Systems biology evaluation of refractory Clostridioides difficile infection including multiple failures of fecal microbiota transplantation

BACKGROUND

Fecal microbiota transplantation (FMT) aims to cure Clostridioides difficile infection (CDI) through reestablishing a healthy microbiome and restoring colonization resistance. Although often effective after one infusion, patients with continued microbiome disruptions may require multiple FMTs. In this N-of-1 study, we use a systems biology approach to evaluate CDI in a patient receiving chronic suppressive antibiotics with four failed FMTs over two years.

METHODS

Seven stool samples were obtained between 2016-18 while the patient underwent five FMTs. Stool samples were cultured for C. difficile and underwent microbial characterization and functional gene analysis using shotgun metagenomics. C. difficile isolates were characterized through ribotyping, whole genome sequencing, metabolic pathway analysis, and minimum inhibitory concentration (MIC) determinations.

RESULTS

Growing ten strains from each sample, the index and first four recurrent cultures were single strain ribotype F078-126, the fifth was a mixed culture of ribotypes F002 and F054, and the final culture was ribotype F002. One single nucleotide polymorphism (SNP) variant was identified in the RNA polymerase (RNAP) β-subunit RpoB in the final isolated F078-126 strain when compared to previous F078-126 isolates. This SNV was associated with metabolic shifts but phenotypic differences in fidaxomicin MIC were not observed. Microbiome differences were observed over time during vancomycin therapy and after failed FMTs.

CONCLUSION

This study highlights the importance of antimicrobial stewardship in patients receiving FMT. Continued antibiotics play a destructive role on a transplanted microbiome and applies selection pressure for resistance to the few antibiotics available to treat CDI.

The metabolic profile of Bifidobacterium dentium reflects its status as a human gut commensal

BACKGROUND

Bifidobacteria are commensal microbes of the mammalian gastrointestinal tract. In this study, we aimed to identify the intestinal colonization mechanisms and key metabolic pathways implemented by Bifidobacterium dentium.

RESULTS

B. dentium displayed acid resistance, with high viability over a pH range from 4 to 7; findings that correlated to the expression of Na+/H+ antiporters within the B. dentium genome. B. dentium was found to adhere to human MUC2+ mucus and harbor mucin-binding proteins. Using microbial phenotyping microarrays and fully-defined media, we demonstrated that in the absence of glucose, B. dentium could metabolize a variety of nutrient sources. Many of these nutrient sources were plant-based, suggesting that B. dentium can consume dietary substances. In contrast to other bifidobacteria, B. dentium was largely unable to grow on compounds found in human mucus; a finding that was supported by its glycosyl hydrolase (GH) profile. Of the proteins identified in B. dentium by proteomic analysis, a large cohort of proteins were associated with diverse metabolic pathways, indicating metabolic plasticity which supports colonization of the dynamic gastrointestinal environment.

CONCLUSIONS

Taken together, we conclude that B. dentium is well adapted for commensalism in the gastrointestinal tract.

Fusobacteriumnucleatum Adheres to Clostridioides difficile via the RadD Adhesin to Enhance Biofilm Formation in Intestinal Mucus

BACKGROUND & AIMS

Although Clostridioides difficile infection (CDI) is known to involve the disruption of the gut microbiota, little is understood regarding how mucus-associated microbes interact with C difficile. We hypothesized that select mucus-associated bacteria would promote C difficile colonization and biofilm formation.

METHODS

To create a model of the human intestinal mucus layer and gut microbiota, we used bioreactors inoculated with healthy human feces, treated with clindamycin and infected with C difficile with the addition of human MUC2-coated coverslips.

RESULTS

C difficile was found to colonize and form biofilms on MUC2-coated coverslips, and 16S rRNA sequencing showed a unique biofilm profile with substantial cocolonization with Fusobacterium species. Consistent with our bioreactor data, publicly available data sets and patient stool samples showed that a subset of patients with C difficile infection harbored high levels of Fusobacterium species. We observed colocalization of C difficile and F nucleatum in an aggregation assay using adult patients and stool of pediatric patients with inflammatory bowel disease and in tissue sections of patients with CDI. C difficile strains were found to coaggregate with F nucleatum subspecies in vitro; an effect that was inhibited by blocking or mutating the adhesin RadD on Fusobacterium and removal of flagella on C difficile. Aggregation was shown to be unique between F nucleatum and C difficile, because other gut commensals did not aggregate with C difficile. Addition of F nucleatum also enhanced C difficile biofilm formation and extracellular polysaccharide production.

CONCLUSIONS

Collectively, these data show a unique interaction of between pathogenic C difficile and F nucleatum in the intestinal mucus layer.

Knowledge and self-perception comparisons between students with and without prior technician experience in community pharmacy lab courses

INTRODUCTION

It is unknown if students with previous pharmacy technician experience benefit from a community pharmacy dispensing lab. Anecdotally, students with previous technician experience often do not feel a substantial benefit from the course. The purpose of this project was to evaluate pharmacy practice knowledge and perceptions of those with and without prior technician experience in a community lab course.

METHODS

Doctor of pharmacy students enrolled in the lab course were included in the study. All students were administered a pre- and post-course self-perceptions survey and knowledge assessment (20 scenario-based multiple-choice questions). The knowledge assessment evaluated understanding of community pharmacy law, workflow, inventory, insurance, and prescription verification. Survey variables analyzed included length of experience, confidence, and course expectations. Results were analyzed using student's t-tests.

RESULTS

A total of 216 students completed the pre- and post-assessments and were included for analysis. Students with previous technician experience scored statistically significantly higher on the knowledge assessment than students without experience (pre: 57% vs. 33%, post: 67% vs. 53%, respectively). Students without prior technician experience had many statistically significant increases in perceptions of knowledge and confidence, while those with prior technician experience had few.

CONCLUSIONS

There is a baseline knowledge gap between students with technician experience and those without in a community pharmacy simulation lab. Results of this study have identified specific gaps which may be useful for course structure and design. This data supports investigation into 'testing out' or providing separate tracks in a community lab for experienced and non-experienced students.

