Difficile Polymerase Chain Reaction Research Articles

P-1629. Reduction in Clostridioides difficile Over-diagnosis Following Suppression of C. difficile Target from Multiplex Molecular Stool Assay in a Pediatric Healthcare System

Abstract Background Clostridioides difficile testing by polymerase chain reaction (PCR) does not differentiate asymptomatic colonization from infection, and children are frequently colonized with toxigenic strains of C. difficile. Over-diagnosis of C. difficile infections can lead to adverse patient outcomes and poorer quality metrics for hospitals.Figure 1:C. difficile PCR orders following change in GI PCR Panel, Interrupted Time Series Methods In January 2023 our pediatric health system enacted multimodal changes to the electronic ordering of stool tests for C. difficile and other gastrointestinal pathogens. A multiplex PCR test for stool was updated to suppress testing for toxigenic C. difficile. The only remaining method to test for C. difficile by PCR in house was a C. difficile toxin gene specific PCR. Additionally, appropriate clinical criteria with a hard stop were added to the C. difficile PCR order (all of: no laxatives in the past 24 hours, at least 3 liquid stools in the past 24 hours, at least one risk factor for C. difficile infection, and patient at least one year old). If providers still sought C. difficile testing without meeting these criteria, infectious disease specialist approval was required. We analyzed the effect of this intervention using interrupted time series analysis and pre-post aggregate rates from January 2019 through February 2024.Figure 2:C. difficile positive rate following change in GI PCR Panel, Interrupted Time Series Results There were 4426 stool PCR tests performed for C. difficile in the pre-intervention period and 622 in the post-intervention period. The mean (± sd) age of those tested was 7.8 years (± 6.1 years). After the intervention, there was an immediate 61% decrease in C. difficile testing incidence (95% CI [53% - 67%], Figure 1) and 51% decrease in C. difficile diagnosis incidence (95% CI [26% - 67%], Figure 2). There was no significant immediate change or change in slope in the C. difficile antibiotic treatment incidence or HFO C. difficile incidence, but there was a trend towards lower rates of healthcare facility onset C. difficile after the change (aggregate rate 4.13 per 10,000 non-NICU patient-days prior to intervention vs. 3.39 after, P = .28). Conclusion Removing C. difficile from multiplex PCR assays and adding required clinical criteria to the electronic order reduces the number of C. difficile tests and diagnoses in a pediatric health system. Disclosures Laura Filkins, PhD, Avsana Labs: Board Member|Avsana Labs: Stocks/Bonds (Private Company)|Biofire Diagnostics: Grant/Research Support

Comparing rates of recurrent infection for first occurrence of Clostridioides difficile between tapered oral vancomycin and standard vancomycin: a retrospective, propensity matched cohort study.

To compare rates of Clostridioides difficile infection (CDI) recurrence following initial occurrence treated with tapered enteral vancomycin compared to standard vancomycin. Retrospective cohort study. Community health system. Adults ≥18 years of age hospitalized with positive C. difficile polymerase chain reaction or toxin enzyme immunoassay who were prescribed either standard 10-14 days of enteral vancomycin four times daily or a 12-week tapered vancomycin regimen. Retrospective propensity score pair matched cohort study. Groups were matched based on age < or ≥ 65 years and receipt of non-C. difficile antibiotics during hospitalization or within 6 months post-discharge. Recurrence rates were analyzed via logistic regression conditioned on matched pairs and reported as conditional odds ratios. The primary outcome was recurrence rates compared between standard vancomycin versus tapered vancomycin for treatment of initial CDI. The CDI recurrence rate at 6 months was 5.3% (4/75) in the taper cohort versus 28% (21/75) in the standard vancomycin cohort. The median time to CDI recurrence was 115 days versus 20 days in the taper and standard vancomycin cohorts, respectively. When adjusted for matching, patients in the taper arm were less likely to experience CDI recurrence at 6 months when compared to standard vancomycin (cOR = 0.19, 95% CI 0.07-0.56, p < 0.002). Larger prospective trials are needed to elucidate the clinical utility of tapered oral vancomycin as a treatment option to achieve sustained clinical cure in first occurrences of CDI.

Influence of microbiota on the growth and gene expression of Clostridioides difficile in an in vitro coculture model.

