In vitro activity of eravacycline against common ribotypes of Clostridioides difficile

Background

Eravacycline is a novel synthetic fluorocycline antibacterial approved for complicated intra-abdominal infections.

Objectives

The purpose of this study was to assess the in vitro activities of eravacycline and comparator antibiotics against contemporary clinical isolates of Clostridioides difficile representing common ribotypes, including isolates with decreased susceptibility to metronidazole and vancomycin.

Methods

Clinical C. difficile strains from six common or emerging ribotypes were used to test the in vitro activities of eravacycline and comparator antibiotics (fidaxomicin, vancomycin and metronidazole) by broth microdilution. In addition, MBC experiments, time–kill kinetic studies and WGS experiments were performed.

Results

A total of 234 isolates were tested, including ribotypes RT001 (n = 37), RT002 (n = 41), RT014-020 (n = 39), RT027 (n = 42), RT106 (n = 38) and RT255 (n = 37). MIC_50/90 values were lowest for eravacycline (≤0.0078/0.016 mg/L), followed by fidaxomicin (0.016/0.063 mg/L), metronidazole (0.25/1.0 mg/L) and vancomycin (2.0/4.0 mg/L). MBCs were lower for eravacycline compared with vancomycin for all ribotypes tested. Both vancomycin and eravacycline demonstrated bactericidal killing, including for epidemic RT027. The presence of the tetM or tetW resistance genes did not affect the MIC of eravacycline.

Conclusions

This study demonstrated potent in vitro activity of eravacycline against a large collection of clinical C. difficile strains that was not affected by ribotype, susceptibility to vancomycin or the presence of certain tet resistance genes. Further development of eravacycline as an antibiotic to be used in patients with Clostridioides difficile infection is warranted.

Human-Derived Bifidobacterium dentium Modulates the Mammalian Serotonergic System and Gut-Brain Axis

BACKGROUND & AIMS

The human gut microbiota can regulate production of serotonin (5-hydroxytryptamine [5-HT]) from enterochromaffin cells. However, the mechanisms underlying microbial-induced serotonin signaling are not well understood.

METHODS

Adult germ-free mice were treated with sterile media, live Bifidobacterium dentium, heat-killed B dentium, or live Bacteroides ovatus. Mouse and human enteroids were used to assess the effects of B dentium metabolites on 5-HT release from enterochromaffin cells. In vitro and in vivo short-chain fatty acids and 5-HT levels were assessed by mass spectrometry. Expression of tryptophan hydroxylase, short-chain fatty acid receptor free fatty acid receptor 2, 5-HT receptors, and the 5-HT re-uptake transporter (serotonin transporter) were assessed by quantitative polymerase chain reaction and immunostaining. RNA in situ hybridization assessed 5-HT-receptor expression in the brain, and 5-HT-receptor-dependent behavior was evaluated using the marble burying test.

RESULTS

B dentium mono-associated mice showed increased fecal acetate. This finding corresponded with increased intestinal 5-HT concentrations and increased expression of 5-HT receptors 2a, 4, and serotonin transporter. These effects were absent in B ovatus-treated mice. Application of acetate and B dentium-secreted products stimulated 5-HT release in mouse and human enteroids. In situ hybridization of brain tissue also showed significantly increased hippocampal expression of 5-HT-receptor 2a in B dentium-treated mice relative to germ-free controls. Functionally, B dentium colonization normalized species-typical repetitive and anxiety-like behaviors previously shown to be linked to 5-HT-receptor 2a.

CONCLUSIONS

These data suggest that B dentium, and the bacterial metabolite acetate, are capable of regulating key components of the serotonergic system in multiple host tissues, and are associated with a functional change in adult behavior.

Clostridioides (Formerly Clostridium) difficile Infection During Hospitalization Increases the Likelihood of Nonhome Patient Discharge

BACKGROUND

Clostridioides (formerly Clostridium) difficile infection (CDI) is associated with significant morbidity and mortality, including frequent hospitalizations. However, the impact of CDI after hospital discharge is poorly understood. The purpose of this study was to assess patient discharge disposition and understand CDI-related risk factors for nonhome discharge.

METHODS

Using a nationally representative database of Veterans Health Administration (VHA) patients (2003-2014) and a validation database from hospitalized non-VHA patients in Houston, Texas, admission and discharge disposition was obtained for patients with CDI and matched controls. Incidence of and clinical/microbiologic risk factors for nonhome discharge were assessed using these databases.

RESULTS

A total of 15173 VHA patients with CDI and 48599 non-CDI control patients originally admitted from the community were included. Significantly more patients with CDI were discharged to a nonhome location compared with controls (18% vs 8%; P < .0001), most commonly hospice/death (12%) or nursing home/long-term care facility (6%). Results were confirmed using a propensity-matched analysis and a validation cohort of 1941 hospitalized patients with CDI in Houston, Texas. Age, comorbidities, severe CDI, and ribotypes F027, F001, and F053-163 were associated with a nonhome discharge (P < .05 for all).

