Nosocomial Infections in Adults Receiving Extracorporeal Membrane Oxygenation: A Review for Infectious Diseases Clinicians.

Over the past ten years, there has been a rapid expansion in the use of extracorporeal membrane oxygenation (ECMO) in the care of patients with refractory cardiac or respiratory failure. Infectious diseases clinicians must reconcile conflicting evidence from limited studies as they develop practices at their own institutions, which has resulted in considerably different practices globally. This review describes infection control and prevention as well as antimicrobial prophylaxis strategies in this population. Data on diagnostics and treatment for patients receiving ECMO with a focus on diagnostic and antimicrobial stewardship is then examined. This review summarizes gaps in the current ECMO literature and proposes future needs, including developing clear definitions for infections and encouraging transparent reporting of practices at individual facilities in future clinical trials.

Impact of SARS-CoV-2 Arrival Surveillance Screening by Nucleic Acid Amplification Versus Rapid Antigen Detection on Subsequent COVID-19 Infections in Military Trainees.

BACKGROUND: For persons entering congregate settings, optimal severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) arrival surveillance screening method, nucleic acid amplification test (NAAT) versus rapid antigen detection test (RADT), is debated. To aid this, we sought to determine the risk of secondary symptomatic coronavirus disease 19 (COVID-19) among military trainees with negative arrival NAAT or RADT screening. METHODS: Individuals who arrived for US Air Force basic military training from 1 January-31 August 2021 were placed into training groups and screened for SARS-CoV-2 via NAAT or RADT. Secondary symptomatic COVID-19 cases within 2 weeks of training were then measured. A case cluster was defined as ≥5 individual symptomatic COVID-19 cases. RESULTS: 406 (1.6%) of 24 601 trainees screened positive upon arrival. The rate of positive screen was greater for those tested with NAAT versus RADT (2.5% vs 0.4%; RR: 5.4; 95% CI: 4.0-7.3; P < .001). The proportion of training groups with ≥1 positive individual screen was greater in groups screened via NAAT (57.5% vs 10.8%; RR: 5.31; 95% CI: 3.65-7.72; P < .001). However, NAAT versus RADT screening was not associated with a difference in number of training groups to develop a secondary symptomatic case (20.3% vs 22.5%; RR: .9; 95% CI: .66-1.23; P = .53) or case cluster of COVID-19 (4% vs 6.6%; RR: .61; 95% CI: .3-1.22; P = .16). CONCLUSIONS: NAAT versus RADT arrival surveillance screening method impacted individual transmission of COVID-19 but had no effect on number of training groups developing a secondary symptomatic case or case cluster. This study provides consideration for RADT arrival screening in congregate settings.

Infectious diseases and infection control prevention strategies in adult and pediatric population on ECMO.

As survival after ECMO improves and use of ECMO support increases in both pediatric and adult population, there is a need to focus on both the morbidities and complications associated with ECMO and how to manage and prevent them. Infectious complications during ECMO often have a significant clinical impact, resulting in increased morbidity or mortality irrespective of the underlying etiology necessitating cardiorespiratory support. In this review article, we discuss the prevention, management, challenges, and differences of infectious complications in adult and pediatric patients receiving ECMO support.

Follow-up of Military Blood Donors Who Test Positive for Syphilis.

BACKGROUND: Several large studies have demonstrated that syphilis carries a risk of future sexually transmitted infections (STI), such as human immunodeficiency virus. There are limited data on outcomes of syphilis infections that occur in populations that undergo universal syphilis screening, such as blood donors. Military trainees who donate blood can be followed through their military career to determine the future risk of STIs. METHODS: Blood donor data were gathered from the Armed Services Blood Bank Center-San Antonio for those with positive Treponema pallidum antibodies between 2014 and 2021. The medical chart of each case was compared with 6 sex- and military accession date-matched controls with negative T. pallidum antibodies to determine the risk of STI in the 3 years after donation. RESULTS: A total of 63,375 individuals donated blood during the study period. A total of 23 military trainees (0.36 per 1000 donors) had positive T. pallidum antibodies. A minority (n = 7; 30%) of cases were treated for early syphilis. Only 6 cases (26%) received a follow-up nontreponemal test within 1 year. Donors who tested positive had a significantly higher risk of developing an STI within 3 years after blood donation compared with blood donors who tested negative (relative risk, 3.8; 95% confidence interval, 1.3-10.5; P = 0.01) including gonorrhea (9% vs. 0%, P = 0.02) and syphilis (9% vs. 0%, P = 0.02). CONCLUSIONS: This study shows the presence of T. pallidum antibodies in blood donors was associated with an increased risk of future STIs. These cases support the need for close follow-up and broad STI testing in blood donors with positive T. pallidum antibodies.