Clostridioides difficile is an anaerobic, spore-forming, Gram-positive pathogenic bacterium. This study aimed to analyze the effect of two samples of healthy fecal microbiota on C. difficile gene expression and growth using an in vitro coculture model. The inner compartment was cocultured with spores of the C. difficile polymerase chain reaction (PCR)-ribotype 078, while the outer compartment contained fecal samples from donors to mimic the microbiota (FD1 and FD2). A fecal-free plate served as a control (CT). RNA-Seq and quantitative PCR confirmation were performed on the inner compartment sample. Similarities in gene expression were observed in the presence of the microbiota. After 12 h, the expression of genes associated with germination, sporulation, toxin production, and growth was downregulated in the presence of the microbiota. At 24 h, in an iron-deficient environment, C. difficile activated several genes to counteract iron deficiency. The expression of genes associated with germination and sporulation was upregulated at 24 h compared with 12 h in the presence of microbiota from donor 1 (FD1). This study confirmed previous findings that C. difficile can use ethanolamine as a primary nutrient source. To further investigate this interaction, future studies will use a simplified coculture model with an artificial bacterial consortium instead of fecal samples.

Clinical Characteristics and Cycle Thresholds Among Discordant and True Positive Test Results for Clostridiodes difficile

Background: The diagnosis of Clostridioides difficile infection (CDI) is challenging. Despite guideline-directed, multistep testing algorithms and diagnostic stewardship, the treatment of C. difficile colonization persists. The testing algorithm at our system utilizes an initial real-time PCR test (PCR) for Toxin B gene, which if positive, reflexes to an enzyme immunoassay (EIA) for detecting Toxins A and B. Discordant results (PCR +/EIA -) are suggestive of colonization, but the majority of patients with discordant results are treated for CDI. Correlation of C. difficile EIA B polymerase chain reaction (PCR) cycle thresholds (Ct) with the presence of free EIA and disease severity has been observed, but the ability to use Ct in the decision to treat patients with discordant results is unclear. Our study assesses if Ct values and other clinical characteristics favor treatment in select patients with discordant Methods: A retrospective chart review was performed of adult patients (≥ 18-year-old) with positive C. difficile PCR results that were admitted to our health system between June 01 and August 31, 2023. C. difficile PCR and Ct results were obtained by Cepheid GeneXpert and Toxin A and B EIA results were obtained by Meridian Bioscience Immunocard. Patients with discordant (PCR+/EIA) and true positive (PCR+/EIA+) results were compared. We assessed demographics, past medical history, clinical characteristics, severity of illness, PCR Ct values, treatment, and clinical outcomes including: 30-day all-cause mortality and re-admission, and 60-day CDI repeat testing and treatment. Results Of the 122 patients identified, 89 patients had discordant results and 43 had true positive Results: Severity of illness and other clinical and laboratory characteristics were similar between both groups. Mean Ct values were significantly lower for true positive results compared to discordant results, 24.28 vs 29.27, respectively (p26 (p=.08). Of the patients with discordant results, 73 completed treatment for CDI and no difference in clinical outcomes was observed compared to patients with discordant results that were not treated. Conclusion Ct values were lower among patients with true positive results compared to patients with discordant Conclusion: There were no statistically significant different rates of severe or fulminant CDI among patients with discordant results and Ct values &lt; 26, although this finding may be limited by sample size and Ct may be helpful in deciding which discordant patients to treat.

Detection of Clostridioides difficile infection by assessment of exhaled breath volatile organic compounds

Clostridioides difficile infection (CDI) is the leading cause of hospital-acquired infective diarrhea. Current methods for diagnosing CDI have limitations; enzyme immunoassays for toxin have low sensitivity and Clostridioides difficile polymerase chain reaction cannot differentiate infection from colonization. An ideal diagnostic test that incorporates microbial factors, host factors, and host-microbe interaction might characterize true infection. Assessing volatile organic compounds (VOCs) in exhaled breath may be a useful test for identifying CDI. To identify a wide selection of VOCs in exhaled breath, we used thermal desorption-gas chromatography-mass spectrometry to study breath samples from 17 patients with CDI. Age- and sex-matched patients with diarrhea and negative C.difficile testing (no CDI) were used as controls. Of the 65 VOCs tested, 9 were used to build a quadratic discriminant model that showed a final cross-validated accuracy of 74%, a sensitivity of 71%, a specificity of 76%, and a receiver operating characteristic area under the curve of 0.72. If these findings are proven by larger studies, breath VOC analysis may be a helpful adjunctive diagnostic test for CDI.

The role of the hospital bed in hospital-onset Clostridioides difficile: A retrospective study with mediation analysis.

