Emergence of Extended-Spectrum ß-Lactamase Urinary Tract Infections Among Hospitalized Emergency Department Patients in the United States.

STUDY OBJECTIVE: Enterobacteriaceae resistant to ceftriaxone, mediated through extended-spectrum ß-lactamases (ESBLs), commonly cause urinary tract infections worldwide, but have been less prevalent in North America. Current US rates are unknown. We determine Enterobacteriaceae antimicrobial resistance rates among US emergency department (ED) patients hospitalized for urinary tract infection. METHODS: We prospectively enrolled adults hospitalized for urinary tract infection from 11 geographically diverse university-affiliated hospital EDs during 2018 to 2019. Among participants with culture-confirmed infection, we evaluated prevalence of antimicrobial resistance, including that caused by ESBL-producing Enterobacteriaceae, resistance risk factors, and time to in vitro-active antibiotics. RESULTS: Of 527 total participants, 444 (84%) had cultures that grew Enterobacteriaceae; 89 of 435 participants (20.5%; 95% confidence interval 16.9% to 24.5%; 4.6% to 45.4% by site) whose isolates had confirmatory testing had bacteria that were ESBL producing. The overall prevalence of ESBL-producing Enterobacteriaceae infection among all participants with urinary tract infection was 17.2% (95% confidence interval 14.0% to 20.7%). ESBL-producing Enterobacteriaceae infection risk factors were hospital, long-term care, antibiotic exposure within 90 days, and a fluoroquinolone- or ceftriaxone-resistant isolate within 1 year. Enterobacteriaceae resistance rates for other antimicrobials were fluoroquinolone 32.3%, gentamicin 13.7%, amikacin 1.3%, and meropenem 0.3%. Ceftriaxone was the most common empirical antibiotic. In vitro-active antibiotics were not administered within 12 hours of presentation to 48 participants (53.9%) with ESBL-producing Enterobacteriaceae infection, including 17 (58.6%) with sepsis. Compared with other Enterobacteriaceae infections, ESBL infections were associated with longer time to in vitro-active treatment (17.3 versus 3.5 hours). CONCLUSION: Among adults hospitalized for urinary tract infection in many US locations, ESBL-producing Enterobacteriaceae have emerged as a common cause of infection that is often not initially treated with an in vitro-active antibiotic.

Innate Sex Bias of Staphylococcus aureus Skin Infection Is Driven by α-Hemolysin.

Numerous studies have reported sex bias in infectious diseases, with bias direction dependent on pathogen and site of infection. Staphylococcus aureus is the most common cause of skin and soft tissue infections (SSTIs), yet sex bias in susceptibility to S. aureus SSTI has not been described. A search of electronic health records revealed an odds ratio of 2.4 for S. aureus SSTI in males versus females. To investigate the physiological basis of this bias, we compared outcomes between male and female mice in a model of S. aureus dermonecrosis. Consistent with the epidemiological data, female mice were better protected against SSTI, with reduced dermonecrosis followed later by increased bacterial clearance. Protection in females was disrupted by ovariectomy and restored by short-term estrogen administration. Importantly, this sex bias was mediated by a sex-specific response to the S. aureus-secreted virulence factor α-hemolysin (Hla). Infection with wild-type S. aureus suppressed inflammatory cytokine production in the skin of female, but not male, mice when compared with infection with an isogenic hla deletion mutant. This differential response was conserved following injection with Hla alone, demonstrating a direct response to Hla independent of bacterial burden. Additionally, neutrophils, essential for clearing S. aureus, demonstrated sex-specific S. aureus bactericidal capacity ex vivo. This work suggests that sex-specific skin innate responsiveness to Hla and neutrophil bactericidal capacity play important roles in limiting S. aureus SSTI in females. Understanding the molecular mechanisms controlling this sex bias may reveal novel targets to promote host innate defense against S. aureus skin infection.

New classifications for Life-threatening foreign body airway obstruction.