A survey to assess experiences and social support of underrepresented minority doctor of pharmacy students

INTRODUCTION

There is little data regarding the experiences of underrepresented minorities in pharmacy school. The objectives of this project were to describe the perceived racial and social climate at a diverse college of pharmacy (COP) and to determine areas of opportunity to improve the experiences of underrepresented minority students.

METHODS

An electronic survey was administered to students from all four professional years at a COP in Houston, Texas. Students anonymously self-identified demographic information along with perceptions of racial climate using modified versions of previously validated survey instruments. The institution's social climate was assessed via several measures comprising composite survey scores.

RESULTS

A total of 126 students completed the survey. Overall, Black students had more negative racial experiences and fewer positive social experiences as compared to their peers. Hispanic/Latino student perceptions of the racial and social climate at our institution were more positive than average. Student recommendations were also captured.

CONCLUSIONS

Not all students experienced the same level of inclusion in the college of pharmacy. The diversity and inclusion initiatives undertaken at this COP appear to have been effective in the Latino student population. There is a need for further investigation and qualitative research to determine the best strategies for inclusion of Black students in COPs with diverse populations.

Visualization of fidaxomicin association with the exosporium layer of Clostridioides difficile spores

BACKGROUND

Fidaxomicin has novel pharmacologic effects on C. difficile spore formation including outgrowth inhibition and persistent spore attachment. However, the mechanism of fidaxomicin attachment on spores has not undergone rigorous microscopic studies.

MATERIALS & METHODS

Fidaxomicin attachment to C. difficile spores of three distinct ribotypes and C. difficile mutant spores with inactivation of exosporium or spore-coat protein-coding genes were visualized using confocal microscopy with a fidaxomicin-bodipy compound (green fluorescence). The pharmacologic effect of the fidaxomicin-bodipy compound was determined. Confocal microscopy experiments included direct effect on C. difficile wild-type and mutant spores, effect of exosporium removal, and direct attachment to a comparator spore forming organism, Bacillus subtilis.

RESULTS

The fidaxomicin-bodipy compound MIC was 1 mg/L compared to 0.06 mg/L for unlabeled fidaxomicin, a 16-fold increase. Using confocal microscopy, the intracellular localization of fidaxomicin into vegetative C. difficile cells was observed consistent with its RNA polymerase mechanism of action and inhibited spore outgrowth. The fidaxomicin-bodipy compound was visualized outside of the core of C. difficile spores with no co-localization with the membrane staining dye FM4-64. Exosporium removal reduced fidaxomicin-bodipy association with C. difficile spores. Reduced fidaxomicin-bodipy was observed in C. difficile mutant spores for the spore surface proteins CdeC and CotE.

CONCLUSION

This study visualized a direct attachment of fidaxomicin to C. difficile spores that was diminished with mutants of specific exosporium and spore coat proteins. These data provide advanced insight regarding the anti-spore properties of fidaxomicin.

Vitamin D Assessment Over 48 Weeks in Treatment-Naive HIV Individuals Starting Lopinavir/Ritonavir Monotherapy

BACKGROUND

Vitamin D deficiency is common in HIV population and has been associated with increased comorbidity risk and poor immunologic status.

OBJECTIVE

To evaluate the effect of protease inhibitor lopinavir/ritonavir monotherapy on changes in serum 25-hydroxyvitamin D [25(OH)D] over 48 weeks.

METHODS

Thirty-four treatment-naïve HIV individuals initiating lopinavir/ritonavir monotherapy and receiving clinical care from private practice in Houston, Texas, were included. Serum 25-hydroxyvitamin D levels from stored plasma samples collected from IMANI-2 pilot study at both baseline and 48 weeks were analyzed using LC-MS assays. Mean 25(OH)D at baseline and 48 weeks were compared using paired t-tests. Linear regression analysis was used to evaluate factors associated with changes in 25(OH)D. Logistic regression analyses were used to determine the effect of vitamin D status and covariates on CD4 cell count recovery.

RESULTS

Mean 25(OH)D was significantly higher at 48 weeks (26.3 ng/mL (SD + 14.9); p=0.0003) compared to baseline (19.8 ng/mL (SD +12.1), with fewer individuals having vitamin D deficiency (41.2%) and severe deficiency (11.8%). Both body mass index and baseline CD4 cell count were significant independent covariates associated with 25(OH)D changes over 48 weeks. Baseline vitamin D status did not affect CD4 cell count recovery. However, in a 24-week multivariate analysis, current tobacco use was significantly associated with a decreased odds of CD4 cell count recovery (AOR 0.106, 95% CI 0.018-0.606; p=0.012).

CONCLUSION

Individuals treated with lopinavir/ritonavir monotherapy had significantly higher 25(OH)D after 48 weeks. Current tobacco users had significantly diminished CD4 cell count recovery after starting treatment, warranting further clinical investigation.

Toxin A-Predominant Pathogenic Clostridioides difficile: A Novel Clinical Phenotype

BACKGROUND

Most Clostridioides difficile toxinogenic strains produce both toxins A and B (A+B+), but toxin A-negative, toxin B-positive (A-B+) variants also cause disease. We report the identification of a series of pathogenic clinical C. difficile isolates that produce high amounts of toxin A with low or nondetectable toxin B.

METHODS

An ultrasensitive, quantitative immunoassay was used to measure toxins A and B in stool samples from 187 C. difficile infection (CDI) patients and 44 carriers. Isolates were cultured and assessed for in vitro toxin production and in vivo phenotypes (mouse CDI model).

RESULTS

There were 7 CDI patients and 6 carriers who had stools with detectable toxin A (TcdA, range 23-17 422 pg/mL; 5.6% of samples overall) but toxin B (TcdB) below the clinical detection limit (<20 pg/mL; median TcdA:B ratio 17.93). Concentrations of toxin A far exceeded B in in vitro cultures of all 12 recovered isolates (median TcdA:B ratio 26). Of 8 toxin A>>B isolates tested in mice, 4 caused diarrhea, and 3 of those 4 caused lethal disease. Ribotyping demonstrated strain diversity. TcdA-predominant samples were also identified at 2 other centers, with similar frequencies (7.5% and 6.8%).

