An updated technique to obtain explosive kinetics data on microsecond timescales.

There are few techniques available for chemists to obtain time-to-explosion data with known temperature inputs at the early stages of the design and synthesis of new explosives. In the 1960s, a technique was developed to rapidly heat milligram-quantities of confined explosives to ∼1000 K on microsecond timescales. Wenograd [Trans. Faraday Soc. 57, 1612 (1961)] loaded explosives inside stainless steel hypodermic needles, connected them to a fireset and rapidly discharged a capacitor through the steel. He obtained the temperature by measuring the needle resistance in a Wheatstone bridge arrangement and the time to explosion from a needle rupture. However, owing to the narrow-gauge needles used in the original research, the experiment was only possible with melt-castable explosives; it was never replicated, and modern diagnostics are now available with advances beyond the 1960s. Here, we report the development of the High Explosives Initiation Time (HEIT) test, which utilizes a 250 J pulsed power system to heat the needles. This work extends the Wenograd approach by using optical diagnostics, computational modeling, and advanced techniques to measure needle resistance and needle rupture. Preliminary rate information for pentaerythritol tetranitrate (PETN) will be presented.

Neuroinvasive Bacillus cereus Infection in Immunocompromised Hosts: Epidemiologic Investigation of 5 Patients With Acute Myeloid Leukemia.

Background: Bacillus cereus is a ubiquitous gram-positive rod-shaped bacterium that can cause sepsis and neuroinvasive disease in patients with acute leukemia or neutropenia. Methods: A single-center retrospective review was conducted to evaluate patients with acute leukemia, positive blood or cerebrospinal fluid test results for B cereus, and abnormal neuroradiographic findings between January 2018 and October 2022. Infection control practices were observed, environmental samples obtained, a dietary case-control study completed, and whole genome sequencing performed on environmental and clinical Bacillus isolates. Results: Five patients with B cereus neuroinvasive disease were identified. All patients had acute myeloid leukemia (AML), were receiving induction chemotherapy, and were neutropenic. Neurologic involvement included subarachnoid or intraparenchymal hemorrhage or brain abscess. All patients were treated with ciprofloxacin and survived with limited or no neurologic sequelae. B cereus was identified in 7 of 61 environmental samples and 1 of 19 dietary protein samples-these were unrelated to clinical isolates via sequencing. No point source was identified. Ciprofloxacin was added to the empiric antimicrobial regimen for patients with AML and prolonged or recurrent neutropenic fevers; no new cases were identified in the ensuing year. Conclusions: B cereus is ubiquitous in the hospital environment, at times leading to clusters with unrelated isolates. Fastidious infection control practices addressing a range of possible exposures are warranted, but their efficacy is unknown and they may not be sufficient to prevent all infections. Thus, including B cereus coverage in empiric regimens for patients with AML and persistent neutropenic fever may limit the morbidity of this pathogen.

Mycobacterium abscessus Cluster in Cardiac Surgery Patients Potentially Attributable to a Commercial Water Purification System.

BACKGROUND: Nontuberculous mycobacteria are water-avid pathogens that are associated with nosocomial infections. OBJECTIVE: To describe the analysis and mitigation of a cluster of Mycobacterium abscessus infections in cardiac surgery patients. DESIGN: Descriptive study. SETTING: Brigham and Women's Hospital, Boston, Massachusetts. PARTICIPANTS: Four cardiac surgery patients. INTERVENTION: Commonalities among cases were sought, potential sources were cultured, patient and environmental specimens were sequenced, and possible sources were abated. MEASUREMENTS: Description of the cluster, investigation, and mitigation. RESULTS: Whole-genome sequencing confirmed homology among clinical isolates. Patients were admitted during different periods to different rooms but on the same floor. There were no common operating rooms, ventilators, heater-cooler devices, or dialysis machines. Environmental cultures were notable for heavy mycobacterial growth in ice and water machines on the cluster unit but little or no growth in ice and water machines in the hospital's other 2 inpatient towers or in shower and sink faucet water in any of the hospital's 3 inpatient towers. Whole-genome sequencing confirmed the presence of a genetically identical element in ice and water machine and patient specimens. Investigation of the plumbing system revealed a commercial water purifier with charcoal filters and an ultraviolet irradiation unit leading to the ice and water machines in the cluster tower but not the hospital's other inpatient towers. Chlorine was present at normal levels in municipal source water but was undetectable downstream from the purification unit. There were no further cases after high-risk patients were switched to sterile and distilled water, ice and water machine maintenance was intensified, and the commercial purification system was decommissioned. LIMITATION: Transmission pathways were not clearly characterized. CONCLUSION: Well-intentioned efforts to modify water management systems may inadvertently increase infection risk for vulnerable patients. PRIMARY FUNDING SOURCE: National Institutes of Health.