INTRODUCTION: Foreign body airway obstruction (FBAO) is a common medical emergency; however, few studies of life-threatening FBAO have been reported and no standard classification system is available. METHODS: We retrospectively evaluated patients who presented to the emergency departments of two hospitals and were diagnosed with FBAO. The primary outcome was cerebral performance category (CPC) score at discharge. To establish a new classification system for FBAO, FBAO was classified into three types based on the anatomical and physiological characteristics of the obstructed airway. RESULTS: A total of 137 patients were enrolled. Median age was 79.0 years. The most common cause of FBAO was meat, followed by bread, rice cake, and rice. Of all patients, 65.7% suffered cardiac arrest and 51.1% died. In contrast, 28.5% had favorable neurological outcomes, defined as CPC 1 and 2. Upper airway obstruction (type 1) was the most common (type 1, 78.1%), while trachea and/or bilateral main bronchus obstruction (type 2, 12.4%) showed significantly higher mortality than type 1 obstruction (82.4% vs 47.7%, P = 0.0078). Patients with unilateral bronchus and/or distal bronchus obstruction (type 3, 9.5%) were significantly more likely to consume a dysphagia diet than type 1 patients (23.1% vs 0%, P < 0.0001). CONCLUSION: The majority of patients with life-threatening FBAO were elderly and had poor neurological outcomes. Our new classification system divides FBAO into three types, and revealed that mortality was significantly higher with type 2 than type 1 obstruction. This classification system may improve the management of patients with FBAO and assessment of patient outcomes.

Sepsis alerts in EMS and the results of pre-hospital ETCO2.

BACKGROUND: Field sepsis alerts have the ability to expedite initial ED sepsis treatment. Our hypothesis is that in patients that meet EMS sepsis alert criteria there is a strong relationship between prehospital end-tidal carbon dioxide (ETCO2) readings and the outcome of diagnosed infection. METHODS: In 2014, our EMS service initiated a protocol requiring hospitals to receive notification of a "sepsis alert" on all suspected sepsis patients. The EMS service transports 70,000 patients/year to a number of urban centers. All patients transported to our major urban teaching hospital by our EMS service in one year in which a sepsis alert was announced were included in this study. The primary outcome variable was diagnosed infection and secondary outcomes were hospital admission, ICU admission and mortality. Positive lactate was defined as >4.0 mmol/L. ROC curve analysis was used to define the best cutoff for ETCO2. RESULTS: 351 patients were announced as EMS sepsis alert patients and transported to our center over a one year period. Positive outcomes were as follows: diagnosed infection in 28% of patients, hospital admission in 63% and ICU admission in 11%. The correlation between lactate and ETCO2 was -0.45. A ROC curve analysis of ETCO2 vs. lactate >4 found that the best cutoff to predict a high lactate was an ETCO2 of 25 or less, which was considered a positive ETCO2 (AUC = 0.73). 27% of patients had a positive ETCO2 and 24% had a positive lactate. A positive ETCO2 predicted a positive lactate with 76% accuracy, 63% sensitivity and 80% specificity. 27% of those with a positive ETCO2 and 44% of those with a positive lactate had a diagnosed infection. 59% of those with a positive ETCO2 and 89% of those with a positive lactate had admission to the hospital. 15% of those with a positive ETCO2 and 18% of those with a positive lactate had admission to the ICU. Neither lactate nor ETCO2 were predictive of an increased risk for diagnosed infection, hospital admission or ICU admission in this patient population. CONCLUSION: While ETCO2 predicted the initial ED lactate levels it did not predict diagnosed infection, admission to the hospital or ICU admission in our patient population but did predict mortality.

Observational Study of Grand Canyon Rim-to-Rim Day Hikers: Determining Behavior Patterns to Aid in Preventive Search and Rescue Efforts.

