Nora Colburn’s research while affiliated with The Ohio State University and other places

Background C. difficile infection (CDI) is an ongoing challenge for healthcare facilities. The mischaracterization of C. difficile colonization as active infection falsely elevates healthcare onset-CDI (HO-CDI) rates and increases antimicrobial overuse and healthcare costs. Two-step testing for CDI helps differentiate colonization from infection. We describe the change in HO-CDI rates and antimicrobial use following implementation of two-step C. difficile testing with analysis of order and treatment practices post-implementation.Figure 1:HO-CDI Rates Pre and Post-InterventionHO-CDI rates per 10,000 patient days pre and post-intervention. The vertical dotted black line indicates the date of intervention. Methods Two-step C. difficile testing (PCR followed by ELISA for toxin if PCR-positive) was implemented Sept. 5, 2023. HO-CDI rates were compared for 6 months pre and post intervention using MedCalc statistical software. Antimicrobial patient days per 1000 patient days for oral vancomycin and fidaxomicin was compared pre and post-intervention using Wilcoxen Rank Sum test. Analysis of all inpatients with a C. difficile order during the post-intervention period was performed including test result, demographics, diarrhea documentation, laxative use, C. difficile treatment and repeat testing.Figure 2:Antimicrobial Patient Days for PO Vancomycin and Fidaxomicin Pre and Post-InterventionAntimicrobial patient days per 1000 pre and post-intervention. The vertical dotted black line indicates the date of intervention. Results HO-CDI rates decreased from 6.44 to 2.89/10,000 patient days pre and post-intervention with an incidence rate ratio of 2.22, P< 0.0001 (Figure 1). Inpatient prescriptions for oral vancomycin and fidaxomicin decreased from 28.4 to 22.2 antimicrobial patient days per 1000 patient days, p=0.0295 (Figure 2). A total of 1836 tests were done in the post-intervention period with detailed analysis included in Table 1. Less than 20% of patients had ≥3 diarrhea stools documented and excluding orders on HD 1 or 2, stool documentation was present in 29% of patients. Analysis of the 66 HO-CDI cases was similar compared to all positive cases with 24 (36%) receiving laxatives and 21 (36%) with diarrhea documented.Table 1:Analysis of All Inpatient C. diff Orders Post-InterventionAnalysis of all inpatient C. diff orders post-intervention, where negative indicates PCR negative / toxin negative; discordant indicates PCR positive / toxin negative; and positive indicates PCR positive / toxin positive. Conclusion HO-CDI rates and C. difficile specific antimicrobial use were significantly decreased after implementation of two-step testing. Despite this decrease, over half of discordant result patients received C difficile treatment, indicating an opportunity for additional education. Optimization of diagnostic stewardship with regards to laxative use and appropriate stool documentation are areas of opportunity. Disclosures All Authors: No reported disclosures

Background: Candida auris is an emerging threat to hospitalized patients and invasive disease is associated with high mortality. This study describes clinical and microbiological characteristics of nine patients identified with C. auris at Ohio State Wexner Medical Center discovered through active surveillance or clinical investigation and uses whole genome sequencing (WGS) to compare isolates. Methods: In November 2022, an active C. auris surveillance program was implemented to screen patients admitted to high-risk units (intensive care units and progressive care units). Bilateral axilla and groin swabs were obtained upon unit admission and, if positive, were submitted for C. auris polymerase chain reaction (PCR) with culture and sensitivity testing. Patients with a positive screening or clinical isolate from November 2022 to November 2023 underwent chart review for clinical characteristics, microbiologic data, and index admission information. For each isolate, DNA was extracted and WGS was performed. Core single nucleotide polymorphism (SNP) variation identified from the sequence data was used to infer genetic relationships among the isolates. Results: Nine patients were identified between November 2022 and November 2023. The clinical and microbiologic characteristics are summarized in Table 1. All patients were hospitalized at various acute care facilities across the state at least once in the preceding 12 months. C. auris was determined to be present on admission for 6 patients. For 5 of these patients, it was their first interaction with our healthcare system. Three patients were not in contact isolation for >3 days before C. auris was identified. Unit wide point-prevalence screening was completed in these cases and no evidence of transmission was found. WGS showed eight of the nine isolates were related with 28 or less core SNP differences between isolates (Figure 1). One isolate (8) was genetically distinct with >45000 core SNP differences. Five isolates were highly related with a range of 4-15 SNP differences. No temporal or spatial overlap at our institution was identified among these five patients. Conclusions: The active surveillance program identified several patients colonized with C. auris in addition to those found through clinical testing. Multiple risk factors for C. auris were identified with high patient mortality (67%). Majority of the isolates were closely related without association with a known outbreak or epidemiologic link, suggesting a possible diffuse common reservoir. Next steps with surveillance in acute care and long-term care facilities will be critical for early detection to halt transmission of this organism.

