As COVID-19 transmission control measures are gradually being lifted, a sensitive and rapid diagnostic method for large-scale screening could prove essential for monitoring population infection rates. However, many rapid workflows for SARS-CoV-2 detection and diagnosis are not amenable to the analysis of large-volume samples. Previously, our group demonstrated a technique for SARS-CoV-2 nanoparticle-facilitated enrichment and enzymatic lysis from clinical samples in under 10 min. Here, this sample preparation strategy was applied to pooled samples originating from nasopharyngeal (NP) swabs eluted in viral transport medium (VTM) and saliva samples diluted up to 1:100. This preparation method was coupled with conventional RT-PCR on gold-standard instrumentation for proof-of-concept. Additionally, real-time PCR analysis was conducted using an in-house, ultra-rapid real-time microfluidic instrument paired with an experimentally optimized rapid protocol. Following pooling and extraction from clinical samples, average cycle threshold (CT) values from resultant eluates generally increased as the pooling dilution factor increased; further, results from a double-blind study demonstrated 100% concordance with clinical values. In addition, preliminary data obtained from amplification of eluates prepared by this technique and analyzed using our portable, ultra-rapid real-time microfluidic PCR amplification instrument showed progress toward a streamlined method for rapid SARS-CoV-2 analysis from pooled samples.

Transfusion of high-titer CIP to non-critically ill patients early after admission with COVID-19 respiratory disease was associated with significantly increased anti-SARS-CoV-2 specific antibodies (compared to baseline) and a non-significant reduction in ICU transfer and death (compared to controls). This prospective phase II trial provides a suggestion that the antiviral effects of CIP from early in the COVID-19 pandemic may delay progression to critical illness and death in specific patient populations.

The diversification of analytical tools for diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is imperative for effective virus surveillance and transmission control worldwide. Development of robust methods for rapid, simple isolation of viral RNA permits more expedient pathogen detection by downstream real-time reverse transcriptase polymerase chain reaction (real-time RT-PCR) to minimize stalled containment and enhance treatment efforts. Here, we describe an automatable rotationally driven microfluidic platform for enrichment and enzymatic extraction of SARS-CoV-2 RNA from multiple sample types. The multiplexed, enclosed microfluidic centrifugal device (μCD) is capable of preparing amplification-ready RNA from up to six samples in under 15 min, minimizing user intervention and limiting analyst exposure to pathogens. Sample enrichment leverages Nanotrap Magnetic Virus Particles to isolate intact SARS-CoV-2 virions from nasopharyngeal and/or saliva samples, enabling the removal of complex matrices that inhibit downstream RNA amplification and detection. Subsequently, viral capsids are lysed using an enzymatic lysis cocktail for release of pathogenic nucleic acids into a PCR-compatible buffer, obviating the need for downstream purification. Early in-tube assay characterization demonstrated comparable performance between our technique and a "gold-standard" commercial RNA extraction and purification kit. RNA obtained using the fully integrated μCDs permitted reliable SARS-CoV-2 detection by real-time RT-PCR. Notably, we successfully analyzed full-process controls, positive clinical nasopharyngeal swabs suspended in viral transport media, and spiked saliva samples, showcasing the method's broad applicability with multiple sample matrices commonly encountered in clinical diagnostics.

