bluuebunny/crossref_metadata_2025 huggingface dataset:
637. Outcomes by Body Mass Index (BMI) in the STRIVE Phase 2 Trial of Once-Weekly Rezafungin for Treatment of Candidemia and Invasive Candidiasis Compared with Caspofungin
Authors: Vazquez Jose A , Flanagan Shawn , Pappas Peter , Thompson George R , Sandison Taylor , Honore Patrick M
Published: January 2021

Background

There is increasing evidence of antifungal underdosing in the treatment of invasive disease, particularly in special populations such as the obese. Body size is often an important variable affecting drug exposure, and pharmacokinetic (PK) models of antifungal dosing have suggested size-based dose adjustments to achieve target drug exposure.

Rezafungin (RZF) is a novel echinocandin in Phase 3 development for treatment of candidemia and invasive candidiasis (IC) and for prevention of invasive fungal disease caused by Candida, Aspergillus, and Pneumocystis in blood and marrow transplant recipients. Distinctive PK properties of RZF (e.g., long half-life, extensive tissue distribution, and front-loaded drug exposure) lend themselves to RZF once-weekly (QWk) dosing and antifungal efficacy. In this sub-analysis of the Phase 2 STRIVE trial of RZF in the treatment of candidemia and/or IC, outcomes based on patient BMI were evaluated.

Methods

The STRIVE trial (NCT02734862) compared the safety and efficacy of RZF QWk compared with once-daily caspofungin (Fig. 1). For this subanalysis, data were stratified by BMI categories of < 30 kg/m2 and ≥ 30 kg/m2. Efficacy (overall response [resolution of clinical signs of infection + mycological eradication], mycological response, and investigator assessment of clinical response) and safety (treatment-emergent adverse events [TEAEs]) endpoints by treatment group were evaluated, as well as PK data (area under the curve [AUC]) from RZF-treated patients.

Figure 1.

Results

Mean BMI values were similar across treatment arms (26.9 kg/m2 in RZF Group 1 and 26.8 kg/m2 in RZF Group 2 and CAS arms). Efficacy outcomes at Day 14 were similar between BMI categories (Table 1). Rates of TEAEs were generally similar between BMI categories as well (Table 2), with no concerning safety trends. Following one dose of RZF 400 mg (Week 1), the ranges of AUCs by BMI category overlapped and there was a minor mean difference of ~20% (lower for those with BMI ≥ 30 kg/m2) (Fig. 2).

Table 1

Table 2

Figure 2.

Conclusion

The safety, efficacy, and PK of RZF in the Phase 2 STRIVE trial was consistent across BMI categories. These results suggest that dose adjustments in obese patients are not necessary. These findings contribute to the evaluation of RZF in a range of patient populations and its ongoing development.

Disclosures

Shawn Flanagan, PhD, Cidara Therapeutics, Inc. (Employee, Shareholder) Peter Pappas, MD, SCYNEXIS, Inc. (Consultant, Advisor or Review Panel member, Research Grant or Support) Taylor Sandison, MD, MPH, Cidara Therapeutics, Inc. (Employee, Shareholder) Patrick M. Honore, MD, PhD, FCCM, Cidara Therapeutics, Inc. (Scientific Research Study Investigator)
639. Short Course Therapy for Urinary Tract Infections (SCOUT) in Children
Authors: Zaoutis Theoklis , Bhatnagar Sonika , Black Stephen I , Coffin Susan E , Coffin Susan E , Downes Kevin J , Fisher Brian T , Fisher Brian T , Gerber Jeffrey , Green Michael D , Lautenbach Ebbing , Liston Kellie , Martin Judith , Muniz Gysella , Myers Sage R , O’Connor Shawn , Rowley Elizabeth , Shaikh Nader , Shope Timothy , Hoberman Alejandro
Published: January 2021

Background

The AAP recommends 7 to 14-days of antimicrobials for the treatment of urinary tract infections (UTIs), one of the most common bacterial infections of childhood. However, most physicians routinely prescribe at least 10 days of therapy. Prior observational studies suggest that courses shorter than 10 days might be effective.

Methods

The primary objective was to determine if halting antimicrobial therapy in children who improved clinically after 5 days of therapy (short course therapy) results in a similar failure rate as children who continue antimicrobials for an additional 5 days (standard course therapy).

This was a multi-center, randomized, double-blind, placebo-controlled non-inferiority clinical trial of children ages 2 to 10 years with UTI. Subjects treated with 1 of 5 antibiotics (trimethoprim-sulfamethoxazole, amoxicillin-clavulanate, cefixime, cefdinir or cephalexin) were eligible. Children were stratified by presence or absence of fever and were enrolled if they had clinical improvement before Day 5 of treatment. The a priori equivalence interval was set at 0.05 for a one-sided analysis. The primary outcome was development of a symptomatic UTI defined as the presence of symptoms, pyuria, and a positive urine culture. The Intent-to-Treat population included children who took at least one dose of study medication.

Results

A total of 693 children were randomized, 345 to short course and 348 to standard course. Median age was 4 years old (IQR; 2-6), 652 (96.3%) were female and 255 were febrile (37%). Treatment success rate was 322/336 (96%) for short course and 326/328 (99%) for standard course. The 95% upper CI limit for the difference was 0.054. Treatment failure was not related to age group, fever at presentation, antibiotic type, or study site. There were no significant differences between groups the in the rates of adverse events, recurrent infection, clinical symptoms that may have been related to UTI, or emergent antibiotic resistance.

Conclusion

In children aged 2 months to 10 years with UTI, halting antimicrobial therapy in children who had exhibited clinical improvement after 5 days and continuing for an additional 5 days both resulted in high success rates. However, short course was inferior to treatment for 10 days.

