840. Clinical Failure Rates Associated with Hemin-induced Metronidazole Resistance in Clostridioides difficile

Background

Current guidelines suggest limiting metronidazole (MTZ) use due to increased treatment failures in patients with Clostridioides difficile infections (CDI). We hypothesized that an increase in the minimum inhibitory concentration (MIC) of MTZ to C. difficile may contribute to these poor response rates. The objective of this study was to examine clinical response rates in patients with CDI based on MTZ MIC and stratified by receipt of MTZ treatment.

Methods

Clostridioides difficile-positive stool samples collected from 2017 to 2018 as part of routine care at two hospital systems in Houston, Texas were collected for MIC determination at 24 h to MTZ by broth microdilution following incorporation of 5 mg/L of hemin. The primary outcome was initial clinical success by Day 7 of treatment in those with MICs ≥1 vs. <1. Results were stratified based on receipt of MTZ within 48 hours of diagnosis. Study objectives were tested using χ 2 and multivariable logistic regression analyses.

Results

A total of 235 C. difficile samples were included, of which 73 (31%) had an MTZ MIC ≥1. Overall, 72% received MTZ within the first 48 hours. Clinical success rates differed based on disease severity (77% in nonsevere, 64% in severe/fulminant; P = 0.03) and infecting ribotype (52% in RT 027, 75% in non-RT 027; P = 0.014). In patients with MTZ receipt, clinical success rates were higher in patients infected with strains with an MTZ MIC < 1 (76%) compared with those with an MIC ≥1 (60%; P = 0.031). The difference in initial clinical success was not different in those that did not receive MTZ (78% for MIC <1 vs. 65% for MIC ≥1, P = 0.28). After controlling for disease severity, treatment failure was higher in patients infected with strains with an MTZ MIC ≥1 and treated with MTZ (OR 2.1; 95% CI, 1.01–4.35; P = 0.048) but not for those with an MIC ≥1 treated with other therapies (OR 1.9; 95% CI, 0.62–5.6; P = 0.27).

Conclusion

This study provides the first preliminary evidence of an association between reduced metronidazole susceptibility and decreased clinical success rates. Larger studies are warranted to validate these findings.

Disclosures

All Authors: No reported Disclosures.

2398. Effect of Eosinopenia and Binary Toxin on Clostridioides difficile Infection Clinical Outcomes

Background

The ability of Clostridioides difficile to cause clinical disease in humans is dependent on toxin production. Significantly fewer eosinophils are seen in the peripheral blood of mice infected with a binary toxin positive (CDT+) C. difficile strain. Furthermore, the presence of CDT and eosinopenia have separately been associated with increased mortality in humans with C. difficile infection (CDI). We hypothesized that CDI due to a CDT+ C. difficile strain accompanied by peripheral eosinopenia would be associated with higher odds of inpatient mortality.

Methods

This multicenter, retrospective cohort study included all patients ≥ 18 years of age with toxigenic CDI in which specimen ribotype data were available as part of our ongoing surveillance study. The cohort was stratified by eosinophil count (0.0 cells/μL vs. > 0.0 cells/μL). The primary outcome was inpatient mortality. A logistic regression model was developed modeling inpatient mortality as a function of the available patient covariates. All P-values were from 2-sided tests, and results were deemed statistically significant at P < 0.05.

Results

A total of 688 patients from 13 institutions in six cities were included. Of those, 132 had a baseline eosinophil count of 0.0 cells/µL and 556 had a baseline eosinophil count > 0.0 cells/µL. While the odds of inpatient mortality were higher among patients with eosinopenia and those infected with a CDT+ ribotype, the combination of these variables remained an independent predictor of inpatient mortality after adjusting for CCI score, WBC count, and serum albumin level (OR, 7.84; 95% CI, 1.85–33.20; P = 0.005).

Conclusion

This is the first attempt to study the in vivo relationship between CDT presence, human immune response, and CDI clinical outcome. We identified an association between CDT presence with concomitant eosinopenia and worsened CDI outcomes. Healthcare facilities should consider identifying this important subset of patients at the time of CDI diagnosis. Future CDI drug development might benefit from targeting C. difficile properties that impair host immune response, which may in turn decrease adverse clinical outcomes associated with this disease.

Disclosures

All authors: No reported disclosures.

LB7. A Randomized, Blinded, Placebo- and Vancomycin-Controlled, First-In-Human (FIH) Study of the Safety, Pharmacokinetics (PK), and Fecal Microbiome Effects of ACX-362E, a Novel Anti-Clostridial DNA Polymerase IIIC (polIIIC) Inhibitor

Background

ACX-362E, a novel DNA polIIIC inhibitor, is a narrow-spectrum antibacterial selectively active against certain Gram-positive bacteria, including Clostridioides difficile (MIC90 = 4 µg/mL). The objectives of this phase I study was to assess the safety, pharmacokinetics, and fecal microbiome effects of ACX-362E

Methods

This three-part FIH phase 1, double-blind, randomized healthy volunteer trial determined the safety profile, food effect, and systemic/stool pharmacokinetics of escalating single (150, 300, 600, and 900 mg) and multiple (300 and 450 mg) doses of oral ACX-362E vs. placebo (PBO). Fecal microbiome effects (metagenomic sequencing and qPCR) of multiple-dose ACX-362E were compared with 6 subjects receiving concomitant open-label vancomycin 125 mg four times daily. Dose escalation to each new cohort occurred following review of safety and PK data by a safety oversight committee.

