile 630 reference genome [21]. Sequences were compared using single-nucleotide polymorphisms (SNPs) between sequences obtained from maximum-likelihood phylogenies [22], corrected for recombination [23]. Potentially toxigenic strains were identified as those containing toxin genes using BLAST searches of de novo [24] assemblies.

Analysis

For each sample, only the hospital, collection date, and fecal-toxin EIA result were known; no further epidemiological data were available. Within each hospital, sequences were compared with all sequences from samples obtained in the prior 90 days. Samples from the community and hospital were included to increase the chance of identifying transmission events occurring in hospital but leading to CDI onset after discharge. From previous estimates of C. difficile evolution and within-host diversity [10, 25, 26], ≤2 SNPs are expected between isolates linked by transmission within 90 days. Therefore, where ≥1 prior sequences within ≤2 SNPs were identified, a case was considered to have been potentially acquired from another case. A 90 day threshold for linking cases was chosen assuming that cases were rapidly treated and infectiousness declined, and that subsequent cases related by direct transmission occurred within incubation periods implied by surveillance definitions [8] and previous studies [13]. As the sources of cases occurring at the start of the study may themselves have been sampled before the study started, the proportion of cases linked to a prior case was only calculated for cases occurring after the first 90 days, with cases in the first 90 days included only as potential sources for subsequent cases.

Two differing case definitions were considered. Initially, all patients with culture-positive potentially toxigenic C. difficile were considered “cases” to capture possible transmission events involving potentially toxigenic C. difficile irrespective of fecal-toxin status. The analysis was then repeated restricted only to fecal-toxin-positive CDI cases. For comparisons with previously published data, the same definition and analysis approach was applied to fecal-toxin-positive CDI cases occurring within 90 days in Oxford (September 2007 to December 2010, split by calendar year) [10] and Leeds (August 2010 to April 2012) [11].

Risk Factor Analysis

Univariate logistic regression was used to determine whether a case’s toxin status affected the risk of it being genetically related to a prior case, that is, potentially acquired from another case. Similarly, logistic regression was used to determine whether a case’s fecal-toxin status affected the risk of it being genetically linked to a subsequent case, that is, to assess the relative infectiousness of fecal-toxin-positive and toxin-negative patients.

To assess whether the locally circulating strain mix affected transmission estimates, hospital-specific estimates were adjusted for ribotype using multivariate logistic regression (see Supplement).

Simulations

To estimate the impact of missing data (as not all sampled cases were sequenced at some hospitals), we simulated transmission at a theoretical hospital. We sub-sampled simulated cases and calculated the change in the percentage of cases linked to a prior case as the proportion of missing samples increases (details in Supplement).

RESULTS

Consecutive samples sent for C. difficile testing at 6 hospitals were studied for 12 months (Table 1). In total, 1052/1098 (96%) of GDH/toxin-PCR screen-positive samples were available: 95/98 (97%) at hospital 1, 144/178 (81%) at hospital 2, 118/127 (93%) at hospital 5 and otherwise 100%. 974/1052 (93%) available samples were confirmed as C. difficile on culture. For the 5 hospitals with available testing data, 887/21539 (4.1%) of samples submitted for testing were culture-positive (Table 1); 971/974 (99.7%) culture-positive samples were successfully sequenced. Of sequenced culture-positive samples, 451/971 (46.4%) were EIA fecal-toxin-positive, 35–71% by hospital. By contrast, 851/971 (87.6%) were potentially toxigenic, that is, had toxin genes detected via sequence data. Hence, 400/851 (47.0%) samples containing potentially toxigenic C. difficile did not have fecal-toxin detected. In the 971 sequenced isolates, the most common ribotypes identified were 014, 015, 005, 002, 020, and 078 (Table 2). Ribotype-027(NAP1/ST-1) only accounted for 16 (2%) cases.