Background: Catheter-Associated Urinary Tract Infections (CAUTI) are preventable hospital acquired infections that contributes to patient morbidity, prolonged hospital stays and increased healthcare costs. Complete compliance to the CAUTI bundle is critical for preventing infection—not only reducing catheter days, but also ensuring appropriate indications are present for urine culture collection. Methods: This retrospective study included 145 patients diagnosed with CAUTI per NHSN definitions from July 1, 2020 to June 30, 2023. Data collected included laboratory data, catheter duration, catheter indication, urinalysis/culture indication and if foley was appropriately removed/changed prior to specimen collection. A urinary catheter indication order was implemented in February 2021 requiring providers to select specific criteria for catheter placement/maintenance. In July 2023, the threshold for urinalysis to reflex to culture was increased to ≥10 WBCs and this criteria was applied to these cases to estimate the effect on diagnosis of CAUTI. Results: The most common indications for urinary catheters were input and output monitoring 76 (52%) and urinary retention/obstruction 34 (23%). No indication was entered on 22 (15%) patients. No difference was seen in the number of catheters without an indication before or after the 2021 order update. Mean catheter duration was 11.5 days with a median of 7 days. The most common indications for obtaining a urine specimen were leukocytosis/fever/sepsis 91 (63%), urinary symptoms/abdominal/flank pain 13 (9%), urine appearance 6 (4%), and altered mental status 4 (3%). In 31 (21%) patients, no indication was identified. A urinalysis with reflex to culture was completed in 105 (72%) and the catheter was removed prior to culture collection in 68 (47%). Of the 127 patients with a urinalysis and culture, 11 had 0-5 WBCs, 16 had 6-9 WBCs, 15 had 10-20 WBCs and 85 had >20 WBCs. Using the new pyuria criteria for urinalysis to reflex to culture, 27 (19%) CAUTIs could have been avoided. Conclusion: Review of CAUTI cases identified opportunities for improving documentation and education of appropriate indications for urinary catheters and evaluation of urinary tract infection. The majority of urine cultures were obtained due to non-specific symptoms and less than 10% had specific urinary symptoms indicating need for continued education and diagnostic stewardship. Increasing the pyuria threshold needed to reflex to culture has the potential to significantly reduce CAUTIs but additional education is needed to ensure catheters are changed prior culture collection and specimens are only sent when signs and symptoms of urinary tract infection are present.