Results

Forty-four subjects received ACX-362E (single dose = 24, multiple doses = 12, food effect = 8) and 12 PBO. Overall, ACX-362E was well tolerated at all dose levels. Adverse events were generally mild and transitory, and no moderate, severe, cumulative, or dose-limiting drug-related adverse events leading to discontinuation were observed. Mean plasma half-life was approximately 2 hours and no accumulation occurred with repeated dosing (Figure 1). Systemic exposure was less than 1 μg/mL and decreased with food. Fecal concentrations during multiple dosing exceeded the C. difficile MIC by multiples of up to ~2,500. ACX-362E had minimal effect on Bacteroidetes phylum and caused significantly less dysbiosis than vancomycin (Figure 2).

Conclusion

This FIH clinical trial with ACX-362E demonstrated a favorable safety profile, low systemic and high fecal concentrations, and favorable gut microbiome changes compared with vancomycin. These results shows promise for further clinical development to treat C. difficile infections.

Disclosures

Kevin W. Garey, MS, PharmD, Acurx (Grant/Research Support), Martin Kankam, MD, PhD, MPH, Acurx Pharmaceuticals, LLC (Research Grant or Support), Julie Mercier, BS, Acurx Pharmaceuticals, LLC (Research Grant or Support), Corinne Seng Yue, BPharm, MSc, PhD, Acurx Pharmaceuticals, LLC (Grant/Research Support), Murray Ducharme, PharmD, Acurx Pharmaceuticals, LLC (Grant/Research Support), Anne J. Gonzales-Luna, PharmD, no financial relationships or conflicts of interest, M Jahangir Alam, PhD, No financial relationships or conflicts of interest, Khurshida Begum, PhD, No financial relationships or conflicts of interest, Michael Silverman, MD, Acurx Pharmaceuticals, LLC (Consultant, Employee, Shareholder).

2382. Recurrent Clostridioides difficile Infection (CDI) Worsens Anxiety-Related Patient-Reported Quality of Life

Background

The Health-Related Quality of life (HR-QOL) instrument, the Cdiff32, allows studies on QOL changes associated with recurrent CDI. An ongoing real-world study of bezlotoxumab (BEZ) provided a unique opportunity to study anxiety-related HR-QOL in patients at high risk for recurrent CDI using the anxiety sub-domain of Cdiff32. The aims of this study were to assess baseline anxiety-related HR-QOL based on the number of prior episodes of CDI and to evaluate changes in patients with or without recurrence.

Methods

Patients at high risk for recurrent CDI given BEZ were administered the anxiety sub-domain questions of the Cdiff32 prior to infusion and at approximately 90 days after administration (0 = worst anxiety; 100 = no anxiety). The number of prior episodes of CDI were collected, along with demographics and co-morbid conditions. Patients were followed for 90 days for CDI recurrence, which was defined as new onset of diarrhea requiring CDI-active antibiotics.

Results

There were 107 patients evaluated, aged 68 ± 14 years (mean ± SD) with multiple co-morbid conditions (mean Charlson: 4 ± 3) and multiple previous CDI episodes (3 ± 1 episodes). Fourteen patients (13%) experienced a further CDI recurrence within 90 days following BEZ. Overall, baseline anxiety HR-QOL was 29 ± 22. Risk factors for lower baseline anxiety-related HR-QOL included immunocompromised conditions (P < 0.046) and receipt of a proton pump inhibitor (P < 0.018). Compared with patients with primary CDI disease (Score: 35 ± 20), baseline anxiety HR-QOL was worse with subsequent prior recurrences (Score: 26 ± 23) for CDI episodes 2–4, and then improved for subsequent episodes (Score: 38 ± 22). Anxiety-related HR-QOL improved by a mean of 32 ± 25 points compared with patients that experienced a further recurrence where HR-QOL declined (P < 0.0001). Results were confirmed in a multivariate model controlling for Charlson score and chronic renal failure.

Conclusion

Poor anxiety-related HR-QOL was observed at baseline in all patients regardless of number of prior episodes. QOL improved 90 days after BEZ infusion in patients without further recurrences of CDIs and worsened in patients with a subsequent recurrence.

Disclosures

All authors: No reported disclosures.

2235. Fecal Biomarkers for Clostridioides difficile Infection in Cancer Patients

Background

The diagnosis of C. difficile infection (CDI) relies on using a nucleic acid amplification test (NAAT) followed by confirmatory toxin enzyme immunoassay (EIA). This study examined the utility of fecal biomarkers and C. difficile bacterial quantity (BQ) in differentiating patients with true infection (NAAT+/EIA+) from patients with colonization (NAAT+/EIA-) in the context of C. difficile ribotypes.

Methods

We studied 136 patients with diarrhea and CDI identified by NAAT in stools for which a confirmatory toxin A, B, EIA was performed. Fecal IL-8, IL-1β, calprotectin, and lactoferrin were studied by ELISA. C. difficile BQ was determined by 16S rRNA qPCR. Data were stratified according to cancer diagnosis into three groups [hematologic (H) n = 43, solid tumor (ST) n = 62, or stem cell transplant (SCT) n = 31].

