bluuebunny/crossref_metadata_2025 huggingface dataset:
585. Development of a Monitoring System for Quality Assurance of Antibiotic Susceptibility Testing in a Microbiology Laboratory
Authors: Lim Gabriel Fang Yih , Lee Wendy Bee Leng , Lee Kar Mun , Low Yuan Shen , Ng Kang Ren , Lim Iris Sing Pei , Yang Huina , Chia Jonathan
Published: November 2023

Background

Antibiotic susceptibility testing (AST) procedures are sensitive to variations in testing conditions. Our diagnostic laboratory is compliant with recommendations set out in Clinical and Laboratory Standards Institute (CLSI) M100 (33rd edition) and M02-A12 (12th edition). A perceived increase in weekly quality control (QC) failures prompted the development of an electronic monitoring system for quality assurance of antibiotic susceptibility testing.

Methods

Zone size data for each antibiotic-organism QC combination were entered on Microsoft® Excel®, and formatted to generate graphs. The data were collected for at least 6 months before and after implementation. This monitoring system allowed the observation of trends which prompted further reviews of laboratory processes.

Results

Persistent recurrent borderline results reflected on the monitoring system sparked the implementation of systematic investigations into QC failures; a replacement program for QC strains; and standardization of incubation timings and desiccant usage. Using new American Type Culture Collection (ATCC) reference strains reduced the percentage of QC antibiotic-organism data which failed or were borderline, and led to greater consistency in testing (see Figure 1). Visual presentation of QC data triggered greater reflection. For instance, recurrent failures of ertapenem disks against Pseudomonas aeruginosa ATCC 27853 led to acknowledgement from the manufacturer that the loss of disk potency was due to the shipment of disks nearing the end of shelf life (see Figure 2). The trends in cefepime zone sizes against P. aeruginosa ATCC 27853 also prompted an internal review and these improved when antibiotic disk dispensers were consolidated to improve disk utilization (see Figure 3).

Conclusion

Systemic monitoring of QC trends is low cost and highlights issues which were previously not apparent. Standardization of practices and a systematic troubleshooting process have improved the quality of our disk diffusion susceptibility testing.

Disclosures

All Authors: No reported disclosures
595. Recovery of Clostridioides difficile Isolates from Cary-Blair Transport Medium Compared to No Transport Medium
Authors: Skinner Andrew M , Petrella Laurica A , Sambol Susan P , Johnson Stuart , Czaja Christopher A , Johnston Helen , Basiliere Elizabeth , Dhonau Robin , Korhonen Lauren C , Paulick Ashley , Adamczyk Michelle , Guh Alice , Gargis Amy , Gerding Dale N
Published: November 2023

Background

Surveillance of C. difficile infection (CDI), one of the most common U.S. healthcare-associated infections, is essential to inform public health response, characterize strains causing disease, and describe changes in strain prevalence over time. The U.S. CDC’s Emerging Infections Program (EIP) has conducted active CDI surveillance, including culturing of C. difficile from a convenience sample of stool samples from cases, since 2009. Cary-Blair transport medium (CBTM) is used by some clinical laboratories for stool testing, but little is known about its impact on the recovery of C. difficile from culture.

Methods

We performed a cross-sectional study of the recovery of C. difficile isolates from C. difficile positive stools received 10/2021 – 10/2022 from Colorado and Georgia EIP sites. Stools were collected and stored within CBTM or within no transport medium per site protocols and subsequently frozen. Frozen samples were thawed and inoculated on taurocholate-cycloserine-cefoxitin-fructose agar plates (TCCFA) for recovery. Specimens from which C. difficile was not recovered on TCCFA plates were subjected to alcohol shock to enhance the recovery rates. We compared the recovery rates of C. difficile from stools in CBTM and stools in no transport medium.

Results

We cultured 825 stools from Colorado and Georgia, recovering C. difficile from 81.5% of stools. Overall, 412 (49.9%) stools were in CBTM and 413 (50.1%) were stools in no transport medium. Of those with known testing data, 410/410 (100%) CBTM stools vs 371/407 (91.2%) non-CBTM stools were C. difficile positive by PCR test (p< 0.01). Colorado stools accounted for 78% of the CBTM specimens. We recovered C. difficile on TCCFA plates from 59% (244/412) of stools in CBTM compared to 84% (348/413) in no transport medium (p< 0.01). After including alcohol shock results, C. difficile was recovered from 72% of CBTM stools, and 91% from stools in no medium (p< 0.01).

Conclusion

Cary-Blair transport medium may limit the recovery of C. difficile from culture and impact the ability to detect emerging strains. A large parallel study is needed to determine if these findings are reproducible and if stool collection methods should be standardized to maximize the recoverability of C. difficile by culture.

Disclosures

Andrew M. Skinner, MD, Academy for Continued Healthcare Learning: Honoraria|American Society of Healthcare Pharmacists: Honoraria|Ferring Pharmaceuticals: Honoraria|MJH Life Sciences: Honoraria Dale N. Gerding, MD, Destiny Pharma,: Advisor/Consultant|Sebela Pharma: Advisor/Consultant
600. Rapid Detection of Antibiotic Resistance Genes Direct from Whole Blood Samples by T2 Magnetic Resonance (T2MR®)
Authors: Wang Jin , Cacciatore Christopher , Snyder Jessica L , Noucas Heather , Smith Roger
Published: November 2023

Background

According to the Centers for Disease Control and Prevention (CDC), more than 2.8 million antibiotic-resistant infections occur in the US each year and more than 35,000 individuals die due to these infections. Rapid identification of drug resistance marker(s) in blood specimens may aid clinicians in getting patients on appropriate antimicrobial treatment early and decrease associated morbidity and mortality.