To determine whether residing in a hospital bed that previously held an occupant with Clostridioides difficile increases the risk of hospital-onset C. difficile infection (HO-CDI). In this retrospective cohort study, we used a real-time location system to track the movement of hospital beds in 2 academic hospitals from April 2018 to August 2019. We abstracted patient demographics, clinical characteristics, and C. difficile polymerase chain reaction (PCR) results from the medical record. We defined patients as being exposed to a potentially "contaminated" bed or room if, within the preceding 7 days from their HO-CDI diagnosis, they resided in a bed or room respectively, that held an occupant with C. difficile in the previous 90 days. We used multivariable logistic regression to determine whether residing in a contaminated bed was associated with HO-CDI after controlling for time at risk and requiring intensive care. We assessed mediation and interaction from a contaminated hospital room. Of 25,032 hospital encounters with 18,860 unique patients, we identified 237 cases of HO-CDI. Exposure to a contaminated bed was associated with HO-CDI in unadjusted analyses (odds ratio [OR], 1.8; 95% confidence interval [CI], 1.4-2.31) and adjusted analyses (OR, 1.5; 95% CI, 1.2-2.0). Most of this effect was due to both mediation from and interaction with a contaminated hospital room. Residing in a hospital bed or room that previously had a patient with C. difficile increases the risk of HO-CDI. Increased attention to cleaning and disinfecting the healthcare environment may reduce hospital transmission of C. difficile.

672. Impact of Multistep Testing Algorithm on Hospital Acquired Clostridioides difficile Infection Rates

Abstract Background Clostridioides difficile infection (CDI) is one of the leading causes of hospital-acquired (HA) infections. Clinically distinguishing true CDI versus colonization is challenging. Our center previously used a polymerase chain reaction (PCR) assay as a standalone test for diagnosing CDI. While PCR is very sensitive for diagnosing CDI, it cannot distinguish between CDI and asymptomatic colonization. A multistep testing algorithm, which consists of an initial C. difficile PCR test followed by a reflex enzyme immunoassay (EIA) for glutamate dehydrogenase (GDH) and Toxin A/B testing, was implemented in our institution. We conducted this study to determine the rates of HA-CDI and C. difficile colonization based on laboratory results. Methods This retrospective observational study was conducted at Allegheny General Hospital (Pittsburgh, PA, US). Patients with a positive C. difficile PCR assay at day 3 or later from admission date were included for analysis. The pre-intervention period was from August 2021 to February 2022 and post-intervention period was from August 2022 to February 2023. Before the intervention, results for C. difficile testing were reported as PCR positive (PCR+) or negative (PCR-). On July 2022, a multistep testing algorithm was implemented with an initial C. difficile PCR assay; if results were positive, a reflex EIA for GDH and Toxin A/B testing was performed and resulted as follows: Figure 1. The HA-CDI rates before and after implementation of a multistep testing algorithm were compared. Results A total of 112 unique patients were included. HA-CDI in the post intervention period decreased by 53% after the intervention (N=57 [pre-intervention] versus N=26 [post-intervention]; P &amp;lt; 0.001). During the post-intervention period, there were 55 PCR+ C. difficile assays, of which 29 (53%) were resulted as "indeterminate, likely C. difficile colonization." Of the 29 indeterminate results, 23 (79%) still received CDI therapy. Conclusion Our study demonstrated that a multistep C. difficile testing algorithm significantly reduced the rates of HA-CDI in our institution. We found that the majority of patients still received CDI therapy despite having a negative EIA toxin result. We plan to analyze the clinical impact of this multistep testing algorithm in a follow-up study. Disclosures Thomas L. Walsh, MD, Accelerate Diagnostics: Advisor/Consultant

129. Evaluation of Two-Step Clostridioides difficile Testing on Treatment Exposure

Abstract Background Clostridioides difficile can colonize or cause symptomatic disease from mild diarrhea to severe colonic inflammation requiring surgical intervention. Multiple C. difficile diagnostics are available and national guidelines recommend standalone or combination testing methods. Testing has mostly shifted to polymerase chain reaction (PCR)-based, which has shown up to a 50% increase in reporting of C. difficile infection (CDI). A two-step testing method has also been used to discern colonization versus active infection. The National Healthcare Safety Network has proposed changes to CDI reporting to include results and treatment, emphasizing the importance of diagnostic and antimicrobial stewardship. Methods In 2021 Saint Luke’s Health System moved from C. difficile PCR standalone to two-step testing with PCR and enzyme immunoassay (EIA) toxin test. If PCR is positive, an EIA is run. Both results are reported including interpretation guidance. A retrospective cohort study was conducted to evaluate if two-step testing impacts antibiotic prescribing rates for C. difficile. The pre-implementation group included PCR-only and post- implementation was split into PCR +/ EIA - and PCR +/ EIA + groups. Results Treatment rates for C. difficile did not significantly change after implementation of two-step testing (100% pre- vs 92% PCR +/ EIA - and 97% PCR +/ EIA +, p = 0.093). For PCR +/ EIA - results, treatment initiation more often occurred prior to results being available compared to the post-implementation PCR +/ EIA + group and pre-implementation group (30.3% PCR +/ EIA - vs 19.6% PCR +/ EIA + and 7.8% pre-implementation, (p = 0.028)). C. difficile antibiotic prescribing rates at discharge were no different between groups as the highest rates of treatment continuation were seen in the PCR +/ EIA - group (79.4% PCR +/ EIA - 72.5% pre-implementation vs 71.7% PCR+/ EIA +, p = 0.706). Conclusion Despite PCR +/ EIA - results, clinicians tended to treat patients irrespective of PCR-only or two-step results. The impact of two-step C. difficile testing on treatment rates was limited and prescribing rates did not significantly change. The findings of this study warrant investigation into alternative solutions to promote aligned diagnostic and antimicrobial stewardship. Disclosures All Authors: No reported disclosures