INTRODUCTION: Grand Canyon National Park has seen an increase in visitors traversing the canyon from rim to rim (R2R) in a single day. R2R hikers travel over 33.8 km (21 mi) over 3300 m (11,000 ft) of elevation change and endure large temperature changes. Grand Canyon emergency medical service providers provide emergency medical services to over 1100 visitors annually. Direct guidance by Preventive Search and Rescue rangers has improved safety. The objective of this study was to examine visitors attempting an R2R traverse and to enhance PSAR rangers' anticipatory guidance. METHODS: We conducted an observational study of R2R hikers in the spring and fall of 2015. Hikers consented to study inclusion and were interviewed at the starting trailhead, canyon bottom, and exit trailhead. We performed a survey and collected biometric data. RESULTS: We enrolled 617 visitors with a median age of 43 y (interquartile range [IQR] 33-53); 65% were male and 46% had hiked the R2R a median number of 3 times previously (IQR 2-7). Hydration strategies included water bottle only (20%), hydration bladder only (31%), and both water bottle and hydration bladder (48%). R2R crossers had an average start time of 0530 (SD 1.3 h) and median crossing time of 11.9 h (IQR 10.7-13.3). Crossing time and self-reported fatigue were negatively correlated with prior R2R experience (P=0.02). CONCLUSIONS: Crossing R2R in a day is hazardous and associated with risk of injury and illness. The results of this study can be used by Preventive Search and Rescue to reduce these risks by educating hikers.

Selective chemical inhibition of agr quorum sensing in Staphylococcus aureus promotes host defense with minimal impact on resistance.

Bacterial signaling systems are prime drug targets for combating the global health threat of antibiotic resistant bacterial infections including those caused by Staphylococcus aureus. S. aureus is the primary cause of acute bacterial skin and soft tissue infections (SSTIs) and the quorum sensing operon agr is causally associated with these. Whether efficacious chemical inhibitors of agr signaling can be developed that promote host defense against SSTIs while sparing the normal microbiota of the skin is unknown. In a high throughput screen, we identified a small molecule inhibitor (SMI), savirin (S. aureus virulence inhibitor) that disrupted agr-mediated quorum sensing in this pathogen but not in the important skin commensal Staphylococcus epidermidis. Mechanistic studies employing electrophoretic mobility shift assays and a novel AgrA activation reporter strain revealed the transcriptional regulator AgrA as the target of inhibition within the pathogen, preventing virulence gene upregulation. Consistent with its minimal impact on exponential phase growth, including skin microbiota members, savirin did not provoke stress responses or membrane dysfunction induced by conventional antibiotics as determined by transcriptional profiling and membrane potential and integrity studies. Importantly, savirin was efficacious in two murine skin infection models, abating tissue injury and selectively promoting clearance of agr+ but not Δagr bacteria when administered at the time of infection or delayed until maximal abscess development. The mechanism of enhanced host defense involved in part enhanced intracellular killing of agr+ but not Δagr in macrophages and by low pH. Notably, resistance or tolerance to savirin inhibition of agr was not observed after multiple passages either in vivo or in vitro where under the same conditions resistance to growth inhibition was induced after passage with conventional antibiotics. Therefore, chemical inhibitors can selectively target AgrA in S. aureus to promote host defense while sparing agr signaling in S. epidermidis and limiting resistance development.

ω-Hydroxyemodin limits staphylococcus aureus quorum sensing-mediated pathogenesis and inflammation.

Antibiotic-resistant pathogens are a global health threat. Small molecules that inhibit bacterial virulence have been suggested as alternatives or adjuncts to conventional antibiotics, as they may limit pathogenesis and increase bacterial susceptibility to host killing. Staphylococcus aureus is a major cause of invasive skin and soft tissue infections (SSTIs) in both the hospital and community settings, and it is also becoming increasingly antibiotic resistant. Quorum sensing (QS) mediated by the accessory gene regulator (agr) controls virulence factor production essential for causing SSTIs. We recently identified ω-hydroxyemodin (OHM), a polyhydroxyanthraquinone isolated from solid-phase cultures of Penicillium restrictum, as a suppressor of QS and a compound sought for the further characterization of the mechanism of action. At concentrations that are nontoxic to eukaryotic cells and subinhibitory to bacterial growth, OHM prevented agr signaling by all four S. aureus agr alleles. OHM inhibited QS by direct binding to AgrA, the response regulator encoded by the agr operon, preventing the interaction of AgrA with the agr P2 promoter. Importantly, OHM was efficacious in a mouse model of S. aureus SSTI. Decreased dermonecrosis with OHM treatment was associated with enhanced bacterial clearance and reductions in inflammatory cytokine transcription and expression at the site of infection. Furthermore, OHM treatment enhanced the immune cell killing of S. aureus in vitro in an agr-dependent manner. These data suggest that bacterial disarmament through the suppression of S. aureus QS may bolster the host innate immune response and limit inflammation.