CONCLUSIONS

Hospitalized patients with CDI frequently required a higher level of medical care residence at discharge compared with non-CDI patients. Risk factors for discharge to a higher level of care included CDI disease severity and variables associated with recurrent CDI.

Efficacy of Bezlotoxumab in Participants Receiving Metronidazole, Vancomycin, or Fidaxomicin for Treatment of Clostridioides (Clostridium) difficile Infection

Background

In phase 3 MODIFY I/II trials, bezlotoxumab significantly reduced recurrence of Clostridioides (Clostridium) difficile infection (rCDI) over 12 weeks. Choice of CDI antibacterial treatment may affect CDI-related outcomes; therefore, this prespecified analysis assessed if the magnitude of bezlotoxumab-induced rCDI reduction was influenced by the antibiotic administered.

Methods

In MODIFY I/II (NCT01241552/NCT01513239), participants received a single infusion of bezlotoxumab (10 mg/kg) or placebo during anti-CDI treatment. Using pooled data from MODIFY I/II, initial clinical cure (ICC) and rCDI were assessed in metronidazole-, vancomycin-, and fidaxomicin-treated subgroups.

Results

Of 1554 participants in MODIFY I/II, 753 (48.5%) received metronidazole, 745 (47.9%) vancomycin, and 56 (3.6%) fidaxomicin. Fewer participants receiving metronidazole had a prior CDI episode in the previous 6 months (12.9%) or ≥1 risk factor for rCDI (66.0%) vs participants receiving vancomycin (41.2% and 83.6%, respectively) and fidaxomicin (55.4% and 89.3%, respectively). ICC rates were similar in the bezlotoxumab (metronidazole, 81.0%; vancomycin, 78.5%; fidaxomicin, 86.7%) and placebo groups (metronidazole, 81.3%; vancomycin, 79.6%; fidaxomicin, 76.9%). In placebo-treated participants, the rCDI was lower in the metronidazole subgroup vs the vancomycin and fidaxomicin subgroups (metronidazole, 28.0%; vancomycin, 38.4%; fidaxomicin, 35.0%). When analyzed by subsets based on history of CDI, rCDI rates were similar in the metronidazole and vancomycin groups. rCDI rates were lower in all antibiotic subgroups for bezlotoxumab vs placebo (metronidazole: rate difference [RD], –9.7%; 95% confidence interval [CI], –16.4% to –3.1%; vancomycin: RD, –15.4%; 95% CI, –22.7% to –8.0%; fidaxomicin: RD, –11.9%; 95% CI, –38.1% to 14.3%).

Conclusion

Bezlotoxumab reduces rCDI vs placebo in participants receiving metronidazole and vancomycin, with a similar effect size in participants receiving fidaxomicin.

Human intestinal enteroids as a model of Clostridioides difficile-induced enteritis

Clostridioides difficile is an important nosocomial pathogen that produces toxins to cause life-threatening diarrhea and colitis. Toxins bind to epithelial receptors and promote the collapse of the actin cytoskeleton. C. difficile toxin activity is commonly studied in cancer-derived and immortalized cell lines. However, the biological relevance of these models is limited. Moreover, no model is available for examining C. difficile-induced enteritis, an understudied health problem. We hypothesized that human intestinal enteroids (HIEs) express toxin receptors and provide a new model to dissect C. difficile cytotoxicity in the small intestine. We generated biopsy-derived jejunal HIE and Vero cells, which stably express LifeAct-Ruby, a fluorescent label of F-actin, to monitor actin cytoskeleton rearrangement by live-cell microscopy. Imaging analysis revealed that toxins from pathogenic C. difficile strains elicited cell rounding in a strain-dependent manner, and HIEs were tenfold more sensitive to toxin A (TcdA) than toxin B (TcdB). By quantitative PCR, we paradoxically found that HIEs expressed greater quantities of toxin receptor mRNA and yet exhibited decreased sensitivity to toxins when compared with traditionally used cell lines. We reasoned that these differences may be explained by components, such as mucins, that are present in HIEs cultures, that are absent in immortalized cell lines. Addition of human-derived mucin 2 (MUC2) to Vero cells delayed cell rounding, indicating that mucus serves as a barrier to toxin-receptor binding. This work highlights that investigation of C. difficile infection in that HIEs can provide important insights into the intricate interactions between toxins and the human intestinal epithelium.NEW & NOTEWORTHY In this article, we developed a novel model of Clostridioides difficile-induced enteritis using jejunal-derived human intestinal enteroids (HIEs) transduced with fluorescently tagged F-actin. Using live-imaging, we identified that jejunal HIEs express high levels of TcdA and CDT receptors, are more sensitive to TcdA than TcdB, and secrete mucus, which delays toxin-epithelial interactions. This work also optimizes optically clear C. difficile-conditioned media suitable for live-cell imaging.