Clostridioides difficile infection (CDI) is the fifth leading cause of death from nonmalignant gastrointestinal disease in the United States. The contribution of resistance to C. difficile-active antibiotics to the outcomes of CDI is unclear. We evaluated the antimicrobial susceptibility of C. difficile isolates in a U.S. hospital and determined associations of clinical variables and binary toxin positivity with antibiotic resistance. C. difficile spores were cultured from fecal specimens of adult patients with CDI for genotyping and antimicrobial susceptibility assay (for clindamycin [CLI], fidaxomicin [FDX], metronidazole [MTZ], moxifloxacin [MXF], tigecycline [TGC], and vancomycin [VAN]). Electronic medical records were reviewed for clinical data extraction. Ninety-seven of 130 (75%) fecal samples grew toxigenic C. difficile in culture. Most of the isolates were tcdA(+) tcdB(+) cdtB(-) (80.4%), and 18.6% and 1% were tcdA(+) tcdB(+) cdtB(+) and tcdA(-) tcdB(+) cdtB(+), respectively. Susceptibility to VAN, MTZ, FDX, TGC, MXF, and CLI was 96%, 94%, 100%, 100%, 8%, and 79%, respectively. Six isolates, all cdtB positive and belonging to the 027 ribotype, were resistant to VAN and/or MTZ. Higher MICs were found in isolates with a mutation in the VAN-related resistance gene vanR, but not vans. In addition, cdtB(+) isolates exhibited higher MICs of VAN, MTZ, TGC, CLI, and MXF compared to cdtB(-) strains. Patients with greater intestinal inflammation or severe disease were more likely to be infected with cdtB(+) strains. Decreased susceptibility to antibiotics is not directly associated with either severe or recurrent CDI. However, antimicrobial susceptibility of C. difficile is decreased in strains positive for the binary toxin gene.

Congregate living poses one of the highest risk situations for the transmission of respiratory viruses including SARS-CoV-2. University dormitories exemplify such high-risk settings. We demonstrate the value of using building-level SARS-CoV-2 wastewater surveillance as an early warning system to inform when prevalence testing of all building occupants is warranted. Coordinated daily testing of composite wastewater samples and clinical testing in dormitories was used to prompt the screening of otherwise unrecognized infected occupants. We overlay the detection patterns in the context of regular scheduled occupant testing to validate a wastewater detection model. The trend of wastewater positivity largely aligned well with the clinical positivity and epidemiology of dormitory occupants. However, the predictive ability of wastewater-surveillance to detect new positive cases is hampered by convalescent shedding in recovered/noncontagious individuals as they return to the building. Building-level pooled wastewater-surveillance and forecasting is most productive for predicting new cases in low-prevalence instances at the community level. For higher-education facilities and other congregate living settings to remain in operation during a pandemic, a thorough surveillance-based decision-making system is vital. Building-level wastewater monitoring on a daily basis paired with regular testing of individual dormitory occupants is an effective and efficient approach for mitigating outbreaks on university campuses.

BACKGROUND:Implementation of the Accelerate PhenoTM Gram-negative platform (RDT) paired with antimicrobial stewardship program (ASP) intervention projects to improve time to institutional-preferred antimicrobial therapy (IPT) for Gram-negative bacilli (GNB) bloodstream infections (BSIs). However, few data describe the impact of discrepant RDT results from standard of care (SOC) methods on antimicrobial prescribing. METHODS:A single-center, pre-/post-intervention study of consecutive, nonduplicate blood cultures for adult inpatients with GNB BSI following combined RDT + ASP intervention was performed. The primary outcome was time to IPT. An a priori definition of IPT was utilized to limit bias and to allow for an assessment of the impact of discrepant RDT results with the SOC reference standard. RESULTS:Five hundred fourteen patients (PRE 264; POST 250) were included. Median time to antimicrobial susceptibility testing (AST) results decreased 29.4 hours (P < .001) post-intervention, and median time to IPT was reduced by 21.2 hours (P < .001). Utilization (days of therapy [DOTs]/1000 days present) of broad-spectrum agents decreased (PRE 655.2 vs POST 585.8; P = .043) and narrow-spectrum beta-lactams increased (69.1 vs 141.7; P < .001). Discrepant results occurred in 69/250 (28%) post-intervention episodes, resulting in incorrect ASP recommendations in 10/69 (14%). No differences in clinical outcomes were observed. CONCLUSIONS:While implementation of a phenotypic RDT + ASP can improve time to IPT, close coordination with Clinical Microbiology and continued ASP follow up are needed to optimize therapy. Although uncommon, the potential for erroneous ASP recommendations to de-escalate to inactive therapy following RDT results warrants further investigation.