Rethinking recovery in adolescent concussions: Network-level functional connectivity alterations associated with motor deficits.

Adolescents who are clinically recovered from concussion continue to show subtle motor impairment on neurophysiological and behavioral measures. However, there is limited information on brain-behavior relationships of persistent motor impairment following clinical recovery from concussion. We examined the relationship between subtle motor performance and functional connectivity of the brain in adolescents with a history of concussion, status post-symptom resolution, and subjective return to baseline. Participants included 27 adolescents who were clinically recovered from concussion and 29 never-concussed, typically developing controls (10-17 years); all participants were examined using the Physical and Neurologic Examination of Subtle Signs (PANESS). Functional connectivity between the default mode network (DMN) or dorsal attention network (DAN) and regions of interest within the motor network was assessed using resting-state functional magnetic resonance imaging (rsfMRI). Compared to controls, adolescents clinically recovered from concussion showed greater subtle motor deficits as evaluated by the PANESS and increased connectivity between the DMN and left lateral premotor cortex. DMN to left lateral premotor cortex connectivity was significantly correlated with the total PANESS score, with more atypical connectivity associated with more motor abnormalities. This suggests that altered functional connectivity of the brain may underlie subtle motor deficits in adolescents who have clinically recovered from concussion. More investigation is required to understand the persistence and longer-term clinical relevance of altered functional connectivity and associated subtle motor deficits to inform whether functional connectivity may serve as an important biomarker related to longer-term outcomes after clinical recovery from concussion.

Ralstonia pickettii and Pseudomonas aeruginosa Bloodstream Infections Associated With Contaminated Extracorporeal Membrane Oxygenation Water Heater Devices.

We report on probable factory-based contamination of portable water heaters with waterborne pathogens and 2 bloodstream infections potentially attributable to off-label use of these water heaters to warm extracorporeal membrane oxygenation circuits. Great caution is warranted when using water-based devices to care for critically ill patients.

Cluster of Burkholderia cepacia Complex Infections Associated With Extracorporeal Membrane Oxygenation Water Heater Devices.

BACKGROUND: Burkholderia cepacia complex is a group of potential nosocomial pathogens often linked to contaminated water. We report on a cluster of 8 B. cepacia complex infections in cardiothoracic intensive care unit patients, which were attributed to contaminated extracorporeal membrane oxygenation (ECMO) water heaters. METHODS: In December 2020, we identified an increase in B. cepacia complex infections in the cardiothoracic intensive care unit at Brigham and Women's Hospital. We sought commonalities, sequenced isolates, obtained environmental specimens, and enacted mitigation measures. RESULTS: Whole-genome sequencing of 13 B. cepacia complex clinical specimens between November 2020 and February 2021 identified 6 clonally related isolates, speciated as Burkholderia contaminans. All 6 occurred in patients on ECMO. Microbiology review identified 2 additional B. contaminans cases from June 2020 that may have also been cluster related, including 1 in a patient receiving ECMO. All 8 definite or probable cluster cases required treatment; 3 patients died, and 3 experienced recurrent infections. After ECMO was identified as the major commonality, all 9 of the hospital's ECMO water heaters were cultured, and B. contaminans grew in all cultures. Cultures from air sampled adjacent to the water heaters were negative. Water heater touch screens were culture positive for B. contaminans, and the sink drain in the ECMO heater reprocessing room also grew clonal B. contaminans. Observations of reprocessing revealed opportunities for cross-contamination between devices through splashing from the contaminated sink. The cluster was aborted by removing all water heaters from clinical service. CONCLUSIONS: We identified a cluster of 8 B. cepacia complex infections associated with contaminated ECMO water heaters. This cluster underscores the potential risks associated with water-based ECMO heaters and, more broadly, water-based care for vulnerable patients.