Using the Theory of Planned Behavior to Evaluate Factors That Influence PharmD Students' Intention to Attend Lectures

Objective. To use the theory of planned behavior (TPB) to evaluate the contribution of attitude, subjective norm, and perceived behavioral control in predicting students' intention to attend class lectures in a Doctor of Pharmacy (PharmD) curriculum in which lecture recordings were available. Methods. A survey instrument based on the TPB was developed from focus groups with PharmD students. The survey was then distributed to first through third year students at the conclusion of the 2017-2018 academic school year. Respondents were asked to evaluate their beliefs regarding lecture attendance and their intention to attend lectures during the upcoming fall semester. Predictors of intention were evaluated using descriptive statistics and multiple logistic regression analyses. Results. Responses from 198 of 383 students contained usable data (52% effective response rate). The TPB constructs of attitude and subjective norm were predictors of high intention to attend lectures. Students with a positive attitude towards lecture attendance (eg, believed that purposeful active learning is desirable and occurs during class) were nearly 30% more likely to have high intention to attend lectures. Students with a positive subjective norm (ie, perceived social pressure from professors and classmates to attend lectures) were 66% more likely to have high intention to attend lectures. Perceived behavioral control was not associated with high intention to attend lectures. Conclusion. Interventions aimed at improving students' attitudes and subjective norm may be beneficial in improving students' intention to attend class lectures.

Clostridioides difficile ribotype 106: A systematic review of the antimicrobial susceptibility, genetics, and clinical outcomes of this common worldwide strain

Clostridioides difficile typing is invaluable for the investigation of both institution-specific outbreaks as well as national surveillance. While the epidemic ribotype 027 (RT027) has received a significant amount of resources and attention, ribotype 106 (RT106) has become more prevalent throughout the past decade. The purpose of this systematic review was to comprehensively summarize the genetic determinants, antimicrobial susceptibility, epidemiology, and clinical outcomes of infection caused by RT106. A total of 68 articles published between 1999 and 2019 were identified as relevant to this review. Although initially identified in the United Kingdom in 1999, RT106 is now found worldwide and became the most prevalent strain in the United States in 2016. Current data indicate that RT106 harbors the tcdA and tcdB genes, lacks binary toxin genes, and does not contain any deletions in the tcdC gene, which differentiates it from other epidemic strains, including ribotypes 027 and 078. Interestingly, RT106 produces more spores than other strains, including RT027. Overall, RT106 is highly resistant to erythromycin, clindamycin, fluoroquinolones, and third-generation cephalosporins. However, the MIC90 in most studies are one to two fold dilutions below the epidemiologic cut-off values of metronidazole and vancomycin, suggesting both are acceptable treatment options from an in vitro perspective. The few clinical outcomes studies available concluded that RT106 causes less severe disease than RT027, but patients were significantly more likely to experience multiple CDI relapses when infected with a RT106 strain. Specific areas warranting future study include potential survival advantages provided by genetic elements as well as a more robust investigation of clinical outcomes associated with RT106.

Real-world Experience of Bezlotoxumab for Prevention of Clostridioides difficile Infection: A Retrospective Multicenter Cohort Study

Background

Bezlotoxumab is approved for prevention of recurrence of Clostridioides difficile infection (CDI) in adults receiving standard of care (SoC) therapy based on findings from MODIFY clinical trials. However, utilization practices and validation of trial results in the real world are limited.

Methods

Records of patients receiving bezlotoxumab between April 2017 and December 2018 across 34 infusion centers in the United States were retrospectively reviewed. Recurrent CDI (rCDI), defined as diarrhea lasting ≥2 days resulting in treatment, was assessed 90 days postbezlotoxumab.

Results

The study cohort included 200 patients (median age, 70 years; 66% female; median Charlson comorbidity index, 5), of whom 86% (n = 173) had prior CDI episodes and 79% (n = 158) had ≥2 risk factors for rCDI. SoC antibiotics included vancomycin (n = 137, 68%), fidaxomicin (n = 60, 30%), and metronidazole (n = 3, 2%). Median time from C. difficile stool test to bezlotoxumab and initiation of SoC to bezlotoxumab were 15 days and 11 days, respectively. Within 90 days, 31 of 195 patients (15.9%) experienced rCDI, which corresponds to a success rate of 84.1%. Patients with ≥2 CDI recurrences prebezlotoxumab had a higher risk of subsequent rCDI compared with those with 1 recurrence or primary CDI (hazard ratio, 2.77; 95% confidence interval, 1.14–6.76; P = .025).

Conclusions

This real-world multicenter study demonstrated successful prevention of rCDI with bezlotoxumab comparable to clinical trial results regardless of type of SoC and timing of infusion. Multiple prior CDI recurrences were associated with a higher risk of subsequent rCDI, supporting the use of bezlotoxumab earlier in the disease course.

Real-world Multicenter Analysis of Clinical Outcomes and Safety of Meropenem-Vaborbactam in Patients Treated for Serious Gram-Negative Bacterial Infections

Fourty patients were treated with meropenem-vaborbactam (MEV) for serious Gram-negative bacterial (GNB) infections. Carbapenem-resistant Enterobacteriaceae (CRE) comprised 80.0% of all GNB infections. Clinical success occurred in 70.0% of patients. Mortality and recurrence at 30 days were 7.5% and 12.5%, respectively. One patient experienced a probable rash due to MEV.