Abstract Background Determining true CDI versus CD colonization through CD testing is a continuing challenge. A previously introduced decision support tool at UVA Health significantly reduced inappropriate testing without adverse outcomes. More recently, our methodology changed from nucleic acid amplification test (NAAT) alone to an initial NAAT followed by ELISA for toxin to improve specificity. The purpose of this analysis was to assess provider interpretation of test results, using targeted CD therapy as a surrogate. Methods This single-center, retrospective study evaluated all patients with a positive NAAT (Cepheid Xpert® C. difficile) on day 4 or later of hospitalization following 2-step algorithm implementation from Feb 2020 through Feb 2021. Toxin negative (TOX-) test results (C. DIFF QUIK CHEK COMPLETE®) were accompanied by a comment that discordance may represent colonization or CDI and to consider ID consult. The proportion of toxin positive (TOX+) versus TOX- patients receiving ≥ 1 dose of CD therapy served as the primary outcome with partial courses considered < 10 days. Clinical outcomes were also compared. Results Ninety patients with NAAT+ results were included, of whom 58 (64%) were TOX-. Thirty-two (100%) TOX+ (median days of therapy [IQR] = 14 [11-17]) versus 51 (88%) TOX- patients (median days of therapy [IQR] = 11 [7-14]) received CD therapy (p=0.04). Treatment decisions were guided by ID physicians for 32 (63%) TOX- patients; ID recommendations to discontinue CD therapy were followed in 2 out of 9 (22%) cases. TOX- patients received partial therapy due to patient death (n=5), presumptive colonization (n=3), and provider error (n=1). Of TOX- patients receiving partial or no treatment, there were no CDI-related adverse outcomes during the admission. CDI-related colectomy occurred in 2 (6%) and 1 (2%) TOX+ and TOX- patients, respectively. Five in-hospital deaths with CDI as a contributing factor occurred in the TOX+ group. Conclusion Adoption of a 2-step NAAT plus toxin testing algorithm for hospital-onset CDI reduced the frequency with which TOX- patients received CD therapy but the vast majority were still treated. Most providers considered a positive NAAT indicative of CDI, regardless of TOX status. Disclosures All Authors: No reported disclosures

Multisystem inflammatory syndrome in children (MIS-C) is a serious, sometimes life-threatening late complication of coronavirus disease 2019 (COVID-19) with multiorgan involvement and evidence of immune activation. The pathogenesis of MIS-C is not known, nor is the pathogenesis of the severe organ damage that is the hallmark of MIS-C. Human herpesvirus 6 (HHV-6), the virus responsible for roseola, is a ubiquitous herpesvirus that causes close to universal infection by the age of 3 years. HHV-6 remains latent for life and can be activated during inflammatory states, by other viruses, and by host cell apoptosis. HHV-6 has been associated with end-organ diseases, including hepatitis, carditis, and encephalitis. In addition, ∼1% of people have inherited chromosomally integrated human herpesvirus 6 (iciHHV-6), which is HHV-6 that has been integrated into chromosomal telomeric regions and is transmitted through the germ line. iciHHV-6 can be reactivated and has been associated with altered immune responses. We report here a case of MIS-C in which an initial high HHV-6 DNA polymerase chain reaction viral load assay prompted testing for iciHHV-6, which yielded a positive result. Additional research may be warranted to determine if iciHHV-6 is commonly observed in patients with MIS-C and, if so, whether it may play a part in MIS-C pathogenesis.