Results

Stools were EIA+ in 36/136 (26%) of the cohort. Although ST patients had a higher Charlson co-morbidity index when compared with the other two groups (P < 0.002), demographic characteristics and symptoms at the time of presentation were similar between groups regardless of EIA status. Most common ribotypes identified included F106 and F014-020. Ribotype distribution differed according to oncologic diagnosis as determined by the Shannon diversity index. There were fewer distinct C. difficile ribotypes in the SCT (n = 8) vs. ST (n = 15) and H (n = 15) groups (P < 0.001 and P < 0.002, respectively). BQ were higher in EIA+ than EIA- across all strata (log of BQ/mg 2.38 ± 1.49 vs. 0.92 ± 1.28, P > 0.001). Similarly, higher levels of fecal IL-8 (1.72 ± 1.9 vs. 0.83 ± 1.6 ng/mL), IL-1β (3.74 ± 13.7 vs.. 1.21 ± 4.6) and calprotectin (14.9 ± 27 vs. 6 ±1.8 ug/mL) levels were seen in EIA+ patients. While IL-8, IL-1β, and calprotectin were increased in EIA+ ST and H, no differences were seen in the SCT group. A sensitivity analysis using ROC curves, revealed that BQ resulted in a greater area under the curve than fecal markers of inflammation (A = 0.77, P < 0.001, 95% CI [0.67–0.86]).

Conclusion

In this study in cancer and immunocompromised patients, C. difficile bacterial burden regardless of infecting ribotype and fecal cytokines showed to be a helpful assay in distinguishing true CDI from colonization.

Disclosures

All authors: No reported disclosures.

2580. Serial Microbiome Analysis in a Patient with Multiple Failed Fecal Microbiome Transplantations

Background

Fecal microbiota transplantation (FMT) is recommended to treat refractory or recurrent cases of Clostridioides difficile infection (CDI) through restoration of a healthy intestinal microbiome. The procedure has reported success rates of 90% or higher for CDI, but several risk factors for FMT failure have been identified. Here we present a case of a patient failing four FMT procedures over a 2-year period, with accompanying microbiome and metagenomic analyses.

Methods

Seven serial C. difficile-positive stool samples were collected as part of an ongoing surveillance system in Texas. Samples, including the index case, represented independent CDI episodes interspersed between four separate FMT procedures between 2016 and 2018. PCR ribotype (RT) testing, 16S rRNA gene sequencing, MIC testing, multidrug-resistant organism (MDRO) screening, and shotgun metagenome sequencing were conducted for each of the samples.

Results

The patient was a 42-year-old female with various comorbidities, including systemic lupus erythematosus. She received continuous non-CDI antibiotic courses throughout her CDI therapy for a variety of infections. The vancomycin MICs in infecting C. difficile strains increased with cumulative vancomycin exposure. Multidrug-resistant organisms were detected in stool, including Enterococcus spp., MRSA, and Candida glabrata. The first five of the seven strains were RT 078–126, one was mixed RT 002 and RT 054, and one was RT 002. The analysis of 16S rRNA gene sequences demonstrated that microbial diversity was never restored after FMT procedures. A strong correlation between microbial and functional gene compositions suggests that fecal samples share many microbial species with associated functional genes.

Conclusion

A number of systems biology changes were observed in a patient with persistent CDI despite multiple FMTs. The lack of FMT engraftment was most likely due to continuous broad-spectrum antibiotic exposure in an immunocompromised patient.

Disclosures

All authors: No reported disclosures.

2410. Molecular Characteristics of Environmental Clostridioides difficile From a Large Texas Hospital

Background

Clostridioides difficile is an anaerobic spore-forming, toxin-producing Gram-positive bacillus listed by the CDC as an “urgent threat” pathogen. Epidemiologic studies using whole-genome sequencing (WGS) have found that genetically distinct lineages infections occur in hospitalized patients, in addition to the fact that C. difficile spores persist on hospital surfaces after disinfection. The purposes of this study were to isolate and characterize C. difficile from the environment of a large Texas hospital.

Methods

We collected 330 swab samples of hospital environmental surfaces using sterile cotton gauze. The samples were then anaerobically enriched in brain heart infusion broth for 48–72 hours and plated onto cycloserine–cefoxitin fructose agar (CCFA). Suspected colonies were then genetically characterized using PCR (for tcdA, tcdB, cdtA, cdtB and tpi genes) and genotyped using fluorescent PCR ribotyping techniques.

Results

A total of 90/330 (27.3%) environmental samples were culture positive for C. difficile, of which 75/90 (82.1%) tested were toxigenic C. difficile by the presence of tcdA, tcdB, cdtA or cdtB. A total of 16 distinct ribotypes were identified from 41 C. difficile isolates tested using a fluorescent-ribotyping method. The predominant ribotypes isolated were F078–126 (8/41), F002 (5/41), F106 (4/41), F255 (4/41), and F014-020 (3/41).

Conclusion

We found a diversity of C. difficile strain types in various hospital high-touch surface environment in addition to ribotype F027 and F078, suggesting the hospital environment a reservoir and significant source C. difficile infections.

Disclosures

All authors: No reported disclosures.

2378. Corticosteroid Use Prevents Primary Clostridioides difficile Infection in the Setting of Broad-Spectrum Antibiotic Use Among Hospitalized Patients

Background

Clostridioides difficile is the most common pathogen causing healthcare-associated infections in the United States and a Centers for Disease Control and Prevention urgent threat-level pathogen. The pathophysiology of C. difficile infection (CDI) involves neutrophil invasion of the colon associated with an inflammatory response. Previous case–control studies investigating an anti-inflammatory corticosteroid (CS) effect on CDI risk demonstrated conflicting results but were unable to control for antibiotic use. We hypothesized that CS use would decrease the risk of CDI in a well-matched, high-risk population.