PCR ribotypes of Clostridioides difficile across Texas from 2011 to 2018 including emergence of ribotype 255

Clostridioides difficile infection (CDI) is the most prevalent healthcare-associated infection in the United States and carries a significant healthcare system burden. As part of an ongoing, active surveillance system of C. difficile throughout Texas, the objective of this study was to assess changes in C. difficile ribotypes of clinical isolates obtained from hospitalized patients in Texas over the past seven years. Fifty hospitals located in Texas, USA sent C. difficile positive stool specimens to a centralized laboratory for PCR ribotyping and toxin characterization between 2011 and 2018. Data collected included specimen collection date, patient age, and sex. Strain genotypes were compiled, and changes in ribotype distribution over time were assessed. Overall, 7796 samples were ribotyped from predominately female patients (58.4%) aged 62 ± 19 years. Samples were obtained from all geographic regions of Texas including Houston/Southwest region (n = 5129; 85%), Dallas/North Texas (n = 579, 9.6%), Central Texas (n = 164; 2.7%), and South Texas (n = 162; 2.6%). The 10 most common ribotypes comprised 73% of all isolates tested during the study period. The most common ribotypes were 027 (17.5%), followed by 014-020 (16.1%), 106 (11.6%), and 002 (9.1%). The prevalence of ribotypes 027, 001, and 078-126 declined significantly over time, while ribotypes 106 and 054 increased in prevalence (P < 0.001). Furthermore, the emergence of a novel ribotype 255 strain was observed. Differences in ribotype distribution were also noted based on age and geographic distribution (P < 0.001, each). This seven-year study demonstrated changing molecular epidemiology of C. difficile in Texas, including the emergence of a novel ribotype 255.

A systematic approach to optimize electronic health record medication alerts in a health system

PURPOSE

The effectiveness of a systematic, streamlined approach to optimize drug-drug interaction alerts in an electronic health record for a health system was studied.

METHODS

An 81-week quasi-experimental study was conducted to evaluate interventions made to medication-related clinical decision-support (CDS) alerts. Medication-related CDS alerts were systematically reduced using a multi disciplinary healthcare committee. The primary endpoint was weekly overall, modification, and acknowledgement rates of medication alerts after drug-drug interaction reclassification. Secondary endpoints included sub analysis of types of medication alerts (drug-drug interaction and duplicate therapy alerts) and alert use by providers (pharmacist and prescribers). Data was analyzed using interrupted time series regression analysis.

RESULTS

After implementation of the new alert system, total number of weekly inpatient alerts decreased from 68,900 (66,300-70,900) and 50,300 (48,600-53,600) in the postintervention period (p < 0.001). The perentage of alerts acknowledged weekly increased from 11.8% (IQR, 11.4-12.1%) in the preintervention period to 13.7% (IQR, 13.3-14.0%) in the postintervention period (p < 0.001). The percentage of alerts that were modified also increased from 5.0% (IQR, 4.9-5.3%) in the preintervention period to 7.3% (IQR, 7.0-7.6%) in the postintervention period (p < 0.001). Both increases were primarily seen with pharmacists versus other healthcare professionals (p < 0.001).

CONCLUSION

A committee-led systematic approach to optimizing drug-drug interactions facilitated a significant decrease in the overall number of alerts and an increase in both medication alert acknowledgement and modification rates.

Eosinopenia and Binary Toxin Increase Mortality in Hospitalized Patients With Clostridioides difficile Infection

Background

Patients with Clostridioides difficile infection (CDI) with either eosinopenia or infected with a binary toxin strain have increased likelihood of mortality. However, the relationship between binary toxin and eosinopenia to synergistically increase mortality has not been studied in humans. We hypothesized that patients with CDI due to binary toxin strains and concomitant peripheral eosinopenia would have a higher likelihood of inpatient mortality.

Methods

This multicenter, retrospective cohort study included adult patients with CDI of known ribotypes stratified by eosinopenia, defined as an absence of eosinophils in the peripheral blood (Houston cohort). The primary outcome was inpatient mortality. Results were supported by a separate national cohort of veterans with CDI (Veterans’ cohort).

Results

In the Houston cohort, a total of 688 patients from 13 institutions in 6 cities were included. Of these, 132 (19%) had an eosinophil count of 0.0 cells/µL (0.0 cells*10⁹/L) and 109 (16%) were infected with a binary toxin strain. After adjusting for covariates, the combination of eosinopenia and infection with a binary toxin strain was an independent predictor of inpatient mortality (odds ratio [OR], 7.8; 95% confidence interval [CI], 1.9–33.2; P = .005). In the separate Veterans’ cohort (n = 790), this combination was also a significant predictor of inpatient mortality (OR, 6.1; 95% CI, 1.5–23.9; P = .009).

Conclusions

In conclusion, the combination of eosinopenia and CDI due to a binary toxin strain was correlated with increased mortality in hospitalized patients from 2 independent cohorts. Prospective studies should further study this important subset of patients at the time of CDI diagnosis.