CONCLUSIONS

We report the discovery of clinical pathogenic C. difficile strains that produce high levels of toxin A but minimal or no toxin B. This pattern of toxin production is not rare (>5% of isolates) and is consistently observed in vitro and in vivo in humans and mice. Our study highlights the significance of toxin A in human CDI pathogenesis and has important implications for CDI diagnosis, treatment, and vaccine development.

Recent developments in antimicrobial therapy for gastrointestinal infections

PURPOSE OF REVIEW

This focused, narrative review summarizes human clinical trial data for direct-acting antimicrobials in development for the treatment of gastrointestinal infections that were published in the past 18 months (1 January 2019 to 30 June 2020).

RECENT FINDINGS

Antimicrobial agents for Clostridioides difficile infection (n = 6), cryptosporidiosis (n = 1), cytomegalovirus infection (n = 3) and Helicobacter pylori infection (n = 1) have completed and/or are undergoing human clinical trials.

SUMMARY

Although this review highlights significant advances in four disease states, many common gastrointestinal pathogens have no antimicrobials in human clinical trials, emphasizing the need for continued prioritization in this field of study.

802. Proton Pump Inhibitors Increase Clostridioides difficile Disease Severity Controlling for Infecting Strains

Background

Proton pump inhibitors (PPI) display pleotropic properties that increase the risk of poor outcomes in patients with C. difficile infection (CDI). However, clinical data on PPI and CDI outcomes is controversial perhaps due to lack of knowledge of infecting strain. The purpose of this study was to assess CDI outcomes in hospitalized patients infected with known C. difficile ribotypes based on use of PPI.

Methods

This was a multicenter study (20 hospitals) of hospitalized patients infected with one of three C. difficile ribotypes (RT027, RT106, and RT014-020). Electronic medical records were reviewed by investigators blinded to RT that collected data on PPI use along with other clinical data. A composite endpoint of disease severity, mortality and 90-day CDI recurrence was assessed based on receipt of PPI and ribotype using multivariate logistic regression.

Results

A total of 380 patients with CDI aged 66±17 years (Female: 59.5%; White: 70.5%) infected with RT 106 (115/380; 30.3%), RT027 (116/380; 30.5%), and RT014-020 (149/380; 39.2%) were included. One hundred and ninety-nine patients (52.4%) were given a PPI at the time of CDI diagnosis and 129 patients (66.1%) experienced either severe disease or CDI recurrence. Disease severity differed significantly between ribotypes (p< 0.05) and increased in patients given PPI (p=0.08). CDI recurrence also differed significantly among ribotypes (p< 0.05) and increased in patients given PPI. Using the composite endpoint, receipt of PPIs significantly increased the likelihood of poor outcomes (OR:1.78; 95% CI: 1.17-2.73; p=0.007) after controlling for infecting ribotype.

Conclusion

In this multicenter study, receipt of PPIs increased the likelihood of poor outcomes in CDI patients after controlling for infecting ribotype.

Disclosures

Kevin W. Garey, PharmD, MS, FASHP, Merck & Co. (Grant/Research Support, Scientific Research Study Investigator)

798. Metronidazole Exposure Prior to Clostridiodes difficile Infection (CDI) is a Risk Factor for Severe C. difficile Disease in Cancer Patients

Background

Antibiotic use is a risk factor for CDI. Few studies have correlated use of prior antibiotics with CDI severity in cancer patients. This study identified clinical and microbiology risk factors associated with severe CDI in patients with cancer. We hypothesized that previous antibiotic exposure and microbiome composition at time of CDI presentation, are risk factors for severe disease in cancer patients.

Methods

This non-interventional, prospective, single-center cohort study examined patients with cancer who had their first episode or first recurrence of CDI between Oct 27, 2016 and Jul 1, 2019. C. difficile was identified using nucleic acid amplification testing. Multivariate analysis was used to determine significant clinical risk factors for severe CDI as defined in the 2018 IDSA/SHEA guidelines. Alpha, and beta diversities were calculated to measure the average species diversity and the overall microbial composition. Differential abundance analysis and progressive permutation analysis were used to single out the significant microbial features that differed across CDI severity levels.

Results

Patient (n=200) demographics show mean age of 60 yrs., 53% female, majority White (76%) and non-Hispanic (85%). Prior 90 day metronidazole use (Odds Ratio OR 4.68 [1.47-14.91] p0.009) was a significant risk factor for severe CDI. Other factors included Horn’s Index > 2 (OR 7.75 [1.05-57.35] p0.045), Leukocytosis (OR 1.29 [1.16-1.43] p< 0.001), Neutropenia (OR 6.01 [1.34-26.89] p0.019) and Serum Creatinine >0.95 mg/dL (OR 25.30 [8.08-79.17] p< 0.001). Overall, there were no significant differences in alpha and beta diversity between severity levels. However, when identifying individual microbial features, the high presence of Bacteroides uniformis, Ruminococceae, Citrobacter koseri and Salmonella were associated with protection from severe CDI (p< 0.05).

Table 1 - Results of multivariate logistic regression analysis of factors associated with severe CDI

Figure 1. Microbiome features identified by progressive permutation analysis as seen in a volcano plot.

Conclusion

A number of risk factors for severe CDI were identified among this population, including prior 90 day metronidazole use. Also, increased relative abundance of Bacteroides uniformis, Ruminococceae, Citrobacter koseri and Salmonella were linked to protection from severe CDI. Reducing metronidazole use in patients with cancer may help prevent subsequent severe CDI.

Disclosures

Adilene Olvera, MPH MLS (ASCP), MERK (Grant/Research Support, Scientific Research Study Investigator) Kevin W. Garey, PharmD, MS, FASHP, Merck & Co. (Grant/Research Support, Scientific Research Study Investigator) Ryan J. Dillon, MSc, Merck & Co., Inc., (Employee) Engels N. Obi, PhD, Merck & Co. (Employee)

784. A Novel Method to Assess Virulence of Clostridioides difficile: Focus on C. difficile Ribotype 106

Background

Clostridioides difficile ribotype (RT) 106 has emerged as one of the most commonly isolated strains in the USA and worldwide. However, studies investigating clinical outcomes associated with this strain are lacking. The purpose of this study was to compare disease severity, clinical cure, and recurrence rates associated with CDI caused by RT106 vs two other comparator strains.