To view graphs and tables, please click the following link:

https://academic.oup.com/cid/article/doi/10.1093/cid/cix338/3857742/Comparison-of-Control-of-Clostridium-difficile

Relatedness to Prior Cases

The proportion of cases plausibly linked to a prior case by recent transmission varied by hospital. Of 851 sequenced potentially toxigenic cases, all were considered as potential sources of infection, but only the 652 obtained after the first 90 days of sampling at each hospital were assessed for linkage to a previous case. Across the 6 hospitals, 128/652 (20%, 95% confidence interval [CI] 17–23%) potentially toxigenic cases were genetically linked to a prior case from the previous 90 days. Hospital 2 had the fewest cases linked to a prior case, 7/105 (7%, 3–13%), hospital 1 had an intermediate number, 9/70 (13%, 6–23%), and hospitals 3–6 had similar numbers of linked cases, 37/153 (24%, 18–32%), 32/134 (24%, 17–32%), 18/76 (24%, 15–35%), and 25/113 (22%, 15–31%), respectively. Hospital 2 had significantly fewer linked cases than hospitals 3–6 (P ≤ .002), with weaker evidence for lower rates in hospital 1 than hospitals 3, 4, and 5 (P = .05, .07, .09, respectively). Overall, 48/128 (38%) of potential transmission recipients were fecal-toxin-negative (11–68% across hospitals, Figure 1A). Fecal-toxin detection in a recipient was associated with increased odds of having a potential transmission donor, odds ratio 1.67 (95% CI 1.12–2.48, P = .01).

 

In total, 59/128 (46%) putative transmission recipients were only linked to ≥1 fecal-toxin-positive potential donors, 50 (39%) to only fecal-toxin-negative donors, and 19 (15%) to both toxin-positive and toxin-negative donors. Considering the 667 cases occurring in the first 270 days at each hospital, that is, the cases with an opportunity to transmit to a sampled case within the next 90 days, 120 (18%) were potential donors. Fecal-toxin-positive and -negative cases were similarly infectious: the odds ratio for a fecal-toxin- positive case, compared to a fecal-toxin-negative case, being a potential transmission donor was 1.01 (95% CI 0.68–1.49, P = .97).

When only considering transmission to and from fecal- toxin-positive cases, fewer cases were genetically linked to a previous case within 90 days, 51/335 (15%, 95% CI 12–20%). We observed a different “ranking” of hospitals compared with the above analysis of linkage rates based on potentially toxigenic isolate-positive patients: hospital 3 had the greatest proportion of fecal-toxin-positive cases genetically related to a prior fecal-toxin-positive case, 31% (22–41%), and hospital 6 the lowest, 0% (0–9%) (Figure 1B).

Results were similar to those for all potentially toxigenic C. difficile (Figure 1A) if all C. difficile sequences, nontoxigenic as well as potentially toxigenic, were considered (Figure 1C). Considering only nontoxigenic isolates, very similarly to potentially toxigenic isolates, 19/96 (20%, 95% CI 12–29%) were genetically linked to a prior patient isolate from the previous 90 days.

There was no evidence that the number of linked cases varied during the study at any hospital (Figure 1D). Because different numbers of sequences were obtained from the different hospitals, we investigated how this affected the estimated proportions of cases linked to a prior case. Estimated proportions of linked cases were relatively stable once approximately 50 cases had been sequenced (Figure 2).

Impact of Testing Frequency

The proportion of originally tested samples that were stored and then culture-positive was similar across the 5 hospitals with testing data, 3.8%–4.3% (P = .89, Table 1). In contrast, testing rates ranged from 98 to 239 samples per 10000 bed-days. There was no association between the estimated proportion of cases linked to a previous case within 90 days and testing rates (P = .19 for all potentially toxigenic cases, Figure 3A, and P = .60 for fecal-toxin-positive cases only, Figure 3B). For comparison, Figure 3B also displays rates of linked cases for previously published data from Oxford and Leeds.