Methods

T2Resistance Panel is a qualitative, multiplex, T2MR assay designed to identify molecular markers of antimicrobial resistance in human whole blood specimens. The Panel detects thirteen molecular markers of resistance: blaKPC, blaCTX-M 14, blaCTX-M 15, blaNDM, blaVIM, blaIMP, blaOXA-48 Group, vanA, vanB, mecA, mecC, blaCMY and blaDHA. Bacterial isolates spiked into whole blood were used to evaluate analytical sensitivity, specificity and reactivity. When possible, testing utilized different bacterial species or gene variants. Assay performance was also assessed in the presence of potential interfering substances.

Results

The average time to result was approximately 3.5 hours. A Limit of Detection of < 20 CFU/mL was demonstrated for all resistance markers. The assay successfully detected drug resistance markers from genetically and geographically diverse strains. There was no cross reactivity observed, and the presence of common interferents did not affect the detection of drug resistance markers.

Conclusion

The T2Resistance Panel is a rapid and sensitive assay that detects 13 antimicrobial resistance markers directly from whole blood specimens. Rapid detection of these resistance markers may allow clinicians to provide targeted and effective antimicrobial therapy earlier to patients.

This project has been supported in whole or in part with federal funds from the Department of Health and Human Services; Administration for Strategic Preparedness and Response; Biomedical Advanced Research and Development Authority (BARDA), under contract number 75A50119C00053. The findings and conclusions in this presentation have not been formally disseminated by the Department of Health and Human Services and should not be construed to represent any agency determination or policy.

Disclosures

Jin Wang, PhD, T2 Biosystems, Inc.: Stocks/Bonds Christopher Cacciatore, BS, T2 Biosystems, Inc.: Stocks/Bonds Jessica L. Snyder, Ph.D., T2 Biosystems, Inc.: Stocks/Bonds Heather Noucas, MS, T2 Biosystems, Inc.: Stocks/Bonds Roger Smith, Ph.D., T2 Biosystems, Inc.: Stocks/Bonds
611. Increased isavuconazole loading dosage yields earlier attainment of serum target concentrations in critical ill patients with extracorporeal membrane oxygenation
Authors: Hatzl Stefan , Kriegl Lisa , Posch Florian , Meinitzer Andreas , Schilcher Gernot , Eller Philipp , Grinschgl Yvonne , Muhr Tina , Hoenigl Martin , Krause Robert
Published: November 2023

Background

Invasive fungal infections (IFI) are a major threat for critical ill patients admitted to the intensive care unit (ICU). Isavuconazole is a triazole antifungal agent recommended for treatment of invasive aspergillosis or mucormycosis. Both IFIs might complicate influenza or COVID-19 in ICU patients. Treatment of acute respiratory failure in those patients may require extracorporeal membrane oxygenation (ECMO). The appropriate dosage of selected antifungal drugs in ECMO patients is of utmost importance for successful antifungal prophylaxis or treatment of IFIs. Isavuconazole plasma concentrations < 1 µg/mL were reported in ECMO patients up to 24h after the first 200mg loading dose.

Methods

Critically ill ECMO patients receiving isavuconazole (first loading dose either 200mg, 300mg or 400mg, followed by isacuconazole administration as recommended) were included. Isavuconazole plasma concentrations were measured starting 2 h after the first isavuconazole loading dose up to 168 h.

Results

Out of 15 ECMO patients in total (median 62 years, range 47-64; 7 (47%) female) seven (46%) received standard isavuconazole loading regimen with 200mg as first dose, 3 (20%) received 300mg isavuconazole as first loading dose and 5 (34%) received 400mg isavuconazole as first loading dose. Twelve patients (80%) had veno-venous ECMO, 2 veno-arterial and one veno-arterial-venosus ECMO cannulation. The patients had a median paO2/FiO2 ratio of 76 (range 68-87) and sequential organ failure assessment score of 8.5. Three patients received isavuconazol for antifungal prophylaxis and 12 for treatment of IFI (Table 1). In comparison to patients receiving a first loading dose of 200mg or 300mg the median plasma concentrations in patients receiving the first loading dose of 400mg were significantly higher and constantly above 1µg/ml up to the first 24h. (Figure 1). No adverse effects related to isavuconazole were observed. No patient had isavuconazole concentrations ≥ 5µg/mL.

Isavuconazole plasma concentrations in ECMO patients

Isavuconazole plasma concentrations in ECMO patients at given timepoints after first isavuconazole dose. At dedicated isavuconazole administration timepoints, samples were obtained just before the next scheduled isavuconazole infusions.

Clinical and laboratory characteristics of the study population of 15 patients receiving isavuconazole and ECMO

Conclusion

Increasing the first loading dose of isavuconazole from 200 to 400mg led to a substantial increase in median isavuconazole plasma concentrations achieving ≥ 1µg/mL constantly after the first loading dose and was not associated with toxic side effects.

Disclosures

Robert Krause, MD, Pfizer: Grant/Research Support
612. Coccidioidal Pulmonary Cavitation: A New Age
Authors: Kooner Lovedip , Garcia Austin , Kaur Akriti , Sharma Rupam , Bustamanate Virginia , Narang Vishal , Berjis Amir , Munoz Augustine , Thompson George R , Kuran Rasha , Johnson Royce H , Heidari Arash
Published: November 2023

Background

The majority of literature on cavitary pulmonary coccidioidomycosis is from four decades ago which was prior to the advent of triazoles and focused on surgical treatment. This observational study is a comprehensive retrospective study of pulmonary cavitary coccidioidomycosis from patients at Valley Fever Institute at Kern Medical over the last 12 years. This observational study aims to explore the spectrum of coccidioidal cavities and the evaluation and management of those cavities.