Practical Guidance for Clinical Microbiology Laboratories: A Comprehensive Update on the Problem of Blood Culture Contamination and a Discussion of Methods for Addressing the Problem

In this review, we present a comprehensive discussion of matters related to the problem of blood culture contamination. Issues addressed include the scope and magnitude of the problem, the bacteria most often recognized as contaminants, the impact of blood culture contamination on clinical microbiology laboratory function, the economic and clinical ramifications of contamination, and, perhaps most importantly, a systematic discussion of solutions to the problem. We conclude by providing a series of unanswered questions that pertain to this important issue.

Clinical Practice Guidelines for Clostridium difficile Infection in Adults and Children: 2017 Update by the Infectious Diseases Society of America (IDSA) and Society for Healthcare Epidemiology of America (SHEA)

A panel of experts was convened by the Infectious Diseases Society of America (IDSA) and Society for Healthcare Epidemiology of America (SHEA) to update the 2010 clinical practice guideline on Clostridium difficile infection (CDI) in adults. The update, which has incorporated recommendations for children (following the adult recommendations for epidemiology, diagnosis, and treatment), includes significant changes in the management of this infection and reflects the evolving controversy over best methods for diagnosis. Clostridium difficile remains the most important cause of healthcare-associated diarrhea and has become the most commonly identified cause of healthcare-associated infection in adults in the United States. Moreover, C. difficile has established itself as an important community pathogen. Although the prevalence of the epidemic and virulent ribotype 027 strain has declined markedly along with overall CDI rates in parts of Europe, it remains one of the most commonly identified strains in the United States where it causes a sizable minority of CDIs, especially healthcare-associated CDIs. This guideline updates recommendations regarding epidemiology, diagnosis, treatment, infection prevention, and environmental management.

Clinical Practice Guidelines for Clostridium difficile Infection in Adults and Children: 2017 Update by the Infectious Diseases Society of America (IDSA) and Society for Healthcare Epidemiology of America (SHEA)

A panel of experts was convened by the Infectious Diseases Society of America (IDSA) and Society for Healthcare Epidemiology of America (SHEA) to update the 2010 clinical practice guideline on Clostridium difficile infection (CDI) in adults. The update, which has incorporated recommendations for children (following the adult recommendations for epidemiology, diagnosis, and treatment), includes significant changes in the management of this infection and reflects the evolving controversy over best methods for diagnosis. Clostridium difficile remains the most important cause of healthcare-associated diarrhea and has become the most commonly identified cause of healthcare-associated infection in adults in the United States. Moreover, C. difficile has established itself as an important community pathogen. Although the prevalence of the epidemic and virulent ribotype 027 strain has declined markedly along with overall CDI rates in parts of Europe, it remains one of the most commonly identified strains in the United States where it causes a sizable minority of CDIs, especially healthcare-associated CDIs. This guideline updates recommendations regarding epidemiology, diagnosis, treatment, infection prevention, and environmental management.

2388. High-risk antibiotics associated with Clostridioides difficile infection: a national, multicenter analysis

Background

Historically, antibiotics with the highest Clostridioides difficile infection (CDI) risk included clindamycin, advanced-spectrum penicillins, and cephalosporins; however, a recent CDI epidemic involving fluoroquinolone (FQ)-resistant ribotype 027-added FQs as a high-risk class. Now that the ribotype 027 strain is part of an endemic population of C. difficile strains, no contemporary analysis of high-risk antibiotics and CDI risk has been conducted. The primary objective of this study was to identify the strongest antibiotic predictors for CDI.

Methods

This was a case–control study in the national United States Veterans Health Administration (VHA). The study included patients 18–89 years old with an ICD-9-CM code for CDI (008.45), a positive stool test, and active CDI therapy between 2002 and 2014. A random sample of VHA patients without a CDI ICD-9-CM code served as the control cohort. Antibiotic use was defined as any use in the 90 days prior to inclusion. Antibiotic risk factors for CDI were evaluated in a multivariable logistic regression model that included 33 covariates. Results were validated in non-VA patients at a quaternary care medical center in Houston, TX.

Results

A total of 85,451 VHA patients were included (26,149 CDI patients and 59,302 controls). FQs were most commonly prescribed: 24.9% (CDI group) and 7.3% (controls). Strongest predictors of CDI included carbapenems (OR 54.39, 95% CI 25.42–116.36), advanced-spectrum penicillins (OR 41.54; 95% CI 31.49–54.78), third/fourth-generation cephalosporins (OR 17.35; 95% CI 14.49–20.77), clindamycin (OR 3.63; 95% CI 3.26–4.02), and FQs (OR 1.48; 95% CI 1.40–1.57). Macrolides (OR 0.83; 95% CI 0.77–0.91) and tetracyclines (OR 0.58; 95 CI 0.51–0.66) were negatively associated with CDI risk. In a validation cohort of 68,795 patients, carbapenems (OR 2.19; 95% CI 1.86–2.57), third/fourth-generation cephalosporins (OR 1.70; 95% CI 1.50–1.93), and advanced-spectrum penicillins (OR 1.64; 95% CI 1.42–1.89) were also the strongest predictors for CDI. FQs were not significantly associated with CDI.