Characteristics and outcomes of Clostridioides difficile infection after a change in the diagnostic testing algorithm.

Polymerase chain reaction (PCR) testing for the detection of C. difficile is a highly sensitive test. Some clinical laboratories have included a 2-step testing algorithm utilizing PCR plus toxin enzyme immunoassays (EIAs) to increase specificity. To determine the risk factors and outcomes of C. difficile PCR-positive/toxin-positive encounters compared to PCR-positive/toxin-negative encounters. Retrospective study. A Veterans' Affairs hospital. A retrospective case-control study of patient encounters with a positive C. difficile test by PCR and either a toxin EIA-positive assay (ie, cases) or toxin EIA-negative assay (ie, controls). Clinically relevant exposures and risk factors were determined to assess CDI recurrence at 30 days. Available encounter stool specimens were cultured for C. difficile and were subjected to restriction endonuclease analysis (REA) strain typing. Among 130 C. difficile PCR-positive patient encounters, 80 (61.5%) were toxin EIA negative and 50 (38.5%) were toxin EIA positive. Encounters that were toxin positive were more frequently treated (96.0%) compared to toxin-negative encounters (71.3%; P < .01). A multivariable logistic regression model revealed that toxin-negative encounters were less likely to suffer a recurrent CDI episode within 30 days (odds ratio [OR], 0.20, 95% confidence interval [CI], 0.05-0.83). Additionally, a higher C. difficile PCR cycle threshold predicted a lower risk of CDI recurrence at 30 days. (OR, 0.82; 95% CI, 0.68-0.98). During the study period, the REA group Y strain accounted for most toxin-negative encounters (32.5%; P = .05), whereas REA group BI strain accounted for most toxin-positive encounters (24.3%; P = .02). A testing strategy of PCR plus toxin EIA helped predict recurrent CDI.

Predictors of hospital-onset Clostridioides difficile infection in children with antibiotic-associated diarrhea

BackgroundThis study aimed to determine the predictors of hospital-onset Clostridioides difficile infection (CDI) in pediatric patients with antibiotic-associated diarrhea (AAD) and to develop a predictive scoring system to identify at-risk patients. MethodsThis retrospective case-control study included patients aged ≥2-18 years with AAD who underwent C. difficile polymerase chain reaction testing >3 days after hospital admission. Patients with hospital-onset CDI were selected as cases and matched with the control patients without CDI. Univariate and multivariate logistic regressions were used to determine predictors of CDI and to construct a prediction score for the outcomes of interest. ResultsSixty-five patients with hospital-onset CDI and 130 controls were enrolled. Independent predictors for CDI identified and combined into the prediction score included abdominal pain (adjusted odds ratio [95% confidence interval]: 7.940 [3.254-19.374]), hospitalization for ≥14 days before the onset of diarrhea (3.441 [1.034-11.454]), antibiotic use for ≥10 days before the onset of diarrhea (6.775 [1.882-24.388]), receipt of meropenem (4.001 [1.098-14.577]) and clindamycin (14.842 [4.496-49.000]). The area under the receiver operating characteristic curve for this score was 0.883. ConclusionsThe presented scoring system can be easily applied by clinicians at the bedside to decide which patients with AAD are likely to have CDI.

180. Impact of a two-step diagnostic bundle on hospital-onset Clostridioides difficile infection rates and treatment across a large health system.