Disclosures

Kevin J. Downes, MD, Merck, Inc. (Grant/Research Support) Brian T. Fisher, DO, MPH, MSCE, Astellas (Advisor or Review Panel member)Merck (Grant/Research Support)Pfizer (Grant/Research Support)
644. Borrelia miyamotoi and Borrelia burgdorferi Seroprevalence in New England
Authors: Johnston Demerise , Kelly Jill , Ledizet Michel , Lavoie Nathalie , Krause Peter J
Published: January 2021

Background

Diseases vectored by the tick species Ixodes scapularis have increased in incidence over the past 50 years and have been expanding into previously non-endemic areas. The emergence of Borrelia miyamotoi, a recently described spirochetal pathogen, has been less well documented than that of Borrelia burgdorferi, the causative agent of Lyme disease. The objective of this study was to compare the geographic range of human exposure to B. miyamotoi and B. burgdorferi in New England, the pattern of their spatial expansion, and factors that influence their frequency.

Methods

Serum samples were collected from 11 study sites across New England. Age, gender, race, and residential zip code or county were recorded for each study participant and aggregate data analyzed by study sites, study site zones, and residential county for spatial analysis. Serum samples were tested for B. miyamotoi antibody using a multiplex Luminex assay and for B. burgdorferi antibody using a recently FDA approved two-tiered ELISA (Zeus ELISA Test Systems). Fischer exact tests and map visualizations in ArcGIS Pro 2.4.2 (Copyright ©2019 Esri Inc.) were used to determine spatial distribution of human B. miyamotoi and B. burgdorferi infection in New England. A logistic regression model was used to determine any association in seropositivity with tick-borne infection risk factors.

Results

B. burgdorferi seroprevalence was greater than that of B. miyamotoi at all but one study site. The average B. burgdorferi seroprevalence at all study sites was not quite double that of B. miyamotoi (mean 2.3% [0.6-6.2%] and mean 4.1% [2.2-7.5%], respectively). No longitudinal or latitudinal gradient was observed for B. miyamotoi or B. burgdorferi seroprevalence by study site zone or county analysis. Men were twice as likely as women to be seropositive for B. miyamotoi and B. burgdorferi.

Conclusion

Human exposure to B. miyamotoi and B. burgdorferi is highly dispersed throughout New England. B. miyamotoi seroprevalence is about half that of B. burgdorferi in New England. Additional studies are needed to explain the disparity between B. burgdorferi and B. miyamotoi infection and disease.

Disclosures

All Authors: No reported disclosures
647. Adoption of the updated fluoroquinolones breakpoints for Gram negative bacteria in clinical microbiology laboratories
Authors: Sfeir Maroun M
Published: January 2021

Background

Despite the multiple safety warnings related to fluoroquinolones (FQs) treatment, their use remains unavoidable in several occasions due to their broad spectrum of coverage including activity against multi-drug resistant glucose non-fermenting Gram-negative bacteria such as Pseudomonas spp., and high oral bioavailability. The Clinical and Laboratory Standards Institute (CLSI) has lowered the FQs minimal inhibitory concentrations (MICs) breakpoints for Salmonella spp. in 2012 and 2013, and for the Enterobacterales and P. aeruginosa in 2019. We aim to explore the number of hospitals that adopted the revised breakpoints.

Methods

We conducted a cross-sectional phone-based survey querying the 43 microbiology laboratories that serve 100% of the acute care and long-term hospitals in Connecticut to determine use of revised FQs MIC breakpoints for Gram-negative bacteria.

Results

Six laboratories refer antimicrobial susceptibility testing to another local hospital microbiology laboratory or to a national reference laboratory. Thus, we obtained information about the study question from a total of 37 microbiology laboratories. Eight laboratories (21.6%) were affiliated to university hospitals and 29 (78.4%) were community-based. Microscan Beckman coulter MicroScan was the most common antimicrobial susceptibility test method used in 15 (40.6%) microbiology laboratories followed by BioMérieux Vitek 2 in 13 (35.1%) laboratories. Four laboratories (10.8%) only adopted the revised CLSI FQs breakpoints for Enterobacterales, P. aeruginosa, and Salmonella spp, 5 (13.5%) implemented the revised breakpoints for Enterobacterales and P. aeruginosa but not for Salmonella spp., and 8 (21.6%) laboratories adopted the revised CLSI breakpoints for Salmonella spp. but not for Enterobacterales and P. aeruginosa.

Conclusion

The use of outdated CLSI breakpoints for FQs against Gram-negative bacteria remains common in the microbiology laboratories. There is an urgent need to mitigate the impact of using the outdated FQs breakpoints and reporting false susceptibility to FQs.

Disclosures

All Authors: No reported disclosures
648. BioFire® FilmArray® Pneumonia plus Panel Performance Evaluation: A Multicenter, International Collaborative Study
Authors: Ginocchio Christine C , Mauerhofer Barbara , Rindlisbacher Cory , Garcia Carolina
Published: January 2021

Background

Classical methods to identify causes of community acquired, healthcare and ventilator associated pneumonia can be insensitive and slow, leading to unnecessary or inappropriate antimicrobial therapy. The BioFire® FilmArray® Pneumonia plus Panel (PNplus) detects 15 bacteria (in semi-quantitative log bin values from 10^4 to > 10^7), 7 antibiotic resistance markers (mecA/C/MREJ, CTX-M, KPC, VIM, IMP, NDM, OXA-48 like), 3 atypical bacteria (AB), and 8 viral classes directly from bronchoalveolar lavage (BAL)-like and sputum-like specimens (including endotracheal aspirates) in about 1 hr. This study compared PNplus results to standard of care testing (SOC).

