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The Streptococcus bovis group (previously group D streptococci) consists of seven distinct species and subspecies. Definitive identification within the group is important, as certain organisms have been associated with gastrointestinal carcinoma, bacteremia, infective endocarditis, meningitis, biliary tract disease, and carcinoma, among others.

Antistaphylococcal penicillins and cefazolin remain the primary treatments for infections with methicillin-susceptible Staphylococcus aureus (MSSA). The cefazolin inoculum effect (CzIE) causes the cefazolin MIC to be elevated in proportion to the number of bacteria in the inoculum. The objective of this multicenter study was to evaluate the prevalence of the CzIE in North American MSSA isolates. Clinical MSSA isolates from six microbiology laboratories in the United States and one microbiology laboratory in Canada were screened for the CzIE by broth microdilution at a standard inoculum (~5 × 10(5) CFU/mL) and a high inoculum (~5 × 10(7) CFU/mL). Genome sequencing was performed to further characterize the MSSA isolates. The CzIE was present in 57/305 (18.6%) MSSA isolates, ranging from 0% to 27.9% across study sites. More of the CzIE-positive isolates (29.8%) had standard inoculum cefazolin MICs of 1.0 μg/mL than the CzIE-negative isolates did (3.2%) (P

Background The threat of surging COVID-19 cases prompted many hospitals in the United States to preemptively suspend elective procedures throughout the pandemic. Utilizing samples from a large hospital in Los Angeles, we sought to determine if temporal trends in SARS-CoV-2 Cycle threshold (Ct) values (proxy for viral RNA loads) were predictive for the number of future COVID-19 cases. Methods Nasopharyngeal specimens on symptomatic patients and asymptomatic admissions were tested using the Xpert Xpress SARS-CoV-2 and SARS-CoV-2/Flu/RSV assays (Cepheid). Ct values for all SARS-CoV-2 detections between October 2020 to March 2021 were compiled for analysis. Results A total of 2,114 SARS-CoV-2-positive samples were included. The number of tests performed per week increased dramatically in December peaking the first week of January before returning to pre-surge numbers by Mid-February. Ct values fell during this same period with values in December and January (25.6±7.8 and 27±7.9, respectively) significantly lower than those of the other months (30±9.3 to 37.7±6.3). Average weekly Ct values for all patients were significantly, negatively correlated with the number of tests run the following week (R= -0.71, P< 0.001) and two weeks later (R= -0.75, P< 0.0001). Ct values for patients who were asymptomatic at the time of testing most strongly correlated with total number of tests performed one month later (R= -0.86, P< 0.0001). Average weekly Ct values and number of test run As cases (light grey) increased during December and January, there was a significant decrease in Ct values (dark grey) during that same time period. Average Ct values are a leading indicator of cases Average weekly Ct values for all patients (light grey) were significantly, negatively correlated with the number of tests run the following week (R= -0.71, P Conclusion Lower Ct values, representing higher levels of viral RNA, have been associated with risk of intubation and infectivity. During the winter surge, we observed significantly lower Ct values suggesting that the increased transmission and morbidity of COVID-19 was temporarily associated with higher viral loads. Interestingly, Ct values for asymptomatic patients were most strongly associated with number of cases observed 1 months in the future, suggesting that asymptomatic viral load may be a leading indicator for forthcoming outbreaks. Given this association, Ct values may be a useful tool for predicting regional outbreaks of COVID-19 and more judicious cessation of elective procedures. Disclosures All Authors: No reported disclosures

Background Bone and Joint Infections (BJIs) present with non-specific symptoms that may include pain, swelling, and fever and are associated with high morbidity and significant risk of mortality. BJIs can be caused by a variety of bacteria and fungi, including anaerobes and microorganisms that can be challenging to culture or identify by traditional microbiological methods. Clinicians primarily rely on culture to identify the pathogen(s) responsible for infection. The BioFire® Bone and Joint Infection (BJI) Panel (BioFire Diagnostics, Salt Lake City, UT) is designed to detect 15 gram-positive bacteria (including seven anaerobes), 14 gram-negative bacteria (including one anaerobe), two yeast, and eight antimicrobial resistance (AMR) genes from synovial fluid specimens in about an hour. The objective of this study was to evaluate the performance of an Investigational Use Only (IUO) version of the BioFire BJI Panel compared to various reference methods. Methods Remnant synovial fluid specimens, which were collected for routine clinical care at 13 study sites in the US and Europe, underwent testing using an IUO version of the BioFire BJI Panel. Performance of this test was determined by comparison to Standard of Care (SoC) consisting of bacterial culture performed at each study site according to their routine procedures. Results A total of 1544 synovial fluid specimens were collected and tested with the BioFire BJI Panel. The majority of specimens were from knee joints (77.9%) and arthrocentesis (79.4%) was the most common collection method. Compared to SoC culture, overall sensitivity was 90.2% and specificity was 99.8%. The BioFire BJI Panel yielded a total of 268 Detected results, whereas SoC yielded a total of 215 positive results for on-panel analytes. Conclusion The BioFire BJI Panel is a sensitive, specific, and robust test for rapid detection of a wide range of analytes in synovial fluid specimens. The number of microorganisms and resistance genes included in the BioFire BJI Panel, together with a reduced time-to-result and increased diagnostic yield compared to culture, is expected to aid in the timely diagnosis and appropriate management of BJIs. Disclosures Benjamin von Bredow, PhD, BioFire (Grant/Research Support) Jennifer Dien Bard, PhD, BioFire Diagnostic (Consultant, Scientific Research Study Investigator) Bart Kensinger, PhD, BioFire Diagnostics (Employee) Benedicte Pons, PhD, bioMerieux SA (Employee) Corinne Jay, PhD, bioMerieux SA (Employee)

Effective evaluations of antimicrobial susceptibility tests (ASTs) require robust study design. The Clinical and Laboratory Standards Institute (CLSI) Subcommittee on Antimicrobial Susceptibility Testing has recognized that many published studies reporting the performance of commercial ASTs (cASTs) suffer from major design and/or analysis flaws, rendering the results difficult or impossible to interpret. This minireview outlines the current consensus of the Methods Development and Standardization Working Group of the CLSI Subcommittee on Antimicrobial Susceptibility Testing regarding best practices for systematic evaluation of the performance of an AST, including the analysis and presentation of essential data intended for publication.

In this work we describe the identification of a copper-inducible regulon in Mycobacterium tuberculosis (Mtb). Among the regulated genes was Rv0190/MT0200, a paralogue of the copper metalloregulatory repressor CsoR. The five-locus regulon, which includes a gene that encodes the copper-protective metallothionein MymT, was highly induced in wild type Mtb treated with copper, and highly expressed in an Rv0190/MT0200 mutant. Importantly, the Rv0190/MT0200 mutant was hyper-resistant to copper. The promoters of all five loci share a palindromic motif that was recognized by the gene product of Rv0190/MT0200. For this reason we named Rv0190/MT0200 RicR for regulated in copper repressor. Intriguingly, several of the RicR-regulated genes, including MymT, are unique to pathogenic Mycobacteria. The identification of a copper-responsive regulon specific to virulent mycobacterial species suggests copper homeostasis must be maintained during an infection. Alternatively, copper may provide a cue for the expression of genes unrelated to metal homeostasis, but nonetheless necessary for survival in a host.