Conclusion

Although FQs were the most prescribed antibiotic class, carbapenems were the strongest predictor of CDI development in a national cohort of veterans and a validation cohort.

Disclosures

All authors: No reported disclosures.

688. In Vitro Activity of Eravacycline, a New Tetracycline Analog, and Comparators Against the Six Most Commonly Isolated Ribotypes of Clostridioides difficile

Background

Eravacycline is a novel, tetracycline class antibacterial indicated for the treatment of complicated intra-abdominal infections in adults. In clinical trials, patients given eravacycline had a low likelihood of developing Clostridioides difficile infection (CDI). We hypothesized this was likely due, in part, to the in vitro susceptibility of eravacycline to C. difficile. The purpose of this study was to test the in vitro susceptibility of eravacycline vs. comparators on contemporary clinical isolates representing common ribotypes, including isolates with decreased susceptibility to metronidazole and vancomycin.

Methods

Two hundred and thirty-four isolates from our biobank were selected from the six most common ribotypes (F001, F002, F014-020, F027, F106, and F255). Minimum inhibitory concentrations (MIC) at 24 hours were measured according to CLSI guidelines for eravacycline, vancomycin, metronidazole and fidaxomicin. MICs results were tabulated and are presented as the geometric mean by ribotype.

Results

Geometric MIC results are shown in Table 1. Eravacycline was the most potent antimicrobial tested followed by fidaxomicin, metronidazole, and vancomycin. Results were consistent amongst all ribotypes, including isolates with reduced susceptibility to vancomycin and metronidazole.

Conclusion

Eravacycline displayed potent in vitro activity against a large collection of clinical C. difficile isolates. These data provide insight into why patients given eravacycline had a low likelihood of developing CDI and support further research to better understand the use of eravacycline to prevent or potentially treat patients with CDI.

Disclosures

All authors: No reported disclosures.

668. Quality of Life Changes in Patients with Clostridium difficile Infection (CDI): A Randomized, Double-Blind Trial of Ridinilazole (RDZ) Compared with Vancomycin (VAN)

Background

C. difficile is the most frequent hospital-acquired bacteria in the United States. CDI is associated with significant morbidity and mortality, and a 46% lower mean EQ-5D index of Health-Related Quality of Life (HRQoL) compared with the general population. However, data on the impact of antibiotic treatment for CDI on HRQoL are lacking.

Methods

RDZ is a novel, narrow-spectrum antibiotic with targeted activity against C. difficile, under development for the treatment of CDI and prevention of recurrence. We evaluated HRQoL prospectively with the EQ-5D-3L in 69 patients enrolled in a Phase 2 randomized, double-blind trial comparing RDZ (n = 36) with VAN (n = 33). EQ-5D-3L was obtained at five time points (baseline, days 5, 10, 12, and 40) with summary index values calculated using US weights (Shaw 2005) evaluating raw scores for mobility, self-care, usual activities, pain/discomfort, and anxiety/depression, and visual analog scale (VAS) scores.

Results

As early as Day 5, CDI patients on RDZ had significant improvements in mean change from baseline in index scores (P = 0.008) and VAS scores (P = 0.01) but no significant improvements were seen in patients on VAN. Time to resolution of diarrhea also occurred sooner with RDZ with a hazard ratio 1.19 in favor of RDZ (90% CI: 0.76, 1.87). Mean changes in index scores in the VAN group took longer to improve significantly compared with baseline and became higher on VAN on Day 12 and Day 40. Treatment-related improvements in pain/discomfort and anxiety/depression are shown in Figures 1 and 2. The mean change from baseline in EQ-5D-3L domains showed the highest (significant) improvements in the pain/discomfort domain for both treatment groups across all time points. However, by Day 40, anxiety/depression improved significantly more with RDZ than with VAN (P = 0.039).

Conclusion

We believe this is the first study to document improvements in HRQoL after antimicrobial treatment for CDI. Patients receiving ridinilazole experienced greater improvements in HRQoL sooner than those on VAN. Anxiety/depression and pain/discomfort improved significantly with treatment. HRQoL should be evaluated in Phase 3 interventional studies for CDI. These results will need to be validated in the ongoing Phase 3 randomized, double-blind, global trials comparing RDZ to VAN for the treatment of CDI.

Disclosures

All authors: No reported disclosures.

2380. Fecal Collinsella Abundance is Negatively Associated with Toxin A/B Production in Cancer Patients with Clostridioides difficile

Background

The detection of C. difficile (CDI) by nucleic acid amplification test (NAAT) with negative toxin enzyme immunoassay (EIA-) is difficult to interpret in cancer patients. Markers that differentiate true infection from colonization, and are associated with clinical outcomes are needed. We hypothesized that the microbiome composition and inflammatory fecal markers in EIA- patients differed from those who are EIA+ and were associated with disease severity and recurrence.