Methods

This nested case–control study included hospitalized patients admitted to a single quaternary care hospital in the Texas Medical Center. The case population included adults who were diagnosed with CDI and received at least one dose of an antibiotic of interest (piperacillin–tazobactam, cefepime, or meropenem) in the 90 days prior to CDI diagnosis. The control population included hospitalized adults who received one of the same antibiotics during their hospital stay but did not develop CDI in the 90 days following their first dose. Patients were excluded if they had a documented history of CDI. CS use was defined as ≥ 20 mg prednisone or equivalent administered in the 48 hours prior to CDI diagnosis (cases) or antibiotic start (controls). The primary study outcome was the development of CDI. A logistic regression model was developed modeling CDI diagnosis as a function of available patient covariates.

Results

A total of 321 patients met the inclusion criteria; 56 patients had a history of CDI, leaving a final study cohort of 265 patients (104 cases and 161 controls). Antibiotic days of therapy were significantly higher in the control group (8 vs. 6 days; P = 0.02). The odds of CDI diagnosis were lower among patients administered CS (OR, 0.17; 95% CI, 0.08–0.38; P < 0.001), which remained protective in the multivariable model after adjusting for age, gender, and invasive GI surgery within 6 months.

Conclusion

We observed an association between CS use and decreased risk of developing primary CDI in hospitalized patients receiving broad-spectrum antibiotics. Future studies are needed to delineate the dose and duration of CS needed to realize this effect.

Disclosures

All authors: No reported disclosures.

2402. Clinical Outcomes Associated with an Emerging Clostridioides difficile Ribotype 255 in Texas

Background

PCR ribotyping of Clostridioides difficile strains is commonly used to describe the epidemiology of C. difficile infection (CDI). Certain ribotypes (RT) have been associated with more severe disease and clinical outcomes, such as RT 027, while others are considered less virulent, such as RT 014-020. Texas statewide surveillance identified the emergence of a rarely-described RT 255 beginning in 2015, which now represents the fifth most common ribotype across the state. Here we describe clinical outcomes associated with an emergent RT 255 in Texas.

Methods

A retrospective cohort study was conducted including patients from two tertiary care centers in Houston, Texas. Patients infected with C. difficile strains of either RT 255, 014-020, or 027 between 2016–18 were included. The primary outcome was disease severity as classified by the 2017 IDSA guidelines. Multivariable logistic regression analysis was done to control for other patient factors. Results were significant at P < 0.05, and all statistical analyses were completed using SPSS, version 25.

Results

A total of 150 patients were included (50 patients infected with each RT). Overall, 53% of the patients had severe or fulminant disease most commonly due to RT 027 (80%) followed by RT 014-020 (40%) and RT 255 (38%). Patients infected with RT 255 or 014-020 had a 75% relative reduction in the odds of severe disease compared with RT 027 after controlling for patient age and serum albumin level (OR, 0.25; 95% CI, 0.86–0.74; P = 0.12;). No differences were seen in the rates of 30- or 90-day recurrence between RTs.

Conclusion

Although RT 255 is becoming increasingly common across Texas, it does not appear to be associated with more severe disease when compared with other common ribotypes. Further studies are warranted to determine contributing factors for its increasing prevalence.

Disclosures

All authors: No reported disclosures.

2581. An Invertebrate Model to Study Gut Microbiome Dysbiosis

Background

Antimicrobials disrupt the gut microbiota by reducing gut microbiome diversity and quantity. Galleria mellonella provides an invertebrate model that is inexpensive, easy to maintain, and does not require specialized equipment. This study investigated the feasibility of using G. mellonella as an in vivo model to evaluate the effect of different antimicrobials on gut microbiota.

Methods

To determine baseline gut microbiota composition, the gut contents of G. mellonella were extracted and genomic DNA underwent shotgun meta-genomic sequencing. To determine the effect of infection and antibiotic use, 30 larvae were injected (left proleg) with ~1 × 105 colony-forming unit (cfu) of methicillin-resistant Staphylococcus aureus (MRSA) and were randomized 1:1:1 to treatment with vancomycin (20 mg/kg) or a natural antimicrobial (Nigella sativa seed oil, 70 mg/kg; NS oil), or a combination. The larvae were kept at 37°C post-infection and monitored daily for 72 hours for activity, extent of cocoon formation/growth, melanization, and survival. Two larvae from each group were randomly selected and homogenized with PBS as controls. After 24 hours of incubation, gut contents were extracted and plated for MRSA and Enterococcus cfu counts.

Results

Metagenomics analysis showed the gut microbiota composition of G. mellonella larvae was dominated by a subset of closely-related Enterococcus species. After 24 hours of exposure, mean Enterococcus counts were 4 × 103 cfu in the vancomycin arm and 6.2 × 104 cfu in the NS oil arm. Mean MRSA counts were 3.3 × 105 cfu in vancomycin arm and 1.5 × 104 cfu in NS oil arm. The combination of vancomycin and NS oil had higher Enterococcus counts than the vancomycin alone arm (6.3 × 104 cfu vs. 4 × 103 cfu, respectively), suggesting that NS oil may have a role in protecting the gut microbiota.

Conclusion

This study provides preliminary evidence to support the potential use of G. mellonella to assess the in vivo effect of a natural and synthetic antimicrobial on the gut microbiota.

Disclosures

All authors: No reported disclosures.

2248. Clinical and Microbiological Outcomes Associated with Real-World Use of Ceftolozane/Tazobactam

Background

Ceftolozane/tazobactam (C/T) is a novel cephalosporin/β-lactamase inhibitor combination for treating Gram-negative infections, particularly Pseudomonas aeruginosa (PA). C/T has been FDA-approved for complicated intra-abdominal and urinary tract infections and has just completed a trial in ventilator nosocomial pneumonia, but real-world outcome data are still emerging.