Methods

IRB approved, retrospective review of electronic medical records of the Valley Fever Institute database was conducted. Demographics, comorbidities, types, and the number of cavities, complications, and medical and surgical treatment were gathered and compared to the literature. PubMed and Google Scholar were searched for cavitary pulmonary coccidioidomycosis

Results

Of the initially 276 identified patients, 137 met the inclusion criteria. This study found 52 (37.2%) patients with hemoptysis. One case (0.7%) required radiologic intervention to occlude the bleeding vessel, and one (0.7%) case of hemorrhage required right upper lobe lobectomy. Nine (6.6%) cases exhibited a ruptured cavity. Eight of those cases had initial chest tube placement, of which three (3/8, 37.5%) did not require surgical intervention. Seven of 137 (5.1%) cases presented with a pleural effusion not associated with a cavity rupture. Five (3.7%) were due to primary coccidioidomycosis. Three of the coccidioidal effusions required therapeutic thoracentesis, and none required a chest tube or surgery. The mean duration of the initial antifungal treatment was found to be 563 days (n=80). In 35% (28/ 80) of them, a triazole was switched to another triazole for variable reasons, including treatment failure or side effects.

Conclusion

Coccidioidal pulmonary cavitation remains a complex disease to evaluate and treat. This study's ethnic demographic differed from other cohorts. It also contradicts the notion that pulmonary coccidioidal cavitary disease and dissemination infrequently manifest in the same patient. In the present age of triazole therapy, indications and the need for surgery continue to decline. Further investigation needs to be conducted to evaluate medical therapy’s efficacy and long-term outcomes.

Disclosures

Rupam Sharma, PGY-1/MD, Astellas: Grant/Research Support George R. Thompson, III, MD, Astellas: Advisor/Consultant|Astellas: Grant/Research Support|Cidara: Advisor/Consultant|Cidara: Grant/Research Support|F2G: Advisor/Consultant|F2G: Grant/Research Support|Mayne: Advisor/Consultant|Mayne: Grant/Research Support|Melinta: Advisor/Consultant|Melinta: Grant/Research Support|Mundipharma: Advisor/Consultant|Mundipharma: Grant/Research Support|Pfizer: Advisor/Consultant|Pfizer: Grant/Research Support
620. Development and Validation of a Novel qPCR Assay for Differentiation of Common Candida Pathogens including C. auris
Authors: Thomas Clayton , Grantham James , Lute Emily , Davidson Jerod , Cowden Scott , Nutt Jamie
Published: November 2023

Background

Candida is a common asymptomatic fungal colonizer of humans. Of the 200+ total species in the genus Candida, only a few are known to cause infection. The most common are C. albicans, C. glabrata, C. parapsilosis, C. tropicalis, C. krusei, and C. auris. In the USA, candidemia is the fourth most common cause of bloodstream infections in hospitalized patients. Although antifungal medication can treat candidemia, mortality rates remain between 30 and 60%. Eurofins Viracor has developed a qPCR assay that will qualitatively detect and differentiate any of the 6 previously listed Candida species in whole blood. Speciation is critical for treatment due to variable drug susceptibility among different species, particularly C. auris due to its multi-drug resistance.

Methods

Multiple primer/probe mixes were designed around and within the ITS1, 5.8s, ITS2, and 28s ribosomal subunit regions in each of the six Candida target species. The 5.8s and 28s regions are heavily conserved, while the ITS regions are highly divergent and used to differentiate species. After optimization, the six primer/probe mixes were partially multiplexed resulting in four mixes covering all species. DNA was extracted from human blood spiked with viable Candida using the MagMAX™ DNA Multi-Sample Ultra 2.0 Kit, and eluates were amplified using the Applied Biosystems™ 7500 Fast platform.

Results

Each assay met all validation acceptance criteria and demonstrated excellent accuracy, precision, linearity and dynamic range, and sensitivity. 32 non-Candida fungal and bacterial pathogens that commonly cause bloodstream infections were used to assess specificity. All specificity samples were negative for all Candida targets. To assess accuracy, 75 of 75 Candida samples representing all six species across a range of concentrations were tested and correctly identified. 24 of 25 known-negative samples were negative, with one positive C. glabrata CT result observed just below the cutoff.

Conclusion

Traditional blood culture methods for Candida species identification can be too time consuming for a quickly progressing infection. The Candida qPCR assay described here not only detects an infection faster but provides accurate speciation allowing for rapid and targeted antifungal treatment options for the patient.

Disclosures

Clayton Thomas, BS in Biology, Eurofins Viracor: Employee James Grantham, n/a, Eurofins Viracor: Employee Emily Lute, n/a, Eurofins Viracor: Employee Jerod Davidson, n/a, Eurofins Viracor: Employee Scott Cowden, MS, MB ASCP(CM), Eurofins Viracor: Employee Jamie Nutt, n/a, Eurofins Viracor: Employee
624. Outbreak of Human Trichinellosis Linked to Bear Meat Infected with Multiple Trichinella Species — Arizona, Minnesota, and South Dakota, 2022
Authors: Cash-Goldwasser Shama , Ortbahn Dustin , Narayan Muthu , Fitzgerald Conor , Maldonado Keila , Maldonado Keila , Maldonado Keila , Straily Anne , Sapp Sarah , Watson Billy , Qvarnstrom Yvonne , Margaret Neja , Berman David , Park Sarah Y , Smith Kirk , Holzbauer Stacy
Published: November 2023

Background

In July 2022, the Minnesota Department of Health was notified of a patient with fevers, myalgias, periorbital edema, and eosinophilia; providers suspected trichinellosis. Human trichinellosis is rare in the United States and usually acquired from wild game meat. We investigated to confirm the diagnosis, ascertain additional cases, and identify the source of infection.