Figure 2:  Proportion of potentially toxigenic cases linked to a previous potentially toxigenic case by hospital and number of sequences obtained. Abbreviation: SNP, single-nucleotide polymorphism.

Adjustment for Ribotype

After adjustment for locally circulating ribotypes, estimates of the proportion of potentially toxigenic cases related to a previous potentially toxigenic case within ≤2 SNPs and ≤90 days remained largely unchanged (Figure 4A). Using the same model, per-ribotype estimates for the proportion of related cases, adjusted for differences across hospitals, showed more variation (Figure 4B, Table 2 for unadjusted proportions). Ribotype-027 had significantly more related cases (adjusted proportion, 57%, 95% CI 29–81%, n = 12) than the comparison group of all other ribotypes (11%, 7–18%, P = .002, n = 124), as did ribotype-002 (25%, 15–38%, P = .04, n = 53), 012 (50%, 29–71%, P = .001, n = 22), and 087 (44%, 23–67%, P = .005, n = 18).

Adjustment for Completeness of Testing

As only 144/178 (81%) of GDH-positive samples at hospital 2 were retrievable for culture we assessed the likely impact of these missing samples on the estimated proportion of linked cases by simulating transmission and sampling at a theoretical hospital (Figure S1). As sampling becomes increasingly less complete, the estimated proportion of linked cases declines proportional to the probability of a case being sampled. Applying our simulation to hospital 2 provides a revised estimate of 8% of cases being linked to a prior case (see Supplement for details).

……………………….

DISCUSSION

Here, we demonstrate the value of WGS as a tool to estimate different rates of C. difficile transmission across institutions. Sequencing consecutive C. difficile isolates from routine testing over one year, we found transmission rates varied between 6 hospitals. Considering all patients with potentially toxigenic C. difficile, irrespective of fecal-toxin status, in the best performing hospital only 7% of patients’ isolates were sufficiently genetically related to a previous isolate from another patient to support transmission (8% adjusting for incomplete sampling). By contrast, approximately 3–4-fold more isolates (22–26%) were related in 4 of the other hospitals. These results remained similar after adjusting for the locally circulating strains.

Restricting to only patients with fecal-toxin-positive CDI, we confirmed previous findings that only a minority of CDI cases arise from contact with another symptomatic case: 35% in Oxford [10], 35% in Leeds [11], and 37% of ribotype-027 cases in Liverpool [12], were genetically linked to a previous case, with only a subset of these cases sharing time and space on the same hospital ward.

Applying the criteria for linking cases used in the present study to the Oxford and Leeds data sets, 38% of cases in Oxford were linked to a previous case in 2008 falling to 19% in 2010, and 30% of cases were similarly linked in Leeds. Across the 6 study hospitals, serving a range of populations, toxin-positive CDI linkage rates were all <15% with the exception of hospital 3, where 31% of cases were linked. It is likely the lower linkage rates in the current study in part reflect the falling incidence of ribotype-027 [11], associated with more onward transmission in this study, likely as a result of national fluoroquinolone restriction [27] but may also represent changes in infection prevention and control practice.

Our findings also support the recently reported role in transmission of GDH-positive patients with toxigenic C. difficile, but no detected fecal-toxin [28]. By sequencing all GDH-positive cases, we were able to compare the probability of fecal-toxin-positive and toxin-negative patients being potential sources of transmission, that is, having C. difficile genetically linked to a subsequent C. difficile isolate in another patient. Fecal-toxin-negative patients were similarly infectious to fecal-toxin-positive patients: fecal-toxin status did not affect the odds of being a potential transmission source. Strategies to identify and institute infection control measures around patients with potentially toxigenic C. difficile without detected fecal-toxin are therefore likely to reduce overall CDI incidence, although may be more costly, for example if toxin gene PCR is used as an initial screen rather than GDH EIA. Toxin-positive patients, that is, CDI cases, were more likely to have an identified potential transmission donor, than toxin-negative patients. This is in keeping with previous observations that recent C. difficile acquisition is associated with increased risk of disease, whereas long-term carriage is relatively protective [29].