Methods

2476 samples (1234 BAL-like; 1242 sputum-like) were tested at 52 laboratories from 13 European countries and Israel by PNplus and SOC. SOC varied by site and physician prescription. Pathogen detection rates were compared. PNplus bin values and SOC descriptive or numerical quantities were evaluated for 1297 bacterial detections.

Results

13 samples (0.5%) gave invalid PNplus results. 3278 bacteria in PNplus were detected by PNplus and/or SOC. SOC detected 1878 bacteria (57.1%) compared to 3128 bacteria (95.8%) for PNplus (p=< 0.0001). SOC detected 73 AB (70.9%) and 134 viruses (21.1%), PNplus detected 93 AB (90.3%) and 618 viruses (97.9%) (p=< 0.0001). Mean number of analytes/sample detected by PNplus and SOC were 1.99 and 1.44, respectively. PNplus bin values were less than SOC, equal to SOC or greater than SOC in 5.9%, 25.4% and 69.6% of results, respectively. PNplus values were on average > 1 log than SOC values (58.5% 1-2 logs; 11.0% 3-4 logs). PNplus identified 98.2% of MRSA and SOC 55.6%. All gram-negative resistance markers were detected at least once. PNplus and SOC results were fully concordant (positive or negative) or partially concordant for 49.1% and 26.4% of samples, respectively.

Conclusion

PNplus detected significantly more potential pathogens than SOC. Lack of routine SOC viral testing was a missed opportunity to define the cause of pneumonia. Semi-quantification may assist in understanding the significance of the pathogens detected. Pathogen and resistance marker detection in about 1 hr could dramatically impact antimicrobial use and enhance patient outcomes.

Disclosures

Christine C. Ginocchio, PhD, MT(ASCP), bioMerieux (Employee)bioMerieux (Employee, Shareholder) Barbara Mauerhofer, Pharmacist, bioMerieux (Employee) Cory Rindlisbacher, n/a, BioFire Diagnostics (Employee) Carolina Garcia, BS, bioMerieux (Employee)
650. Clinical Performance Evaluation of Virtuo Blood Culture System in a Tertiary Care Hospital
Authors: Chavez Miguel A , Munigala Satish , Burnham Carey-Ann , Yarbrough Melanie L , Warren David K
Published: January 2021

Background

Bloodstream infections are a major cause of morbidity and mortality. BACT/ALERT VIRTUO (VIRTUO) blood culture system is an automated, closed system used with resin-containing media which may enhance the growth of microorganisms. Our objective was to assess the real-world performance of the VIRTUO system.

Methods

We retrospectively reviewed all blood cultures performed between January-December 2018 (VersaTREK) and January-December 2019 (VIRTUO) at a 1250-bed academic medical center. Blood culture positivity rates, contamination rates, and time from collection to arrival in the laboratory were compared pre- versus post-VIRTUO implementation. Contamination was defined as a single blood culture with common skin microbiota.

Results

A total of 101803 blood cultures were performed during the study period: 48969 (48.1%) were processed with VersaTREK system and 52834 (51.9%) with VIRTUO system. A decreased median time from collection until arrival to the laboratory was seen post-implementation (2.0 pre- vs. 0.8 hours post-implementation, p< 0.001). The positivity rate increased from 3987 (8.1%) pre-implementation to 6141 (11.6%) post-implementation (p < 0.001) (Table and Figure). Staphylococcus aureus was the most frequently isolated species for both periods and had higher recovery rate with the VIRTUO system (717 (1.5%) pre- vs. 1764 (3.3%) post-implementation, p< 0.001). Higher recovery rate was also noted for other Staphylococcus spp. in the post-implementation period (985 (2.0%) pre- vs. 1644 (3.1%) post-implementation, p< 0.001). No difference in the organism recovery rate was noted for Streptococcus spp., Enterococcus faecium, E. faecalis, Pseudomonas aeruginosa, Enterobacterales, and Candida spp. The inpatient contamination rate was higher post-implementation (1.5% pre- vs. 1.9% post-implementation, p < 0.001).

Comparison of blood culture positivity rate pre- vs. post-implementation, by culture location

Daily positivity rate for blood cultures processed at BJH during the study period

Conclusion

The VIRTUO system showed a higher rate of positive blood cultures compared to the VersaTREK system primarily from a higher detection of Staphylococcus spp. Further studies are needed to assess whether an increased rate of positive blood cultures is associated with changes in management and clinical outcomes.

Disclosures

All Authors: No reported disclosures
656. Development and Application of a Pragmatic Algorithm for the Detection of Carbapenemase-Producing Pseudomonas aeruginosa (CP-PA)
Authors: Gill Christian M , Asempa Tomefa E , Nicolau David P
Published: January 2021

Background

Historically, carbapenem-resistance in P. aeruginosa (PA) has been mediated by inducible AmpC, drug efflux, and porin loss; however, carbapenemase production is an increasingly recognized entity. Of these mechanisms, carbapenemases can drastically reduce treatment options and rapidly disseminate. Since broad applications of phenotypic (mCIM/eCIM) and PCR-based detection can be labor intensive and costly, we developed an MIC derived algorithm to streamline use of these definitive carbapenemase detection methodologies.