Methods

Trichinellosis was defined as compatible symptoms in a person who consumed an epidemiologically implicated meal (probable) or had Trichinella antibodies (confirmed). Blood samples from exposed persons were tested for Trichinella antibodies and with unbiased sequencing for microbial cell-free DNA. Microscopy and a parasite detection assay based on deep sequencing were performed on suspected source meat.

Results

One week before symptom onset, the patient and 8 relatives from 3 states shared a meal including meat from a bear harvested in Saskatchewan, Canada. The meat was frozen for 5 weeks until being grilled with vegetables and served rare. There were a total of 6 cases (4 probable and 2 confirmed, attack rate = 75%). Six persons had a trichinellosis-compatible illness, of whom five submitted samples for Trichinella antibody testing and two had positive results. Plasma samples from the two antibody-positive patients were tested for microbial cell-free DNA, and both were positive for Trichinella spp. DNA. Motile Trichinella species larvae ( >800 larvae per gram) were identified in bear meat frozen for 4 months. Deep sequencing detected 3 Trichinella genotypes, 2 of which matched reference sequences for T. nativa and Trichinella T6. The third genotype did not match any reference sequence; the closest match (94%) was Trichinella T9, which has only been detected in Japan.

Conclusion

We used multimodal diagnostic testing to characterize an outbreak of human trichinellosis and confirm bear meat as the source. Freezing kills Trichinella species commonly implicated in pork-associated outbreaks, but T. nativa and Trichinella T6 are freeze-resistant. Consumers of wild game meat should be informed that adequate cooking is required to kill Trichinella parasites. Further work on identification and classification of Trichinella species in North America is needed.

Disclosures

David Berman, DO, Precision Health Solutions, St. Petersburg, Florida: Advisor/Consultant
626. Antibiotic Stewardship Practices in hospitalized patients with Dengue in South India
Authors: Balasubramaniam Aishwarya , Dorairajan Sureshkumar , Chellapandian Yogavigneshwaran
Published: November 2023

Background

Antibiotics are commonly prescribed for upper respiratory viral infections, including COVID–19 infections worldwide. However, in the developing world, tropical viral infections like dengue, chikungunya, and zika are common causes of hospitalization throughout the year. But antibiotic prescribing behaviors for these infections were not studied well. Here, we are reporting the antibiotic prescribing practices for hospitalized patients with dengue in South India.

Methods

We conducted a retrospective analysis during the period of October 2022 to April 2023 at multiple tertiary care hospitals, involving serologically confirmed dengue (NS-1 antigen positive) fever patients in South India. Demographic data, laboratory parameters, antibiotic prescribing practices, supportive care treatment like papaya leaf extract tablets, and antibiotics on discharge were recorded using an audit tool. Descriptive statistics were used to analyze the data and the results were tabulated.

Results

During the study period 298 patients were admitted with confirmed dengue fever, other findings are listed in Table 1

Conclusion

Antibiotics were prescribed to 44% of hospitalized dengue patients and 41% of the patients were discharged with antibiotics. Doxycycline and cefixime were commonly prescribed antibiotics for the patients. Most (72%) of the dengue patients were receiving papaya leaf extract as a platelet-stimulating agent despite no evidence. In the future, antimicrobial stewardship practices in the developing world should focus on tropical infections apart from bacterial and fungal infections.

Disclosures

All Authors: No reported disclosures
630. SARS COV-2 genomic surveillance in Pakistan, an innovative approach
Authors: Ahmad Saeed , Idrees Fahmeeda
Published: November 2023

Background

Novel strains of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)harboring diverse gene mutations have periodically emerged and are spreading globally. Importantly, mutations within the spike gene's receptor-binding domain (RBD)are linked to SARS-CoV-2 transmissibility, disease severity, or decreased diagnostics vaccine efficacy. To identify SARS-CoV-2 variants rapidly,

Methods

we used a single primer-based PCR method in conjunction with Sanger sequencing. We focused on a region of the spike gene's RBD and S2 domains that contained lineage-defining mutational combinations.

Results

The genetic data obtained showed that delta and omicron subvariants were prevalent in the Khyber Pakhtunkhwa (KPK) region from January to February2022. Our survey found the highest prevalence of SARS-CoV-2 in the city of Peshawar (5.2%), followed by the districts of Mardan (1.8%), Karak (1.4%), Malakand(0.6%), and other districts.

Conclusion

We recommend that SARS-CoV-2 be monitored continuously to detect single-nucleotide polymorphisms (SNPs) that are causally linked to the emergence of new lineages. In resource-constrained settings, our method provides a rapid and cost-effective detection assay for SARS-CoV-2.