Methods

We studied the fecal microbiome composition (16s rRNA, V3) of 147 cancer patients with CDI diagnosed by a two-step testing algorithm. Clinical data, CDI bacterial quantity (BQ) by qPCR and markers of intestinal inflammation (calprotectin, lactoferrin, IL-1β and IL-8) were analyzed. Data were stratified according to cancer type [hematologic (H) n = 49, solid tumor (ST) n = 66, or stem cell transplant (SCT) n = 32].

Results

Demographic characteristics and symptoms were similar between the three groups. At baseline, species diversity by Shannon index was similar in all three groups regardless of EIA detection and did not correlate with clinical presentation, response to therapy or recurrence. Microbiome composition did not correlate with inflammatory response except in H in whom a higher diversity correlated with increased IL-8 (P = 0.021) and calprotectin (P = 0.01) levels. At the genus level across all strata and when compared with EIA- cases, EIA+ cases presented with a higher abundance of Peptoclostridium (P = 0.0008) which correlated with CDI BQ qPCR (log of BQ/mg 2.38 ± 1.49 vs 0.92 ± 1.28, P < 0.001). In contrast, EIA- cases had a higher abundance of Collinsella (P = 0.001). SCT patients carried fewer Peptoclostridium when compared with other groups, whereas all three patient groups carried similar amounts of Collinsella. The relative abundance of Peptoclostridium and Collinsella was not associated with response to therapy, or fecal markers of inflammation. Principal component analysis did not demonstrate differences between the three groups studied.

Conclusion

In this study, the presence of Collinsella, a known butyrate and bile salt hydrolase producer, was associated with the lack of CDI toxin A/B production. Loss of Collinsella may represent a novel risk factor for active CDI.

Disclosures

All authors: No reported disclosures.

1720. Isolation and Characterization of Candida auris From an Active Surveillance System in Texas

Background

Candida auris is an emerging new multi-drug-resistant fungal pathogen spreading globally. C. auris is associated with outbreaks due to the bloodstream, ear, and wound infections with a high mortality rate (30 to 60%). As part of our multi-pathogen surveillance system, we began screening for C. auris to understand the ecology, sources, and epidemiology of this important pathogen from leftover stool samples collected from hospitalized patients.

Methods

Four hundred and seventeen stool samples were collected, enriched in brain heart infusion broth for 2–3 days at 37°C, and sub-cultured onto selective Candida agar plates. Agar plates were incubated at 37°C for another 2–3 days and suspected Candida colonies were stocked for DNA extraction, PCR identification, and whole-genome sequencing. PCR amplicons were sequenced to confirm the identification C. auris. Enrichment samples were also screened by PCR to directly detect C. auris. Minimum inhibitory concentration (MIC) of various anti-fungal drugs was determined by the micro-dilution method using a commercial MIC plate (Sensititre “YeastOne”).

Results

Three C. auris samples were identified by PCR (0.7%; 3/417) of which one was able to be cultured. The isolated strain was resistant to fluconazole, itraconazole, voriconazole, posaconazole, and caspofungin. WGS data analysis demonstrates our isolate has high similarity with the Pakistani strains.

Conclusion

We have detected C. auris from stool samples of hospitalized patients in Texas for the first time. WGS data indicate our isolate has high similarity with South Asian patient strains. Long-term surveillance of C. auris is essential to understand the infection or colonization sources and epidemiology of this newly emerging fungal pathogen.

Disclosures

All authors: No reported disclosures.

2391. Increased Risk of Systemic Infections with Multidrug-Resistant Organisms in Patients with Severe Clostridioides difficile Infection

Background

The gut microbiota is a defense mechanism against colonization of multidrug-resistant organisms (MDROs), including carbapenem-resistant Enterobacteriacae (CRE). Gut dysbiosis caused by broad-spectrum antibiotics favors MDRO colonization and increased susceptibility of intestinal infections, including C. difficile infection (CDI). Increased CDI severity may increase the risk of bacterial translocation due to damage to colonic epithelial layer. The aim of this study was to assess CDI disease severity and subsequent risk for MDRO systemic infection.

Methods

This was a prospective, observational study of adult hospitalized patients tested for CDI at a large, university-affiliated tertiary care hospital. Patients with a history of systemic MDRO infection in the past 90-days of stool testing were excluded. Patients were stratified by test positivity (CDI vs. antibiotic-associated diarrhea (AAD)), as well as, CDI disease severity and followed for 30-days for subsequent MDRO infections defined as presence of MDRO cultures from systemic, normally sterile sites (blood, urine, cerebrospinal fluid). Stool samples were collected and grown for MDRO colonization.

Results

A total of 335 CDI-positive and 135 antibiotic-associated diarrhea (AAD) hospitalized patients were included. No differences were found in rates of MDRO colonization by test positivity or disease severity (overall 68% VRE, 53% Candida spp., 30.4% MRSA, and 1.8% CRE). Significantly more patients with severe CDI had higher rates of developing systemic MDROs compared with mild-moderate CDI and AAD (23.2%, n = 112 vs. 8.1%, n = 223 P < 0.001; vs. 11.9%, p = 0.018). Severe CDI was found to be an independent risk factor for subsequent systemic MDRO infection via logistic regression.