Methods

To develop the testing criteria, a challenge set of PA (n=92), NDM, IMP, VIM, KPC, SPM, GES, cephalosporinase or efflux/porin mutation and wild-type isolates were utilized. Broth microdilution MICs were determined for: ceftazidime (CAZ), cefepime (FEP), piperacillin/tazobactam (TZP), meropenem (MEM), imipenem (IPM), ceftolozane/tazobactam (C/T), and ceftazidime/avibactam (CZA). To assess the utility of CAZ, FEP, TZP, and C/T screening criteria from the challenge set, 1,209 clinical PA isolates from a US surveillance program were tested. Confirmatory genotypic and phenotypic testing for evidence of carbapenemases was conducted on all criteria-derived isolates using the Xpert Carba-R assay and the modified carbapenem inactivation method (mCIM)/EDTA-modified carbapenem inactivation method (eCIM), respectively.

Results

Test performance and characteristics of the challenge set are displayed in Table 1. Of the 1,209 clinical isolates, 230 (19%) were IPM and MEM resistant. 116 isolates met the defined criteria (using most common anti-pseudomonal β-lactams) of: IPM and MEM resistance; non-susceptibility to CAZ, FEP, and TZP. Carba-R identified 5 carbapenemase-producing isolates (all blaVIM-positive), while the mCIM/eCIM detected 7 carbapenemase-producing isolates (including the 5 blaVIM-positive isolates).

Table 1. Characteristics of the Challenge Set of 92 P. aeruginosa isolates utilized in algorithm development.

Conclusion

In the presence of carbapenem resistance, non-susceptibility to FEP, CAZ, and TZP (or C/T when available) is a useful starting point to delineate CP-PA versus non-CP-PA. This MIC criterion combined with either mCIM/eCIM or PCR-based testing is a pragmatic and streamlined approach to identify CP-PA, while providing vital information to guide therapeutic and infection control measures.

Disclosures

David P. Nicolau, PharmD, Cepheid (Other Financial or Material Support, Consultant, speaker bureau member or has received research support.)Merck & Co., Inc. (Consultant, Grant/Research Support, Speaker’s Bureau)Wockhardt (Grant/Research Support)
658. Effect of HIV Status on Tuberculosis Load as Detected by Xpert MTB/RIF in Sputum vs. Saliva Samples
Authors: Burger Zoe C , Aung Si Thu , Aung Hlaing Thazin , Rodwell Timothy , Seifert Marva
Published: January 2021

Background

Tuberculosis (TB) is the most common co-infection among people living with HIV, but HIV positivity is associated with a lower Mycobacterium tuberculosis (MTB) bacillary load in sputum, making TB often difficult to diagnose with current diagnostic solutions. GeneXpert MTB/RIF (Cepheid, USA), a rapid, molecular diagnostic assay, has transformed the TB diagnostic landscape and can be used to diagnose TB and limited drug resistance in HIV patients from direct clinical samples in < 2 hours, but results can be significantly affected by sample bacterial load, which is quantified by the GeneXpert MTB/RIF (Xpert) instrument using Ct values. Our primary objective was to assess how a patient’s HIV status affected their MTB bacterial load in sputum vs. saliva samples submitted for Xpert diagnosis of TB.

Methods

We completed a retrospective analysis of >4,000 patient records from the Myanmar National TB Program captured as part of a nation-wide electronic reporting system developed with the assistance of FIND (Geneva). De-identified records included HIV status, Xpert testing results, and for a subset of patients, specimen type. With this diagnostic information, we compared the distribution of MTB load (quantified by Xpert Ct values) in sputum and saliva in HIV positive vs. HIV negative patients using STATA.

Results

Based on mean Ct value comparison independent of HIV status, saliva samples (mean Ct = 22.7) contained a significantly lower bacterial load of MTB as compared to sputum samples (mean Ct=19.2, p < .001).Within saliva samples, a lower bacterial load was also detected in HIV positive patients (mean Ct = 26.9) compared to HIV negative patients (mean Ct = 22.3, p< .05). Similarly, in sputum samples, a lower bacterial load was detected in HIV positive patients (mean Ct = 21.6) compared to HIV negative patients (mean Ct = 19.0, p < .001) (Figure 1).

Figure 1. Ct Values by HIV Status and Specimen Type

Conclusion

Sputum samples have a significantly higher bacterial load on average compared to saliva samples independent of HIV status. Additionally, when looking at both saliva and sputum as sample types, HIV positive patients have significantly lower bacterial load than individuals who are HIV negative. Based on these results, sputum is the optimal sample type for Xpert TB detection, especially in people living with HIV.

Disclosures

All Authors: No reported disclosures
659. Evaluation of Four Chromogenic Agars for Urine Culture Including Time and Cost Savings Analysis
Authors: Capistran Eve , Lévesque Simon , Martin Philippe , Girard Diane , Papirakis Marie-Eve , Cloutier Claudia , Cameron Mélissa , Brown Nathalie , LeBlanc Louiselle
Published: January 2021

Background

With a volume of approximately 5000 urine culture specimens per month in our tertiary-care university center hospital’s microbiology laboratory, we wanted to evaluate methods aiming to improve workflow and performance while reducing turnaround time and potentially overall cost.

Methods

310 urine culture specimens as well as selected less frequent pathogens (A. urinae - 26 strains, C. urealyticum - 4 strains) were plated on four chromogenic agars in parallel with standard protocol MacConkey (MAC) and blood agar (BA). Chromogenic agars evaluated were: UriSelectTM 4 (Bio-Rad), CHROMID® CPS® Elite (bioMérieux), BrillanceTM UTI ClarityTM agar Biplate (Oxoid) and BDTM CHROMagarTM Orientation (BD). Primary outcome was overall growth performance for frequent pathogens and for gram positives, where chromogenic agars were previously reported to underperform.The number of additional tests needed and the appreciation of different media by laboratory personnel were also assessed. A sub-analysis measured the total time required to plate and to read 50 consecutive specimens comparatively for the 4 chromogenic agars and for MAC/BA.