Methods

Demographic, microbiologic, treatment and outcome data of patients who received C/T for ≥48 hours from January 2016 to August 2018 at multiple centers within a single hospital system were retrospectively collected. Available isolates were analyzed for C/T susceptibility (by Etest) and whole-genome sequencing (WGS). Spades v.3.11.1 was used for assembly, multi-locus sequence typing v2.10 performed for in silico MLST with the PubMLST database and Abricate v0.7 was used for resistance gene screening with the CARD database.

Results

Among 45 patients, 58% were non-white, 53% were female and 13% were immunocompromised. The median age was 64 years (IQR, 50 to 69). At the time of the index event, a high proportion of patients required ICU care (42%) and pressor support (13%) as well as had invasive devices in place (64%). A minority (2.4%) had prior exposure to C/T. Respiratory infections were most common (38%) followed by urinary tract (20%). Concomitant Gram-negative agents were used in 18%. 69% achieved clinical success (i.e., recovery from infection-related signs and symptoms). The in-hospital mortality rate was 16% of which 5 out of 7 were attributed to infection. Microbiology was available for 91% of patients; 84% had PA isolates resistant to at least 3 antipseudomonal classes (Figures 1 and 2). Ten PA isolates were analyzed with WGS (Table 1). C/T resistance arose during therapy in one patient (MIC increase from 1 to 128 µg/mL). WGS showed a substitution in AmpC β-lactamase (A46D) and presence of bla_CARB-2.

Conclusion

Although C/T was used in a critically ill population with highly resistant organisms, cure rates were high and mortality was low. Acquired β-lactamases were not frequently seen among the PA isolates. C/T is a vital therapeutic option, particularly on MDR isolates for which options are limited.

Disclosures

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

Combating resistance while maintaining innovation: the future of antimicrobial stewardship

Antimicrobial resistance represents a significant global health threat. However, a commercial model that does not offer a return on investment resulting in a lack of investment in antibiotic R&D, means that the current pipeline of antibiotics lacks sufficient innovation to meet this challenge. Those responsible for defining, promoting and monitoring the rationale use of antibiotics (the antimicrobial stewardship programme) are key to addressing current shortcomings. In this personal perspective, we discuss the future role stewardship can play in stimulating innovation, a need to move away from a pharmacy budget dominated view of antibiotic use, and the impact of the ever-increasing sophistication and interdisciplinary nature of antimicrobial control programs. Changes are needed to optimize clinical outcomes for patients.

Economic health care costs of blood culture contamination: A systematic review

BACKGROUND

Blood culture contamination with gram-positive organisms is a common occurrence in patients suspected of bloodstream infections, especially in emergency departments. Although numerous research studies have investigated the cost implications of blood culture contamination, a contemporary systematic review of the literature has not been performed. The aim of this project was to perform a systematic review of the published literature on the economic costs of blood culture contamination.

METHODS

PubMed was searched (January 1, 1978, to July 15, 2018) using the search terms "blood culture contamination" or "false-positive blood cultures." Articles were title searched and abstracts were reviewed for eligible articles that reported immediate or downstream economic costs of blood culture contamination.

RESULTS AND DISCUSSION

The PubMed search identified 151 relevant articles by title search, with 49 articles included after abstract review. From the studies included, overall blood culture contamination rates ranged from 0.9%-41%. Up to 59% of patients received unnecessary treatment with parenteral vancomycin as a result of blood culture contamination, resulting in increased pharmacy charges between $210 and $12,611 per patient. Increases in total laboratory charges between $2,397 and $11,152 per patient were reported. Attributable hospital length of stay increases due to blood culture contamination ranged from 1-22 days.

CONCLUSIONS

This systematic review of the literature identified several areas of health care expenditure associated with blood culture contamination. Interventions to reduce the risk of blood culture contamination would avoid downstream economic costs.

Molecular epidemiology of toxigenic Clostridioides difficile isolates from hospitalized patients and the hospital environment in Dhaka, Bangladesh

Epidemiology of Clostridioides difficile (syn. Clostridium difficile) infection (CDI) in Bangladesh is poorly understood. This study assessed the epidemiology of CDI in hospitalized patients and hospital environmental contamination of toxigenic C. difficile at two large urban Bangladesh hospitals. This 12-month prospective observational cohort study collected stool samples from adults with diarrhea and recent antimicrobial exposure during 2017. Environmental samples were collected by swabbing surfaces of hospital common areas. Samples underwent toxigenic culture. C. difficile isolates were tested for toxins A and B and PCR-ribotyped. Of 208 stool samples, 18 (8.7%) were positive for toxigenic C. difficile. Of 400 environmental samples, 45 (11%) were positive for toxigenic C. difficile. Ribotypes present in ≥10% of stool isolates were 017 (38%), 053-163 (13%), and a novel ribotype (FP435 [13%]). Common ribotypes in environmental isolates were 017 (22%), 053-163 (11%), 106 (24%). This is the first report describing current epidemiology of CDI in at risk hospitalized adult patients in Bangladesh.