Methods

This multicenter study (20 hospitals) assessed hospitalized patients infected with C. difficile RT106 compared to patients infected with a known hypervirulent strain (RT027) and a strain associated with less virulence (RT014-020). Electronic medical records were reviewed by investigators blinded to RT. Disease severity was calculated using the 2017 IDSA/SHEA guidelines, initial clinical cure was defined as resolution of symptoms by day 6 of treatment, and recurrence assessed 90-days after the initial positive toxin test. All isolates were ribotyped using PCR fluorescent ribotyping.

Results

A total of 380 patients with CDI aged 66 ± 17 years (Female: 59.5%; White: 70.5%) infected with RT 106 (115/380; 30.3%), RT027 (116/380; 30.5%), and RT014-020 (149/380; 39.2%) were included. Approximately half of the patients had severe CDI (47.6%). Disease severity was highest for RT027 (59.3%) followed by RT014-020 (45%), and RT106 (41.2%). Clinical cure rates were lowest for RT027 (74.8%) followed by RT106 (77.8%), and RT014-020 (85.5%). 90-day recurrence rates were highest for RT027 (20.7%) followed by RT106 (13.3%), and RT014-020 (8.7%). Compared to RT014-020, virulence increased with RT106 (OR:1.10; 95% CI: 0.67-1.8) and RT027 (OR: 2.0: 95% CI: 1.2-3.5) was noted.

Conclusion

Our novel analysis method established RT106 as a moderately virulent C. difficile strain vs. comparator ribotypes. This study presents a novel method for comparing clinical outcomes for emerging ribotypes.

Disclosures

Kevin W. Garey, PharmD, MS, FASHP, Merck & Co. (Grant/Research Support, Scientific Research Study Investigator)

645. Absence of Toxemia in Clostridioides difficile infection: Results from Ultrasensitive Toxin Assay of Serum

Background

Clostridioides difficile infection (CDI) is the major cause of hospital-acquired bacterial infectious diarrheacaused by Toxin A (TcdA) and Toxin B (Tcd B), secreted from pathogenic strains of C.difficle bacteria. This infection can vary greatly in symptom severity and presentation. In fulminant CDI, these toxins lead to systemic complications such as toxemia, however, identification of toxemia in CDI patients is extremely rare. We hypothesized that this rarity of detection may be due to low concentrations of circulating toxins in the blood, below the limit of detection of commercially available assays.

Methods

The previously developed Single Molecule Array (Simoa) assay, capable of detecting TcdA and TcdB in stool, was modified for the detection of toxins in serum and applied to a panel of serum samples from patients with confirmed CDI.

Results

Our cohort included 169 patients with a median age of 68 years (IQR 54-78), most with severe CDI and many with severe clinical outcomes attributed to CDI (Table 1). We found no detectable TcdA or TcdB in the serum of our patient cohort despite a wide range of toxin concentrations in paired stool (Figure 1). The detection of toxin may be limited by the interference of anti-toxin anti-bodies circulating in serum. When serum samples were spiked with TcdA and/or TcdBvarying amounts of IgA, IgG or IgM anti-toxin, high serum anti-toxin antibody concentrations were associated with loss of Simoa signal, suggesting substantial inhibition of toxin measurements.

Table 1. Demographics, Baseline Laboratory Values, and Clinical Outcomes for the cohort

Figure 1. Comparison of TcdA and TcdB concentrations, as measured by Simoa, in serum and stool. Clinical cutoffs are shown: stool, 20 pg/ml for TcdA and for TcdB; serum 15.0 pg/ml for TcdA and is 26.7 pg/ml for TcdB. Signals below these cut-offs are below backgrounds and so negative.

Conclusion

In contrast to earlier published findings which reported on the presence of detectable toxin in the serum of a small number of patients with CDI, our work did not support this observation. Although Simoa is highly sensitive for detection of picogram quantities of TcdA or TcdB it was unable to detect either toxin in serum during CDI. This result does not support the hypothesis that toxemia develops even in severe C. difficile infection.

Disclosures

Alice Banz, Ph.D, BioMerieux (Employee) Kevin W. Garey, PharmD, MS, FASHP, Merck & Co. (Grant/Research Support, Scientific Research Study Investigator) Carolyn D. Alonso, MD, FIDSA, Alnylam Pharmaceuticals (Employee)Merck (Research Grant or Support) Ciarán Kelly, MD, Artugen (Consultant)Facile Therapeutics (Consultant)Finch (Consultant)First Light Biosciences (Consultant)Matrivax (Consultant)Merck (Consultant)Vedanta (Consultant)

741. Antifungal Resistant Candida glabrata Are Most Commonly Colonized in Clostridioides difficile Infection (CDI) Patient Guts in Texas

Background

Candida glabrata is the second most common cause of invasive candidiasis in the United States. The echinocandin class of antifungals, including caspofungin has become the preferred therapy for invasive candidiasis due to C. glabrata and other species demonstrating decreased azole susceptibility. Caspofungin resistance has been uncommon, but reports suggest that the incidence is increasing, particularly among C. glabrata isolates. The dysbiosis associated with Clostridium difficile allows for overgrowth of Candida spp. However, the prevalence of C. glabrata in stool of C. difficile infection (CDI) patients is not well studied. Therefore, our objectives were to investigate the incidence of potentially pathogenic species of C. glabrata in stool samples of CDI patients.

Methods

We collected 1,241 Clostridioides difficile infection (CDI) patient stool samples from two large hospitals in Houston, Texas and enrich the samples in brain heart infusion (BHI) broth at 37C for 48-72 hours and then sub-cultured onto selective HardyChrom Candida agar and incubated at 37C for 48 to 72 hours. Characteristic Candida colonies were stocked in cryovials and kept at -80C for further analyses. Isolates were then identified by multiplex PCR. C. glabrata isolates were screened for caspofungin resistance on Muller-Hinton agar (with 8.0 ug/ml).