Infectious etiologies among post-donation deferrals in a military blood donation center.

BACKGROUND: The burden of transfusion-transmitted infections among blood recipients remains low due to extensive pre- and post-donation screening. However, the military has the unique challenge of providing blood in austere environments with limited testing capabilities. This study evaluates the infectious etiologies of deferred blood donors at a large military blood donation center. METHODS: All blood donors at the Armed Service Blood Bank Center, San Antonio, between 2017 and 2022 with positive post-donation screening for hepatitis C (HCV), hepatitis B (HBV), human immunodeficiency virus (HIV), human T-lymphotropic virus (HTLV-I/II), Zika (2018-2021), West Nile virus, Trypanosoma cruzi, Treponema pallidum, or Babesia microti (2020-2022) were evaluated. Donors were deferred based on Food and Drug Administration (FDA) guidance. RESULTS: Two-hundred and thirteen (213) donors met FDA criteria for deferral. T. pallidum (n = 45, 50.3 per 100,000), HCV (n = 34, 38.0 per 100,000), and HBV (n = 19, 21.2 per 100,000) were the most common pathogens among those with both positive screening and confirmatory testing. The majority of HIV (95%), Chagas (78%), HTLV-I/II (50%) deferrals were due to indeterminate confirmatory tests following initial positive screens. The majority of deferrals for HBV were for a second occurrence of a positive screen despite negative confirmatory testing. CONCLUSION: The rates of post-donation deferral for transfusion-transmissible infections were low in this military cohort. Our findings suggest that donor testing in deployed service members should focus on HBV, HCV, and T. pallidum and highlight the need for better diagnostics for HIV, Chagas, and HTLV-I/II.

Clearance of blood stream infections in patients receiving extracorporeal membrane oxygenation: a retrospective single-center cohort study.

BACKGROUND: There are limited data on the treatment of blood stream infections (BSIs) in patients receiving extracorporeal membrane oxygenation (ECMO). Current guidance recommends documenting clearance only in fungal and Gram-positive BSIs. This study investigates the incidence and clinical significance of blood stream infections with positive repeat cultures (BSIPRC) in ECMO as well as clinical factors that may predict positive repeat cultures. METHODS: All BSIs in patients receiving ECMO at Brooke Army Medical Center between September 2012 and October 2021 were included in this study. BSIPRC was defined as re-isolation of the same organism on repeat blood cultures following an initial positive blood culture. RESULTS: A total of 60 patients developed 87 BSI (38.5 BSI per 1000 ECMO days). Of the 80 (92%) BSIs who had repeat blood cultures drawn, patients had BSIPRC in 35 (44%) of cases. Fever, leukocytosis, and vasopressor requirement on day of repeat culture were not associated with persistent positivity. There was no difference in survival to discharge for patients with BSIPRC as compared to single day BSI (58% vs. 63%, p = 0.78). 19% of patients with Gram-negative bacteremia had BSIPRC, and gram-negative bacteremia in general was associated with an 83% morality. CONCLUSIONS: There were no clinical findings that differentiated patients with BSIPRC from those who had a single day of positivity. BSI was associated with high mortality in patients with Gram-negative bacteremia. Given high incidence of positive repeat cultures being seen in Gram-negative BSIs, repeat blood cultures have utility for all BSIs in patients receiving ECMO.