Bifidobacterium dentium Fortifies the Intestinal Mucus Layer via Autophagy and Calcium Signaling Pathways

Much remains unknown about how the intestinal microbiome interfaces with the protective intestinal mucus layer. Bifidobacterium species colonize the intestinal mucus layer and can modulate mucus production by goblet cells. However, select Bifidobacterium strains can also degrade protective glycans on mucin proteins. We hypothesized that the human-derived species Bifidobacterium dentium would increase intestinal mucus synthesis and expulsion, without extensive degradation of mucin glycans. In silico data revealed that B. dentium lacked the enzymes necessary to extensively degrade mucin glycans. This finding was confirmed by demonstrating that B. dentium could not use naive mucin glycans as primary carbon sources in vitro To examine B. dentium mucus modulation in vivo, Swiss Webster germfree mice were monoassociated with live or heat-killed B. dentium Live B. dentium-monoassociated mice exhibited increased colonic expression of goblet cell markers Krüppel-like factor 4 (Klf4), Trefoil factor 3 (Tff3), Relm-β, Muc2, and several glycosyltransferases compared to both heat-killed B. dentium and germfree counterparts. Likewise, live B. dentium-monoassociated colon had increased acidic mucin-filled goblet cells, as denoted by Periodic Acid-Schiff-Alcian Blue (PAS-AB) staining and MUC2 immunostaining. In vitro, B. dentium-secreted products, including acetate, were able to increase MUC2 levels in T84 cells. We also identified that B. dentium-secreted products, such as γ-aminobutyric acid (GABA), stimulated autophagy-mediated calcium signaling and MUC2 release. This work illustrates that B. dentium is capable of enhancing the intestinal mucus layer and goblet cell function via upregulation of gene expression and autophagy signaling pathways, with a net increase in mucin production.IMPORTANCE Microbe-host interactions in the intestine occur along the mucus-covered epithelium. In the gastrointestinal tract, mucus is composed of glycan-covered proteins, or mucins, which are secreted by goblet cells to form a protective gel-like structure above the epithelium. Low levels of mucin or alterations in mucin glycans are associated with inflammation and colitis in mice and humans. Although current literature links microbes to the modulation of goblet cells and mucins, the molecular pathways involved are not yet fully understood. Using a combination of gnotobiotic mice and mucus-secreting cell lines, we have identified a human-derived microbe, Bifidobacterium dentium, which adheres to intestinal mucus and secretes metabolites that upregulate the major mucin MUC2 and modulate goblet cell function. Unlike other Bifidobacterium species, B. dentium does not extensively degrade mucin glycans and cannot grow on mucin alone. This work points to the potential of using B. dentium and similar mucin-friendly microbes as therapeutic agents for intestinal disorders with disruptions in the mucus barrier.

Characterization of Clostridioides difficile ribotypes in domestic dogs in Rio de Janeiro, Brazil

Clostridioides difficile is the major etiologic agent of nosocomial bacterial diarrhoea and pseudomembranous colitis. The pathogenesis of C. difficile infection (CDI)involves two cytotoxic enzymes (TcdA, TcdB) that cause colonic epithelial damage, fluid accumulation and enteritis. CDI has been demonstrated in a variety of animal species and some reports have recently raised the importance of wild animals as a reservoir of this pathogen and possible transmission to humans and domestic animals. The aim of this study was to characterize C. difficile isolates obtained from pet dogs in Rio de Janeiro, Brazil. A total of 50 faecal samples were obtained from healthy and diarrheic dogs. Five of fifty samples (10%) grew C. difficile. Of those, three belonged to the PCR ribotype 106 (ST 42) and were toxigenic (A⁺B⁺). The other two strains belonged to the PCR ribotype 010 (ST 15) and were not toxin producers (A^-B^-). None of the isolates tested positive for the binary toxin genes. Considering the antimicrobial resistance patterns of all isolates using EUCAST breakpoints, all strains were sensitive to metronidazole and vancomycin. However, two strains (ribotype 106 and ribotype 010), were resistant to clindamycin (≤256 μg/mL). All strains were strong biofilm producers. Our study provides evidence that dogs can act as reservoirs for C. difficile epidemic ribotypes.

Molecular epidemiology of Clostridioides difficile in domestic dogs and zoo animals

Animals such as domestic dogs and zoo animals reside in close proximity to humans and could contribute to the dissemination of Clostridioides difficile spores which are common in the community environment. The purpose of this study was to assess C. difficile colonization in domestic dogs attending a day boarding facility and zoo animals receiving systemic antibiotics. Stool samples and paw swabs were collected from dogs who attended a day boarding facility. Stool samples were also collected from zoo animals starting systemic antibiotics. Finally, environmental samples were collected from nearby public parks. Stool samples and swabs were incubated anaerobically in enrichment broth for C. difficile growth, PCR was done to confirm presence of toxin genes, and PCR ribotyping was performed for strain characterization. During the study period, 136 dog stool samples were obtained, the paws of 16 dogs were swabbed, and 250 environmental swabs from surrounding public parks were obtained. Twenty-three of 136 dog stool samples (17%) and 9 of 16 dog paws sampled (56%) grew toxigenic C. difficile. One hundred and four stool samples from 49 zoo animals were collected of which 19 (18%) grew toxigenic C. difficile. Rates of toxigenic C. difficile colonization increased significantly during antibiotic therapy (33%) and then returned to baseline during the follow-up (11%) period (p = 0.019). Fifty-five of 250 environmental swabs from public parks (22%) grew toxigenic C. difficile. Ribotypes associated with human disease including 106 and 014-020 were isolated from all sources. This study demonstrated a high rate of toxigenic C. difficile colonization in domestic dogs and zoo animals with ribotypes similar to those causing human disease. These results demonstrate the relationship between humans, animals, and the environment in the dissemination of spores.