Results

Global performance was 90% for Uriselect, 88% for ChromID, 89% for Chromagar and 81% for Brillance compared to 84% for standard method. ChromID and Brillance supported the growth of more A. urinae and C. urealyticum than the other 2 chromogenic agars. All monoplate chromogenic agars were appreciated equally by technologists. In addition, for all chromogenic agars, working time was reduced by half as compared to MAC/BA. We estimated a time economy of approximately 80 hours per month in our laboratory, translating in a net annual economy.

Conclusion

All 4 chromogenic medias evaluated in our study had an acceptable performance, with specific strengths and weaknesses for each one. The choice of ChromID CPS Elite (bioMérieux) for our center was based on pre-established criteria including performance for more fastidious gram positives, best time and cost economy, and compatibility with current identification method and susceptibility testing platform. However, since the 4 chromogenic agars have been adequately verified in our laboratory, we consider that they could be interchangeable if needed.

Disclosures

All Authors: No reported disclosures
662. Identification of Clinically Relevant Microbes with the MasSpec Pen
Authors: Povilaitis Sydney C , Chakraborty Ashish D , Downey Rachel D , Hauger Sarmistha Bhaduri , Eberlin Livia
Published: January 2021

Background

In the age of antimicrobial resistance, rapid identification of infectious agents is critical for antimicrobial stewardship and effective therapy. To this end, ambient ionization mass spectrometry techniques have been applied for rapid identification of microbes directly from culture isolates. We have developed a handheld, mass spectrometry-based device, the MasSpec Pen, that permits direct molecular analysis of a biological sample in seconds (Scheme 1). Here, we employ the MasSpec Pen to identify clinically relevant microbes directly from culture isolates.

Methods

Staphylococcus aureus, Staphylococcus epidermidis, Group A and B Streptococcus, Kingella kingae (K.k), and Pseudomonas aeruginosa (P.a) were cultured on 5% sheep’s blood nutrient agar at 37 °C overnight. Colonies were transferred to a glass slide where they were analyzed directly with the MasSpec Pen coupled to a Q Exactive mass spectrometer (Thermo Scientific) in negative ion mode. For MasSpec Pen analysis, a 10 µL droplet of water was held in contact with the sample surface for 3 seconds and then aspirated to the mass spectrometer for analysis.

Data was normalized and the molecular features resulting from the analysis solvent and nutrient medium were removed. The least absolute shrinkage and selection operator (lasso) statistical method was used to build classification models for prediction of bacterial identity. Model performance was evaluated by leave-one-out cross-validation and a validation set of samples.

Scheme 1: MasSpec Pen workflow

Results

Various small molecules were detected including metabolites and glycerophospholipid species. The mass spectral profiles for each species exhibited qualitative differences among them (Figure 1). Additionally, several quorum-sensing molecules were observed in P.a. including hydroxy-heptyl-quinoline (m/z 242.155).

Lasso statistical classifiers were created to differentiate organisms at the level of Gram type, genus, and species with each model comprised of a sparse set of molecular features. Accuracies of 90% or greater were achieved for all lasso models and as high as 98% for the differentiation of Staphylococcus (Staph.) and Streptococcus (Strep.).

Figure 1: Molecular profiles of species analyzed

Figure 2: Statistical classification results

Conclusion

These results demonstrate the potential of the MasSpec Pen as a tool for clinical analysis of infected biospecimens.

Disclosures

Sydney C. Povilaitis, BA, MS Pen Technologies, Inc. (Other Financial or Material Support, Patent) Livia Eberlin, PhD, MS Pen Technolpogies, Inc. (Board Member, Shareholder)
663. Improved Detection of ESBL and AmpC Beta-Lactamase Producing Isolates of Enterobacteriaceae in Pediatric Patients with Bloodstream Infections Using Combined Genotypic and Phenotypic Antimicrobial Susceptibility Testing
Authors: Khalil Nadim , Powell Eleanor , Mortensen Joel
Published: January 2021

Background

Infections secondary to pathogens resistant to third-generation cephalosporins (3GC), such as extended-spectrum (ESBL) and AmpC β-lactamase (AmpC) producing Enterobacteriaceae, are increasing. Currently, there are no recommendations regarding identification of AmpC in Citrobacter, Enterobacter, Morganella and Serratia spp. (CEMS organisms). This study’s aim was to increase the detection of AmpC and ESBL producing Enterobacteriaceae in blood cultures from pediatric population by combining genotypic with phenotypic antimicrobial susceptibility testing (AST).

Methods

All first time Enterobacteriaceae isolates recovered from blood cultures of pediatric patients at CCHMC between January 2017 and December 2018 were evaluated. The Check-MDR CT103XL assay was used to determine the presence of AmpC and ESBL. AST was performed using the Vitek 2 platform. Phenotypic ESBL resistance was defined by resistant to either ceftriaxone of ceftazidime using CLSI breakpoints. Combined cefoxitin resistance with ceftriaxone or ceftazidime resistance was used to define phenotypic AmpC (EUCAST standards).

Results

There were 170 isolates, from 147 patients, with 21 (12.4%) AmpC and 18 (10.6%) ESBL genes detected. Using AST, 11 (6.5%) and 26 (15.3%) isolates met AmpC and ESBL phenotypic criteria respectively. However, 14 of the isolates with AmpC genes detected and 2 of isolates with ESBL genes detected failed to meet phenotypic criteria. In addition, 4 (19%) of 21 AmpC isolates were susceptible to cefoxitin and 3GC while both E. coli and S. marcescens genotypic ESBL isolates were susceptible to 3GC.