The utility of sepsis scores for predicting blood stream infections in extracorporeal membrane oxygenation.

INTRODUCTION: Extracorporeal membrane oxygenation (ECMO) is an increasingly used modality of life support with high risk for nosocomial infections. The accuracy of sepsis prediction tools in identifying blood stream infections (BSI) in this population is unknown as measurement of multiple variables commonly associated with infection are altered by the circuit. METHODS: This study compares all blood stream infections for patients receiving ECMO between January 2012 and December 2020 to timepoints when blood cultures were negative using the Sequential Organ Failure Assessment (SOFA), Logistic Organ Dysfunction Score (LODS), American Burn Association Sepsis Criteria (ABA), Systemic Inflammatory Response Syndrome (SIRS) scores. RESULTS: Of the 220 patients who received ECMO during the study period, 40 (18%) had 51 blood stream infections and were included in this study. Gram-positive infections composed 57% (n = 29) of infections with E. faecalis (n = 12, 24%) being the most common organism isolated. There were no significant differences in sepsis prediction scores at the time of infection compared to infection-free time points for SOFA (median (IQR) 7 (5-9) vs. 6 (5-8), p = 0.22), LODS (median (IQR) 12 (10-14) vs. 12 (10-13), p = 0.28), ABA (median (IQR) 2 (1-3) vs. 2 (1-3) p = 0.75), or SIRS (median (IQR) 3 (2-3) vs. 3 (2-3), p = 0.20). CONCLUSIONS: Our data shows that previously published sepsis scores are elevated throughout a patient's ECMO course, and do not correlate with bacteremia. Better predictive tools are needed to determine the appropriate timing for blood cultures in this population.

COVID-19 Monitoring and Response Among U.S. Air Force Basic Military Trainees - Texas, March-April 2020.

The coronavirus disease 2019 (COVID-19) pandemic has resulted in substantial morbidity and mortality since it was first described in December 2019 (1). Based on epidemiologic data showing spread in congregate settings (2-4), national, state, and local governments instituted significant restrictions on large gatherings to prevent transmission of disease in early March 2020. This and other nonpharmaceutical interventions (NPIs) have shown initial success in slowing the pandemic across the country (5). This report examines the first 7 weeks (March 1-April 18) of implementation of NPIs in Basic Military Training (BMT) at a U.S. Air Force base. In a population of 10,579 trainees, COVID-19 incidence was limited to five cases (47 per 100,000 persons), three of which were in persons who were contacts of the first patient. Transmission of symptomatic COVID-19 was successfully limited using strategies of quarantine, social distancing, early screening of trainees, rapid isolation of persons with suspected cases, and monitored reentry into training for trainees with positive test results after resolution of symptoms.

A systematic review of variability in the reporting of extracorporeal membrane oxygenation-associated infections and recommendations for standardization.

BACKGROUND: Extracorporeal membrane oxygenation (ECMO) utilization has surged in recent years, particularly amidst the COVID-19 pandemic, yet standardization of ECMO-associated infection (EAI) reporting remains lacking. METHODS: This systematic review assessed 60 studies from 2018 to 2023 in PubMed, which used key words related to EAIs. Adherence to reporting data elements that may bias reporting, including the use of standardized rates of infections per 1,000 patient days, describing the use of antimicrobial prophylaxis, infection control, and culture practices, describing the definitions for infection by site, and listing pathogens by infection site were evaluated by study. RESULTS: Our review revealed considerable heterogeneity in data elements and infection definitions. While 51 (85%) studies reported definition by site, only 17 (28%) reported infection control practices, and only 6 (10%) studies adhered to all the identified essential reporting elements. Variation in infection rates was also evident across the definitions, with studies using their own definition having the greatest variability in reported infection rates. Microbiological differences by geographic region further underscored the need for standardized reporting and challenges with generalizability in the EAI literature. CONCLUSIONS: Our findings underscore the imperative for consensus on ECMO infection definitions and transparent reporting practices to facilitate meaningful comparisons and advance patient care protocols.