Rapid Control of Hospital-Based Severe Acute Respiratory Syndrome Coronavirus 2 Omicron Clusters Through Daily Testing and Universal Use of N95 Respirators.

The highly contagious severe acute respiratory syndrome coronavirus 2 Omicron variant increases risk for nosocomial transmission despite universal masking, admission testing, and symptom screening. We report large increases in hospital-onset infections and 2 unit-based clusters. The clusters rapidly abated after instituting universal N95 respirators and daily testing. Broader use of these strategies may prevent nosocomial transmissions.

Altered white matter diffusivity and subtle motor function in a pilot cohort of adolescents with sports-related concussion.

BACKGROUND AND OBJECTIVE: Adolescents with sports-related concussion (SRC) demonstrate acute and persistent deficits in subtle motor function. However, there is limited research examining related neurological underpinnings. This pilot study examined changes in motor-associated white matter pathways using diffusion tensor imaging (DTI) and their relationship with subtle motor function. METHODS: Twelve adolescents with SRC (12-17 years) within two-weeks post-injury and 13 never-injured neurotypical peers completed DTI scanning. A subset of 6 adolescents with SRC returned for a follow-up visit post-medical clearance from concussion. Subtle motor function was evaluated using the Physical and Neurological Examination of Subtle Signs (PANESS). RESULTS: Adolescents with SRC showed higher mean diffusivity (MD) of the superior corona radiata and greater subtle motor deficits compared to controls. Across all participants, greater subtle motor deficits were associated with higher (more atypical) MD of the superior corona radiata. Preliminary longitudinal analysis indicated reduction in fractional anisotropy of the corpus callosum but no change in the MD of the superior corona radiata from the initial visit to the follow-up visit post-medical clearance. CONCLUSIONS: These findings support preliminary evidence for a brain-behavior relationship between superior corona radiata microstructure and subtle motor deficits in adolescents with SRC that merits further investigation.

Observational bias within a hospital-wide hand hygiene program.

We assessed the extent to which healthcare workers report more favorable hand hygiene rates when observing members of their own professional group versus other groups' observations of them. Healthcare workers consistently reported higher compliance rates for their own group compared to others' observations of them (97 vs 92%; P ≤ .001).

The Risk of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Transmission from Patients With Undiagnosed Coronavirus Disease 2019 (COVID-19) to Roommates in a Large Academic Medical Center.

We assessed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission between patients in shared rooms in an academic hospital between September 2020 and April 2021. In total, 11 290 patients were admitted to shared rooms, of whom 25 tested positive. Among 31 exposed roommates, 12 (39%) tested positive within 14 days. Transmission was associated with polymerase chain reaction (PCR) cycle thresholds ≤21.

Prospective Clinical Assessments of Hospitalized Patients With Positive SARS-CoV-2 PCR Tests for Necessity of Isolation.

We prospectively assessed 536 hospitalized patients with positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) polymerase chain reaction tests for infectiousness based on symptoms, cycle thresholds, and SARS-CoV-2 history, with repeat testing and serologies in select cases. One hundred forty-eight (28%) patients were deemed noninfectious, most with evidence of prior infection, and managed on standard precautions without evidence of transmission.

Transmission of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) From Asymptomatic and Presymptomatic Individuals in Healthcare Settings Despite Medical Masks and Eye Protection.

We describe 3 instances of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission despite medical masks and eye protection, including transmission despite the source person being masked, transmission despite the exposed person being masked, and transmission despite both parties being masked. Whole genome sequencing confirmed perfect homology between source and exposed persons' viruses in all cases.

A SARS-CoV-2 Cluster in an Acute Care Hospital.