Results

Overall, 14.8% (184/1241) samples were culture positive for Candida spp. The predominant species was C. glabrata (9.2 %) followed by C. albicans (2.3%), C. tropicalis (1.6%), C. parapsilosis (1.2%), C. krusei (0.6%) or not speciated (6.9%). The majority of C. glabrata isolates (70.2%; 80/114) were caspofungin resistant.

Conclusion

The results of this study showed that colonization of C. glabrata is common in patients with CDI and could be a source of antifungal-resistant pathogens.

Disclosures

All Authors: No reported disclosures

1575. Predictors of Negative Clinical Outcomes among Patients treated with Meropenem-Vaborbactam for Serious Gram-Negative Bacterial Infections: Impact of Delayed Appropriate Antibiotic Selection

Background

Numerous number of studies have found a positive correlation between delayed appropriate antibiotic therapy and negative clinical outcomes (NCO) in Gram-negative bacterial infections (GNBI). The combination of meropenem with vaborbactam (MVB) received Food and Drug Administration approval for the treatment of complicated urinary tract infections and acute pyelonephritis caused by susceptible organisms in August 2017. We sought to determine the impact of delayed appropriate therapy with MVB on NCO among patients with GNBI.

Methods

Multi-center, retrospective cohort study from October 2017 to March 2020. We included adult patients treated with MVB for &gt;72 hours. We excluded patients who received alternative appropriate antibiotics for GNB prior to MVB and patients with unknown dates for index culture. NCO were defined as 30-day mortality and/or microbiological recurrence. All outcomes were measured from MVB start date. Classification and regression tree analysis (CART) was used to identify the time breakpoint (BP) that delineates the risk of NCO. Multivariable logistic regression analysis (MLR) was used to examine the independent association between the CART-derived-BP and NCO. Variables were retained in the model if P&lt; 0.2 and removed in a backward stepwise approach.

Results

A total of 86 patients were included from 13 institutions in the United States: median(IQR) age 55 (37-67) years, 67% male, and 48% Caucasian. Median(IQR) APACHE II and Charlson Comorbidity index scores were 18(11-26) and 4(2-6), respectively. Common sources of infection were respiratory (37%) and intra-abdominal (21%). The most common pathogens were carbapenem-resistant Enterobacterales (83%). CART-derived BP between early and delayed treatment was 48 hours, where NCO was increased (36% vs.7%; P=0.04). Delayed MVB initiation was independently associated with NCO in the MLR (aOR=7.4, P=0.02).

Results of Regression Analysis of Variables Associated With Negative Clinical Outcomes and Delayed Appropriate Therapy with Meropenem-vaborbactam

Conclusion

Our results suggest that delaying appropriate antibiotic therapy with MVB for &gt;48 hours significantly increases the risk of NCO in patients with GNBI. Clinicians must ensure timely administration of MVB to assure best outcomes in patients with GNBI.

Disclosures

Kevin W. Garey, PharMD, MS, FASHP, Merck & Co. (Grant/Research Support, Scientific Research Study Investigator) Michael J. Rybak, PharmD, MPH, PhD, Paratek (Grant/Research Support)

1608. Efficacy of Ceftolozane/Tazobactam for Multidrug-Resistant Gram-Negative Infections in Multiple Urban Hospitals

Background

Ceftolozane/tazobactam (C/T) is a novel cephalosporin/beta-lactamase inhibitor combination developed for use against multidrug-resistant (MDR) Gram-negative infections, particularly Pseudomonas aeruginosa (PA). C/T is approved for complicated urinary tract and intraabdominal infections as well as hospital-acquired/ventilator-associated bacterial pneumonias. However, comprehensive clinical characterization of patients treated with C/T in non-FDA-approved indications is limited.

Methods

Patients ≥18 years who received C/T for ≥48 hours while hospitalized in 9 acute care centers in Houston, TX from January 2016 through September 2018 were included. Demographic, microbiologic, treatment and clinical outcome data were retrospectively collected by chart review. In patients who received multiple inpatient courses of C/T, only the first course with C/T was assessed.

Results

210 patients met inclusion criteria: 58% were non-white, 35% were female and 13% were immunocompromised. Median age was 61 years (IQR, 48 to 69). Median Charlson comorbidity index was 5 (IQR, 2 to 6). At the onset of the index episode, a significant proportion of patients required intensive care unit admission (44%), mechanical ventilation (37%) and pressor support (22%). Respiratory sources were the most common (50%) followed by urine (15%). Positive cultures were documented in 93% of the cases and PA was found in 86%. Majority (95%) of PA which were MDR. C/T use was guided by susceptibility testing of the index isolate in ca. 52%. In 5.7% of cases, C/T was used to escalate therapy without any documented C/T-susceptible organism. Half (51%) of the cohort received initial dosing appropriate for renal function while 36% receiving a lower than recommended dose. Clinical success (i.e., recovery from infection-related signs and symptoms) occured in 77%. The in-hospital mortality rate in our cohort was 15% with 26 of 31 deaths deemed infection-related.

Conclusion

We report a large multicenter observational cohort that received C/T. A 77% clinical success with the use of C/T was documented. These data support the use of C/T in critically ill patients infected with MDR PA.

Disclosures

William R. Miller, MD, Entasis Therapeutics (Scientific Research Study Investigator)Merck (Grant/Research Support)Shionogi (Advisor or Review Panel member) Laura A. Puzniak, PhD, Merck (Employee) Cesar A. Arias, MD, MSc, PhD, FIDSA, Entasis Therapeutics (Scientific Research Study Investigator)MeMed (Scientific Research Study Investigator)Merck (Grant/Research Support)

1197. Inhibitory Effect of Ursodeoxycholic Acid on Clostridioides difficile Growth

Background

Ursodeoxycholic acid (UDCA), a secondary bile acid, inhibits germination and growth of Clostridioides difficile in vitro, but the results from in vivo experiments have been conflicting. We evaluated the effects of UDCA on C. difficile in vitro and in a wax moth, Galleria mellonella model.

Methods

The in vitro growth and germination effects of UDCA on C. difficile were assessed with increased concentration of UDCA (0.001, 0.01, 0.05, and 0.1%). To assess treatment effects of UDCA, C. difficile spores (approximately 1x10^6-8 colony forming units (CFU)) were force fed to G. mellonella larvae treated with UDCA (50 mg/kg/day) 24 hours prior to C. difficile inoculation. Forty G. mellonella larvae were used for each experiment, which was repeated with two distinct strains (R20291 and CD196). Larvae were housed at 37°C and monitored for the next five days for mortality.