The utility of procalcitonin for identifying secondary infections in patients with influenza or COVID-19 receiving extracorporeal membrane oxygenation.

Background: Identifying secondary infections in patients receiving extracorporeal membrane oxygenation (ECMO) presents challenges due to the ECMO circuit's influence on traditional signs of infection. Objectives: This study evaluates procalcitonin as a diagnostic marker for secondary infections in patients receiving ECMO with influenza or COVID-19 infection. Design: Single-center retrospective cohort study. Methods: All adult patients receiving veno-venous ECMO with underlying influenza or COVID-19 from November 2017 to October 2021 were included. Patient demographics, time receiving ECMO, culture data, and procalcitonin levels were examined. The first procalcitonin within 3 days of infection was compared to negative workups that were collected at least 10 days from the last positive culture. Furthermore, we compared procalcitonin levels by the type of pathogen and site of infection. Results: In this study, 84 patients with influenza or COVID-19 who received ECMO were included. A total of 276 procalcitonin labs were ordered in this cohort, with 33/92 (36%) of the secondary infections having an associated procalcitonin value. When comparing procalcitonin levels, there was no significant difference between the infection and negative workup groups [1 ng/mL (interquartile ranges, IQR: 0.4-1.2) versus 1.3 (0.5-4.3), p = 0.19]. Using 0.5 ng/mL as the cut-off, the sensitivity of procalcitonin was 67% and the specificity was 30%. In our cohort, the positive predictive value of procalcitonin was 14.5% and the negative predictive value was 84%. There was no difference in procalcitonin by type of organism or site of infection. Procalcitonin levels did not routinely decline even after an infection was identified. Conclusion: While procalcitonin is a proposed potential diagnostic marker for secondary infections in patients receiving ECMO, this single-center study demonstrated low sensitivity and specificity of procalcitonin in identifying secondary infections. Furthermore, there was no association of procalcitonin levels with etiology of infection when one was present. Procalcitonin should be used cautiously in identifying infections in veno-venous ECMO.

BACKGROUND: It is very difficult to determine whether patients receiving ECMO have infections as both vital signs and laboratory markers have not shown good utility. Procalcitonin is a laboratory test sometimes used to identify infections, but its test performance is not known in this population. METHODS: We performed a study of adult patient patients receiving ECMO to determine if there were differences in procalcitonin levels when patients had infections as compared to when they did not have infections. We also looked to see if procalcitonin levels routinely dropped after an infection was diagnosed. RESULTS: Procalcitonin values were no different when patients had an infection as compared to when they did not have an infection. Using standard laboratory cut-offs, the procalcitonin sensitivity was 67%, and specificity was 30%. Procalcitonin levels did not routinely decline even after an infection was identified. CONCLUSIONS: Procalcitonin poorly differentiated patients with infections from those without infections and should be used with caution in patients receiving ECMO.

The utility of procalcitonin for identifying secondary infections in patients with influenza or COVID-19 receiving extracorporeal membrane oxygenation Aim: To determine if procalcitonin performs well as a diagnostic marker in identifying additional infections in adult patients receiving ECMO with influenza or COVID-19.

Epidemiology and clinical significance of persistent bacteremia in severely burned patients.

BACKGROUND: The utility of follow-up blood cultures (FUBC) for gram-negative bloodstream infections (BSIs) are controversial due to low rates of positivity. However, recent studies suggest higher rates of positivity in critically ill patients. The utility of FUBC in gram-negative BSI in patients with severe burn injuries is unknown. METHODS: Patients ≥ 18 years old admitted to the US Army Institute of Surgical Research Burn Center for combat-related thermal burns from 1/2003-6/2014 with a monomicrobial BSI were included. FUBC were defined as repeat cultures 1-5 days from index BSI. Persistent BSI (pBSI) was defined as isolation of the same organism from initial and FUBC. The primary endpoint was all-cause in-hospital mortality in patients with gram-negative pBSI. RESULTS: Of 126 patients meeting inclusion criteria with BSI, 53 (42%) had pBSI. Compared to patients without persistence, patients with pBSI had more severe burns with median total body surface area (TBSA) burns of 47% ([IQR 34-63] vs. 35.3% [IQR 23.3-56.6], p = 0.02), increased mortality (38 vs. 11%, p = 0.001) compared to those with non-persistent BSI. On multivariate analysis, pBSI was associated with an odds ratio for mortality of 5.3 [95% CI 1.8-15.8, p = 0.003). Amongst gram-negative pathogens, persistence rates were high and associated with increased mortality (41% vs. 11%, p = 0.001) compared to patients without pBSI. CONCLUSION: In this cohort of military patients with combat-related severe burns, pBSI was more common than in other hospitalized populations and associated with increased mortality. Given this high frequency of persistence in patients with burn injuries and associated mortality, FUBC are an important diagnostic and prognostic study in this population.