Abstract Background Distinguishing true Clostridioides difficile Infection (CDI) from colonization is a challenge, with nearly 20% of hospitalized adults being carriers of C. difficile. Polymerase chain reaction (PCR) testing alone is not able to distinguish colonization from infection, leading to over-diagnosis and unnecessary treatment. Despite interventions including pre-approval by antimicrobial stewardship programs (ASP), reportable hospital-onset CDI (HO-CDI) rates across our health system remained high. In 2021, we implemented a C. difficile PCR with reflex toxin enzyme immunoassay (EIA) testing strategy to improve diagnostic accuracy and treatment outcomes. The purpose of this study was to evaluate the impact of this two-step testing algorithm bundled with education, ASP support and order set changes on HO-CDI rates and C. difficile treatment across our health system. Methods PCR with EIA testing algorithm was implemented between May and August 2021 across seven hospitals within the Northwestern Medicine Health System. Multifaceted education was delivered to leadership and clinicians in person and electronically to. ASP performed daily diagnostic prospective audit and management support. Clinical decision support (CDS) was incorporated into order sets to promote diagnostic stewardship (Table 1, Figure 1). Standardization of analyst-developed tracking reports allowed for longitudinal monitoring across the system and at each facility, including unit- and patient-level data. Figure 1C. Difficile Testing Algorithm PCR/Reflex Toxin EIA Results The HO-CDI standardized infection ratio (SIR) reduced significantly from 0.8 to 0.57 p&amp;lt; 0.001), and reportable HO-CDI cases reduced by 238 cases across the health system between May 2021 and March 2022. 6043 samples were tested, of which 282 (4.7%) were confirmed CDI cases (PCR+/toxin+) and 687 (11%) were non-CDI cases (PCR+/toxin-), of which 438 (67%) received CDI treatment. (Figure 2 and 3). Figure 3 Actual versus avoided HO C. difficile cases. Conclusion The two-step CDI diagnostic and treatment bundle significantly reduced the SIR of HO-CDI. Although treatment of colonized patients remained high, a large number of patients safely avoided CDI treatment. Testing and education bundles can help advance antimicrobial and diagnostic stewardship by improving detection, treatment, and tracking of CDI. Disclosures Asra Salim, MPH, CPH, FAPIC, IRhythym Technologies Inc: Stocks/Bonds.

386. Clostridioides difficile PCR Cycle Threshold to Determine Toxin Positivity Status

Abstract Background Many clinical laboratories rely on polymerase chain reaction (PCR) as the sole test for diagnosis of C. difficile infection (CDI). The objective of this study was to determine if the C. difficile (CD) PCR cycle threshold could be used to predict a positive CD toxin test. Methods We reviewed the characteristics and outcomes of 149 consecutive patients who tested positive for by PCR (Xpert CD, Cepheid) between October 2019 and December 2021 at one VA Hospital where reflex toxin testing (Cdiff quick check complete, Alere/TechLab) was performed after a positive PCR result. Baseline characteristics, symptoms, initial laboratory data, and treatments were compared as well as clinical outcomes. Determination of CDI or CD colonization was made for each patient after review of symptoms: including chronicity of symptoms, laboratory values, stool frequency, use of laxatives, and response to treatment. The cycle threshold for the CD-PCR results were recorded and positive stools were cultured for CD. Results Toxin testing was positive in 38% (57/149) of cases. The mean PCR cycle threshold value for all specimens tested was 27.89 (95% CI [27.14, 28.66]). Toxin-positive stools had lower mean PCR cycle thresholds when compared to toxin-negative stools (24.56 and 29.97, respectively p &amp;lt; 0.0001). Among the 149 cases reviewed, 109 were determined to be CDI (73%), 36 were colonized (24%), and 4 cases were undetermined. Among those with toxin-positive stools, 96% (54/56) patients were determined to have CDI. 98% (56/57) of all toxin-positive stools had a cycle threshold of ≤ 32.2 compared to 63% (58/92) of toxin-negative stools, resulting in a negative predictive value of 97.2% (p &amp;lt; 0.0001). The mean cycle threshold was lower in patients who were determined to have a CDI when compared to colonized patients (27.02 vs 30.44, p = 0.0001). [Figure] Of the patients that had CDI, 83% (91/109) had a cycle threshold of ≤ 32.2 and 58% (21/36) of colonized patients had a cycle threshold of ≤ 32.2. Conclusion Conclusions: In a setting where a CD toxin assay is not readily available, a CD stool PCR cycle threshold could be used to predict toxin status. In our study, a cycle threshold of ≤ 32.2 predicted both toxin-positivity and CDI. Disclosures Stuart Johnson, M.D., Ferring Pharmaceuticals: Membership on Ferring Publication Steering Committee|Ferring Pharmaceuticals: Employee|Summit Plc: Advisor/Consultant.

Melatonin as an Antimicrobial Adjuvant and Anti-Inflammatory for the Management of Recurrent Clostridioides difficile Infection.

