Comparison of Risk Stratification Approaches to Identify Patients with Clostridioides difficile Infection at Risk for Multidrug-Resistant Organism Gut Microbiota Colonization

INTRODUCTION

Multidrug-resistant organisms (MDRO) commonly colonize the gut microbiota of patients with Clostridioides difficile infection (CDI). This increases the likelihood of systemic infections with these MDROs. To help guide MDRO screening and/or empiric antibiotic therapy, we derived and compared predictive indices for MDRO gut colonization in patients with CDI.

METHODS

This was a multicenter, retrospective cohort study of adult patients with CDI from July 2017 to April 2018. Stool samples were screened for MDRO via growth and speciation on selective antibiotic media and confirmed using resistance gene polymerase chain reaction. A regression-based risk score for MDRO colonization was constructed. Predictive performance via area under the receiver operating characteristic curve (aROC) of this index was compared with two other simplified risk stratification approaches: (1) prior healthcare exposure and/or high-CDI risk antibiotics; (2) number of prior high-CDI risk antibiotics.

RESULTS

50 (20.8%) of 240 included patients had MDRO colonization; 35 (14.6%) VRE, 18 (7.5%) MRSA, 2 (0.8%) CRE. Prior fluoroquinolone (aOR 2.404, 95% CI 1.095-5.279) and prior vancomycin (1.996, 95% CI 1.014-3.932) were independently associated with MDRO colonization while prior clindamycin (aOR 3.257, 95% CI 0.842-12.597) and healthcare exposure (aOR 2.138, 95% CI 0.964-4.740) were retained as explanatory variables. The regression-based risk score significantly predicted MDRO colonization (aROC 0.679, 95% CI 0.595-0.763), but was not significantly more predictive than prior healthcare exposure + prior antibiotics (aROC 0.646, 95% CI 0.565-0.727) or number of prior antibiotic exposures (aROC 0.642, 95% CI 0.554-0.730); P > 0.05 for both comparisons.

CONCLUSION

A simplified approach using prior healthcare exposure and receipt of prior antibiotics known to increase CDI risk identified patients at risk for MDRO gut microbiome colonization as effectively as individual patient/antibiotic risk modeling.

Reduced Susceptibility to Metronidazole Is Associated With Initial Clinical Failure in Clostridioides difficile Infection

Background

Clinical studies have demonstrated inferior cure rates when metronidazole (MTZ) is used to treat Clostridioides difficile infection (CDI). We hypothesized that a newly identified, heme-inducible form of reduced MTZ susceptibility in C. difficile leads to higher odds of initial clinical failure in patients with CDI treated with MTZ.

Methods

This multicenter cohort study included adults diagnosed with CDI between 2017 and 2018. C. difficile isolated from stool samples underwent agar dilution MTZ susceptibility testing with incorporation of fresh heme. Blinded investigators reviewed medical records for initial clinical failure and other relevant clinical variables. Classification and regression tree (CART) analysis was used to identify the MTZ minimum inhibitory concentration (MIC) breakpoint that was predictive of initial clinical failure. Results were confirmed using univariate and multivariable logistic regression analyses to account for potential confounders.

Results

Of the 356 patients included, 72% received MTZ-based therapy and 27% experienced initial clinical failure. CART analysis identified an MTZ MIC ≥1 µg/mL above which patients had a higher rate of initial clinical failure. MTZ MICs ranged from 0.25 to 8 µg/mL (MIC_50/90 = 0.25/2 µg/mL), and approximately 18% of isolates had MTZ MICs ≥1 µg/mL. In multivariable analysis, an MTZ MIC ≥1 µg/mL was an independent predictor of initial clinical failure in patients receiving an MTZ-based treatment regimen (odds ratio, 2.27 [95% confidence interval, 1.18–4.34]).

Conclusions

Using a reproducible method to determine C. difficile MICs to MTZ, a breakpoint of ≥1 µg/mL identified patients at higher risk of initial clinical failure.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

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

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

Background

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

Methods

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

Results

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

Conclusion

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

Disclosures

All authors: No reported disclosures.

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.