Fever and Leukocytosis Are Poor Predictors of Bacterial Coinfection in Patients With COVID-19 and Influenza Who Are Receiving Extracorporeal Membrane Oxygenation.

Background: Fever and leukocytosis are 2 parameters commonly cited in clinical practice as indications to perform an infectious workup in patients receiving extracorporeal membrane oxygenation (ECMO), but their utility is unknown. Methods: All patients who received ECMO between December 2014 and December 2020 with influenza or COVID-19 were included in this retrospective cohort study. Cultures were included if they were drawn from patients without signs of decompensation. Maximum temperature and white blood cell count were recorded on the day of culture collection. Workups with infections were compared with those that were negative. Results: Of the 137 infectious workups in this 45-patient cohort, 86 (63%) were performed in patients with no signs of decompensation, totaling 165 cultures. These workups yielded 10 (12%) true infections. There were no differences in median (IQR) temperature (100.4 °F [100.2-100.8] vs 100.4 °F [99.3-100.9], P = .90) or white blood cell count (18.6 cells/mL [16.8-20.1] vs 16.7 cells/mL [12.8-22.3], P = .90) between those with and without infections. Conclusions: In patients with influenza or COVID-19 who require ECMO, fever and leukocytosis were common indications for infectious workups, yet results were frequently negative. Despite their use in clinical practice, fever and leukocytosis are not reliable indicators of infection in patients who are hemodynamically stable and receiving ECMO.

Infections complicating extracorporeal membrane oxygenation in patients with traumatic injuries.

INTRODUCTION: Extracorporeal Membrane Oxygenation (ECMO) has increasing utility in adult patients with traumatic injuries. There is currently limited data on the pathogens complicating a trauma patient's ECMO course, making empiric antibiotic decisions difficult. This study aims to characterize the types of infection among patients with traumatic injuries on ECMO. METHODS: A chart review was performed on all trauma patients at Brooke Army Medical Center receiving ECMO between February 2013 and July 2021. Charts were reviewed to identify pathogens by culture site as well as time to infection following cannulation. RESULTS: Twenty-one trauma patients underwent ECMO during the study period. The majority of patients were men (90%) with a median age of 30 [IQR 27-38], and a median ECMO course of 9.8 days [IQR 3.9-14.1]. Motor vehicle crashes (81%) accounted for the majority of mechanisms of injury. Of the 24 infections, the majority were respiratory (n = 13, 58/1000 ECMO days) followed by skin and soft tissue (n = 6, 26/1000 ECMO days), blood stream (n = 4, 18/1000 ECMO days), and urinary tract (n = 1, 5/1000 ECMO days). Gram-negative bacteria were the most commonly isolated organism from all sites and at all time periods following cannulation. Multi-drug resistant organisms accounted for 35% (n = 9) of infections and were independent of time from cannulation. DISCUSSION/CONCLUSION: This is the first study to describe infections in trauma patients requiring ECMO support. We observed majority Gram-negative infections regardless of culture site or time after cannulation. Thus, with infection in this population, empiric antibiotics should have broad spectrum coverage of Gram-negative organisms.

Sensitivity of Symptom-Based Screening for COVID-19 in Active Duty Basic Trainees.