Nox2 modification of LDL is essential for optimal apolipoprotein B-mediated control of agr type III Staphylococcus aureus quorum-sensing.

Staphylococcus aureus contains an autoinducing quorum-sensing system encoded within the agr operon that coordinates expression of virulence genes required for invasive infection. Allelic variation within agr has generated four agr specific groups, agr I-IV, each of which secretes a distinct autoinducing peptide pheromone (AIP1-4) that drives agr signaling. Because agr signaling mediates a phenotypic change in this pathogen from an adherent colonizing phenotype to one associated with considerable tissue injury and invasiveness, we postulated that a significant contribution to host defense against tissue damaging and invasive infections could be provided by innate immune mechanisms that antagonize agr signaling. We determined whether two host defense factors that inhibit AIP1-induced agrI signaling, Nox2 and apolipoprotein B (apoB), also contribute to innate control of AIP3-induced agrIII signaling. We hypothesized that apoB and Nox2 would function differently against AIP3, which differs from AIP1 in amino acid sequence and length. Here we show that unlike AIP1, AIP3 is resistant to direct oxidant inactivation by Nox2 characteristic ROS. Rather, the contribution of Nox2 to defense against agrIII signaling is through oxidation of LDL. ApoB in the context of oxLDL, and not LDL, provides optimal host defense against S. aureus agrIII infection by binding the secreted signaling peptide, AIP3, and preventing expression of the agr-driven virulence factors which mediate invasive infection. ApoB within the context of oxLDL also binds AIP 1-4 and oxLDL antagonizes agr signaling by all four agr alleles. Our results suggest that Nox2-mediated oxidation of LDL facilitates a conformational change in apoB to one sufficient for binding and sequestration of all four AIPs, demonstrating the interdependence of apoB and Nox2 in host defense against agr signaling. These data reveal a novel role for oxLDL in host defense against S. aureus quorum-sensing signaling.

EMS patients and walk-in patients presenting with severe sepsis: differences in management and outcome.

OBJECTIVES: Sepsis is a significant problem. The differences between patients with sepsis who walk into the emergency department (ED) and those who are transported via emergency medical services (EMS) have not been clarified. The aim of the study was to determine whether there was a difference in outcome between patients arriving by EMS and those presenting directly to the ED. METHODS: We prospectively collected and reviewed a cohort of all cases of severe sepsis and septic shock admitted to the medical intensive care unit from the ED from November 2009 to March 2012. Extracted data were basic demographic information (including mode of ED arrival), clinical data, and treatments. We calculated Systemic Inflammatory Response Syndrome criteria, Acute Physiology and Chronic Health Evaluation II scores, and Sequential Organ Failure Assessment (SOFA) scores. The primary outcome was mortality in severely ill patients with sepsis. RESULTS: A total of 378 subjects (78%) presented by EMS and 107 subjects were walk-in patients (22%). Patients transported via EMS were older (P < 0.01), had fewer lactates >4 (P < 0.02), a more altered mental status (P < 0.01), and higher respiratory rates (P < 0.05) than did walk-in patients. Patients transported by EMS had worse disease severity when measured by an Acute Physiology and Chronic Health Evaluation II score (P < 0.01) but not by SOFA score. EMS patients had a shorter time to receiving antibiotics (P = 0.02) and central line placement (P < 0.01) than did walk-in patients. In a logistic model, mortality was associated with increasing age (adjusted odds ratio 1.3; 95% confidence interval [CI] 1.2-1.4), higher first-measured ED lactates (1.2; 95% CI 1.1-1.2), and increased initial SOFA score (adjusted odds ratio 1.2; 95% CI 1.1-1.3) but not EMS arrival or prehospital fluids. CONCLUSIONS: Neither arrival by EMS nor fluid administration by EMS is associated with decreased mortality in severe sepsis.