Some of the most severe outbreaks of COVID-19 have taken place in places where persons live together, such as nursing homes. Wastewater testing from individual buildings could be used for frequent pooled surveillance of virus from all occupants, including those who are contagious, with or without symptoms. ABSTRACT Wastewater-based monitoring for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) at the individual building level could be an efficient, passive means of early detection of new cases in congregate living settings, but this approach has not been validated. Preliminary samples were collected from a hospital and a local municipal wastewater treatment plant. Molecular diagnostic methods were compared side by side to assess feasibility, performance, and sensitivity. Refined sample collection and processing protocols were then used to monitor two occupied dormitory complexes (n = 105 and 66) over 8 weeks. Wastewater results were validated using known case counts from external clinical testing of building occupants. Results confirm that ultracentrifugation from a 24-h composite collection had a sensitivity of 96.2% and a specificity of 100%. However, the method could not distinguish new infectious cases from persistent convalescent shedding of SARS-CoV-2 RNA. If the detection of convalescent shedding is considered a false positive, then the sensitivity is 100% and specificity drops to 45%. It was determined that the proposed approach constitutes a highly sensitive wastewater surveillance method for detecting SARS-CoV-2, but it could not distinguish new infectious cases from persistent convalescent shedding. Future work must focus on approaches to distinguish new infections from convalescent shedding to fully realize the potential of building wastewater as a surveillance tool for congregate living. IMPORTANCE Some of the most severe outbreaks of COVID-19 have taken place in places where persons live together, such as nursing homes. Wastewater testing from individual buildings could be used for frequent pooled surveillance of virus from all occupants, including those who are contagious, with or without symptoms. This work provides a sensitive practical method for detecting infected individuals, as validated in two building complexes housing occupants who underwent frequent clinical testing performed by external entities. Although this sensitive method could be deployed now for pooled surveillance as an early warning system to limit outbreaks, the study shows that the approach will require further refinement to differentiate contagious, newly infected individuals from persons who have persistent viral fragments shedding in their stool outside the contagious period.

Background. Clostridioides difficile is the leading health care-associated pathogen, but clinicians lack a test that can reliably differentiate colonization from infection. Health care costs attributed to C. difficile are substantial, but the economic burden associated with C. difficile false positives is poorly understood. Methods. A propensity score matching model for cost per hospitalization was developed to estimate the costs of both true infection and false positives. Predictors of C. difficile positivity used to estimate the propensity score were age, Charlson comorbidity index, white cell count, and creatinine. We used polymerase chain reaction (PCR) cycle threshold to identify and compare 3 groups: (1) true infection, (2) C. difficile colonization, and (3) C. difficile negative. Results. A positive test was associated with $3018 higher unadjusted hospital cost. Among the 3 comparisons made with propensity-matched negative controls (all positives [+$179; P = .934], true positives [-$1892; P = .100], and colonized positives), only colonization was associated with significantly increased (+$3418; P = .012) cost. Differences in lengths of stay (all positives 0 days, P = .126; true 0 days, P = .919; colonized 1 day, P = .019) appeared to underly cost differences. Conclusions. In the first C. difficile cost analysis to utilize PCR cycle threshold to differentiate colonization, we found high propensity-matched hospital costs associated with colonized but not true positives. This unexpected finding may be due to misdiagnosis of non-C. difficile diarrhea or unadjusted factors associated with colonization.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a zoonotic RNA virus characterized by high transmission rates and pathogenicity worldwide. Continued control of the COVID-19 pandemic requires the diversification of rapid, easy to use, sensitive, and portable methods for SARS-CoV-2 sample preparation and analysis. Here, we propose a method for SARS-CoV-2 viral enrichment and enzymatic extraction of RNA from clinically relevant matrices in under 10 min. This technique utilizes affinity capture hydrogel particles to concentrate SARS-CoV-2 from solution, and leverages existing PDQeX technology for RNA isolation. Characterization of our method is accomplished with reverse transcription real-time polymerase chain reaction (RT-PCR) for relative, comparative RNA detection. In a double-blind study analyzing viral transport media (VTM) obtained from clinical nasopharyngeal swabs, our sample preparation method demonstrated both comparable results to a routinely used commercial extraction kit and 100% concordance with laboratory diagnoses. Compatibility of eluates with alternative forms of analysis was confirmed using microfluidic RT-PCR (mu RT-PCR), recombinase polymerase amplification (RPA), and loop-mediated isothermal amplification (LAMP). The alternative methods explored here conveyed successful amplification from all RNA eluates originating from positive clinical samples. Finally, this method demonstrated high performance within a saliva matrix across a broad range of viral titers and dilutions up to 90% saliva matrix, and sets the stage for miniaturization to the microscale. (c) 2021 Published by Elsevier B.V.