Background:Clostridioides difficile (C. difficile) infection (CDI) is strongly associated with inflammation and has the potential to cause recurrent infections. Pre-clinical data suggest that melatonin has beneficial effects in the gastrointestinal tract due to its anti-inflammatory and antibacterial properties. This analysis examines the association between melatonin and the risk of recurrent CDI. Methods: A retrospective cohort study was conducted among patients with an inpatient diagnosis of CDI along with a positive C. difficile polymerase chain reaction (PCR) or enzyme immunoassay (EIA) test result. Patients were followed until the first study end point (death) or the first instance of recurrent infection. Propensity-score weighting was utilized accounting for confounding factors and weighted Cox models were estimated. Results: A total of 24,782 patients met the inclusion criteria, consisting of 3457 patients exposed to melatonin and 21,325 patients with no melatonin exposure. The results demonstrate that those exposed to melatonin were associated with a 21.6% lower risk of recurrent CDI compared to patients without melatonin exposure (HR = 0.784; 95% CI = 0.674-0.912). Conclusion: Our results demonstrate a decreased rate of recurrent CDI in patients exposed to melatonin. Further research on melatonin as an antimicrobial adjuvant and anti-inflammatory is warranted for the management of recurrent CDI.

The emergence of Clostridioides difficile PCR ribotype 127 at a hospital in northeastern Taiwan.

Several studies have highlighted the incidence of Clostridioides difficile infections (CDIs) in Taiwan and certain ribotypes have been related to severe clinical diseases. A study was conducted to investigate the polymerase chain reaction (PCR) ribotypes and genetic relatedness of clinical C. difficile strains collected from January 2009 to December 2015at a hospital in northeastern Taiwan. A modified two-step typing algorithm for C. difficile was used by combining a modified 8-plex and 3'-truncated tcdA screening PCR. In addition, MLVA typing was adopted for investigation of bacterial clonality and transmission. Among a total of 86 strains, 24 (28%) were nontoxigenic and 62 (72%) had both tcdA and tcdB (A+B+). No tcdA-negative and tcdB-positive (A-B+) strains were identified. Binary toxin (CDT)-producing (cdtA+/cdtB+) strains were started to be identified in 2013. The 21 (34%) A+B+ clinical strains with binary toxin and tcdC deletion were identified as RT127 strains, which contained both RT078-lineage markers and fluoroquinolone (FQ)-resistant mutations (Thr82Ile in gyrA). Multiple loci variable-number tandem repeat analysis (MLVA) for phylogenetic relatedness of RT127 strains indicated that 20 of 21 strains belonged to a clonal complex that was identical to a clinical strain collected from southern Taiwan in 2011, suggestive of a clonal expansion in Taiwan. A two-step typing method could rapidly confirm species identification and define the toxin gene profile of C. difficile isolates. The clonal expansion of RT127 strains in Taiwan indicates monitoring and surveillance of toxigenic C. difficile isolates from human, animal, and environment are critical to develop One Health prevention strategies.

Pseudomembranous colitis with negative Clostridium difficile PCR presenting with massive ascites: a case report and literature review

Pseudomembranous colitis (PMC) is characterized by the presence of an inflammatory pseudomembrane overlying the colonic mucosa, and is primarily caused by Clostridium difficile infection (CDI). PMC is often associated with the use of broad-spectrum antibiotics. Common symptoms include watery diarrhea, mucus in stool, abdominal cramps, and fever. We report a case of a 52-year-old female presenting with new abdominal distention, frequent bloody, mucoid, jelly-like diarrhea, and abdominal pain. Peritoneal fluid analysis showed neutrocytic ascites with low serum-ascites albumin gradient (SAAG). A diagnosis of pseudomembranous colitis was confirmed by flexible sigmoidoscopy. However, polymerase chain reaction (PCR) test for Clostridium difficile was negative. The patient was treated with metronidazole (500 mg IV q8h) and vancomycin (250 mg PO QID). Her symptoms resolved after several days of treatment with no ascites found by ultrasound. Neutrocytic ascites can be a complication of PMC. Physicians should also be aware that empirical treatment of Clostridium difficile may cause false negative diagnostic test result.

P074 Comparative Risk of Clostridioides Difficile Infection in Vedolizumab vs anti-TNFa Agents in Biologic-Naïve Patients With Ulcerative Colitis.