BACKGROUND: Little is known about clusters of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in acute care hospitals. OBJECTIVE: To describe the detection, mitigation, and analysis of a large cluster of SARS-CoV-2 infections in an acute care hospital with mature infection control policies. DESIGN: Descriptive study. SETTING: Brigham and Women's Hospital, Boston, Massachusetts. PARTICIPANTS: Patients and staff with cluster-related SARS-CoV-2 infections. INTERVENTION: Close contacts of infected patients and staff were identified and tested every 3 days, patients on affected units were preemptively isolated and repeatedly tested, affected units were cleaned, room ventilation was measured, and specimens were sent for whole-genome sequencing. A case-control study was done to compare clinical interactions, personal protective equipment use, and breakroom and workroom practices in SARS-CoV-2-positive versus negative staff. MEASUREMENTS: Description of the cluster, mitigation activities, and risk factor analysis. RESULTS: Fourteen patients and 38 staff members were included in the cluster per whole-genome sequencing and epidemiologic associations. The index case was a symptomatic patient in whom isolation was discontinued after 2 negative results on nasopharyngeal polymerase chain reaction testing. The patient subsequently infected multiple roommates and staff, who then infected others. Seven of 52 (13%) secondary infections were detected only on second or subsequent tests. Eight of 9 (89%) patients who shared rooms with potentially contagious patients became infected. Potential contributing factors included high viral loads, nebulization, and positive pressure in the index patient's room. Risk factors for transmission to staff included presence during nebulization, caring for patients with dyspnea or cough, lack of eye protection, at least 15 minutes of exposure to case patients, and interactions with SARS-CoV-2-positive staff in clinical areas. Whole-genome sequencing confirmed that 2 staff members were infected despite wearing surgical masks and eye protection. LIMITATION: Findings may not be generalizable. CONCLUSION: SARS-CoV-2 clusters can occur in hospitals despite robust infection control policies. Insights from this cluster may inform additional measures to protect patients and staff. PRIMARY FUNDING SOURCE: None.

Sources of exposure identified through structured interviews of healthcare workers who test positive for severe acute respiratory coronavirus virus 2 (SARS-CoV-2): A prospective analysis at two teaching hospitals.

We interviewed 1,208 healthcare workers with positive SARS-CoV-2 tests between October 2020 and June 2021 to determine likely exposure sources. Overall, 689 (57.0%) had community exposures (479 from household members), 76 (6.3%) had hospital exposures (64 from other employees including 49 despite masking), 11 (0.9%) had community and hospital exposures, and 432 (35.8%) had no identifiable source of exposure.

Implementation of long solids retention time activated sludge process for rural residential community.

Most rural communities in the United States are facing increasingly rigorous effluent criteria, especially ammonia, for their wastewater treatment facilities. A new baffled bioreactor (BBR) technology, which employs a preanoxic activated sludge process operated with a long solids retention time (SRT), was installed in a small community in Missouri to address the more stringent effluent limits. In a recent full-year normal operation cycle (2018), the average effluent concentrations of BOD5 , TSS, and ammonia-nitrogen were 3.2, 2.2, and 0.5 mg/L, respectively, with removal efficiencies of 96%, 85%, and 98%, respectively. All these parameters were significantly better than their respective permit limits. The long SRT afforded an enhanced factor of safety for the process, conferring the ability to nitrify at sustained ambient temperatures as low as -22°C. Long SRT also resulted in significant reductions in waste sludge production, resulting in dramatically reduced operational costs for sludge handling. Ultimately, the long SRT activated sludge process afforded the ability to meet stringent effluent quality standards including ammonia and the numerous unique challenges that are inherent to small flows. PRACTITIONER POINTS: Small community hydraulic and mass loadings are highly variable and difficult to quantify during facility design. A long SRT activated sludge process warrants superior performance and enhanced factor of safety. The long SRT process with preanoxic zones generated no excess sludge during the extended operation period, significantly simplifying plant operation. Long SRT process is well suited to accommodate wastewater variability associated with small communities while maintaining superior treatment quality.

Low Risk of Coronavirus Disease 2019 (COVID-19) Among Patients Exposed to Infected Healthcare Workers.

Many patients are fearful of acquiring coronavirus disease 2019 (COVID-19) in hospitals and clinics. We characterized the risk of COVID-19 among 226 patients exposed to healthcare workers with confirmed COVID-19. One patient may have been infected, suggesting that the risk of COVID-19 transmission from healthcare workers to patients is generally low.

Incidence of Nosocomial COVID-19 in Patients Hospitalized at a Large US Academic Medical Center.

