Schuetz, Audrey N.

Abstract Background Accurate microbiologic diagnosis is important for appropriate management of infectious diseases. Sequencing-based molecular diagnostics are increasingly used for precision diagnosis of infections. However, their clinical utility is unclear. Methods We conducted a retrospective analysis of specimens that underwent 16S ribosomal RNA (rRNA) gene polymerase chain reaction (PCR) followed by Sanger sequencing at our institution from April 2017 through March 2019. Results A total of 566 specimens obtained from 460 patients were studied. Patients were considered clinically infected or noninfected based on final diagnosis and management. In 17% of patients, 16S rRNA PCR/sequencing was positive and in 5% of patients, this test led to an impact on clinical care. In comparison, bacterial cultures were positive in 21% of patients. Specimens with a positive Gram stain had 12 times greater odds of having a positive molecular result than those with a negative Gram stain (95% confidence interval for odds ratio, 5.2–31.4). Overall, PCR positivity was higher in cardiovascular specimens (37%) obtained from clinically infected patients, with bacterial cultures being more likely to be positive for musculoskeletal specimens (P < .001). 16S rRNA PCR/sequencing identified a probable pathogen in 10% culture-negative specimens. Conclusion 16S rRNA PCR/sequencing can play a role in the diagnostic evaluation of patients with culture-negative infections, especially those with cardiovascular infections.

Abstract Introduction/Objective Matrix-assisted laser desorption ionization/ time-of-flight mass spectrometry (MALDI-TOF MS) direct from positive blood culture bottles has facilitated drastic drops in turn-around times for microorganism identification but has been poorly studied for anaerobes. We investigated the ability of MALDI-TOF to provide early anaerobe identification at 4 hours and 18-24 hours of growth on agar from anaerobic blood culture bottles. Additionally, we reviewed medical records of such patients to ascertain impact of early identification on antimicrobial treatment. Methods Over 9 months, we ran MALDI-TOF on early growth from blood cultures positive for growth in BACTEC™ Lytic/ 10 Anaerobic/F bottles. Broth from each bottle was subbed to sheep blood agar (4 hours, 5% CO2) and 2 CDC (BD-BBL™) anaerobic blood agar plates (examined 18-24 hours and 48 hours). Bruker Biotyper® RUO v7854 and Mayo Clinic Custom MALDI-TOF MS libraries were used for identification. Results 144/184 (78%) bottles resulted in growth of aerobic bacteria. Of the remaining bottles with growth of anaerobes, 38 were assessed by early MALDI-TOF. Early MALDI-TOF at 4 hours identified 3 Clostridium perfringens (8%) and an additional 26/38 (68%) isolates at 18-24 hours (both Gram-positive and –negative). Routine 48 hour identification was required for 9 (24%) isolates. In 7 cases, early MALDI-TOF resulted in a change to more appropriate antimicrobial therapy, most often for Bacteroides. Conclusion 29/38 (76%) of anaerobes from blood culture bottles were identified by early MALDI-TOF and reported to the clinician at least 24 hours before routine review of anaerobic sub plates for growth. All C. perfringens and Bacteroides were identified by 4 and 24 hours, respectively. Although early MALDI-TOF resulted in antimicrobial therapy adjustments in a minority of cases, it may allow for more targeted and earlier antimicrobial therapy. Early MALDI-TOF from anaerobic blood culture bottles should be considered for improved patient care and antimicrobial stewardship.

On 24 August 2020, the Centers for Disease Control and Prevention (CDC) updated its website to highlight that asymptomatic individuals, even those with exposure to a COVID-19-positive contact, do not necessarily need to be tested unless they have medical conditions associated with increased risk of severe illness from COVID-19. The CDC subsequently updated its guidance on 19 September 2020 to support testing of asymptomatic persons, including close contacts of persons with documented SARS-CoV-2 infection.

Interest continues to grow regarding the role of serologic assays for the detection of prior infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The U.S. Food and Drug Administration (FDA) has granted emergency use authorization (EUA) status to many SARS-CoV-2 serologic assays. In this document, expert recommendations from clinical microbiologist members of the American Society for Microbiology (ASM) concerning detailed verification strategies for SARS-CoV-2 serologic assays with FDA EUA are provided, as are insights into assay limitations and reporting considerations for laboratories.