Disclosures

All Authors: No reported disclosures
633. Nanopore Sequencing and In-house Bioinformatic Pipeline for Rapid and Accurate Detection of NRTI, NNRTI, PI, and INSTI Drug Resistance Mutations
Authors: Salvaña Edsel Maurice , Arevalo Geraldine M , Dungca Niña Theresa , Alpay Riacarl , Schwem Brian
Published: November 2023

Background

Sanger-based sequencing (SBS) remains the gold standard for HIV-1 drug resistance testing (DRT). However, SBS output is still limited to an approximately 800-1000 bp read length. This is inadequate for amplifying the pol gene region that contains most of the clinically significant drug resistance mutation (DRM) positions, requiring separate steps for the protease (PR) and reverse transcriptase (RT) regions as is available in most commercial genotyping kits. Integrase (IN) gene is typically not sequenced, a major drawback since the WHO-recommended first-line treatment is now IN strand transfer inhibitor-based. We explore an alternative workflow for HIV-1 genotyping and DRT using the MinION sequencer to sequence a ∼2,800 bp amplicon covering PR and RT, and the first 224 codons of the IN region. This workflow also aims to reduce the turnaround time and cost of DRT.

Methods

Thirty samples (VL 3,160-3,520,000 copies/mL) previously tested for drug resistance underwent PCR amplification using customized primers targeting the pol gene. Agarose gel electrophoresis and library preparation (SQK-RBK110.96 kit, Oxford Nanopore Technologies) were then performed, followed by MinION sequencing. An in-house bioinformatic pipeline was used to analyze the sequencing data.

Results

MinION sequencing was able to detect all DRMs detected by SBS in all 27 samples and did not detect any DRMs in the ones without DRMs on SBS. A few additional DRMs undetected by SBS were detected by MinION sequencing which is expected since MinION is known to have higher minority variant sensitivity. Comparison of the resistance profiles showed that SBS and MinION sequencing are concordant with a kappa value of 95.8 interpreted as having perfect agreement (Landis & Koch, 1977). DRMs from IN could not be properly evaluated due to lack of positive SBS controls but will be assessed at a later time using deep-sequenced controls. The entire workflow from RNA extraction to data analysis for all samples was completed within 22 hours, significantly shorter than that of the WHO protocol for HIV-1 DRT. The projected cost per run is comparable with that of SBS with a more rapid turnaround time.

Conclusion

Our findings show that MinION sequencing and our in-house analysis pipeline can rapidly and accurately detect DRMs in HIV-1 positive patients.

Disclosures

Edsel Maurice Salvaña, MD, MSD: Advisor/Consultant|Pfizer: Advisor/Consultant
640. Efficacy of the Use of Bacteriophages to Combat Pectobacterium atrosepticum
Authors: Fabris Ian N , Kingett Melanie
Published: November 2023

Background

This inquiry aimed to investigate the potential of bacteriophages vB_PatP_CB3, vB_PatP_CB4, and vB_PatP_CB5 as methods for controlling the spread of Pectobacterium atrosepticum, a bacterial pathogen that causes black-leg disease and extensive crop damage.

Structure of Podovirus

Morphology of typical N4-like podovirus (Anatomy of an N4-like Podovirus phage, (adapted from Insight into DNA and Protein Transport in Double-stranded DNA Viruses: The Structure of Bacteriophage N4, J. McPartland, et al.))

Soft Rot in Potato

Pectobacterium atrosepticum infection in potato (Pectobacterium atrosepticum infection in Solanum tuberosum, the common potato (M. Kuznetsova All-Russian Institute of Phytopathology))

Methods

Phages were initially selected based on the location of isolation of the phage and its proximity to a field with a known current, or recent previous, Pectobacterium atrosepticum infection among potato crops. Phages were narrowed down by the specificity of their receptor-binding proteins for the protein receptors on the bacterium cell wall, as determined by FASTA sequence comparison between phage tail fiber RBPs and bacterial integral glycoproteins. A standard serial dilution and phage titration protocol in conjunction with a plaque assay were subsequently used to evaluate the efficacy of each phage, both individually and in a cocktail.

Plaque Assay Diagram

Standard plaque assay procedure used inoculate plates to obtain plaques

Results

Plaque assays showed that vB_PatP_CB5 produced a large number of plaques, indicating successful cell lysis and bacteriophage propagation within the bacterial colony. In contrast, vB_PatP_CB3 and vB_PatP_CB4 produced no measurable plaques.

Plaques on Bacterial Lawn

Observed plaque formation after initial 24 hour period

Plaque Charts from Trial 1

Plaque formation from trial 1

Plaque Charts from Trial 3

Plaque Charts from Trial 3

Conclusion

Based on these findings, it was concluded that vB_PatP_CB5 is the most effective at lysing and controlling growth of P. atrosepticum. These results have implications for the development of new phage-based treatments for black-leg disease and for limiting the associated crop damage.

Disclosures

All Authors: No reported disclosures
645. " Risk of Disease Severity and Disease Outcomes with Serotype-Specific Dengue Virus among Hospitalized Dengue Patients in a Tertiary Infectious Diseases Hospital: A Five-Year Retrospective Study"
Authors: San Diego Micaela J , SAYO A N A R I A A , EDRADA E D N A M
Published: November 2023

Background

Dengue fever is a significant cause of morbidity throughout the world caused by the dengue virus (DENV). Four antigenically different dengue virus serotypes (DENV-1,2,3, and 4) are known to cause infections in humans (Halsey,2012). Chances for developing dengue hemorrhagic fever-dengue shock syndrome increases significantly with history of previous infection with one of the four serotypes.

Methods

A retrospective study of hospitalized dengue patients in span of five years was done. One-hundred forty three (143) patients aged

>19 years admitted due to fever, positive for NS1 antigen and with DENV serotype results were included. Clinical data were extracted from medical records including demographics, co-morbidities, clinical presentation, laboratory investigations, length of hospital stay and outcome.