Background: Clostridioides difficile PCR is extremely sensitive but cannot differentiate colonization versus active disease. Over diagnosis of C. difficile infection (CDI) has negative consequences including overuse of antibiotics targeting C. difficile, increased hospital-acquired (HA)-CDI rates, and increased healthcare costs. We describe the implementation of a Clinical Decision Support tool embedded in the C. difficile order and the result on testing, HA-CDI rates and healthcare costs. Methods: The C. difficile order was updated in June 2023 with 4 dynamic questions that reflex if specific criteria are identified in the electronic medical record in the prior 24 hours: less than 3 loose stools documented, receipt of laxative, opioid antagonist, oral contrast, or tube feed initiation. If any criteria are identified, an embedded alert triggers and the provider must choose “yes, high clinical suspicion” or “no (exit and cancel order)” in addition to providing an order indication. All inpatient C. difficile tests were reviewed from July 1 to Sept 30, 2022 (pre-update) and July 1 to Sept 30, 2023 (post-update). An order rate was calculated per 10,000 patient days as well as HA-CDI rate. Cost analysis was completed using direct lab costs and published costs of $35,000 per HA-CDI. Results of the order questions were reviewed post-update. Incident rate comparison was completed using medcalc. Results: Pre-update, 1147 tests were conducted, with an order rate of 104.3. Post-update, 919 tests were performed, with an order rate of 86.6. The positivity rate was 16.1% pre-update and 14.7% post-update. The incidence rate difference was 0.00177 (P 15 (145, 16%). 166 (18%) patients who received laxatives (18 positive, positivity rate 11%) were still tested. Conclusion: Implementation of a dynamic order led to a significant reduction in the total number of C. difficile PCR tests performed with associated reduction in HA-CDI and cost savings. Despite this, patients receiving laxatives were still being tested for C. difficile, highlighting the need for ongoing education and feedback. These results support the use of dynamic ordering for diagnostic stewardship, which can benefit both patients and hospitals.

Background: Whole genome sequencing (WGS) is a relatively new method for analyzing outbreaks and modes of transmission, particularly for multidrug resistant bacteria. This study sought to investigate clusters of patients with genetically related Vancomycin-Resistant Enterococcus spp. (VRE) bacteremia for shared hospital environmental exposures. Methods: All VRE blood culture isolates from patients from July 1, 2021 to June 30, 2022 underwent Illumina WGS. Core single nucleotide polymorphisms (SNPs) were identified, and multi-locus sequence typing (MLST) was performed across the VRE isolates. Clusters were defined as isolates with 15 or fewer core genome SNPs and were investigated for potential transmission routes. For each cluster, patients were evaluated in the 12 weeks before and after the first VRE isolate for shared hospital environmental exposures (hospital unit, patient rooms, procedural rooms, and radiology suites). Hospital units were comprised of patient rooms located geographically together on the same floor of the hospital. Results: A total of 82 VRE isolates underwent WGS. Thirty-eight (46%) clustered genetically with at least one other isolate. Clusters included 2 to 15 patients per group and represented 10 distinct MLST subgroups (Figure 1). Nine hundred and thirty-nine hospital environmental exposures were identified across the 38 patients. For each cluster, there was a total of 341 (36.3%) shared exposures. Shared environmental exposures occurred in radiology suites (35, 38.5%), patient rooms (32, 35.6%) and procedural rooms (23, 25.6%). Of the patients who shared the same hospital unit, 10 (31.3%) had the same patient room with 7 (70%) of them being in the emergency department (ED). Overall, the ED represented 7 (21.9%) of the shared hospital units. Each cluster had at least one shared hospital environmental exposure found. Conclusions: Use of WGS can help investigate outbreak clusters of resistant organisms such as VRE. In this study, nearly half of all VRE blood isolates were able to be segregated into clusters with at least one other isolate. Although VRE colonization of hospital rooms is well described, patient rooms represented the smallest proportion of shared hospital environmental exposures. This study thus suggests other environmental transmission routes such as radiology suites and procedural rooms warrant closer investigation.

A healthcare-associated group A Streptococcus outbreak involving six patients, four healthcare workers, and one household contact occurred in the labor and delivery unit of an academic medical center. Isolates were highly related by whole genome sequencing. Infection prevention measures, healthcare worker screening, and chemoprophylaxis of those colonized halted further transmission.