It is likely that differing clinical CDI testing thresholds applied across the study hospitals, despite each being guided by national recommendations; notably, testing rates varied more than 2-fold between hospitals (98–239 tests/10000 bed-days). However, despite this variation, the overall proportion of samples tested that were C. difficile culture-positive was very similar across hospitals (~4%). These 2 findings combined resulted in varying rates of potentially toxigenic C. difficile isolation, 4.2–8.2/10000 bed-days, and varying (fecal-toxin-positive) CDI rates, 1.8–5.7/10000 bed-days. As the proportion of samples that were C. difficile culture-positive was close to reported community asymptomatic C. difficile colonization rates (~4%), and lower than reported colonization rates in asymptomatic hospital inpatients, (~10%) [30], it is possible that the higher reported CDI rates in some study hospitals may reflect overascertainment; independent assessment of which symptomatic patients are tested for CDI would be required to resolve this with certainty [7]. As designed, the study did not measure the extent of transmission involving asymptomatic patients, and therefore it is likely that not all hospital-associated transmission is captured. However, as this was the case for all hospitals, comparisons can still be made between hospitals and with previous studies investigating symptomatic patients.

Interestingly, we did not find any evidence of a relationship between rates of C. difficile testing and proportions of cases that could be linked to a previous case. Differing sampling/testing will likely mean the study populations at each hospital varied, for example with some institutions potentially more likely to include milder CDI cases than others. It should also be noted that differences in the population sampled by a particular testing strategy may affect the proportion of cases linked differently to incomplete sampling of a given population. We quantified the impact of the latter through simulation. Unfortunately, incomplete sampling could appear very similar to the impact of good infection control, as both results in low proportions of linked cases. One study limitation is that we only sequenced 81% GDH-positive samples at hospital 2. However, we demonstrate it may be possible to adjust for incomplete sampling, providing missed cases as assumed missing at random, and the number of onward transmissions from each case was random.

Both a limitation and a strength of our approach is that it relies only on sequencing laboratory samples and sampling dates. We demonstrate this allows comparative hospital surveillance with very limited, and no personal, sensitive or confidential, data. However, without ward admission and patient contact data, it is possible some genetically linked cases do not represent direct transmission from other cases. Genetic links might also arise through indirect healthcare-associated transmission via unsampled hosts or the hospital environment. Additionally, a minority of cases, without healthcare exposure in the last 90 days, may still have been genetically linked. However, there is no obvious reason why genetically related community C. difficile exposures, and therefore the proportion of such cases linked, should vary across England at a population level, even if other CDI risk factors do vary geographically, for example, antimicrobial use. Therefore, although we analyze transmission within the populations served by each hospital, as most CDI cases have recent healthcare exposure, the overall proportion of linked cases is still likely to be a reasonable combined indicator of infection control performance around cases and more generally. Without patient-level identifiers some repeat tests from the same patient may have been wrongly assigned as transmission events; however, we anticipate this was uncommon; repeat testing within 28 days is discouraged in national guidelines [17], and such samples are frequently not routinely processed.

Our method of comparing infection control performance depends on culturing C. difficile, which is not routinely undertaken, and on sequencing at least 6 months of samples, at around US$100 per sample. However, if samples are stored, as recommended in England, C. difficile could be cultured and sequenced retrospectively if increased incidence was noted and then continued prospectively to monitor the impact of any interventions. The cost-effectiveness of such an approach needs further evaluation.

In summary, here we present a novel method that enables assessment of the extent of hospital-acquired infection transmission within healthcare institutions. This approach revealed differences in CDI transmission rates across 6 English hospitals. It demonstrates the potential of whole-genome sequencing as a nationwide tool to identify institutions with excellent and also suboptimal infection control and therefore has the potential to allow targeted efforts to reduce CDI incidence.

