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A multicenter study was conducted to evaluate the diagnostic accuracy (sensitivity and specificity) of the Verigene Gram-Positive Blood Culture Test (BC-GP) test to identify 12 Gram-positive bacterial gene targets and three genetic resistance determinants directly from positive blood culture broths containing Gram-positive bacteria. 1,252 blood cultures containing Gram-positive bacteria were prospectively collected and tested at five clinical centers between April, 2011 and January, 2012. An additional 387 contrived blood cultures containing uncommon targets (e.g., Listeria spp., S. lugdunensis, vanB-positive Enterococci) were included to fully evaluate the performance of the BC-GP test. Sensitivity and specificity for the 12 specific genus or species targets identified by the BC-GP test ranged from 92.6%-100% and 95.4%-100%, respectively. Identification of the mecA gene in 599 cultures containing S. aureus or S. epidermidis was 98.6% sensitive and 94.3% specific compared to cefoxitin disk method. Identification of the vanA gene in 81 cultures containing Enterococcus faecium or E. faecalis was 100% sensitive and specific. Approximately 7.5% (87/1,157) of single-organism cultures contained Gram-positive bacteria not present on the BC-GP test panel. In 95 cultures containing multiple organisms the BC-GP test was in 71.6% (68/95) agreement with culture results. Retrospective analysis of 107 separate blood cultures demonstrated that identification of methicillin resistant S. aureus and vancomycin resistant Enterococcus spp. was completed an average of 41.8 to 42.4 h earlier using the BC-GP test compared to routine culture methods. The BC-GP test was unable to assign mecA to a specific organism in cultures containing more than one Staphylococcus isolate and does not identify common blood culture contaminants such as Micrococcus, Corynebacterium, and Bacillus. The BC-GP test is a multiplex test capable of detecting most leading causes of Gram-positive bacterial blood stream infections as well as genetic markers of methicillin and vancomycin resistance directly from positive blood cultures.

The prompt and accurate identification of bacterial pathogens is fundamental to patient health and outcome. Recent advances in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) have revolutionized bacterial identification in the clinical laboratory, but uniform incorporation of this technology in the U.S. market has been delayed by a lack of FDA-cleared systems. In this study, we conducted a multicenter evaluation of the MALDI Biotyper CA (MBT-CA) System (Bruker Daltonics Inc, Billerica, MA) for the identification of aerobic gram-negative bacteria as part of a 510(k) submission to the FDA. A total of 2,263 aerobic gram negative bacterial isolates were tested representing 23 genera and 61 species. Isolates were collected from various clinical sources and results obtained from the MBT-CA System were compared to DNA sequencing and/or biochemical testing. Isolates that failed to report as a \"high confidence species ID\" [log(score) ≥2.00] were re-tested using an extraction method. The MBT-CA System identified 96.8% and 3.1% of isolates with either a \"high confidence\" or a \"low confidence\" [log(score) value between 1.70 and <2.00] species ID, respectively. Two isolates did not produce acceptable confidence scores after extraction. The MBT-CA System correctly identified 99.8% (2,258/2,263) to genus and 98.2% (2,222/2,263) to species level. These data demonstrate that the MBT-CA System provides accurate results for the identification of aerobic gram-negative bacteria.