Cefiderocol (CFDC) is a siderophore cephalosporin with activity against Gram-negative bacterial species that are resistant to carbapenems and other drugs. The MICs of CFDC were determined for 610 Gram-negative bacilli, including 302 multinational Enterobacterales isolates with characterized mechanisms of beta-lactam resistance, 180 clinical isolates from the Mayo Clinic and Mayo Clinic Laboratories not characterized for specific resistance mechanisms, and 128 isolates with CFDC MICs of ≥8 μg/ml obtained from International Health Management Associates, Inc.

This study aimed to determine whether agar dilution, research-use-only disk diffusion (Mast Group Ltd., Bootle Merseyside, UK), Etest (bioMérieux, Inc., Durham, NC), and MIC test strip (MTS) (Liofilchem, Inc., Waltham, MA) methods yield equivalent results to those of broth microdilution (BMD) for imipenem-relebactam susceptibility testing using a collection of 297 Gram-negative bacilli, including members of the order Enterobacterales and Pseudomonas aeruginosa , enriched for drug resistance.

Abstract Background Rapid blood culture diagnostics are of unclear benefit for patients with gram-negative bacilli (GNB) bloodstream infections (BSIs). We conducted a multicenter, randomized, controlled trial comparing outcomes of patients with GNB BSIs who had blood culture testing with standard-of-care (SOC) culture and antimicrobial susceptibility testing (AST) vs rapid organism identification (ID) and phenotypic AST using the Accelerate Pheno System (RAPID). Methods Patients with positive blood cultures with Gram stains showing GNB were randomized to SOC testing with antimicrobial stewardship (AS) review or RAPID with AS. The primary outcome was time to first antibiotic modification within 72 hours of randomization. Results Of 500 randomized patients, 448 were included (226 SOC, 222 RAPID). Mean (standard deviation) time to results was faster for RAPID than SOC for organism ID (2.7 [1.2] vs 11.7 [10.5] hours; P < .001) and AST (13.5 [56] vs 44.9 [12.1] hours; P < .001). Median (interquartile range [IQR]) time to first antibiotic modification was faster in the RAPID arm vs the SOC arm for overall antibiotics (8.6 [2.6–27.6] vs 14.9 [3.3–41.1] hours; P = .02) and gram-negative antibiotics (17.3 [4.9–72] vs 42.1 [10.1–72] hours; P < .001). Median (IQR) time to antibiotic escalation was faster in the RAPID arm vs the SOC arm for antimicrobial-resistant BSIs (18.4 [5.8–72] vs 61.7 [30.4–72] hours; P = .01). There were no differences between the arms in patient outcomes. Conclusions Rapid organism ID and phenotypic AST led to faster changes in antibiotic therapy for gram-negative BSIs. Clinical Trials Registration NCT03218397.

Abstract Aims Wound infections involving Candida albicans can be challenging to treat because of the fungus’ ability to penetrate wound tissue and form biofilms. The goal of this study was to assess the activity of a hypochlorous acid (HOCl)-generating electrochemical scaffold (e-scaffold) against C. albicans biofilms in vitro and on porcine dermal explants (ex vivo). Methods and Results C. albicans biofilms were grown either on acrylic-bottom six-well plates (in vitro) or on skin tissue excised from porcine ears (ex vivo), and the polarized e-scaffold was used to generate a continuous supply of low concentration HOCl near biofilm surfaces. C. albicans biofilms grown in vitro were reduced to undetectable amounts within 24 h of e-scaffold exposure, unlike control biofilms (5·28 ± 0·034 log10 (CFU cm-2); P < 0·0001). C. albicans biofilms grown on porcine dermal explants were also reduced to undetectable amounts in 24 h, unlike control explant biofilms (4·29 ± 0·057 log10 (CFU cm-2); P < 0·0001). There was a decrease in the number of viable mammalian cells (35·6 ± 6·4%) in uninfected porcine dermal explants exposed to continuous HOCl-generating e-scaffolds for 24 h compared to explants exposed to nonpolarized e-scaffolds (not generating HOCl) (P < 0·05). Conclusions Our HOCl-generating e-scaffold is a potential antifungal-free strategy to treat C. albicans biofilms in chronic wounds. Significance and Impact of the Study Wound infections caused by C. albicans are difficult to treat due to presence of biofilms in wound beds. Our HOCl producing e-scaffold provides a promising novel approach to treat wound infections caused by C. albicans.