Resources:  https://academic.oup.com/cid/article/doi/10.1093/cid/cix338/3857742/Comparison-of-Control-of-Clostridium-difficile

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.

Two UK Researchers, Prof.Alistair Leanord and Dr. David Enoch, Present CDI Data At the 27th European Congress of Clinical Microbiology and Infectious Diseases (ECCMID)

Repeated infection with the bacterium Clostridium difficile (C. difficile, C.diff.), which causes abdominal pain, fever, diarrhea is linked to higher death rates, as well as having a significant impact on health services in terms of cost and hospital beds occupied.

In the first of two presentations at the 27th European Congress of Clinical Microbiology and Infectious Diseases (ECCMID) (tomorrow (Saturday), Professor Alistair Leanord, from Glasgow University, UK, will say that in Scotland the extra impact on the health service from C. difficile infections amounted to 10,600 bed days a year. “This is the equivalent to a 30-bed hospital ward being fully occupied all year,” he will say.

He will tell the congress that the (median) average cost of a patient with C. difficile infection was £7,500 (€8,600 approximately) compared to £2,800 (€3,200 approx) for patients with other medical conditions. In Scotland over a one year period, from October 2015 to October 2016, there were 1,150 cases of C. difficile infection in patients aged 15 and over. This cost the National Health Service (NHS) in Scotland a total of £8,650,000. Out of this amount, the additional costs of treating C. difficile infection, over and above the basic cost of a hospital bed and normal medical care, was £1,955,000. The calculations were carried out at Strathclyde University, which is part of the Scottish Healthcare Associated Infection Prevention Institute (SHAIPI) research consortium.

Until now, little has been known about the impact on health service resources from C. difficile infections, and on patients in terms of recurrence of infection, readmission to hospital, length of stay and death rates.

Prof. Leanord and his colleagues in Scotland identified 3,304 patients with C. difficile in Scottish hospitals between 2010 and 2013 and matched them with 9,516 patients who did not have the infection (the control group). Approximately two-thirds of the C. difficile patients acquired the infection in hospital.

They found that patients with C. difficile infection had more than double the risk of dying from any cause within two months of being admitted to hospital; nearly a third of all C. difficile cases (29%) died within two months compared to 14% of patients in the control group. Patients with C. difficile stayed in hospital a (median) average 9.7 days longer than the patients without the infection. Of the 1,712 C. difficile patients who were discharged from hospital within 30 days of the first episode of infection, 59% were readmitted within six months; of the 626 cases discharged more than 30 days after the first episode 53% were readmitted within six months. Few of these re-admissions were directly related to C. difficile infection.

“However, nearly a sixth of patients (14%) who were cured of the initial infection recurred within three months, and nearly one third of them (29%) had a second recurrence within a year,” says Prof. Leanord.

Older people were more vulnerable to a recurrence. Among the patients with C. difficile infection, 22% were aged 85 or over, and patients aged 75 and over had approximately double the risk of a recurrence of the infection compared to those aged under 65. Patients aged between 65-74 had 1.5 times the risk of recurrence compared to younger patients.

Prof. Leanord will conclude: “Having a clear understanding of the nature of C. difficile infections in Scotland will allow the Scottish government to target resources at the most appropriate patients to try to reduce the overall burden of the disease on the health service. Our findings are very likely to be applicable to the rest of the UK and other countries as well.”

………………….

In a second presentation on Saturday, Dr David Enoch, a consultant microbiologist and infection control doctor at the National Infection Service, Public Health England, Cambridge (UK), will report the outcomes of 6,874 patients who had acquired C. difficile infection in hospital between 2002 and 2013 in England. Of these, 1,141 (16.6%) had recurrences of the infection.