Number of AmpC- and ESBL- Producing Isolates Detected Using Phenotypic Method a,b, Genotypic Method and Combined Testing

Conclusion

We identified 16 (9.4%) isolates with resistance genes detected but that failed to meet phenotypic criteria.

Without molecular testing, patients with these isolates may have been treated with 3GC which could have resulted in treatment failure.

The addition of genotypic testing to AST improved the identification of AmpC and ESBL organisms and provided clinically relevant data to guide treatment of resistant organisms. Combined testing is also beneficial for infection control and epidemiological purposes.

Disclosures

All Authors: No reported disclosures
665. Lower Indeterminate Rates and Resolution by Retesting Using a Single Lithium-Heparin Tube Blood Collection Method for the QuantiFERON®-TB Gold Plus (QFT®-Plus)
Authors: Clark Richard B , Master Ronald N , Kapoor Hema , Bi Caixia , Kroll Martin H , Salm Ann , Meyer William B
Published: January 2021

Background

The QuantiFERON-TB Gold Plus (QFT-Plus) test is an assay for detecting a cell-mediated immune response to M. tuberculosis (MTB). The assay measures the in vitro quantitative IFN-γ responses to MTB or control antigens in an incubated blood sample. There are 2 options for QFT-Plus blood collection. One option is a lithium-heparin transport tube with sample aliquots subsequently transferred to 4 QFT-Plus Blood Collection Tubes (1-tube QFT-Plus); the 2nd option is to directly collect the blood sample in 4 QFT-Plus collection tubes (4-tube QFT-Plus). In this study, we compared the indeterminate (IND) rates by the 2 blood collection methods to assess which method was superior.

Methods

For both blood collection methods, QFT-Plus ELISA testing was performed at various Quest Diagnostics sites as specified in the assay’s package insert. A retrospective data analysis of results for the above 2 blood processing methods was conducted. Also, we evaluated the rates of IND results in follow up blood collections. Statistical analyses were performed by the proportion test.

Results

In 2019, the IND result rate for greater than an 1.8 million 1-tube QFT-Plus draws was less than 1% whereas, the IND result rate for 0.3 million 4-tube draws was 4% This difference was significant. The overall MTB positive rate was 7% for the 1-tube method and 6% for the 4-tube method. Within a one-month interval following an initial blood collection event, 464 patients with an original IND result had a 2nd blood sample collected and tested. Only 35% of the 2nd blood collection events produced an IND result, with 52% of the 2nd sample results reporting as negative and 13% were positive.

Conclusion

This study found that the 1-tube QFT-Plus collection method reduces the IND rates by 4-fold compared to the observed rate in the 4-tube process. Additionally, two thirds of patients with an initial IND result resolved to either a positive or a negative result when retested within 1 month.

Disclosures

All Authors: No reported disclosures
669. Rapid Molecular Testing of Sputum for Identification of Pulmonary Tuberculosis: Impact on Duration of Respiratory Isolation
Authors: Acosta Tommy J Parraga , Vahia Amit T , Hanna Zachary W , Nair Sashi N , Tibbetts Robert , Alangaden George J , Samuel Linoj
Published: January 2021

Background

Current guidelines recommend molecular testing directly on sputum of patients with suspected pulmonary tuberculosis (TB) to facilitate discontinuation of airborne infection isolation (AII). Henry Ford Hospital (HFH), a tertiary care center in Detroit, MI serves a population at high-risk for TB. Molecular testing of sputum using GeneXpert/MTB RIF (Xpert; Cepheid) (GXTB) was implemented at HFH on March 2019. Providers were permitted to remove patients from AII using 3 negative acid-fast bacillus smears (AFB) or 2 negative GXTB results. We evaluated the impact of GXTB on duration of AII over a 2-year period: Pre-implementation (January 2018 to February 2019) and post-implementation (March 2019 to February 2020).

Methods

Retrospective data was abstracted for all patients placed in AII during the study period. Demographic data, TB risk factors, duration of AII, length of hospital stay (LOS), accuracy and turn-around-times (TAT) of AFB and GXTB were compared in the pre- and post-implementation periods. Categorical variables were studied using chi-square testing, and continuous variables were studied using T-test or Mann Whitney U test as appropriate.

Results

During the study period, 269 patients with suspected TB were placed in AII: 137 pre-implementation and 132 post-implementation. Clinical characteristics and TB risk factors were generally comparable in both groups (Table 1). Abnormal chest X-ray was more frequent in patients in the post-implementation phase. All cases of culture positive TB were detected by AFB and GXTB. TAT of AFB results before and after implementation were similar and ranged from 20-24 hours (Table 2). In the post-implementation period, TAT of GXTB compared to AFB was 6.35 vs 21.28 hours (p < 0.0001). Duration of AII was shortened by almost 24 hours (70.2 vs 93.7 hours, p=0.031) (Table 3). Time from first sample collection to final results of all samples was 19.2 vs 52.6 hours, p< 0.0001. There was no difference in total LOS pre and post-implementation.

Table 1. Clinical Characteristics of Patients with Suspected Pulmonary Tuberculosis

Table 2. Turnaround times (TAT) of AFB and GeneXpert/MTB (Xpert) RIF before and after implementation

Table 3. Duration of Airborne Isolation, Total Turn-Around Times, and Hospital Length of Stay in the Pre- and Post-implementation Period

Conclusion

Implementation of rapid direct molecular testing reduced the duration of respiratory isolation for patients with suspected pulmonary TB. Further provider education regarding the reliability of GXTB in excluding TB may be necessary to reduce overall hospital LOS.