Results

In vitro experiment demonstrated inhibition of C. difficile growth at 0.1% concentration (P &lt; 0.001 vs control). Larvae treated with UDCA had a numerically higher survival rate (60% / 24/40) compared to controls (40% / 16/40) but the results were not statistically significant (p=0.14). Identical rates of survival were observed in the control arms for both strains (40%) and similar in the treatment arms (R20291: 70%; CD 196: 50%).

Conclusion

Overall, UDCA shows inhibitory effect of growth and germination of C. difficile in vitro. However, in our G. mellonella model, a single dose of UDCA given prior to infection did not prevent CDI. Further dose dependent, and multiday studies investigating the role of UDCA in CDI is needed to better understand this in vitro / in vivo paradox.

Disclosures

Kevin W. Garey, PharMD, MS, FASHP, Merck & Co. (Grant/Research Support, Scientific Research Study Investigator)

787. Evaluation of Clostridioides difficile Environmental Contamination Surrounding C. difficile Patients vs. non-C. difficile Patients in Outpatient Infusion Centers

Background

Clostridioides difficile infection (CDI) is the most common cause of healthcare-associated infection. CDI and non-CDI patients (pts) are often treated at the same time in outpatient infusion centers (OICs). This proximity may allow horizontal transfer of spores. However, C. difficile (C. diff) spores are ubiquitous in nature and baseline contamination rates at OICs are unknown. The purpose of this pilot study was to determine toxigenic C. diff contamination in the OIC surrounding CDI pts receiving bezlotoxumab compared to non-CDI pts receiving another infusion in the same OIC before and after cleaning.

Methods

OIC contamination rates were assessed at baseline, after infusion and after cleaning the environment of CDI pts receiving bezlotoxumab compared to non-CDI pts receiving other infusions. For each pt receiving an infusion, 11 areas were sampled at each time period; the infusion chair (n=4), medical and non-medical equipment (n=3), and the floor surrounding the infusion chair (n=4). Five high traffic control areas per sampling day were included. Swabs were cultured anaerobically and PCR was used to identify toxin genes. Proportion of toxigenic C. diff positive samples were compared between CDI and non-CDI pts for each time point. Cleaning was performed using a standard protocol of bleach (CDI pt) or non-bleach (non-CDI pt) products.

Results

Samples (n=709) were obtained from 10 pts in each group (329 CDI, 330 non-CDI, 50 high-traffic) from 7 OICs over 4 months. Overall, 55 patient area cultures (8%) were positive for C. diff. Positive sampling areas were highest for floors (13%) followed by infusion chairs (7%) and equipment (4%). Baseline contamination in high traffic areas was 6%. Contamination rates (Table 1) for CDI were 7% at baseline, higher after infusion (15%) and lower after cleaning (5%). For non-CDI pts, rates were similar at baseline (8%), after infusion (6%) and after cleaning (9%).

Table 1. Proportion of toxigenic C. difficile-positive samples in the environment of CDI and non-CDI patients.

Conclusion

Compared to non-CDI pts, CDI pts had similar baseline but lower after cleaning contamination rates. These preliminary results suggest that with a proper cleaning protocol in place, the presence of CDI patients in an OIC does not increase the likelihood of C. diff transmission for other at-risk populations.

Disclosures

Kevin W. Garey, PharmD, MS, FASHP, Merck & Co. (Grant/Research Support, Scientific Research Study Investigator) Richard L. Hengel, MD, Merck & Co. (Other Financial or Material Support, Grant Steering Committee Member) Timothy E. Ritter, MD, Merck & Co. (Other Financial or Material Support, Grant Steering Committee Member) Ramesh V. Nathan, MD, FIDSA, Merck & Co. (Other Financial or Material Support, Grant Steering Committee Member) Engels N. Obi, PhD, Merck & Co. (Employee) Lucinda J. Van Anglen, PharmD, Merck & Co. (Grant/Research Support)

795. Impact of Revised Infectious Diseases Society of America and Society for Healthcare Epidemiology of America Guideline on the Classification of Clostridioides difficile Infection Severity

Background

The Infectious Diseases Society of America (IDSA) and Society for Healthcare Epidemiology of America (SHEA) revised their Clostridioides difficile infection (CDI) severity classification criteria in 2017 to include a serum creatinine (SCr) value above a threshold (≥ 1.5 mg/dL) rather than a relative increase from baseline (≥ 1.5 times the premorbid level). To date, these criteria have not been validated and may overestimate the number of severe CDI cases in patients with underlying renal insufficiency.

Methods

This multicenter, retrospective cohort study included all patients ≥ 18 years of age with CDI diagnosed in two large health systems in the Houston, Texas area between 2016 and 2018. Patients were assessed for presence of acute kidney injury (AKI) and chronic kidney disease (CKD), defined per the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines, and IDSA/SHEA CDI severity classification criteria per the 2010 and 2017 CDI guidelines. The primary outcome was all-cause inpatient mortality.

Results

The study cohort consisted of 770 CDI episodes from 12 hospitals. A large proportion of episodes occurred in patients with preexisting CKD (36.5%) and concomitant AKI (29.6%). Eighty-two episodes (10.6%) showed discordant results when applying the 2017 revised severity classification criteria due to the identification of patients with preexisting CKD. However, the 2017 severity classification criteria were better correlated with all-cause mortality (OR, 5.40; 95% CI, 1.84-15.86; P = 0.002) than were the 2010 severity classification criteria (OR, 3.12; 95% CI, 1.35-7.19; P = 0.008) as the 2017 SCr criterion was an independent predictor of mortality (OR, 3.66; 95% CI, 1.66-8.05; P = 0.001) while the 2010 SCr criterion was not (OR, 1.47; 95% CI, 0.71-3.08; P = 0.30).

Conclusion

Our findings support the inclusion of the 2017 IDSA/SHEA CDI severity classification criteria in future CDI guideline updates.