Effectiveness of a bivalent mRNA vaccine dose against symptomatic SARS-CoV-2 infection among U.S. Healthcare personnel, September 2022-May 2023.

BACKGROUND: Bivalent mRNA vaccines were recommended since September 2022. However, coverage with a recent vaccine dose has been limited, and there are few robust estimates of bivalent VE against symptomatic SARS-CoV-2 infection (COVID-19). We estimated VE of a bivalent mRNA vaccine dose against COVID-19 among eligible U.S. healthcare personnel who had previously received monovalent mRNA vaccine doses. METHODS: We conducted a case-control study in 22 U.S. states, and enrolled healthcare personnel with COVID-19 (case-participants) or without COVID-19 (control-participants) during September 2022-May 2023. Participants were considered eligible for a bivalent mRNA dose if they had received 2-4 monovalent (ancestral-strain) mRNA vaccine doses, and were ≥67 days after the most recent vaccine dose. We estimated VE of a bivalent mRNA dose using conditional logistic regression, accounting for matching by region and four-week calendar period. We adjusted estimates for age group, sex, race and ethnicity, educational level, underlying health conditions, community COVID-19 exposure, prior SARS-CoV-2 infection, and days since the last monovalent mRNA dose. RESULTS: Among 3,647 healthcare personnel, 1,528 were included as case-participants and 2,119 as control-participants. Participants received their last monovalent mRNA dose a median of 404 days previously; 1,234 (33.8%) also received a bivalent mRNA dose a median of 93 days previously. Overall, VE of a bivalent dose was 34.1% (95% CI, 22.6%-43.9%) against COVID-19 and was similar by product, days since last monovalent dose, number of prior doses, age group, and presence of underlying health conditions. However, VE declined from 54.8% (95% CI, 40.7%-65.6%) after 7-59 days to 21.6% (95% CI 5.6%-34.9%) after ≥60 days. CONCLUSIONS: Bivalent mRNA COVID-19 vaccines initially conferred approximately 55% protection against COVID-19 among U.S. healthcare personnel. However, protection waned after two months. These findings indicate moderate initial protection against symptomatic SARS-CoV-2 infection by remaining up-to-date with COVID-19 vaccines.

Active ascent accelerates the time course but not the overall incidence and severity of acute mountain sickness at 3,600 m.

Acute mountain sickness (AMS) typically peaks following the first night at high altitude (HA) and resolves over the next 2-3 days, but the impact of active ascent on AMS is debated. To determine the impact of ascent conditions on AMS, 78 healthy Soldiers (means ± SD; age = 26 ± 5 yr) were tested at baseline residence, transported to Taos, NM (2,845 m), hiked (n = 39) or were driven (n = 39) to HA (3,600 m), and stayed for 4 days. AMS-cerebral (AMS-C) factor score was assessed at HA twice on day 1 (HA1), five times on days 2 and 3 (HA2 and HA3), and once on day 4 (HA4). If AMS-C was ≥0.7 at any assessment, individuals were AMS susceptible (AMS+; n = 33); others were nonsusceptible (AMS-; n = 45). Daily peak AMS-C scores were analyzed. Ascent conditions (active vs. passive) did not impact the overall incidence and severity of AMS at HA1-HA4. The AMS+ group, however, demonstrated a higher (P < 0.05) AMS incidence in the active vs. passive ascent cohort on HA1 (93% vs. 56%), similar incidence on HA2 (60% vs. 78%), lower incidence (P < 0.05) on HA3 (33% vs. 67%), and similar incidence on HA4 (13% vs. 28%). The AMS+ group also demonstrated a higher (P < 0.05) AMS severity in the active vs. passive ascent cohort on HA1 (1.35 ± 0.97 vs. 0.90 ± 0.70), similar score on HA2 (1.00 ± 0.97 vs. 1.34 ± 0.70), and lower (P < 0.05) score on HA3 (0.56 ± 0.55 vs. 1.02 ± 0.75) and HA4 (0.32 ± 0.41 vs. 0.60 ± 0.72). Active compared with passive ascent accelerated the time course of AMS with more individuals sick on HA1 and less individuals sick on HA3 and HA4.NEW & NOTEWORTHY This research demonstrated that active ascent accelerated the time course but not overall incidence and severity of acute mountain sickness (AMS) following rapid ascent to 3,600 m in unacclimatized lowlanders. Active ascenders became sicker faster and recovered quicker than passive ascenders, which may be due to differences in body fluid regulation. Findings from this well-controlled large sample-size study suggest that previously reported discrepancies in the literature regarding the impact of exercise on AMS may be related to differences in the timing of AMS measurements between studies.