Disclosures

All Authors: No reported disclosures
670. Rapid, Non-invasive Detection of Invasive Mycoplasma hominis Infection using the Karius Test, A Next-Generation Sequencing Test for Microbial Cell-free DNA in Plasma
Authors: Edward Priya , Via William V La , Arshad Mehreen , Gajurel Kiran
Published: January 2021

Background

Mycoplasma hominis is typically associated with genital infections in women and is a rare cause of musculoskeletal infections often in immunocompromised hosts. Diagnosis of invasive Mycoplasma hominis infections are difficult due to challenges in culturing these organisms. Molecular diagnostics require an index of suspicion which may not be present at the time of tissue sampling. Accurate, rapid diagnosis of Mycoplasma hominis infections are important for antibiotic management.

Methods

Two cases of invasive Mycoplasma hominis infections are presented in which the Karius test (KT) was used to make the diagnosis. The KT is a CLIA certified/CAP-accredited next-generation sequencing (NGS) plasma test that detects microbial cell-free DNA (mcfDNA). After mcfDNA is extracted and NGS performed, human reads are removed and remaining sequences are aligned to a curated database of > 1400 organisms. Organisms present above a statistical threshold are reported. Case review was performed for clinical correlation.

Results

A young woman with lupus nephritis status post renal transplant developed persistent fever with progressive multifocal culture-negative osteoarticular infection despite empiric ceftriaxone. An adolescent female presented with an ascending pelvic infection progressing to purulent polymicrobial peritonitis (see table) requiring surgical debridement and cefipime, metronidazole and micafungin therapy; her course was complicated by progressive peritonitis/abscesses. Karius testing detected high-levels of Mycoplasma hominis mcfDNA in both cases – at 3251 molecules/microliter (MPM) in the first case and 3914 MPM in the second case. The normal range of Mycoplasma hominis mcfDNA in a cohort of 684 normal adults is 0 MPM. The patients rapidly improved with atypical coverage with doxycycline and levofloxaxin.

Clinical findings in 2 patients with M. hominis infection detected by the Karius Test

Conclusion

Open-ended, plasma-based NGS for mcfDNA provides a rapid, non-invasive method to diagnose invasive Mycoplasma hominis infection. This case series highlights the potential to diagnose infections caused by fastidious pathogens to better inform antimicrobial therapy and achieve favorable outcomes.

Disclosures

William V. La Via, MD, Karius (Employee)
672. The Pediatric Endotracheal Aspirate Culture Survey (Petacs): Examining Practice Variation Across Pediatric Microbiology Laboratories in the United States
Authors: Prinzi Andrea , Curtis Donna , Parker Sarah , Ziniel Sonja
Published: January 2021

Background

In the absence of evidence-based laboratory guidelines, the workup and interpretation of tracheal aspirate (TA) cultures remains controversial and confusing within the fields of clinical microbiology, infectious diseases, and critical care.

Methods

Between January 22 and February 24, 2020, we conducted a national, web-based survey of microbiology laboratory personnel in free-standing pediatric hospitals and adult hospitals containing pediatric facilities regarding the laboratory practices used for TA specimens. We hypothesized that there would be substantial center-level variability in laboratory processes of TA cultures.

Results

The response rate for the survey was 48%. There was a high level of variability in the criteria used for all processes including specimen receipt, Gram staining and culture reporting. Nearly a quarter of respondents (23%) reject TA specimens based on Gram stain criteria, and 56% of labs require that a minimum number of Gram stain fields be reviewed prior to reporting results. Overall, non-academic hospital laboratories and pediatric-only laboratories are more likely to identify, report and perform susceptibility testing on organisms from tracheal aspirate cultures, regardless of organism quantity or predominance.

Conclusion

There is a substantial amount of process variability among pediatric microbiology laboratories that affects TA culture reporting, which is used to make treatment decisions. This variation within and among labs makes clinical outcome studies related to TA cultures very difficult. Research is needed to determine best laboratory practices for TA culture workup and to provide evidence for the development of clinical guidelines.

Disclosures

All Authors: No reported disclosures
674. Variations in Agreement and Epidemiological Cutoff Value (ECV) between Fosfomycin (FOF) Agar Dilution and Broth Microdilution Using Standard- and High-Inoculum Protocols for Klebsiella pneumoniae (KP)
Authors: Krueger Amanda R , Anderson Jadyn C , Smith Elizabeth C , Bixby Morgan L , Brigman Hunter V , Hirsch Elizabeth B
Published: January 2021

Background

FOF has been used in the treatment of multidrug-resistant (MDR) KP infections despite established susceptibility breakpoints. At present, agar dilution (AD) is considered the reference method for FOF while broth microdilution (BMD) is specifically recommended against despite its convenience over AD. We therefore sought to assess FOF activity against KP, along with essential and categorical agreement between AD and BMD methods to determine if BMD could be used as a reliable testing method.

Methods

Minimal inhibitory concentration (MIC) values were determined for a convenience collection of 69 KP isolates (59.4% MDR) from three US institutions. MIC testing was conducted in duplicate on separate days using AD and BMD methods; essential and categorical agreement were calculated using AD as the reference method. Fourteen isolates were also analyzed using high-inoculum AD (105.3-5.9 CFU/mL) similar to the BMD method. MIC values were categorized using Clinical and Laboratory Standards Institute (CLSI) interpretive criteria for Escherichia coli (≤ 64 mg/L, susceptible). ECVs were determined according to CLSI methodology.