Initial public health data show that Black race may be a risk factor for worse outcomes of coronavirus disease 2019 (COVID-19). To characterize the association of race with incidence and outcomes of COVID-19, while controlling for age, sex, socioeconomic status, and comorbidities. This cross-sectional study included 2595 consecutive adults tested for COVID-19 from March 12 to March 31, 2020, at Froedtert Health and Medical College of Wisconsin (Milwaukee), the largest academic system in Wisconsin, with 879 inpatient beds (of which 128 are intensive care unit beds). Race (Black vs White, Native Hawaiian or Pacific Islander, Native American or Alaska Native, Asian, or unknown). Main outcomes included COVID-19 positivity, hospitalization, intensive care unit admission, mechanical ventilation, and death. Additional independent variables measured and tested included socioeconomic status, sex, and comorbidities. Reverse transcription polymerase chain reaction assay was used to test for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). A total of 2595 patients were included. The mean (SD) age was 53.8 (17.5) years, 978 (37.7%) were men, and 785 (30.2%) were African American patients. Of the 369 patients (14.2%) who tested positive for COVID-19, 170 (46.1%) were men, 148 (40.1%) were aged 60 years or older, and 218 (59.1%) were African American individuals. Positive tests were associated with Black race (odds ratio [OR], 5.37; 95% CI, 3.94-7.29; P = .001), male sex (OR, 1.55; 95% CI, 1.21-2.00; P = .001), and age 60 years or older (OR, 2.04; 95% CI, 1.53-2.73; P = .001). Zip code of residence explained 79% of the overall variance in COVID-19 positivity in the cohort (ρ = 0.79; 95% CI, 0.58-0.91). Adjusting for zip code of residence, Black race (OR, 1.85; 95% CI, 1.00-3.65; P = .04) and poverty (OR, 3.84; 95% CI, 1.20-12.30; P = .02) were associated with hospitalization. Poverty (OR, 3.58; 95% CI, 1.08-11.80; P = .04) but not Black race (OR, 1.52; 95% CI, 0.75-3.07; P = .24) was associated with intensive care unit admission. Overall, 20 (17.2%) deaths associated with COVID-19 were reported. Shortness of breath at presentation (OR, 10.67; 95% CI, 1.52-25.54; P = .02), higher body mass index (OR per unit of body mass index, 1.19; 95% CI, 1.05-1.35; P = .006), and age 60 years or older (OR, 22.79; 95% CI, 3.38-53.81; P = .001) were associated with an increased likelihood of death. In this cross-sectional study of adults tested for COVID-19 in a large midwestern academic health system, COVID-19 positivity was associated with Black race. Among patients with COVID-19, both race and poverty were associated with higher risk of hospitalization, but only poverty was associated with higher risk of intensive care unit admission. These findings can be helpful in targeting mitigation strategies for racial disparities in the incidence and outcomes of COVID-19.

Abstract Objectives We examined the distribution of reverse transcription polymerase chain reaction (RT-PCR) cycle threshold (CT) values obtained from symptomatic patients being evaluated for coronavirus disease 2019 (COVID-19) to determine the proportion of specimens containing a viral load near the assay limit of detection (LoD) to gain practical insight to the risk of false-negative results. We also examined the relationship between CT value and patient age to determine any age-dependent difference in viral load or test sensitivity. Methods We collected CT values obtained from the cobas severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) assay corresponding to 1,213 combined nasopharyngeal-oropharyngeal specimens obtained from symptomatic individuals that were reported as positive or presumptive positive for SARS-CoV-2. CT values were stratified by SARS-CoV target and patient age group. Results In total, 93.3% to 98.4% of specimens demonstrated CT values greater than 3× the assay LoD, at which point false-negative results would not be expected. The mean of CT values between age groups was statistically equivalent with the exception of patients in age group 80 to 89 years, which demonstrated slightly lower CTs. Conclusions Based on the distribution of observed CT values, including the small proportion of specimens with values near the assay LoD, there is a low risk of false-negative RT-PCR results in combined nasopharyngeal-oropharyngeal specimens obtained from symptomatic individuals.

In late 2015 and early 2016, 11 patients were identified with cultures positive for Elizabethkingia anophelis in our health system. All patients had positive blood cultures upon admission. Chart review showed that all had major comorbidities and recent health care exposure. The attributable mortality rate was 18.2%.

Campylobacter diagnosis is hampered because many laboratories continue to use traditional stool culture, which is slow and suffers false-negative results. This large multi-site study used a composite reference method consisting of a new FDA-cleared immunoassay and four molecular techniques to compare to culture. Prospectively collected patient fecal specimens (1552) were first preliminarily categorized as positive or negative by traditional culture. All specimens were also tested by EIA, and any EIA-positive or culture-discrepant results were further characterized by 16S rRNA qPCR, eight species-specific PCR assays, bidirectional sequencing, and an FDA-cleared multiplex PCR panel. The five non-culture methods showed complete agreement on all positive and discrepant specimens which were then assigned as true-positive or true-negative specimens. Among 47 true-positive specimens, culture incorrectly identified 13 (28%) as negative, and 1 true-negative specimen as positive, for a sensitivity of 72.3%. Unexpectedly, among the true-positive specimens, 4 (8%) were the pathogenic species C. upsaliensis. Culture had a 30% false result rate compared to immunoassay and molecular methods. More accurate results lead to better diagnosis and treatment of suspected campylobacteriosis.