Results

Out of the 143 adult dengue patients, the most prevalent serotype was DENV 3 at 64.34% followed by DENV 2 (18.18%), DENV 1 (11.19%), with DENV 4 as the least prevalent serotype (6.29%). In terms of clinical manifestations, the most prevalent symptoms were fever (98.60%), myalgia (78.32%), body malaise (69.23%), headache (59.44%), nausea and vomiting in 42.66%. Majority tested positive for Dengue NS1 (87.94%), with more than half testing positive for Dengue IgG at 54.24%. The adjusted risk for dengue with warning signs for DENV-2 was 5.94, indicating that the risk of dengue with warning signs was 5.94 times higher among those with DENV 2 than those with DENV 1; however, the association was not statistically significant. Results showed that the ARR for serotypes 3 and 4 for all dengue severity categories were not statistically significant (p>0.05). The clinical outcome of patients was recovery at 98.60%, with only 1.40% mortality. Comparative analyses indicated that the clinical management and outcomes of the patients did not significantly differ according to dengue virus serotype (p>0.05).

Conclusion

This study provided more information on the dengue serotypes, its effect on severity and outcome of the disease. Infecting dengue serotype play an important role in disease severity among adult dengue patients in the Philippines.

Disclosures

All Authors: No reported disclosures
649. Expansion Of A Low-Cost, Open-Source, Saliva-Based PCR Test For The Detection Of Mpox Virus
Authors: Thomas Russell , Yolda-Carr Devyn , Steel Sydney A , Tobik Emily R , Zepeda Theresa , Brownlee Maurice , Saladi Shyam , Parkin James , Fajardo Katherine , Allicock Orchid M , Wyllie Anne L
Published: November 2023

Background

Clinical diagnosis of mpox (monkeypox) virus relies on lesion swabs. Many patients experience prodromal symptoms prior to lesion-onset. Earlier detection could bolster outbreak response by mitigating transmission and facilitating access to antiviral treatments. With a growing number of studies reporting mpox detection in saliva, we adapted our saliva-based, extraction-free PCR test developed for SARS-CoV-2, for the detection of mpox virus.

Methods

We first compared five PCR assays for their detection of mpox DNA extracted from 30 saliva specimens collected into Spectrum SDNA-1000 tubes. Next, we investigated the stability of mpox detection in five raw, unsupplemented saliva samples diluted 1:5 in mpox-negative saliva, after storage at 4°C, ∼19°C (room temp.), 30°C, and 40°C for 72 hours. We also examined the stability of virus detection in three samples as per the FDA guidance for shipping of samples for testing. Additionally, we performed amplicon sequencing on 10 saliva samples and assessed concordance of the PCR assays against mpox virus sequences.

Results

The Logix Smart™ Mpox (2-Gene) RUO (Co-Diagnostics, Inc.) performed better at detection. Despite identifying three different substitutions in the CDC’s Monkeypox Virus Generic Real-Time PCR Test’s primers, results from ANOVA did not suggest a mean difference in cycle threshold values between assays. Detection following storage at 4°C, ∼19°C, and 30°C remained relatively stable for 24-48 hours but this declined by 72 hours. At 40°C, detection was stable at 24 hours but declined by 48 hours. Detection following simulated summer and winter shipping temperature profiles also remained stable.

Conclusion

Findings of this pilot investigation support a flexible, extraction-free, saliva-based PCR test as a promising approach for the low-cost detection of mpox virus. With stability observed for 24-48 hours as well as over simulated shipping temperatures, saliva-based sampling and simplified testing could reduce mpox diagnostic costs, increase access to testing and address hurdles in low- and middle-income countries. Future studies should assess the temporal dynamics of mpox virus in saliva.

Disclosures

Shyam Saladi, n/a, Neelyx Labs: Ownership Interest|SalivaDirect Inc: Board Member James Parkin, PhD, Neelyx Labs: employee Anne L. Wyllie, PhD, Co-Diagnostics: Board Member|Merck: Grant/Research Support|Pfizer: Advisor/Consultant|Pfizer: Grant/Research Support
652. Foodborne outbreak investigation at a wedding event – Batken, Kyrgyzstan, June 2022
Authors: Dautov Timur , Kemelbek Nasyat , Malisheva Marina , Otorbaeva Dinagul , Horth Roberta , Nabirova Dilyara
Published: November 2023

Background

On August 2nd, 2022, local health departments were informed that over a hundred people had sought care or reported gastrointestinal illness after attending the same wedding event in Batken, Kyrgyzstan, on July 30th. We investigated to identify the source and associated risk factors to stop transmission.

Methods

Using a retrospective cohort study design, we interviewed consenting wedding participants. A case was anyone who was linked to the event who became acutely ill or sought medical care with food poisoning symptoms. We searched public health surveillance records for additional cases who sought healthcare for suspected foodborne disease, a reportable illness, from July 30th to August 2nd. Food and environmental samples were collected and tested. We used logistic regression to determine associations with case status.

Results

Of 250 attendees, 201 consented; 110 were cases and 91 non-cases. Among cases, 8%were < 20 years old, 27% were >61 years old, and 80% were female. Top symptoms were fatigue (96%), abdominal pain (95%), diarrhea (95%), and fever (84%). Most cases developed symptoms < 24 hours of the event and 79% sought care. Odds ratio was 7.8 for egg salad containing chicken (95% confidence interval [CI]: 4.1-14.4, p< 0.01), 5.1 for grilled chicken (CI: 2.8-9.4, p< 0.01) and 3.9 for chicken salad (CI: 2.2-7.1, p< 0.01). Attack rate was 66% (105/160) among people who ate any chicken (95% of cases and 60% of non-cases). Patients were not tested. Proteus vulgaris, Klebsiella spp., and Escherichia coli were detected in chicken samples. E. coli was detected in 3/32 environmental samples.