Disclosures

Kevin W. Garey, PharmD, MS, FASHP, Merck & Co. (Grant/Research Support, Scientific Research Study Investigator)

43. A Pharmacoepidemiologic Evaluation of Echinocandin Use

Background

Invasive candidiasis (IC) is a common healthcare-associated infection. Rates of IC caused by drug-resistant Candida spp., designated by the CDC as a serious threat, are increasing, and Candida auris alone was recently added as an urgent threat. Echinocandins are guideline-preferred for the treatment of invasive candidiasis due to in vitro potency, a favorable toxicity profile, and convenient dosing. The purpose of this study was to perform a pharmacoepidemiologic analysis on patterns of echinocandin use at a large, quaternary care medical center.

Methods

Data reporting echinocandin use, pharmacy data, and clinical microbiologic data obtained from 2017–19 were pooled. Monthly days of therapy (DOT) per 1,000 patient days were calculated during the study period along with number of unique orders. Investigators evaluated the proportion of echinocandin-treated patients with or without positive Candida cultures; the relationship between echinocandin use and hospital admission and discharge dates was also evaluated.

Results

Echinocandin monthly DOT/1,000 patient days present averaged 26 (± 5) DOT and did not change appreciably during the study period. Of the patients with microbiologic evidence of Candida, 842 (51%) received echinocandin courses. Length of echinocandin therapy was significantly longer for patients with positive Candida cultures (5.5 ± 5.9 days) compared to those without positive cultures (3.9 ± 5.0 days; p< 0.001). Of 1,659 echinocandin courses evaluated, 549 courses (33%) were initiated within 2 days of hospital admission and the average time from hospital admission to echinocandin start was 9 (± 13) days. A total of 505 (24%) echinocandin courses were continued until the day of discharge.

Conclusion

The rate of echinocandin use did not change appreciably during the study period. A significant proportion of echinocandin courses were either started upon hospital admission or were continued until the day of discharge. Further studies to evaluate antifungal stewardship opportunities for the echinocandin pharmacologic class are warranted.

Disclosures

Nicholas D. Beyda, PharmD, BCPS, Astellas (Advisor or Review Panel member)Cidara (Grant/Research Support, Scientific Research Study Investigator) Kevin W. Garey, PharMD, MS, FASHP, Merck & Co. (Grant/Research Support, Scientific Research Study Investigator)

825. An Academic-Information Technology Partnership to Create an Infectious Diseases Translational Science Database

Background

Translational science is the process of turning observations in the laboratory, clinic, and community into interventions that improve human health. The coordinated effort to maintain integrated, validated laboratory and clinical data is often a rate-limiting step for research laboratories, especially for multi-site studies. Previous research shows a rate of error between 2.3 and 5.2% for basic data collection in clinical databases, up to 26.9% for more complex data points. The purpose of this project was to create a translational science database prototype that would be responsive to the unmet needs of the translational research community.

Methods

Translational scientists, IT experts, and lab technicians mapped the workflow of a high-throughput research laboratory including clinical and laboratory data. Database goals were to develop processes that would minimize data entry time, avoid redundancies, and validate data in a secure environment (HIPAA-compliant). Unique to this platform was the ability to map creation of new samples (for example, PCR products) from parent samples (biologic samples). The platform was developed in an iterative process utilizing interviews, workflow study, analysis of supporting artifacts, and mock-ups.

Results

The current prototype allows for electronic upload or manual data entry of clinical data. In a small controlled study we found the rate of error for basic data entry to be below 1% within it. Pre-populated data entry screens map laboratory work-flow with custom data entry fields produced based on laboratory results earlier in the work flow. Work-flow mapping includes microbiology, phenotypic descriptions (MIC), molecular biology (PCR), and customized experiments. Sequence data, housed separately, has data linkers stored in the database. The launch screen and data entry forms are populated based on specific criteria entered for each user.

Conclusion

The Translational Science Database allows for efficient capture of high-quality data with baseline validation enabling seamless linking of translational data for single or multi-site laboratories. Future development work will expand the number of experiments and also incorporate stored biobank information into the database.

Disclosures

Jeffrey Beairsto, BSc Eng (ME), Populus (Employee, Shareholder) Randal Neptune, BSc., MSc., Populus Global Solutions (Employee) Beth Webster, BSc, MBA, Populus Global Solutions Inc (Employee, Shareholder) John N. Rutter, BscEng, Populus Global Solutions (Board Member, Employee, Shareholder) Tristan Rutter, BA, Populus (Employee) Kevin W. Garey, PharMD, MS, FASHP, Merck & Co. (Grant/Research Support, Scientific Research Study Investigator)

195. Antimicrobial Stewardship Incorporating New Antimicrobials for Use against Multi-Drug Resistant Pseudomonas aeruginosa in Cystic Fibrosis

Background

Cystic fibrosis (CF) is a life-limiting genetic disease affecting approximately 80,000 people worldwide, including 30,000 in the United States. Chronic Pseudomonas aeruginosa (PA) infections in CF often develop to be multidrug-resistant (MDR) and are associated with worse clinical outcomes. Ceftolozane/Tazobactam (C/T) has shown benefits over other standards of therapy in selected populations with MDR-PA infections, but studies are lacking in the CF population. The objective of this study was to evaluate the current use and antimicrobial stewardship of C/T in CF patients with MDR-PA.

Methods

This is a retrospective study of hospitalized CF patients with infections due to positive cultures for MDR-PA from 2016–2019 at Baylor St. Luke’s Medical Center in Houston, Texas. Electronic medical records were reviewed for patient demographics, presence of infectious diseases (ID) consult, antibiotics use, and clinical outcomes. A descriptive analysis was performed to compare the patient demographics and clinical outcomes between patients receiving C/T-based and non-C/T therapies.