Abstract Background Pneumonia is a common illness, accounting for a staggering amount of worldwide morbidity and mortality. The diagnosis of pneumonia is challenging given the variety of responsible pathogens. Diagnostic testing for bacterial pneumonia has traditionally relied on time-consuming culture-based methods, though recently multiplexed molecular approaches have been described. Multiplexed molecular assays for pneumonia have the potential to provide broad diagnostic information in a rapid timeframe. Much has yet to be learned about these assays regarding analytical performance, potential impact, and optimal implementation strategy. Content Herein we provide a summary of what is known and what has yet to be learned about multiplexed molecular pneumonia assays. We provide a comparison of the different commercially available assays and summarize the most current performance data for each. We further describe outcome data and lessons learned from those who have implemented these assays worldwide. Finally, based on the current state of performance and outcome data, we provide informed strategies and considerations for laboratories contemplating implementation. Summary Multiplexed molecular assays for the diagnosis of pneumonia boast high accuracy though the diagnostic information gained from these assays is inherently different from culture and must be interpreted in cultural context. Despite this, these assays can be powerful and effective diagnostic tools with a potential to positively impact patient care. The extent to which this is realized varies from setting to setting, though is dependent on thoughtful implementation and a focus on delivering clear, rapid, and actionable results that can be interpreted in the appropriate context.

Abstract Objectives Aerococcus spp are Gram-positive cocci increasingly recognized as uropathogens. The Clinical and Laboratory Standards Institute recently published specific breakpoints for Aerococcus spp (M45, third edition); however, the standardized method used for antimicrobial susceptibility testing (AST) requires media not often maintained in clinical laboratories. The purpose of this study was to evaluate and compare alternative methods of AST for Aerococcus isolates. Methods AST was performed on 134 clinical isolates using the Etest on three different types of agar, Vitek 2, and BD Phoenix. These results were compared with broth microdilution using the Sensititre STP6F. Results Aerococcus exhibited low minimum inhibitory concentrations to benzylpenicillin, meropenem, linezolid, and vancomycin. Variable resistance was seen to levofloxacin, ceftriaxone, and tetracycline. Meropenem and vancomycin met all acceptance criteria with every alternative method tested. Benzylpenicillin and linezolid did not meet essential agreement on any AST method. Tetracycline met the majority of acceptance criteria with the exception of more than 3% very major error when using the Etest on chocolate agar, the Vitek 2, and BD Phoenix. Conclusions Overall, the alternate AST method with the highest agreement with broth microdilution was the Etest on Mueller-Hinton agar with 5% sheep blood and may be an optimal alternative to broth microdilution.

Abstract Objectives The purpose of this study is to describe and evaluate the impact of the participation of an antimicrobial stewardship program (ASP) pharmacist in microbiology rounds at our institution. Methods This single-center retrospective descriptive study included inpatient and ambulatory adults (≥18 years) with a susceptibility request reviewed during microbiology rounds between October 2018 and March 2019. In October 2018, multidisciplinary telephone microbiology rounds were initiated with the medical directors of the clinical microbiology laboratory and ASP pharmacist to review susceptibility requests. Numbers and types of interventions made by an ASP pharmacist and potential benefits were recorded and analyzed. Results Sixty-seven susceptibility requests were reviewed by an ASP pharmacist, of which 83.6% were inpatient. An ASP pharmacist completed chart reviews for 92.5% of requests and contacted the requester or primary team 74.6% of the time. About half (47.8%) of susceptibility requests were approved, and only 65.2% of requests from an infectious diseases provider were approved (P = .039). The most frequent potential benefits of the intervention included preventing unnecessary susceptibility testing (47.8%), improving clinician understanding (40.3%), and preventing treatment of a culture result deemed as a contaminant (19.4%). Conclusions ASP pharmacists are uniquely accessible and able to assist with preventing unnecessary susceptibility testing, optimizing antimicrobial therapy, and providing education to other health care professionals.