“We found that 49% of hospital patients who suffer a recurrent episode of C. difficile infection die within a year, compared to 38% of those who suffer an initial infection only,” he will say. “In addition, 21% of patients with a recurrence suffered other complications as well, such as dehydration, malnourished and sometimes even perforation of the bowel, compared to 18% of patients who did not have a recurrence.”

Dr Enoch estimates that there are approximately 125,000 cases of C. difficile infection in Europe each year, and between 15-30% of these recur. “Cases in the UK have been coming down since 2008, which is most probably due to improvements in antibiotic prescribing and cleaning regimens in hospitals. This is encouraging but more still needs to be done.”

The average age of the patients was 77 and the average length of stay in hospital was 38 days.

“The main risk factor for developing C. difficile infection is prior antibiotic use. These patients are often already ill from some other underlying illness, which explains why they needed antibiotics in the first place. Older people are at greater risk of C. difficile infection as they are often sicker, have other illnesses or conditions, and so need more antibiotics,” he will say.

Dr Enoch continues: “Although much has been done, particularly in the UK, to try to prevent C. difficile infection, strict adherence to antibiotic guidelines by clinicians and thorough cleaning of the hospital environment are crucial in ensuring that patients don’t develop C. difficile infection in the first place. Treatment with a new drug called fidaxomicin has also been shown to reduce the risk of recurrence in patients who are unfortunate enough to develop an infection. However, we still have a lot to learn, particularly about how C. difficile infection occurs in the community, and how best to treat it.”

Treatments for recurrences of C. difficile infection  —–  include stopping the antibiotic that made the patient susceptible to the infection and starting a different antibiotic that is effective against C. difficile infection. These antibiotics include metronidazole, vancomycin and fidaxomicin. Supportive therapy, such as extra fluids, and surgery in serious or life-threatening cases may also be necessary. Faecal transplantation is emerging as a promising option; this is a process in which the good bacteria that the gut needs but which has been killed off by antibiotics is transplanted into the patient from a healthy donor.

(CDF:  Consider contacting an organization conducting Clinical Trials to Treat and Prevent.  Click on the following link for more information :  https://cdifffoundation.org/clinical-trials-2/

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Abstract no: #1672, presented by Prof. Alistair Leanord in the “Clostridium difficile infections: epidemiology and outcome” oral session, 16.30-18.30 hrs, Saturday 22 April, Hall A.

Abstract no: #883, presented by Dr Enoch in the “Clostridium difficile: guts and glory” e-poster mini-oral session, 15.30-16.30 hrs, Saturday 22 April, ePoster Arena 4.

 

To read the article in its entirety – please click on the following link:

https://www.eurekalert.org/pub_releases/2017-04/esoc-cdi041917.php

Clostridium difficile Infection More Prevalent In Patients Undergoing Allogeneic Stem Cell Transplantation

Clostridium difficile infection was more prevalent in patients undergoing allogeneic stem cell transplantation compared with patients undergoing autologous stem cell transplantation, according to findings published in Infection Control & Hospital Epidemiology.

 

C. difficile infection is the most common cause of infectious diarrhea in hospitalized patients,” Nishi N. Shah, MD, MPH, resident at the University of Arkansas for Medical Sciences, Little Rock, Arkansas and colleagues wrote. “Epidemiological studies evaluating the incidence of and morbidity and mortality due to C. difficile infection in hematopoietic stem cell transplant recipients are limited.”

To read the article in its entirety, please click on the following link:

http://www.healio.com/infectious-disease/nosocomial-infections/news/in-the-journals/%7B889c4781-fda5-43e5-84ce-629cf3692f57%7D/cdi-more-prevalent-in-allogeneic-stem-cell-recipients

The researchers reviewed patient data from the NIS database, analyzing records on adults admitted for allogeneic stem cell transplantation (n = 33,189) and autologous stem cell transplantation (n = 53,072) between January 2001, and December 2010.