Results

A total of 56 CF patients with positive MDR-PA cultures were identified (18 receiving C/T and 38 receiving non-C/T antibiotics). Most MDR-PA was cultured from the lungs (94.6%, 54/56). Patient age, weight, and body mass index were similar between those receiving C/T and non-C/T therapies as was the overall duration of antibiotic therapy 16.3 (± 8.7) vs. 13.9 (± 3.5) days in C/T and non-C/T groups, respectively. More patients in the C/T group had severe forced expiratory volume in 1 s (FEV1) [£40%] at baseline (66.7% vs. 21.1%) and higher ICU admission rates (44.4% vs 2.6%). All C/T patients had an ID consult placed (3 ± 3.1 days after admission) but none in the non-C/T group. The 30-day recurrent pulmonary exacerbation rate was comparable between C/T and non-C/T groups (22.2% vs. 15.8%).

Conclusion

C/T was reserved for the sickest group of CF patients with severe FEV1. Given the devastating disease progression with MDR organisms in CF, new antibiotics with better clinical outcomes against chronic MDR-PA should be considered earlier in therapy for this population. Larger studies are warranted to analyze cost-effectiveness and clinical outcomes.

Disclosures

Kevin W. Garey, PharMD, MS, FASHP, Merck & Co. (Grant/Research Support, Scientific Research Study Investigator)

Factors associated with abnormal glucose readings in a pharmacy-led community health fair using the ADA risk assessment tool

OBJECTIVES

The objective of this study was to evaluate whether the American Diabetes Association (ADA) risk tool correctly identified high-risk patients with abnormal glucose readings requiring referral to a health care provider in an underserved population at a large student pharmacist-led health fair. In addition, the association of abnormal glucose readings compared with alternative ADA risk score cut point values and other collected variables was evaluated.

METHODS

This was a retrospective, cross-sectional study using deidentified data from a large student pharmacist-led health fair.

RESULTS

A total of 35 of 188 (19%) patients were considered high risk per the ADA risk tool, and 11 of those 35 (31%) had abnormal glucose results. After controlling for ADA risk score, no additional collected clinical variables were independently associated with abnormal glucose results. Although the ADA cut point associated with an abnormal glucose screening with the highest area under the curve was greater than or equal to 4, a cut point of 3 or greater resulted in a sensitivity of 91.2%.

CONCLUSION

The optimal method to identify patients who are at risk for an abnormal glucose screening is the ADA risk tool compared with the individual components of the tool or other evaluated risk factors. We suggest using an ADA risk cut point of greater than or equal to 3 instead of greater than or equal to 5 to identify patients likely to have abnormal glucose results in the health fair setting as this would greatly increase the chance of identifying patients who would need to be referred to their primary care provider for diagnostic testing.

Antibiotic utilization within 18 community hospitals in the United States: A 5-year analysis

BACKGROUND

Antibiotic overuse is associated with antibiotic resistance. We evaluated antibiotic utilization defined by days of therapy/1000 patient days (DOT/1000 PD) in various community hospitals across the United States.

METHODS

Community hospitals within the Cardinal Health Drug Cost Opportunity Analytics database were evaluated for the availability of DOT/1000 PD data between 2012 to 2016 for overall and specific antibiotic use and the following classes: narrow-spectrum β-lactams (ampicillin, nafcillin, oxacillin, cefazolin, and cephalexin), non-carbapenem antipseudomonal β-lactams (piperacillin/tazobactam, ceftazidime, and cefepime), carbapenems, anti-methicillin-resistant Staphylococcus aureus agents (vancomycin, linezolid, daptomycin, and tigecycline), and fluoroquinolones. Antibiotic utilization and change in utilization during the study period was calculated using linear regression (β coefficient).

RESULTS

Eighteen hospitals had antibiotic utilization data available. Hospitals were primarily urban (72%) with an average of 209 total beds and 22 intensive care unit beds. Mean number of pharmacists in these hospitals was nine with a mean pharmacist: bed ratio of 0.05. While all hospitals had antimicrobial stewardship programs established during the study period, only 78% and 22% had infectious diseases (ID) physician and ID pharmacist on staff, respectively. A decrease in antipseudomonal β-lactams (excluding carbapenems) and fluoroquinolones was observed (β coefficients = -1.2 and -2.6, respectively), all other antibiotic classes had increased utilization.

CONCLUSION

Overall antibiotic utilization increased over 5 years. The increase in narrow-spectrum β-lactams utilization along with the reduction in the use of antipseudomonal β-lactams and fluoroquinolones indicate appropriate antimicrobial stewardship. Institutional antibiotic utilization should be evaluated for appropriateness to limit the overuse of broad-spectrum antibiotics in an effort to reduce resistance development.

Assessment of Kidney Injury as a Severity Criteria for Clostridioides Difficile Infection

BACKGROUND

The Infectious Diseases Society of America (IDSA) and Society for Healthcare Epidemiology of America (SHEA) revised their Clostridioides difficile infection (CDI) severity classification criteria in 2017 to include an absolute serum creatinine (SCr) value above a threshold (≥1.5 mg/dL) rather than a relative increase from baseline (≥1.5 times the premorbid level). To date, how to best define kidney injury as a CDI disease severity marker has not been validated to assess severe outcomes associated with CDI.

METHODS

This multicenter cohort study included adult hospitalized patients with CDI. Patients were assessed for the presence of acute kidney injury (AKI), chronic kidney disease (CKD), and CDI severity using the 2010 and 2017 IDSA/SHEA CDI guidelines. Primary outcome was all-cause inpatient mortality.

RESULTS

The final study cohort consisted of 770 CDI episodes from 705 unique patients aged 65 ± 17 years (female, 54%; CKD, 36.5%; AKI, 29.6%). Eighty-two episodes (10.6%) showed discordant severity classification results due to the inclusion of more patients with preexisting CKD in the severe disease category using an absolute SCr threshold criterion. The absolute SCr criterion better correlated with all-cause mortality (odds ratio [OR], 4.04; 95% confidence interval [CI], 1.76-9.28; P = .001) than the relative increase in SCr (OR, 1.34; 95% CI, 0.62-2.89; P = .46). This corresponded to an increased likelihood of the 2017 CDI severity classification criteria to predict mortality (OR, 5.33; 95% CI, 1.81-15.72; P = .002) compared with the 2010 criteria (OR, 2.71; 95% CI, 1.16-6.32; P = .02).

CONCLUSIONS

Our findings support the 2017 IDSA/SHEA CDI severity classification criteria of a single pretreatment SCr in future CDI guideline updates.