Genomic characterization of Staphylococcus aureus isolates causing osteoarticular infections in otherwise healthy children.

BACKGROUND: Pediatric osteoarticular infections are commonly caused by Staphylococcus aureus. The contribution of S. aureus genomic variability to pathogenesis of these infections is poorly described. METHODS: We prospectively enrolled 47 children over 3 1/2 years from whom S. aureus was isolated on culture-12 uninfected with skin colonization, 16 with skin abscesses, 19 with osteoarticular infections (four with septic arthritis, three with acute osteomyelitis, six with acute osteomyelitis and septic arthritis and six with chronic osteomyelitis). Isolates underwent whole genome sequencing, with assessment for 254 virulence genes and any mutations as well as creation of a phylogenetic tree. Finally, isolates were compared for their ability to form static biofilms and compared to the genetic analysis. RESULTS: No sequence types predominated amongst osteoarticular infections. Only genes involved in evasion of host immune defenses were more frequently carried by isolates from osteoarticular infections than from skin colonization (p = .02). Virulence gene mutations were only noted in 14 genes (three regulating biofilm formation) when comparing isolates from subjects with osteoarticular infections and those with skin colonization. Biofilm results demonstrated large heterogeneity in the isolates' capacity to form static biofilms, with healthy control isolates producing more robust biofilm formation. CONCLUSIONS: S. aureus causing osteoarticular infections are genetically heterogeneous, and more frequently harbor genes involved in immune evasion than less invasive isolates. However, virulence gene carriage overall is similar with infrequent mutations, suggesting that pathogenesis of S. aureus osteoarticular infections may be primarily regulated at transcriptional and/or translational levels.

Neutrophil bleaching of GFP-expressing staphylococci: probing the intraphagosomal fate of individual bacteria.

Successful host defense against bacteria such as Staphylococcus aureus (SA) depends on a prompt response by circulating polymorphonuclear leukocytes (PMN). Stimulated PMN create in their phagosomes an environment inhospitable to most ingested bacteria. Granules that fuse with the phagosome deliver an array of catalytic and noncatalytic antimicrobial peptides, while activation of the NADPH oxidase at the phagosomal membrane generates reactive oxygen species within the phagosome, including hypochlorous acid (HOCl), formed by the oxidation of chloride by the granule protein myeloperoxidase in the presence of H(2)O(2). In this study, we used SA-expressing cytosolic GFP to provide a novel probe of the fate of SA in human PMN. PMN bleaching of GFP in SA required phagocytosis, active myeloperoxidase, H(2)O(2) from the NADPH oxidase, and chloride. Not all ingested SA were bleached, and the number of cocci within PMN-retaining fluorescent GFP closely correlated with the number of viable bacteria remaining intracellularly. The percent of intracellular fluorescent and viable SA increased at higher multiplicity of infection and when SA presented to PMN had been harvested from the stationary phase of growth. These studies demonstrate that the loss of GFP fluorescence in ingested SA provides a sensitive experimental probe for monitoring biochemical events within individual phagosomes and for identifying subpopulations of SA that resist intracellular PMN cytotoxicity. Defining the molecular basis of SA survival within PMN should provide important insights into bacterial and host properties that limit PMN antistaphylococcal action and thus contribute to the pathogenesis of staphylococcal infection.