Most patients had received autologous stem cell transplantation (61.5%). Of patients in the allogeneic group, 8.5% had C. difficile infection, compared with 5.8% in the autologous group, the researchers reported. Shah and colleagues wrote that univariate analyses identified a number of risk factors for C. difficile infection, including: age, gender, indication for stem cell transplantation, radiation as part of the conditioning regimen, respiratory failure, septicemia and lengthy hospital stay.

Multivariate analyses for autologous transplantation showed significant correlation between age and indication for transplant, but this indication was not associated with C. difficile infection in either group upon multivariate analysis.

Through multivariate analysis, the researchers found multiple factors associated with C. difficile infection: septicemia (autologous OR = 1.64; 95% CI, 1.35-2; allogeneic OR = 1.69; 95% CI, 1.36-2.1), male gender (autologous OR = 1.29; 95% CI, 1.09-1.53; allogeneic OR = 1.36; 95% CI, 1.18-1.57), lengthy hospital stay (autologous OR = 2.81; 95% CI, 2.29-3.45; allogeneic OR = 2.63; 95% CI, 2.15-3.22) and presence of multiple comorbidities (autologous OR = 1.32; 95% CI, 1.11-1.57; allogeneic OR = 1.18; 95% CI, 1-1.4).

“The current study helps identify higher risk groups for such clinical interventions. Among allogeneic stem cell transplantation recipients, interventions to reduce or treat gut GVHD could also impact C. difficile infection rates,” the researchers wrote. “Many topics of study remain to be explored in the prevention of C. difficile infection among stem cell transplantation patients. Certainly, further interventions to improve outcomes, such as reducing the rate of C. difficile infection, are needed.” – by Andy Polhamus

Rebiotix Reports Topline Results From a Controlled Open-label Phase 2 Trial of RBX2660 (PUNCH™ Open Label) For the Prevention of Recurrent Clostridium difficile (C. diff.) Infection (rCDI)

In The News

April 2017

 

 

Rebiotix Inc., a clinical-stage microbiome company focused on harnessing the power of the human microbiome to treat challenging diseases, today announced topline results from a controlled open-label Phase 2 trial of RBX2660 (PUNCH™ Open Label) for the prevention of recurrent Clostridium difficile (C. diff.) infection.

Data indicated that RBX2660 was well-tolerated and achieved the primary efficacy endpoint of preventing C. diff. recurrence; patients treated with RBX2660 exhibited a treatment success rate of 78.8% compared with a historical control of 51.8% (p<0.0001). RBX2660 is a broad-spectrum microbiota suspension that is designed to rehabilitate the human microbiome by delivering live microbes into a patient’s intestinal tract to treat disease.

Lee Jones, president and CEO of Rebiotix, stated, “The 78.8% treatment success achieved in this open label Phase 2 trial demonstrates the potential of RBX2660, a broad spectrum microbiota drug product, to rehabilitate the gut microbiome and break the cycle of C. diff. recurrence. These results, coupled with the safety and efficacy data observed in our prior Phase 2b and Phase 2 clinical trials, position Rebiotix to advance RBX2660 into Phase 3 clinical development, solidifying our standing as the most clinically advanced microbiome company in the industry.”

PUNCH™ Open Label was designed as a prospective, multicenter, open-label, controlled Phase 2 study to assess the efficacy and safety of RBX2660 for the prevention of recurrent C. diff.

The primary efficacy endpoint involved a comparison of patients treated with RBX2660 to a closely matched set of antibiotic only treated historical controls through 56 days. There were 31 active treatment sites and four control sites in the US and Canada. 132 RBX2660 and 110 historical control subjects were included in this topline analysis.

Actively treated patients, after determining eligibility, were administered two doses of RBX2660; the first at day one and the second at day seven. Patients were then monitored for eight weeks to determine whether there was a recurrence of C. diff.

Top line results from the trial, which examined responses from 132 patients versus a historical control of 110 patients, indicated a treatment success rate of 78.8% as compared to a historical control of 51.8% (p<0.0001). Overall, RBX2660 was generally well-tolerated with the most commonly reported adverse events being gastrointestinal, including diarrhea, abdominal pain, flatulence, constipation and distension.