Immune dysregulation is characteristic of the more severe stages of SARS-CoV-2 infection. Understanding the mechanisms by which the immune system contributes to COVID-19 severity may open new avenues to treatment. Here, we report that elevated IL-13 was associated with the need for mechanical ventilation in 2 independent patient cohorts. In addition, patients who acquired COVID-19 while prescribed Dupilumab, a mAb that blocks IL-13 and IL-4 signaling, had less severe disease. In SARS-CoV-2-infected mice, IL-13 neutralization reduced death and disease severity without affecting viral load, demonstrating an immunopathogenic role for this cytokine. Following anti-IL-13 treatment in infected mice, hyaluronan synthase 1 (Has1) was the most downregulated gene, and accumulation of the hyaluronan (HA) polysaccharide was decreased in the lung. In patients with COVID-19, HA was increased in the lungs and plasma. Blockade of the HA receptor, CD44, reduced mortality in infected mice, supporting the importance of HA as a pathogenic mediator. Finally, HA was directly induced in the lungs of mice by administration of IL-13, indicating a new role for IL-13 in lung disease. Understanding the role of IL-13 and HA has important implications for therapy of COVID-19 and, potentially, other pulmonary diseases. IL-13 levels were elevated in patients with severe COVID-19. In a mouse model of the disease, IL-13 neutralization reduced the disease and decreased lung HA deposition. Administration of IL-13-induced HA in the lung. Blockade of the HA receptor CD44 prevented mortality, highlighting a potentially novel mechanism for IL-13-mediated HA synthesis in pulmonary pathology.

Wastewater-based monitoring for SARS-CoV-2 holds promise as tool to inform public health-decision making. Testing at individual building-level could be an efficient, passive means of preventing early detection of new cases in congregate living settings, but this approach has not been validated. Sample collection protocols were developed and refined during preliminary sampling from a hospital and a local municipal wastewater treatment plant. Molecular diagnostic methods were compared side-by-side to assess feasibility, performance and sensitivity. Optimized sample collection and processing protocols were then used to monitor two occupied dormitory complexes (n=105 and 66) over eight weeks. Wastewater results were validated using known case counts from external clinical testing of building occupants. Results confirm that ultracentrifugation from a 24 hour composite collection had a sensitivity of 95% and a specificity of 100%. However, if the detection of convalescent shedding is considered a false positive then the sensitivity would be 95.2% but the specificity would drop to 52%. We determined a highly sensitive method for detecting SARS-CoV-2 shedding in building wastewater however our methods could not distinguish new infectious cases from persistent convalescent shedding of SARS-CoV-2 RNA. Future work must focus on methods to distinguish new infections from convalescent shedding to widely deploy this promising wastewater surveillance tool.

We describe 4 children (11–17 years in age) at our institution with acute appendicitis in the setting of SARS-CoV-2 infection, suggesting a possible association. Providers should consider testing for this infection in patients with severe gastrointestinal symptoms, in order to take appropriate transmission based precautions, until more is understood.

An abstract is not available for this content so a preview has been provided. As you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

INTRODUCTION: The optimal diagnostic approach for C. difficile infection (CDI) is controversial. Infectious Disease Society of America currently recommends a high sensitivity test such as a nucleic acid amplification test (NAAT) PCR, followed by a stool toxin enzyme immunoassay to confirm clinical suspicion of CDI. C. difficile PCR cycle threshold (Ct) is the number of cycles required for a signal to exceed background fluorescence with low numbers reflecting a larger C. difficile nucleic acid burden. Recent reports correlate Ct in symptomatic patients with disease severity and mortality. Data regarding the predictive value of PCR Ct in recurrence of CDI is preliminary. We aim to determine the association between Ct and recurrence of CDI. METHODS: This was an IRB approved, single-center retrospective chart review cohort of 76 randomly chosen patients ≥18 y.o., with completely unformed stools that were C.difficile NAAT positive. 10 patients were excluded due to lack of Ct values. Recurrence defined as any positive test for C. difficile within 3 months after treatment for CDI. Severe CDI defined as WBC >15,000 or creatinine ≥1.5 md/dL and fulminant disease as refractory hypotension, ileus or megacolon. Poor clinical outcome defined as severe or fulminant CDI, or death within 30 days of diagnosis. A t-test or Mann Whitney U test was performed on populations with or without a normal distribution, respectively. A scatterplot was generated with Ct values for patients with initial vs recurrent episodes of CDI. RESULTS: Of 66 patients, mean Ct values of 8 patients with recurrent CDI (12.1%) and 58 without recurrence were 25.71 and 26.15 respectively (P = 0.79). Recurrence rates after the initial episode of CDI (n = 4), 1st recurrence (n = 1), and 2nd/subsequent recurrence (n = 3) were 9.1%, 12.5% and 21.2%, respectively. Mean Ct values trended lower for patients with poor outcomes (25.40 vs 26.42, P = 0.37). CONCLUSION: In our single center study, Ct values did not associate with a recurrence of CDI. Our findings suggest that Ct cannot be used to predict which patients will be at risk for recurrent CDI. The trend of lower Ct values associating with worse outcomes is worth a prospective study. Interestingly, there was no association with Ct values and common risk factors for CDI such as prior antibiotic use, suggesting that Ct values may not clarify current controversies in testing for CDI.