Aerosol generation with various approaches to oxygenation in healthy volunteers in the emergency department.

OBJECTIVES: Health care workers experience an uncertain risk of aerosol exposure during patient oxygenation. To improve our understanding of these risks, we sought to measure aerosol production during various approaches to oxygenation in healthy volunteers in an emergency department. METHODS: This was a prospective study conducted in an empty patient room in an academic ED. The room was 10 ft. long x 10 ft. wide x 9 ft. tall (total volume 900 ft3) with positive pressure airflow (1 complete turnover of air every 10 minutes). Five oxygenation conditions were used: humidified high-flow nasal cannula (HFNC) at 3 flow rates [15, 30, and 60 liters per minute (LPM)], non-rebreather mask (NRB) at 1 flow rate (15 LPM), and closed-circuit continuous positive airway pressure (CPAP) using the ED ventilator; in all cases a simple procedural mask was used. The NRB and HFNC at 30 LPM maneuvers were also repeated without the procedural mask, and CPAP was applied both with and without a filter. Each subject then sequentially underwent 8 total oxygenation conditions, always in the same order. Each oxygenation condition was performed with the participant on a standard ED bed. Particles were measured by laser aerosol spectrometer, with the detector sampling port positioned directly over the center of the bed, 0.35 meters away and at a 45-degree angle from the subject's mouth. Each approach to oxygenation was performed for 10 minutes, followed by a 20-minute room washout (≈ 2 complete room air turnovers). Particle counts were summated for 2 size ranges (150-300 nm and 0.5-2.0 µm) and compared before, during, and after each of the 8 oxygenation conditions. RESULTS: Eight adult subjects were enrolled (mean age 42 years, body mass index 25). All subjects completed 8 oxygenation procedures (64 total). Mean particle counts per minute across all oxygenation procedures was 379 ± 112 (mean ± SD) for smaller aerosols (150-300 nm) and 9.3 ± 4.6 for larger aerosols (0.5-2.0 µm). HFNC exhibited a flow-dependent increase in particulate matter (PM) generation-at 60 LPM, HFNC had a substantial generation of small (55% increase) and large particles (70% increase) compared to 15 LPM. CPAP was associated with lowered small and large particle generation (≈ 10-15% below baseline for both sizes of PM). A patient mask limited particle generation with the NRB, where it was associated with a reduction in small and large particulates (average 40% and 20% lower, respectively). CONCLUSION: Among 3 standard oxygenation procedures, higher flow rates generally were associated with greater production of both small and large aerosols. A patient mask lowered aerosol counts in the NRB only. Protocol development for oxygenation application should consider these factors to increase health care worker safety.

Emergence in late 2020 of multiple lineages of SARS-CoV-2 Spike protein variants affecting amino acid position 677.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein (S) plays critical roles in host cell entry. Non-synonymous substitutions affecting S are not uncommon and have become fixed in a number of SARS-CoV-2 lineages. A subset of such mutations enable escape from neutralizing antibodies or are thought to enhance transmission through mechanisms such as increased affinity for the cell entry receptor, angiotensin-converting enzyme 2 (ACE2). Independent genomic surveillance programs based in New Mexico and Louisiana contemporaneously detected the rapid rise of numerous clade 20G (lineage B.1.2) infections carrying a Q677P substitution in S. The variant was first detected in the US on October 23, yet between 01 Dec 2020 and 19 Jan 2021 it rose to represent 27.8% and 11.3% of all SARS-CoV-2 genomes sequenced from Louisiana and New Mexico, respectively. Q677P cases have been detected predominantly in the south central and southwest United States; as of 03 Feb 2021, GISAID data show 499 viral sequences of this variant from the USA. Phylogenetic analyses revealed the independent evolution and spread of at least six distinct Q677H sub-lineages, with first collection dates ranging from mid-August to late November 2020. Four 677H clades from clade 20G (B.1.2), 20A (B.1.234), and 20B (B.1.1.220, and B.1.1.222) each contain roughly 100 or fewer sequenced cases, while a distinct pair of clade 20G clusters are represented by 754 and 298 cases, respectively. Although sampling bias and founder effects may have contributed to the rise of S:677 polymorphic variants, the proximity of this position to the polybasic cleavage site at the S1/S2 boundary are consistent with its potential functional relevance during cell entry, suggesting parallel evolution of a trait that may confer an advantage in spread or transmission. Taken together, our findings demonstrate simultaneous convergent evolution, thus providing an impetus to further evaluate S:677 polymorphisms for effects on proteolytic processing, cell tropism, and transmissibility.