About Rebiotix Inc.

Rebiotix Inc. is a clinical-stage microbiome company focused on harnessing the power of the human microbiome to revolutionize the treatment of challenging diseases. Rebiotix is the most clinically advanced microbiome company in the industry, with its lead drug candidate, RBX2660, expected to enter Phase 3 clinical development for the prevention of recurrent Clostridium difficile (C. diff.) infection. Previously, RBX2660 was the subject of three Phase 2 trials in recurrent C. diff, including a Phase 2b randomized, double-blind, placebo-controlled trial (PUNCH™ CD2), with data indicating the drug was well-tolerated and demonstrated statistically significant treatment efficacy. RBX2660 has been granted Orphan Drug status, Fast Track status and Breakthrough Therapy Designation from the FDA for its potential to prevent recurrent C. diff. infection.

Rebiotix’s development pipeline includes multiple formulations targeting several disease indications and is built around its pioneering Microbiota Restoration Therapy (MRT) platform. MRT is a standardized, stabilized drug technology that is designed to rehabilitate the human microbiome by delivering a broad spectrum of live microbes into a patient’s intestinal tract via a ready-to-use and easy-to-administer format.

For More Information About C. difficile Clinical Trials In Progress : 

https://cdifffoundation.org/clinical-trials-2/

 

For more information on Rebiotix and its pipeline of human microbiome-directed therapies, visit www.rebiotix.com

 

Source:  Rebiotix 4/17

Researchers Suggest a Portion Of C. diff. Cases In Europe Involve Infections Associated With Other Sources Outside of Healthcare-Associated Infections

As part of a multicenter study, investigators from the University of Oxford, the University of Leeds, Astellas Pharma Europe, and elsewhere used a combination of ribotyping, sequencing, phylogenetics, and geographic analyses to retrace the genetic diversity and potential sources of C. difficile isolates involved in infections in European hospitals.

Recent research suggests a proportion of Clostridium difficile cases in Europe involve not only hospital-acquired infections but also infections associated with other sources, such as food.

As stated in the article:

https://www.genomeweb.com/sequencing/clostridium-difficile-genetic-patterns-europe-point-possible-infection-sources-beyond?utm_source=Sailthru&utm_medium=email&utm_campaign=GWDN%20Mon%20PM%202017-04-24&utm_term=GW%20Daily%20News%20Bulletin

David Eyre, a clinical lecturer at the University of Oxford, was slated to present the work at the European Congress of Clinical Microbiology and Infectious Diseases annual 2017 meeting in Vienna this past weekend. The study was funded by Astellas Pharma’s Europe, Middle East, and Africa (EMEA) program.

“We don’t know much about how C. difficile might be spread in the food chain, but this research suggests it may be very widespread,” Eyre said in a statement. “If that turns out to be the case, then we need to focus on some new preventative strategies such as vaccination in humans once this is possible, or we might need to look at our use of animal fertilizers on crops.”

“This study doesn’t give us any definitive answers,” he explained, “but it does suggest other factors [than hospital infections] are at play in the spread of C. difficile and more research is urgently needed to pin them down.”

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Some of the strains clustered by locale, consistent with spread from one individual to the next, for example in a healthcare setting. But more unexpectedly, the team also saw strains smattered across seemingly unconnected sites. And because at least one of those strains had previously been linked to pig farming, the researchers speculated that some infections may have been transmitted through food sources.

 

To read the article in its entirety click on the following link:

https://www.genomeweb.com/sequencing/clostridium-difficile-genetic-patterns-europe-point-possible-infection-sources-beyond?utm_source=Sailthru&utm_medium=email&utm_campaign=GWDN%20Mon%20PM%202017-04-24&utm_term=GW%20Daily%20News%20Bulletin