Objective: Women without regular health care providers or a medical home routinely fail to complete recommended cervical cancer screening. At-home self-collection of samples to test for high-risk strains of human papillomavirus (hrHPV) can improve screening rates. This study documents acceptability and feasibility of community lay navigator (LN)-facilitated at-home self-collection for underscreened women in Appalachian Virginia. Materials and Methods: This study used mixed methods in three phases. Phase I involved focus groups of LNs to ensure cultural acceptability of self-collection, and to enhance recruitment of medically underserved women. An environmental scan of community resources and climate was created in Phase II. During Phase III, underscreened women in Appalachian Virginia (the far southwest corner of Virginia) were recruited to complete hrHPV testing using LN-provided self-collection kits. Results: LN-facilitated at-home self-collection for HPV testing was deemed culturally acceptable and feasible to participants in this community-based pilot study. Self-kit training included 64 LNs, of which 35 engaged in the study and were provided 77 kits and instructions. A total of 59 self-kits were returned, of which 42 were correctly completed with valid HPV results, yielding a 16.6% hrHPV rate. Conclusions: Over a quarter of the women LNs recruited had no medical home, indicating this delivery model may have potential to reach women at increased risk of being underscreened for cervical cancer. Research is needed to identify optimal approaches to increase LN participation in outreach self-collection interventions.

BackgroundWe report a case of prosthetic hip joint infection in a heart transplant recipient due to Anaerobiospirillum succiniciproducens, a genus of spiral-shaped curved anaerobic gram-negative rod which colonizes the gastrointestinal tract of cats and dogs. Invasive infections in humans are rare and typically occur in immunocompromised hosts.Case presentationA 65-year-old male dog breeder with a history of rheumatoid arthritis, bilateral hip arthroplasties, and non-ischemic cardiomyopathy with a heart transplant 10years ago presented with a three month history of progressive left hip pain and frank purulence on hip aspiration. He underwent irrigation and debridement of the left hip and one-stage revision with hardware exchange. Although gram stain and culture from synovial fluid and intraoperative cultures were initially negative, anaerobic cultures from tissue specimens later grew a spiral-shaped gram-negative rod, identified as Anaerobiospirillum spp. by 16S rRNA gene sequencing. The patient was treated with ceftriaxone 2g daily for 6weeks with a good response to treatment. A similar organism was unable to be isolated from culture of 2 of the patient's dogs, however, they were thought to be the most likely source of his infection.ConclusionAnaerobiospirillum spp. should be considered in immunocompromised patients with exposure to dogs or cats who present with bacteremia, gastrointestinal infection, pyomyositis, or prosthetic joint infections, especially in cases of culture-negative or with anaerobic culture growth.