Clostridioides difficile infection (CDI) is associated with adverse outcomes in ulcerative colitis (UC). There is concern that vedolizumab, which inhibits lymphocyte trafficking to the intestines, may increase the risk of gastrointestinal infections such as CDI when compared to other biologics. We conducted a retrospective cohort study to determine if vedolizumab is associated with an increased risk of CDI compared to anti-TNFa agents in UC. Retrospective cohort study of adult patients with UC initiating infliximab, adalimumab, or vedolizumab 6/1/14-12/31/20 at a large academic health system. Electronic records were manually reviewed. Patients with Crohn's disease, indeterminate colitis, prior biologic exposures, prior colectomy, and non-UC indications for biologics were excluded. Patients were followed until CDI, colectomy, biologic discontinuation/switch, or last gastroenterology encounter through 8/1/21. The primary outcome was time from biologic initiation to first CDI, defined as positive stool C. difficile toxin or toxigenic C. difficile polymerase chain reaction (PCR) with associated CDI antibiotic prescriptions. Secondary outcomes included CDI-related hospitalization, colectomy, or death within 30 days of CDI. The primary exposure was vedolizumab vs anti-TNFa therapy. Other independent variables included demographics and UC history/severity factors. Propensity scores (PSs) were calculated using logistic regression of vedolizumab vs anti-TNFa on the following covariates: age, sex, Caucasian, body mass index (BMI), disease duration, current systemic corticosteroid use, UC-related hospitalization within prior 12 months, last Mayo endoscopic subscore, Montreal disease extent, albumin, and malignancy history. Inverse probability of treatment weighting (IPTW) was performed using PSs. An univariable Cox proportional hazards model was fit to calculate the unadjusted hazard ratio (HR) of CDI for vedolizumab vs anti-TNFa. A multivariable, IPT-weighted Cox model was then fit with two additional covariates extrinsic to the PS: pre-biologic CDI and immunomodulator exposure (time-varying covariate). Patients were censored at loss of follow-up, biologic discontinuation, or colectomy. 805 UC patients initiated vedolizumab (n = 195) or anti-TNFa agents (n = 610). Vedolizumab patients were older and less commonly received systemic corticosteroids or had UC-related hospitalization within 12 months pre-biologic initiation. There were 43 CDIs over 1,436 patient-years follow-up. CDI and CDI hospitalization occurred less commonly with vedolizumab vs anti-TNFa (CDI: 1.0% vs 6.7%, p = 0.001; CDI hospitalization: 1.0% vs 3.8%, p = 0.042 by log-rank test). There were no differences in colectomies or deaths or exposure to antibiotics/corticosteroids during follow-up or within 30 days preceding CDI. The unadjusted Cox model demonstrated a lower hazard of CDI for vedolizumab vs anti-TNFa (HR 0.17, 95% CI 0.04-0.71). The multivariable IPT-weighted Cox model demonstrated no difference in hazard of CDI for vedolizumab vs anti-TNFa (HR 0.33, 95% CI 0.05-2.03) or immunomodulator exposure (HR 1.01, 95% CI 0.41-2.40). Pre-biologic CDI was associated with an increased hazard of CDI (HR 5.95, 95% CI 2.93-12.09). Among patients who developed CDI, 17/43 (39.5%) had pre-biologic CDI a median of 227 days (IQR 160-550 days) preceding CDI. Our study did not identify an increased risk of CDI associated with vedolizumab vs anti-TNFa agents after controlling for UC severity. We hope that these findings will reassure UC providers considering vedolizumab as a first-line biologic agent in the context of gastrointestinal infectious risks.

Genetic Relatedness of 5-Year Isolates of Clostridioides difficile Polymerase Chain Reaction Ribotype 017 Strains in a Hospital.

The objective of this study was to analyse the genetic relatedness of Clostridioides difficile polymerase chain reaction ribotype 017 (RT017) strains from patients with hospital-acquired C. difficile infection (HA-CDI) in a hospital with a high RT017 prevalence. From 2009 to 2013, 200 RT017 strains (26.8%) were collected from 745 HA-CDI patient isolates. They comprised 64 MLVA types, and 197 (98.5%) strains were genetically related to 5 clonal complexes (CCs). The largest cluster, CC-A, included 163 isolates of 40 MLVA types. CC-A accounted for 20% of RT017 strains in 2009 and sharply increased to 94.9% in 2010, 94% in 2011, 86.2% in 2012, and 73.5% in 2013. The other 4 CCs included 20 isolates with 7 MLVA types. The resistance rates of antimicrobials were as follows: clindamycin 100%, moxifloxacin 99%, rifaximin 88.5%, and vancomycin 1%. All isolates were susceptible to metronidazole and piperacillin/tazobactam. Comparing antibiotic resistance among CCs, the geometric mean of the minimum inhibitory concentrations of moxifloxacin, vancomycin, and piperacillin/tazobactam were significantly higher for CC-A isolates than for the other CCs. RT017 clones constantly evolved over the 5 years studied with regard to genetic relatedness. The levels of antibiotic resistance may contribute to the persistence of organisms in the institution.