Conclusion

Contaminated chicken was the likely source of illness. Source pathogen is uncertain because patients were not tested. Symptoms and onset were more consistent with Klebsiella spp. than E. coli, but Klebsiella spp food-associated outbreaks are rare. Recommendations were made to ensure restaurant compliance with food safety measures. Diagnostic testing for gastrointestinal illness needs strengthening.

Disclosures

All Authors: No reported disclosures
658. Oral Vancomycin Taper for First Occurrence of Clostridioides difficile Compared to Standard of Care: An Observational Retrospective Matched Cohort Study
Authors: Moore Sarah E , Swingler Elena A , Song Matthew , Wilde Ashley M
Published: November 2023

Background

Clostridioides difficile infection (CDI) recurrence rates may be reduced with fidaxomicin, but financial barriers can limit access. Tapered and/or pulsed oral vancomycin is recommended in patients with recurrent CDI, however there is currently limited data for use in treating initial CDI.

Methods

Multicenter retrospective propensity-matched cohort study in patients ≥ 18 years old hospitalized with a first occurrence of CDI from 6/18/2018 – 12/21/2021 conducted at Norton Healthcare in Louisville, Kentucky. Standard of care (SOC) was receipt of oral vancomycin for 10-14 days compared to a standardized oral vancomycin taper (Figure 1). Subjects were matched based on age < or ≥ 65 and receipt of non-CDI antibiotics during index hospitalization or within 6 months post-discharge. Selected baseline characteristics and receipt of CDI and non-CDI antibiotics were collected. Non-CDI antibiotics were stratified by high, medium or low risk for CDI. The primary outcome was CDI recurrence within 6 months of hospital discharge. Secondary outcomes included time to recurrence, recurrence rates stratified by age group < or ≥ 65 years, CDI severity of illness per IDSA guidelines and all-cause mortality within 6 months of hospital discharge. Categorical variables were analyzed using Chi-squared and Fisher’s exact tests as appropriate.

Standardized Oral Vancomycin Taper

Results

Recurrence rates at 6 months were 5.3% (4/75) in the taper arm and 28% (21/75) in the SOC arm (p=0.002). All-cause mortality was 20% (15/75) in the taper arm and 5.3% in the SOC arm (p=.026). Severe/fulminant CDI occurred in 49.3% of the taper arm and 58.7% of the SOC arm (p=0.53). Both groups received antibiotics at the same rate based on matching, and rates of antibiotics considered high risk for CDI were similar at 65% in the taper and SOC groups (65% vs. 61.3%, p=0.809). More patients in the taper arm were immunocompromised (25.3% vs 9.3%, p=0.029).

Conclusion

A significantly lower rate of CDI recurrence was observed at 6 months with tapered oral vancomycin coupled with higher all-cause mortality in patients being treated for first CDI. Additional information is needed to elucidate the clinical utility of this approach.

Disclosures

Ashley M. Wilde, PharmD, BCIDP, Pfizer: Grant/Research Support
659. Geographical Clustering of the Likelihood of Treatment in Histologically Diagnosed Helicobacter pylori in the BOSTON-HP Cohort
Authors: Noriega Marco , Lee Christina , Feuerstein Joseph , Bonilla Silvana , Flier Sarah , Villafuerte-Gálvez Javier
Published: November 2023

Background

The BIDMC Optimization & Standardization for Treatment Outcomes in New England for Helicobacter Pylori (BOSTON-HP) study included 1002 patients with confirmed Helicobacter pylori (HP) via gastric histopathology from 2016-2022 to evaluate the effects of a Multidisciplinary Division Wide Program. Our previous data showed that demographic factors, such as race/ethnicity and preferred language, are associated with treatment, test-of-cure, and eradication outcomes. We hypothesize that given an unlikely even geographic distribution of demographic factors, HP outcomes may cluster geographically.

Methods

The BOSTON-HP cohort patient addresses were transformed to georeferenced coordinates which were mapped using QGIS (3.30 's-Hertogenbosch) onto OpenStreetMap. We calculated the maximum Euclidean distance matrix to assign heatmap weights for each outcome, and calculated global spatial autocorrelation to evaluate the extent of spatial clustering.

Results

Eight hundred and sixty-eight patients (86.6%) received treatment with confirmed eradication in 416 (47.9%) of them. A statistically significant positive spatial autocorrelation of clusters (Moran’s I = 0.080, p =0.003, z=2.787) was observed for the likelihood of treatment. Layering transportation and healthcare units revealed key clustering patterns (see Figures 1. & 2.). Clusters in the vicinity of Longwood Medical Area (LMA), and South Cove Medical Center (SCMC) were more likely to receive treatment, while those in the Brighton collegiate area (BCA) and along the Red Line Axis in Roxbury-Dorchester (RLRD) were less likely to receive treatment. Test-of-cure and eradication success were not statistically significant for clustering (Moran’s I = 0.007, p =0.388, z=0.284) (Moran’s I = 0.006, p =0.441, z=0.149), respectively.Figure 1. BOSTON-HP Treatment Cohort.Figure 2. Untreated in the BOSTON-HP Cohort.