Precision Pharmacotherapy: Integrating Pharmacogenomics into Clinical Pharmacy Practice

Precision pharmacotherapy encompasses the use of therapeutic drug monitoring; evaluation of liver and renal function, genomics, and environmental and lifestyle exposures; and analysis of other unique patient or disease characteristics to guide drug selection and dosing. This paper articulates real-world clinical applications of precision pharmacotherapy, focusing exclusively on the emerging field of clinical pharmacogenomics. This field is evolving rapidly, and clinical pharmacists now play an invaluable role in the clinical implementation, education, and research applications of pharmacogenomics. This paper provides an overview of the evolution of pharmacogenomics in clinical pharmacy practice, together with recommendations on how the American College of Clinical Pharmacy (ACCP) can support the advancement of clinical pharmacogenomics implementation, education, and research. Commonalities among successful clinical pharmacogenomics implementation and education programs are identified, with recommendations for how ACCP can leverage and advance these common themes. Opportunities are also provided to support the research needed to move the practice and application of pharmacogenomics forward.

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.

Significant Publications on Infectious Diseases Pharmacotherapy in 2017

PURPOSE

The most significant peer-reviewed articles pertaining to infectious diseases (ID) pharmacotherapy, as selected by panels of ID pharmacists, are summarized.

SUMMARY

Members of the Houston Infectious Diseases Network (HIDN) were asked to nominate peer-reviewed articles that they believed most contributed to the practice of ID pharmacotherapy in 2017, including the areas of human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS). A list of 33 articles related to general ID pharmacotherapy and 4 articles related to HIV/AIDS was compiled. A survey was distributed to members of the Society of Infectious Diseases Pharmacists (SIDP) for the purpose of selecting 10 articles believed to have made the most significant impact on general ID pharmacotherapy and the single significant publication related to HIV/AIDS. Of 524 SIDP members who responded, 221 (42%) and 95 (18%) members voted for general pharmacotherapy- and HIV/AIDS-related articles, respectively. The highest ranked articles are summarized below.

CONCLUSION

Remaining informed on the most significant ID-related publications is a challenge when considering the large number of ID-related articles published annually. This review of significant publications in 2017 may aid in that effort.

Outcomes associated with Clostridium difficile infection in patients with chronic liver disease

Patients with chronic liver disease (CLD) have frequent exposure to Clostridium difficile infection (CDI) risk factors but the incidence and aetiology of CDI on this population is poorly understood. The aim of this study was to assess the incidence, disease presentation and outcomes of CDI in patients with underlying CLD. The Health Care and Utilization Project National Inpatient Sample (HCUP-NIS) 2009 dataset was used to identify patients with CLD who developed CDI along with matched non-CLD patients with CDI. Using the NIS dataset, the incidence rate of CDI was 189.4/10 000 discharges in CLD patients vs. 83.7/10 000 discharges in the non-CLD matched cohort (P < 0.001). Compared with non-CLD, comorbidity-matched controls with CDI, CLD patients with CDI had higher likelihood of in-hospital mortality (8.8% vs. 18.6%, P < 0.001), increased length of stay by 1.19 days (P < 0.001) and increased total costs by $8632 (P < 0.001). In separate analyses using a tertiary case database of hospitalised patients in Houston, Texas (2006-2016) with CLD and CDI (n = 41) compared with patients with CDI but not CLD (n = 111), CLD patients had significantly higher Charlson comorbidity index (P < 0.0001) but similar risk factors for CDI and CDI-related disease presentation compared with non-CLD patients. In conclusion, CDI-related risk factors were almost universally present in the CLD population. CDI resulted in worse outcomes in this population.

Novel antibiotics in development to treat Clostridium difficile infection

PURPOSE OF REVIEW

Clostridium difficile infections (CDI) remain a challenge to treat clinically due primarily to limited number of antibiotics available and unacceptably high recurrence rates. Because of this, there has been significant demand for creating innovative therapeutics, which has resulted in the development of several novel antibiotics.

RECENT FINDINGS

This review updates seven different antibiotics that are currently in development to treat CDI including fidaxomicin, surotomycin, ridinilazole, ramoplanin, cadazolid, LFF571, and CRS3123. Available preclinical and clinical data are compared between these antibiotics.

SUMMARY

Many of these new antibiotics display almost ideal properties for antibiotics directed against CDI. Despite these properties, not all clinical development of these compounds has been successful. These studies have provided key insights into the pathogenesis of CDI and will continue to inform future drug development. Successful phase III clinical trials should result in several new and novel antibiotics to treat CDI.