Clinical Characteristics and Fecal Microbiome in Recurrent Versus Nonrecurrent Clostridioides difficile Infection

Background: Up to 30% of patients with Clostridioides difficile infection (CDI) develop recurrent infection, which is associated with a 33% increased risk of mortality at 180 days. The gut microbiome plays a key role in initial and recurrent episodes of CDI. We examined the clinical characteristics and gut microbial diversity in patients with recurrent (rCDI) versus nonrecurrent CDI at a tertiary-care academic medical center. Methods: Stool samples were collected from 113 patients diagnosed with CDI between 2018 and 2019. Clinical and demographic data were extracted from the electronic medical record (Table 1), and 16S rRNA sequencing of the v4 region was carried out on the Illumina MiSeq using 2×250 paired-end reads. Sequences were binned into operational taxonomic units (OTUs) using mothur and were classified to the genus level whenever possible using the ribosomal database project data set version 16. Alpha diversity was calculated using the Shannon diversity index. Β diversity was calculated using the Bray-Curtis dissimilarity matrix. Differential abundance testing was done using DESeq to assess taxonomic differences between groups. A P value of .05 was used to assess significance. Results: In total, 55 patients had rCDI (prior positive C. difficile polymerase chain reaction in last 7–365 days) and 58 had nonrecurrent CDI (Table 1). Patients with rCDI had a higher frequency of organ transplant and comorbidity. No differences in α not β diversity were observed between groups. Also, 4 OTUs were more abundant in those with rCDI: Ruminococcus (n = 2), Odoribacter, and Lactobacillus. Patients with rCDI had microbiomes with greater proportions of Bacteroidetes (27% of OTUs) compared to the nonrecurrent group (18%) as well as fewer OTUs belonging to the Firmicutes phyla compared to the nonrecurrent patients (56% vs 59%). Among the rCDI patients, those experiencing 2 or more recurrences had greater abundances of Bacteroides and Ruminococcus, while those experiencing only 1 recurrence had significantly greater abundances of Akkermensia, Ruminococcus, Streptococcus, Roseburia, Clostridium IV, and Collinsella compared to those with only 1 recurrence (Table 2). Conclusions: Patients with rCDI had a more impaired microbiome than those with initial CDI. Ruminococcus OTUs have been previously indicated as a risk factor for recurrence and treatment failure, and they were significantly more abundant in those with rCDI and among those with multiple recurrences. The greatest differences in the microbiome were observed between those with 1 recurrence compared to those with multiple recurrences. Interventions for gut microbiome restoration should focus particularly on those with recurrent CDI.Funding: NoDisclosures: None

Isolated Colonic Post-Transplantation Lymphoproliferative Disease

A 61-year-old woman with a diagnosis of left-sided ulcerative colitis presented with recurrence of watery nonbloody diarrhea. She was status post liver transplant 2 years prior for primary sclerosing cholangitis, currently on tacrolimus and mesalamine. Following a negative Clostridium difficile polymerase chain reaction, colonoscopy demonstrated Mayo 1 appearance throughout the colon, with an area of friable and hemorrhagic mucosa in the cecum (Figure A). Random colon biopsies showed mild chronic active colitis, but specific biopsies of the cecal patch identified a monomorphous infiltrate of atypical lymphocytes (Figure B).

Clostridium difficile appendicitis in an immunocompromised patient: a case report and review of the literature

BackgroundClostridium difficile (C. difficile) is a common cause of infectious colitis in individuals with prior antibiotic or hospital exposure. Extraintestinal manifestations of C. difficile infections, however, are rare. Here we present a case of C. difficile appendicitis in an immunocompromised patient.Case presentationA 53-year-old Caucasian male presented to the emergency room for two days of lower abdominal pain associated with nausea and subjective fevers. He otherwise denied having diarrhea or hematochezia. He did not have any recent hospitalizations, nursing home stays, or antibiotic exposure. His past medical history was notable for stage III tonsillar squamous cell carcinoma for which he was status post tonsillectomy, radiation therapy, and chemotherapy (cisplatin 4 days prior to presentation). He was afebrile with tenderness to palpation in the bilateral lower quadrants, right greater than left. His white blood cell (WBC) count was 15.6 × 103 cells/μL. Computed tomography (CT) of the abdomen and pelvis showed marked edema and inflammation of the cecum and ascending colon as well as an enlarged appendix with surrounding inflammatory changes with a small amount of free fluid in the right paracolic gutter. He was treated non-surgically with antibiotics. He did not clinically improve and on hospital day 3, he developed diarrhea for which C. difficile stool polymerase chain reaction was sent. Repeat CT of the abdomen and pelvis was performed which showed progression to pan-colitis and persistent appendicitis. C. difficile testing later resulted positive, for which oral vancomycin was started. The patient markedly improved with medical management alone and was subsequently discharged on oral vancomycin.ConclusionsOur case highlights the importance of maintaining a high index of suspicion for C. difficile in a patient presenting with both appendicitis and colitis, with prompt diagnosis and treatment being essential.