Ridinilazole for the treatment of Clostridioides difficile infection

INTRODUCTION

Ridinilazole is a novel antibiotic being developed for the treatment of Clostridioides difficile infection (CDI). Ridinilazole has completed two phase II trials and phase III trials which are denoted Ri-CoDIFy 1 and 2, are planned (ClinicalTrials.gov identifiers: NCT03595553 and NCT03595566). Areas covered: This article covers the chemistry, mechanism of action, in vitro microbiology versus C. difficile and host microbiota, pre-clinical and clinical efficacy, pharmacokinetics, pharmacodynamics and safety and tolerability of ridinilazole. Expert opinion: Ridinilazole is a novel antibiotic with ideal properties for the treatment of CDI. Given the promising results from the phase II clinical trial, ridinilazole may have the capability to lower the risk for CDI recurrence thus improving sustained clinical response rates - a current unmet medical need. Assuming a positive phase III trial, ridinilazole will enter a market with heightened awareness on the importance of prevention of CDI. This along with further research into the economic consequences and decreased patient quality of life associated with recurrent CDI, should provide clinicians with further evidence for the need for therapy that limits CDI recurrence and improves sustained clinical cure.

Epidemic Clostridioides difficile Ribotype 027 Lineages: Comparisons of Texas Versus Worldwide Strains

Background

The epidemic Clostridioides difficile ribotype 027 strain resulted from the dissemination of 2 separate fluoroquinolone-resistant lineages: FQR1 and FQR2. Both lineages were reported to originate in North America; however, confirmatory large-scale investigations of C difficile ribotype 027 epidemiology using whole genome sequencing has not been undertaken in the United States.

Methods

Whole genome sequencing and single-nucleotide polymorphism (SNP) analysis was performed on 76 clinical ribotype 027 isolates obtained from hospitalized patients in Texas with C difficile infection and compared with 32 previously sequenced worldwide strains. Maximum-likelihood phylogeny based on a set of core genome SNPs was used to construct phylogenetic trees investigating strain macro- and microevolution. Bayesian phylogenetic and phylogeographic analyses were used to incorporate temporal and geographic variables with the SNP strain analysis.

Results

Whole genome sequence analysis identified 2841 SNPs including 900 nonsynonymous mutations, 1404 synonymous substitutions, and 537 intergenic changes. Phylogenetic analysis separated the strains into 2 prominent groups, which grossly differed by 28 SNPs: the FQR1 and FQR2 lineages. Five isolates were identified as pre-epidemic strains. Phylogeny demonstrated unique clustering and resistance genes in Texas strains indicating that spatiotemporal bias has defined the microevolution of ribotype 027 genetics.

Conclusions

Clostridioides difficile ribotype 027 lineages emerged earlier than previously reported, coinciding with increased use of fluoroquinolones. Both FQR1 and FQR2 ribotype 027 epidemic lineages are present in Texas, but they have evolved geographically to represent region-specific public health threats.

Estimated Clinical and Economic Impact through Use of a Novel Blood Collection Device To Reduce Blood Culture Contamination in the Emergency Department: a Cost-Benefit Analysis

Blood culture contamination results in increased hospital costs and exposure to antimicrobials. We evaluated the potential clinical and economic benefits of an initial specimen diversion device (ISDD) when routinely utilized for blood culture collection in the emergency department (ED) of a quaternary care medical center. A decision analysis model was created to identify the cost benefit of the use of the ISDD device in the ED. Probabilistic costs were determined from the published literature and the direct observation of pharmacy/microbiology staff. The primary outcome was the expected per-patient cost savings (microbiology, pharmacy, and indirect hospital costs) with the routine use of an ISDD from a hospital perspective. The indirect costs included those related to an increased hospital length of stay, additional procedures, adverse drug reactions, and hospital-acquired infections. Models were created to represent hospitals that routinely or do not routinely use rapid diagnostic tests (RDT) on positive blood cultures. The routine implementation of ISDD for blood culture collection in the ED was cost beneficial compared to conventional blood culture collection methods. When implemented in a hospital utilizing RDT with a baseline contamination rate of 6%, ISDD use was associated with a cost savings of $272 (3%) per blood culture in terms of overall hospital costs and $28 (5.4%) in direct-only costs. The main drivers of cost were baseline contamination rates and the duration of antibiotics given to patients with negative blood cultures. These findings support the routine use of ISDD during blood culture collection in the ED as a cost-beneficial strategy to reduce the clinical and economic impact of blood culture contamination in terms of microbiology, pharmacy, and wider indirect hospital impacts.

471. Prevalence and Characteristics of Clostridioides difficile Infection in Bangladesh

Background

The estimated prevalence of Clostridioides difficile infection (CDI) in several South Asian countries is 10.5%, similar to that in North America and Europe. However, the epidemiology of CDI in Bangladesh is unknown. We aimed to assess the prevalence of CDI and assess hospital environmental contamination of toxigenic C. difficile in Bangladesh.

Methods

This was a prospective observational cohort study at two large tertiary care centers in Dhaka, Bangladesh, conducted from January 2017 to December 2017. Stool samples were collected from hospitalized adults with diarrhea (≥3 loose stools in a 24-hour period) and antimicrobial exposure within the past 30 days. Hospital environmental samples were collected by swabbing surfaces of common areas in the hospital. All samples underwent toxigenic culture. C. difficile isolates were tested for toxins A and B and PCR-ribotyped.

Results

Of 204 stool samples collected, 16 (7.8%) were positive for toxigenic C. difficile. Patients with CDI shared a room with significantly more patients (Table 1). Of 392 environmental samples, 48 (12.2%) were positive for toxigenic C. difficile, which was more common in patient care vs. nonpatient care areas (14.4% vs. 7.8%, P = 0.057). Twelve clinical stool isolates and 42 environmental isolates were ribotyped. Ribotypes identified in stool isolates were F017 (50%), FP053-163 (17%), FP435 (17%), F106 (8%), and F014-020 (8%). With the exception of FP435, these were also the most common ribotypes in environmental isolates: F017 (24%), FP053-163 (12%), F106 (26%), and F014-020 (10%).