Conclusion

A moderate and significant spatial correlation existed between the likelihood of HP treatment and the geographic location of the patient’s residence. Identification of groups for targeted quality improvement interventions (RLRD) and models of success within the system (SCMC) can help improve treatment outcomes and reduce geographic disparities.

Disclosures

Javier Villafuerte-Gálvez, MD, Milky Way Biosciences: Partial Research Support.
670. Clinical Characteristics and Outcomes in Patients with Healthcare Facility-Onset Clostridiodes difficile Infections
Authors: Joshi Seema , Alvi Rija B R , Shanahan Clare , Ruby Abigail , Chami Eman , Suleyman Geehan
Published: November 2023

Background

Healthcare facility-onset (HCFO) Clostridiodes difficile infection (CDI) is the most common hospital-acquired infection. Although risk factors associated with CDI have been described, characterization and outcome of HFCO-CDI are limited.

Methods

This was a retrospective observational study comparing disease severity among adult patients with HCFO-CDI from January 1, 2020, to December 31, 2022, at an 877-bed tertiary care hospital in Detroit. Patients were identified using National Healthcare Safety Network (NHSN) definition. CDI was classified as nonsevere, severe, or fulminant. Severe disease was defined as having white blood cell (WBC) count ≥ 15,000 cells/mm3 or acute kidney injury (AKI) defined as increase in creatinine of ≥ 0.3mg/dL within 48 hours of diagnosis. Fulminant disease included patients with ileus or toxic megacolon, or need for colectomy, intensive care unit or vasopressors. Risk factors, treatment and outcomes were evaluated.

Results

98 patients were diagnosed with HFCO CDI during the study period (Table 1); 37 (38%) were non-severe, 47 (38%) severe and 14 (24%) fulminant. Median age was 66 years, 50% were female and 45% white. Almost half were immune suppressed; 5% had prior CDI. Most patients (88%) were exposed to antibiotics (abx) prior to CDI with no difference between the groups (p=0.427); 61% received cephalosporins. Cirrhosis was more common among patients with fulminant disease (p=0.048) and receipt of chemotherapy was associated with severe and/or fulminant disease cases (p=0.049). AKI (p< 0.001), fever (p=0.030), and WBC >25,000 or < 2,000 cells/mm3 (p< 0.001) were more prevalent among patients with fulminant CDI; combination or alternative therapy was more common among fulminant cases (p< 0.001). Most were eligible, but only 6% received bezlotoxumab (BZX). Although outcomes were not significantly different between the groups, length of stay was longer and refractory disease and recurrence were more common in severe/fulminant CDI.

Conclusion

In our HCFO-CDI cohort, most patients were exposed to abx, and cirrhosis and chemotherapy were associated with more severe CDI. Efforts should focus on appropriate abx utilization and increasing use of BZX to reduce burden of CDI and risk of recurrence and readmission.

Disclosures

All Authors: No reported disclosures
675. The Fidaxomicin Cascade: Analysis of Success Rates and Barriers of Fidaxomicin Discharge Prescriptions for Inpatients Diagnosed with Clostridiodes Difficile
Authors: Cook Ellen , Mehta Jigar , Blecher Alexis L , Lee Matthew S
Published: November 2023

Background

Current IDSA guidelines prefer Fidaxomicin for initial and first recurrent Clostridiodes difficile (C. difficile) infection. A barrier to increasing Fidaxomicin usage has been the medication’s potential high co-pay. The objective of this study was to evaluate the discharge success rate and financial/co-pay barriers for inpatients initiated on Fidaxomicin at our institution.

Methods

Our cohort consisted of inpatients that received Fidaxomicin for the treatment of C. difficile during 2022. For inpatient discharges, a transitions of care (TOC) pharmacy evaluation is available for high co-pay medications. Charts were retrospectively reviewed for demographic, clinical, insurance, and pharmacy data.  The primary outcome was the proportion of patients successfully discharged on Fidaxomicin. Secondary outcomes included proportion of patients with co-pays >$50 and direct out-of-pocket patient cost after TOC pharmacy intervention.

Results

29 patients were initiated on Fidaxomicin for CDI treatment in 2022. The majority of patients had Medicare (62%), a prior history of CDI (75%), were immunocompromised (55%), and met non-severe IDSA criteria (62%) (Table 1). 7% (2/29) switched to oral vancomycin early due to ID consult or stewardship recommendations and 28% (8/29) completed the course prior to discharge (Figure). All the remaining patients (19/19) discharged to extended care or home were able to be discharged on Fidaxomicin.

74% (14/19) of patients discharged on Fidaxomicin had TOC pharmacy evaluations with co-pay data available (Figure). 50% of these patients (7/14) had high co-pays (Figure) with a mean co-pay of $470.25 (range $65-1384.95) (Table 2). The majority (5/7) of the “high co-pay” group had Medicare; three Medicare patients had out-of-pocket cost reduced after TOC pharmacy intervention (Table 2). Post-TOC intervention, the mean patient out-of-pocket cost was $181.20 (range $0-566.44).Table 1:Patient Demographic and Clinical DataTable 2:“High Co-Pay” Patient Group (defined as Co-Pay > $50)Figure:Fidaxomicin Prescribing Cascade

Conclusion

All inpatients continued on Fidaxomicin for the treatment of C. difficile were able to be “successfully” discharged with the medication. However, the co-pay remains potentially high for certain individuals, particularly those with Medicare and prolonged tapers. TOC pharmacy evaluations, if available, are critical for financial assistance prior to discharge.

Disclosures

All Authors: No reported disclosures