The antibacterial activity of human neutrophils and eosinophils requires proton channels but not BK channels.

Electrophysiological events are of central importance during the phagocyte respiratory burst, because NADPH oxidase is electrogenic and voltage sensitive. We investigated the recent suggestion that large-conductance, calcium-activated K(+) (BK) channels, rather than proton channels, play an essential role in innate immunity (Ahluwalia, J., A. Tinker, L.H. Clapp, M.R. Duchen, A.Y. Abramov, S. Page, M. Nobles, and A.W. Segal. 2004. Nature. 427:853-858). In PMA-stimulated human neutrophils or eosinophils, we did not detect BK currents, and neither of the BK channel inhibitors iberiotoxin or paxilline nor DPI inhibited any component of outward current. BK inhibitors did not inhibit the killing of bacteria, nor did they affect NADPH oxidase-dependent degradation of bacterial phospholipids by extracellular gIIA-PLA(2) or the production of superoxide anion (O(2*)(-)). Moreover, an antibody against the BK channel did not detect immunoreactive protein in human neutrophils. A required role for voltage-gated proton channels is demonstrated by Zn(2+) inhibition of NADPH oxidase activity assessed by H(2)O(2) production, thus validating previous studies showing that Zn(2+) inhibited O(2*)(-) production when assessed by cytochrome c reduction. In conclusion, BK channels were not detected in human neutrophils or eosinophils, and BK inhibitors did not impair antimicrobial activity. In contrast, we present additional evidence that voltage-gated proton channels serve the essential role of charge compensation during the respiratory burst.

Nosocomial infections after severe trauma are associated with lower apolipoproteins B and AII.

BACKGROUND: Infection after severe trauma is a significant cause of morbidity and mortality days to weeks after the initial injury. Apolipoproteins play important roles in host defense and circulating concentrations are altered by the acute inflammatory response. The purpose of this study was to determine if patients who acquire infection after severe trauma have significantly lower apolipoprotein levels than trauma patients who do not become infected. METHODS: We conducted a case-control study on a prospectively identified cohort of adult patients admitted to our intensive care unit after severe trauma (Injury Severity Score ≥ 16). We compared plasma apolipoprotein levels between patients who acquired an infection within 30 days after trauma (cases) and those that remained infection free (controls). RESULTS: Of 40 patients experiencing severe trauma, we identified 22 cases that developed an infection within 30 days after injury. Cases had significantly lower posttrauma plasma levels of apolipoprotein B (p = 0.02) and apolipoprotein AII (p = 0.02) compared with controls. Consistent with previous studies, cases also received greater volumes of crystalloid infusions (p < 0.01) and blood transfusions (p < 0.01). Cases also had a more profound inflammatory response as measured by interleukin 6 levels (p = 0.02). CONCLUSION: Infection after severe trauma is associated with decreased circulating apolipoproteins as compared with uninfected controls. Profoundly decreased plasma apolipoproteins B and AII could potentially contribute to the impaired immunity after severe trauma. Apolipoproteins are potential targets for identifying those patients at risk of infection after trauma and for interventions aimed at preventing nosocomial infections. LEVEL OF EVIDENCE: Prognostic study, level III.