Importance: Some patients are avoiding essential care for fear of contracting coronavirus disease 2019 (COVID-19) in hospitals. There are few data, however, on the risk of acquiring COVID-19 in US hospitals. Objective: To assess the incidence of COVID-19 among patients hospitalized at a large US academic medical center in the 12 weeks after the first inpatient case was identified. Design, Setting, and Participants: This cohort study included all patients admitted to Brigham and Women's Hospital (Boston, Massachusetts) between March 7 and May 30, 2020. Follow-up occurred through June 17, 2020. Medical records for all patients who first tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by reverse-transcription polymerase chain reaction (RT-PCR) on hospital day 3 or later or within 14 days of discharge were reviewed. Exposures: A comprehensive infection control program was implemented that included dedicated COVID-19 units with airborne infection isolation rooms, personal protective equipment in accordance with US Centers for Disease Control and Prevention recommendations, personal protective equipment donning and doffing monitors, universal masking, restriction of visitors, and liberal RT-PCR testing of symptomatic and asymptomatic patients. Main Outcomes and Measures: Whether infection was community or hospital acquired based on timing of tests, clinical course, and exposures. Results: Over the 12-week period, 9149 patients (mean [SD] age, 46.1 [26.4] years; median [IQR] age, 51 years [30-67 years]; 5243 female [57.3%]) were admitted to the hospital, for whom 7394 SARS-CoV-2 RT-PCR tests were performed; 697 COVID-19 cases were confirmed, translating into 8656 days of COVID-19-related care. Twelve of the 697 hospitalized patients with COVID-19 (1.7%) first tested positive on hospital day 3 or later (median, 4 days; range, 3-15 days). Of these, only 1 case was deemed to be hospital acquired, most likely from a presymptomatic spouse who was visiting daily and diagnosed with COVID-19 before visitor restrictions and masking were implemented. Among 8370 patients with non-COVID-19-related hospitalizations discharged through June 17, 11 (0.1%) tested positive within 14 days (median time to diagnosis, 6 days; range, 1-14 days). Only 1 case was deemed likely to be hospital acquired, albeit with no known exposures. Conclusions and Relevance: In this cohort study of patients in a large academic medical center with rigorous infection control measures, nosocomial COVID-19 was rare during the height of the pandemic in the region. These findings may inform practices in other institutions and provide reassurance to patients concerned about contracting COVID-19 in hospitals.

A Flexi-PEGDA Upconversion Implant for Wireless Brain Photodynamic Therapy.

Near-infrared (NIR) activatable upconversion nanoparticles (UCNPs) enable wireless-based phototherapies by converting deep-tissue-penetrating NIR to visible light. UCNPs are therefore ideal as wireless transducers for photodynamic therapy (PDT) of deep-sited tumors. However, the retention of unsequestered UCNPs in tissue with minimal options for removal limits their clinical translation. To address this shortcoming, biocompatible UCNPs implants are developed to deliver upconversion photonic properties in a flexible, optical guide design. To enhance its translatability, the UCNPs implant is constructed with an FDA-approved poly(ethylene glycol) diacrylate (PEGDA) core clad with fluorinated ethylene propylene (FEP). The emission spectrum of the UCNPs implant can be tuned to overlap with the absorption spectra of the clinically relevant photosensitizer, 5-aminolevulinic acid (5-ALA). The UCNPs implant can wirelessly transmit upconverted visible light till 8 cm in length and in a bendable manner even when implanted underneath the skin or scalp. With this system, it is demonstrated that NIR-based chronic PDT is achievable in an untethered and noninvasive manner in a mouse xenograft glioblastoma multiforme (GBM) model. It is postulated that such encapsulated UCNPs implants represent a translational shift for wireless deep-tissue phototherapy by enabling sequestration of UCNPs without compromising wireless deep-tissue light delivery.

COVID-19 infections among HCWs exposed to a patient with a delayed diagnosis of COVID-19.

We report on COVID-19 risk among HCWs exposed to a patient diagnosed with COVID-19 on day 13 of hospitalization. There were 44 HCWs exposed to the patient before contact and droplet precautions were implemented: of these, 2 of 44 (5%) developed COVID-19 potentially attributable to the exposure.