Abstract Background Rapid diagnostic testing paired with ASP intervention optimizes therapy and improves outcomes but few data guide ASP response in the absence of organism identification (ID). We describe the microbiology for organisms unidentified by Accelerate Pheno™ Gram-negative platform (AXDX) in order to inform ASP-provider team communication (PTC). Methods Consecutive, non-duplicate inpatient blood cultures with Gram-negative bacilli (GNB) following AXDX implementation at a single university hospital between April 2018 and March 2019 were included. Standard of care (SOC) ID and susceptibility followed AXDX. Clinical Microbiology emailed AXDX results to the ASP in real time; results were released into the EMR paired with telephone PTC or withheld after ASP review. Bloodstream Infections (BSIs) and patient outcomes for organisms labeled no/indeterminate ID by the AXDX were characterized. Results AXDX was performed on 351 blood cultures. Among 52 (15%) labeled no/indeterminate ID, SOC methods revealed: Enterobacteriaceae (40%; 9 monomicrobial with AXDX targets), anaerobes (21%), non-lactose fermenters (NLFs) other than Pseudomonas aeruginosa (21%), and fastidious GNB (10%). Frequent organisms without AXDX targets included: Raoultella planticola (4); Bacteroides fragilis, Cupriavidus spp., Haemophilus spp., Prevotella spp., Providencia spp., non-aeruginosa Pseudomonas spp., Salmonella spp. (3 each); Pasteurella multocida, Stenotrophomonas maltophilia (2 each). BSI sources were most commonly intra-abdominal (21%), central line-associated (17%), or unknown (17%). CLABSIs were associated with immune suppression and/or substance abuse in all but 1 case. BSIs without active empiric therapy included: NDM-producing Providencia stuartii SSSI; OXA-48-producing R. planticola intraabdominal infection (IAI); Pandoraea spp. CLABSI after liver transplant; enteric fever; B. fragilis, Leptotrichia wadei, and S. maltophilia, each of unknown source. In-hospital mortality occurred in 4 of these cases. Conclusion When AXDX yields no/indeterminate ID, ASP chart review for possible anaerobic/IAI, unique environmental exposures, and travel history may assist in guiding empiric therapy. GNB with AXDX targets are not excluded. Disclosures All authors: No reported disclosures.

We read with interest the article by Kamboj et al., who demonstrated that low Clostridium difficile real-time polymerase chain reaction (PCR) cycle thresholds of detection (CT) were predictive of toxin enzyme immunoassay positivity and disease severity in oncology patients who showed a positive C. difficile nucleic acid amplification test (NAAT) result. 1 Kamboj M Brite J McMillen T Robilotti E Herrera A Septowitz K et al. Potential of real-time PCR threshold cycle (CT) to predict presence of free toxin and clinically relevant C. difficile infection (CDI) in patients with cancer. J Infect. 2018; 76: 369-375https://doi.org/10.1016/j.jinf.2017.12.001 Abstract Full Text Full Text PDF PubMed Scopus (34) Google Scholar These findings are consistent with those reported in other studies that found C. difficile PCR CT (i.e., ≤ 26.0-28.0) may be similar to the results obtained from the cell cytotoxicity neutralization assay (CCNA) and superior to those obtained from toxin enzyme immunoassay in differentiating clinical C. difficile infection (CDI). 2 Polage CR Gyorke CE Kennedy MA Leslie JL Chin DL Wang S et al. Overdiagnosis of Clostridium difficile Infection in the Molecular Test Era. JAMA Intern Med. 2015; 175: 1792-1801https://doi.org/10.1001/jamainternmed.2015.4114 Crossref PubMed Scopus (364) Google Scholar , 3 Garvey MI Bradley CW Wilkinson MAC Holden E Can a toxin gene NAAT be used to predict toxin EIA and the severity of Clostridium difficile infection?. Antimicrob Resist Infect Control. 2017; 6: 127https://doi.org/10.1186/s13756-017-0283-z Crossref PubMed Scopus (21) Google Scholar , 4 Senchyna F Gaur RL Gombar S Truong CY Schroeder LF Banaei N J Clin Microbiol. 2017; 55: 2651-2660https://doi.org/10.1128/JCM.00563-17 Crossref PubMed Scopus (49) Google Scholar , 5 Hitchcock M Holubar M Infectious LTOFPCR cycle-threshold-derived toxin identifies patients at low-risk for complications of C. difficile infection who do not require treatment. Open Forum Infect Dis. 2017; 4: S395https://doi.org/10.1093/ofid/ofx163.985 Crossref Google Scholar