Conclusion

For the first time, we report the prevalence of CDI and ribotypes in at risk patients in Bangladesh. Rates and ribotypes are similar to other resource-rich or resource-limited countries.

Disclosures

K. W. Garey, Merck & Co.: Grant Investigator, Grant recipient.

510. First Environmental Investigation of Toxigenic Clostridium difficile Strains in Texas Hospitals

Background

Clostridium difficile is the most common cause of infectious diarrhea in hospitalized patients in the developed world and an emerging pathogen in developing countries due to increased use of broad-spectrum antibiotics worldwide. Spores of toxigenic C. difficile can survive and disseminate in any environs and act as sources for human colonization or infections. Although likely ubiquitous in any environs, the prevalence of C. difficile spores in the hospital environment of Texas hospitals is poorly understood. The objectives of the study are to isolate and characterize C. difficile from the hospital environs of three hospitals in three cities in Texas.

Methods

As part of a Texas hospital-wide surveillance effort, we collected shoe-bottom swabs samples from hospital employees, patients, and visitors inside three large hospital from three cities. Samples were analyzed for C. difficile using anaerobic enrichment culture and molecular methods. Suspected colonies from cycloserine cefoxitin fructose agar (CCFA) plates were identified by PCR (tcdA, tcdB, cdtA, cdtB, tpi) and genotyped using fluorescent PCR ribotyping.

Results

A total 229 of 1079 (21.2%) surface swab and 81 of 121 (66.9%) shoe swab samples were culture positive for toxigenic C. difficile (tcdA and tcdB). A total of 29 distinct ribotypes were identified from 166 C. difficile isolates tested. Predominant ribotypes were F106, F019, F014-020, F002, and F255. Interestingly, ribotype F027 was not a predominant strain among the swab samples. Each hospital had widely diverse strains. Shoes were the most contaminated item in all the hospitals.

Conclusion

We identified a high prevalence of toxigenic C. difficile with diverse ribotypes from hospital environmental shoe-bottom swabs and high touch surface swabs in hospitals in three cities of Texas. Our findings suggest that patients might be at higher risk for C. difficile colonization or infection in these hospitals.

Disclosures

K. W. Garey, Merck & Co.: Grant Investigator, Grant recipient.

501. Evaluation of Bezlotoxumab in Prevention of Recurrent C. difficile Infection: A Multicenter Single-Arm Study in Outpatient Infusion Centers

Background

Bezlotoxumab (BEZ) was approved in October 2016 for the prevention of recurrent C. difficile (rCDI) infection in patients receiving standard-of-care (SoC) antibiotic therapy for active CDI who are at high risk for CDI recurrence. Presently, there are little real-world data on recurrence rates and factors associated with recurrence in patients receiving BEZ. This study describes characteristics of patients receiving BEZ in US Outpatient Infusion Centers (OICs) and analyzes subsequent CDI recurrences.

Methods

Medical records from 24 OICs were retrospectively reviewed of all patients treated with BEZ through December 2017. Data collected included demographics, comorbidities, and all therapy parameters, including SoC antibiotic therapy. Risk factors for rCDI were assessed and included age, immunocompromised status, prior number of CDI episodes, use of gastric acid suppressants, inflammatory bowel disease (IBD), and history of fecal microbiota transplant (FMT). rCDI, defined as diarrhea lasting ≥2 days with treatment for CDI with or without a positive stool test for toxigenic C. difficile, was assessed through a follow-up visit or phone call 90 days post BEZ administration. Risk factors for rCDI were evaluated using Student’s t-test and Pearson χ² test.

Results

Eighty patients received BEZ (10 mg/kg) with 78 available for follow-up evaluation for rCDI ≥90 days post treatment. Mean age was 65 ± 16 years with 51% female. Mean number of CDI episodes were 3 ± 1 with a mean Charlson score of 4 ± 3. SoC antibiotics included vancomycin (66% of patients) with 41% on long-term taper, fidaxomicin (33% of patients), and metronidazole (25% of patients). Nineteen (24%) patients received more than one SoC antibiotic during their treatment course, most commonly with metronidazole and another SoC antibiotic. Of the 78 patients with follow-up data, 17 (22%) developed rCDI with a mean time to recurrence of 33 ± 22 days. Risk factors for rCDI are shown in the table. The use of BEZ earlier in the disease course (first or second CDI episode) was associated with a decreased risk of rCDI (OR: 0.21 95% CI: 0.04–0.98; P = 0.033).

Conclusion

In highly comorbid patients with recurrent C. difficile infection, bezlotoxumab use was effective in prevention of recurrence at 90 days and consistent with that of the randomized trials.

Disclosures

R. L. Hengel, Merck & Co.: Scientific Advisor, Consulting fee. T. E. Ritter, Merck & Co.: Scientific Advisor, Consulting fee. R. V. Nathan, Merck & Co.: Scientific Advisor and Speaker’s Bureau, Consulting fee and Speaker honorarium. The Medicines Company: Speaker’s Bureau, Speaker honorarium. Allergan: Speaker’s Bureau, Speaker honorarium. L. J. Van Anglen, Merck & Co.: Grant Investigator, Research grant. S. Marcella, Merck & Co.: Employee and Shareholder, Salary. K. W. Garey, Merck & Co.: Grant Investigator, Grant recipient.

240. Estimated Clinical and Economic Impact Through Use of an Initial Specimen Diversion Device to Reduce Blood Culture Contamination: A Cost–benefit Analysis

Background

Methods

Results

Conclusion

Disclosures