Background Patients undergoing revision total hip (THA) and knee (TKA) arthroplasties are at increased risk for surgical site infections (SSI) with prior infection representing a common indication for revision. Our aim was to evaluate patient characteristics and risk factors in patients with THA and TKA infection following revision arthroplasty. Methods A single center retrospective review of patients with THA or TKA SSIs from 01/01/2017 to 11/01/2022 was performed utilizing National Healthcare Safety Network (NHSN) definitions and surgical revision codes. Index surgery was defined as the THA or TKA to which the SSI was attributed per NHSN guidelines. Patients meeting NHSN PATOS (present at time of surgery) definition were excluded. Pertinent demographics data, surgical histories and microbiology were collected and the determination of new vs. persistent infection was made based on microbiologic data. Results Forty-seven cases were included with median age of 62, 45% male and 51% current/former smokers. BMI was ≥35 in 36% of patients, with 33% having diabetes mellitus and 13% were immunocompromised. Twenty-seven (57%) patients had a prior infection at the involved joint with 18/27 (67%) occurring within 1 year of the index surgery. Table 1 includes index surgery details and infection data. Median time to infection was 25 days. Leading pathogens were S. aureus 16 (34%), Enterococcus species 11 (23%), enterobacterales 10 (21%), and polymicrobial infections 10 (21%). Conclusion Over half of patients that developed revision THA/TKA SSI had a prior infection but less than 15% had a persistent infection. Most patients had multiple prior surgeries which may contribute to longer operative times and delayed wound healing. S. aureus was the most common pathogen identified but many cases involved less typical SSI pathogens. These results highlight the importance of focusing on patient specific risk factors, surgical infection prevention strategies and wound care, rather than additional pathogen specific antibiotics. While more study is needed to delineate SSI risk factors following revision arthroplasty, our study highlights the multitude of potential factors involved in these highly morbid infections. Disclosures All Authors: No reported disclosures

Background: Multidrug-resistant organisms (MDROs) are increasingly implicated in nosocomial outbreaks worldwide. We evaluated whole-genome sequencing (WGS) as an adjunctive epidemiological tool to identify infection clusters and MDRO transmission in the healthcare setting. Methods: Clinical isolates of carbapenem-resistant Enterobacterales (CRE) from July 1, 2021, to June 30, 2022, underwent Illumina WGS. Assembled genomes were taxonomically classified with GTDB-Tk software and were typed using multilocus sequence typing (MLST). Average nucleotide identity (ANI) was calculated between genomes. Numbers of differences among core single-nucleotide polymorphisms (SNPs) were calculated for pairs within taxonomic groups, and the data were evaluated in the context of patient dates and locations of care obtained from the electronic medical record. Results: In total, 39 CRE isolates underwent WGS (Fig. 1). Klebsiella pneumoniae represented the largest number of isolates (n = 18). Using MLST, 2 distinct groups of K. pneumoniae were identified (ST307 and ST258) with 5 and 4 isolates, respectively (Fig. 2). Within ST307, SNP differences ranged between 8 and 115. 3 isolates (CRE8, CRE10, and CRE12) were collected within 4 weeks of each other and had ≤26 pairwise SNP differences. Notably, CRE8 and CRE10 were located on the same unit at the same time and used the same MRI scanner on the same day. CRE35 had >95 SNP differences and was admitted 8 months prior to others in ST307 but had surgery in the same OR as CRE8. Within ST258, pairwise comparison of samples revealed 139–588 SNP differences. CRE21, CRE31, and CRE33 had SNP differences of ≤150. These patients were in the same hospital room (CRE33 and CRE21) and unit (CRE31 and CRE33), but they did not overlap temporally. CRE37 had >580 SNP differences, with no overlap in hospitalization dates or locations with other patients. Conclusions: Two closely related K. pneumoniae isolate populations were identified using WGS. Strong temporal and spatial commonalities were identified among isolates with few SNP differences. Isolate pairs with intermediate SNP differences shared spatial commonalities, suggesting possible indirect transmission between patients. No common exposures were identified for pairs with large numbers of SNP differences. WGS is an evolving tool to detect outbreak clonal populations of MDRO not identified through traditional epidemiologic techniques. WGS can provide insight into transmission patterns and the role of environmental contamination in propagating these nosocomial infections. More studies are needed to define the role and clinical significance of isolates with intermediate SNP differences in transmission of these pathogens between hosts and the healthcare environment. Disclosures: None