Results

MIC values varied between methods, withMIC50/MIC90 values being 32/256 mg/L for AD and 128/256 mg/L for BMD. Using E. coli criteria, susceptible/intermediate/resistant rates were 82.6/2.9/14.5% (AD) and 44.9/21.7/33.3% (BMD). Essential agreement was 44.9% and categorical agreement was 60.8%. When using high-inoculum AD, MIC values were on average three-fold higher compared to standard-inoculum AD, with 10 of the 14 (71.4%) isolates brought into essential agreement with BMD. Calculated ECVs were 128 mg/L for standard-inoculum AD and 1024 mg/L for BMD.

Conclusion

Our collection of KP displayed high MIC values to FOF, in addition to substantial discrepancies between AD and BMD methods. Essential agreement increased with the use of high-inoculum AD testing, which better correlated with BMD results. ECV for BMD was three dilutions higher than that for standard-AD ECV. Based on these results, we recommend further investigation of BMD for FOF testing using a larger isolate collection, along with optimization of currently recommended testing methods. In light of these results, KP-specific breakpoints should also be examined.

Disclosures

Elizabeth B. Hirsch, PharmD, Merck (Grant/Research Support)Nabriva Therapeutics (Advisor or Review Panel member)
676. New PLST Locus for Sequence-based Typing of Candida glabrata Clinical Isolates
Authors: Edlind Tom , Katiyar Santosh
Published: January 2021

Background

Healthcare-associated infections (HAI) with the opportunistic yeast Candida glabrata have become increasingly common in the fluconazole era, and may be endogenous or nosocomial in origin. Effective intervention requires distinguishing between these sources, which in turn requires epidemiological analysis in conjunction with isolate typing. Multiple approaches to C. glabrata typing have been described, ranging from length-based microsatellite and PFGE analyses to sequence-based MLST and WGS; however, issues of cost and technical complexity preclude their routine use in clinical labs. Polymorphic locus sequence typing (PLST) addresses these issues by employing conventional PCR and Sanger sequencing of selected tandem repeat loci that exhibit high rates of both SNPs and insertion/deletion. In our previous study, PLST loci CgMT-J and CgMT-M resolved 104 isolates into 10 phylogenetic clusters and 20 to 24 alleles (Katiyar et al., 2016, J. Clin. Microbiol. 54:1042). Within clusters N and P, isolates from 4 patients each (sets DSY and KM) who received treatment at the same healthcare facilities shared alleles. While consistent with nosocomial transmission, these alleles were also shared by epidemiologically unrelated strains.

Methods

CgMT-J/CgMT-M were identified by bioinformatic analysis of the only two, closely related C. glabrata genome sequences available at the time. Since current GenBank databases include sequences for 16 strains, including 4 epidemiologically related pairs, we bioinformatically searched for new loci exhibiting greater strain resolution.

Results

Locus CgMT-C represents an intergenic region on chromosome C that includes multiple tandem repeats and has no detectable homolog in other yeast. Phylogenetic analysis of database sequences resolved all 12 unrelated strains. In the laboratory, the CgMT-C locus was readily amplified and sequenced directly from C. glabrata colony lysates, including those prepared from chromogenic agars. Most importantly, CgMT-C analysis confirmed identities of the cluster N and P isolates from DSY and KM patients, and resolved them from all unrelated strains.

Conclusion

CgMT-C PLST represents a powerful new tool for C. glabrata epidemiology and infection control.

Disclosures

Tom Edlind, PhD, MicrobiType LLC (Employee, Scientific Research Study Investigator)
678. Polymorphic Locus Sequence Typing for Pseudomonas aeruginosa Outbreak Detection and Investigation
Authors: Edlind Tom
Published: January 2021

Background

Pseudomonas aeruginosa is a common agent of healthcare-associated infection (HAI), which can be challenging to treat due to intrinsic or acquired antibiotic resistance. In contrast to most HAI, the source of P. aeruginosa infection is typically environmental; e.g., from the faucets, drains, and showers in patient rooms. To unambiguously identify the source, strain typing of patient and environmental isolates is required. Typing methods include sequence-based MLST and WGS which resolve strains based on relatively rare SNPs, and length-based MLVA which resolves strains based on relatively frequent insertions/deletions within tandem repeats. These and other methods previously applied to P. aeruginosa have one or more limitations relating to cost, technical complexity, reproducibility, and turnaround time that preclude their routine use. Polymorphic locus sequence typing (PLST) is a hybrid approach that employs sequence analysis of the one or two most phylogenetically informative tandem repeat-containing loci within the genome of a microbial species. Strain resolution equals or exceeds MLST and MLVA and approaches that of WGS. Here, the identification and evaluation of candidate PLST loci for P. aeruginosa epidemiology are described.

Methods

Tandem repeats were bioinformatically identified in representative genome sequences, and screened by BLASTN queries of GenBank genome databases followed by clustal alignments and phylogenetic analysis. Candidate loci were amplified from heat-treated colony lysates and Sanger sequenced.

Results

PLST locus PaMT1 (Mbp 2.568-2.569 in the PA01 genome) resolved 99 alleles from 144 epidemiologically unrelated isolates with GenBank genome sequences, yielding diversity index = 0.991. Nineteen sets of isolates shared healthcare facility and PaMT1 allele, consistent with nosocomial transmission. Examples, confirmed by WGS-SNP analysis, include isolates from 8 VAP patients, 2 sets of cancer patient isolates, and a pair of isolates from patient and hospital sewage. In the laboratory, locus PaMT1 was readily amplified and sequenced from colony lysates, yielding typing data with 1-2 day turnaround.

Conclusion

PaMT1 PLST provides an affordable, user-friendly, and timely tool for P. aeruginosa outbreak detection and investigaton.

Disclosures

Tom Edlind, PhD, MicrobiType LLC (Employee, Scientific Research Study Investigator)