Conclusion

Severe CDI disease is associated with an increased risk of systemic MDRO infections.

Disclosures

All authors: No reported disclosures.

1038. Impact of an Electronic Antibiotic Timeout on the Utilization of Frequently Prescribed Antibiotics in Hospitalized Patients

Background

Methods to operationalize antibiotic timeouts (ATO) among hospitalized patients are often constrained by the high volume of antibiotic orders that surpass the capabilities of the antimicrobial stewardship program (ASP) to intervene. Houston Methodist Hospital implemented a streamlined electronic ATO process that alerted providers to evaluate the need for continued antibiotics on day 4 of predefined anti-infective therapy. Unresolved alerts were reviewed by clinical pharmacists the following day. The objective of this study was to determine the impact of this electronic ATO on frequently prescribed antibiotics.

Methods

This was a quasi-experimental study in a 924-bed quaternary care hospital comparing days of therapy (DOT) in patients admitted prior to (February 2017 – January 2018) and after implementing an ATO process (March 2018 – February 2019). Antibiotics evaluated included vancomycin, cefepime, piperacillin/tazobactam, and meropenem. ATO alert logic was simulated retrospectively to capture the pre-ATO cohort. The primary outcome was mean composite DOT per patient admission. Secondary outcomes included total hospitalization cost, Clostridioides difficile infection (CDI) and multidrug-resistant organism (MDRO) rates.

Results

A total of 8,458 patients met ATO alert criteria for inclusion in the pre-ATO timeframe and 6,901 patients with an ATO alert in the post-ATO group; 2,642 (38%) prompted a pharmacists’ review. The average composite DOT was 11.5 per admission in the pre-ATO cohort compared with 11.1 in the post-ATO cohort (P = 0.02). After multivariate linear regression, the ATO was significantly associated with a decrease of 0.5 DOT per patient admission (P < 0.001). Other factors associated with a reduction in DOT included age (P < 0.001), service line (P = 0.003), and admission source (P = 0.031). Mean hospital costs per admission were significantly reduced in the post-ATO group: $67,613 vs. $66,615 (P = 0.01). There was no difference in rates of CDI and MDRO.

Conclusion

Implementation of our electronic ATO process demonstrated significant reductions in overall DOT for frequently prescribed antibiotics and decreased total hospital costs across a diverse patient population. This process provides a real-world strategy to operationalize a large-scale ATO as an adjunct to an ASP.

Disclosures

All authors: No reported disclosures.

2682. Prophylaxis-Driven Molecular Epidemiology of Pseudomonas aeruginosa Bloodstream Infections in Adults With Leukemia

Background

Fluoroquinolones (FQs) are routinely used as antimicrobial prophylaxis in leukemia patients receiving chemotherapy to prevent Pseudomonas aeruginosa infections. Patients who are intolerant to FQs may receive cefpodoxime (CPD) or other agents. How FQ use affects the resistance profile and epidemiology of breakthrough P. aeruginosa infections is unknown. To determine this, we performed a whole-genome sequencing (WGS)-driven epidemiologic study of leukemia patients with P. aeruginosa bloodstream infections.

Methods

All adult (age > 17 years) inpatients with leukemia and a first episode of monomicrobial P. aeruginosa bloodstream infection were included. Clinical data were extracted from the electronic medical record. Isolates were sequenced using an Illumina NextSeq and phylogenomics was performed using an in-house analysis pipeline consisting of Bowtie2, SAMtools and bcftools.

Results

110 patients were included and most had a diagnosis of acute myeloid leukemia (n = 66). Twenty (18%) patients received FQ prophylaxis, 56 (54%) received CPD, and the remaining 34 (31%) received other agents. 9 (8%) isolates were multidrug-resistant (MDR). MDR was more common in those receiving FQ prophylaxis (20% vs 6%, P = 0.06). 76 sequence types (STs) were represented with ST235 (n = 8) being most common followed by ST244 (n = 7). ST235 strains were genetically distinct, but closely related (>10 but < 250 SNPs) in comparison to other STs. 2 ST244 strains were genetically identical despite being isolated 4 months apart, suggesting horizontal transmission. MDR was more common among ST235 isolates compared with other STs (38% vs 6%, P = 0.02). ST235 strains were more common in patients receiving FQ vs other prophylaxis (20% vs 4%, P = 0.04). 1 ST244 isolate harbored a VIM-2 β-lactamase. In 20 FQ-resistant isolates, 80% had mutations in either parC (S87L) or gyrA (T83I) and 50% had both. FQ-resistance mutations were more common in FQ recipients (50% vs 8%, P < 0.01).

Conclusion

Most P. aeruginosa infections occurred in non-FQ recipients, while MDR P. aeruginosa infections were more common in FQ recipients. These data suggest that decisions on empiric treatment of patients with P. aeruginosa bacteremia must take antimicrobial prophylaxis history into account.

Disclosures

Samuel L. Aitken, PharmD, Melinta Therapeutoics: Grant/Research Support, Research Grant; Merck, Sharpe, and Dohme: Advisory Board; Shionogi: Advisory Board.