INTRODUCTION: Symptomatic Coronavirus Disease 2019 (COVID-19) screening has been a cornerstone of case identification during the pandemic. Despite the myriad of COVID-19 symptoms, symptom screens have primarily focused on symptoms of influenza-like illnesses such as fever, cough, and dyspnea. It is unknown how well these symptoms identify cases in a young, healthy military population. This study aims to evaluate the utility of symptom-based screening in identifying COVID-19 through three different COVID-19 waves. MATERIALS AND METHODS: A convenience sample of 600 military trainees who arrived at Joint Base San Antonio-Lackland in 2021 and 2022 were included. Two hundred trainees with symptomatic COVID-19 before the emergence of the Delta variant (February-April 2021), when Delta variant was predominant (June-August 2021), and when Omicron was the predominant variant (January 2022) had their presenting symptoms compared. At each time point, the sensitivity of a screen for influenza-like illness symptoms was calculated. RESULTS: Of the 600 symptomatic active duty service members who tested positive for COVID-19, the most common symptoms were sore throat (n = 385, 64%), headache (n = 334, 56%), and cough (n = 314, 52%). Although sore throat was the most prominent symptom during Delta (n = 140, 70%) and Omicron (n = 153, 77%), headache was the most common before Delta (n = 93, 47%). There were significant differences in symptoms by vaccination status; for example, ageusia was more common in patients who were not completely vaccinated (3% vs. 0%, P = .01). Overall, screening for fever, cough, or dyspnea had a 65% sensitivity with its lowest sensitivity in the pre-Delta cases (54%) and highest sensitivity in Omicron cases (78%). CONCLUSIONS: In this descriptive cross-sectional study evaluating symptomatic military members with COVID-19, symptom prevalence varied based on predominant circulating COVID-19 variant as well as patients' vaccination status. As screening strategies evolve with the pandemic, changing symptom prevalence should be considered.

Treatment and outcome of gram-positive bacteremia in patients receiving extracorporeal membrane oxygenation.

BACKGROUND: While guidance exists for management of blood stream infections with various invasive devices, there are currently limited data to guide antibiotic selection and duration for bacteremia in patients receiving extracorporeal membrane oxygenation (ECMO). OBJECTIVE: To evaluate the treatment and outcomes of thirty-six patients with Staphylococcus aureus and Enterococcus bacteremia on ECMO support. METHODS: Blood culture data was retrospectively analyzed from patients with Staphylococcus aureus bacteremia (SAB) or Enterococcus bacteremia who underwent ECMO support between March 2012 and September 2021 at Brooke Army Medical Center. RESULTS: Of the 282 patients who received ECMO during this study period, there 25 (9%) patients developed Enterococcus bacteremia and 16 (6%) developed SAB. SAB occurred earlier in ECMO as compared to Enterococcus (median day 2 IQR (1-5) vs. 22 (12-51), p = 0.01). The most common duration of antibiotics was 28 days after clearance for SAB and 14 days after clearance for Enterococcus. 2 (5%) patients underwent cannula exchange with primary bacteremia, and 7 (17%) underwent circuit exchange. 1/3 (33%) patients with SAB and 3/10 (30%) patients with Enterococcus bacteremia who remained cannulated after completion of antibiotics had a second episode of SAB or Enterococcus bacteremia. CONCLUSION: This single center case series is the first to describe the specific treatment and outcomes of patients receiving ECMO complicated by SAB and Enterococcus bacteremia. For patients who remain on ECMO after completion of antibiotics, there is a risk of a second episode of Enterococcus bacteremia or SAB.

Outcomes of Fungemia in Patients Receiving Extracorporeal Membrane Oxygenation.

There are limited data on the treatment of fungal infections complicating extracorporeal membrane oxygenation (ECMO). In 14 patients who developed fungal bloodstream infections on ECMO, 8 (57%) survived to discharge. Of the 5 patients completing treatment prior to decannulation, 2 (40%) developed recurrent fungal infections.

Rates of nosocomial infection associated with interhospital transfer of patients receiving extracorporeal membrane oxygenation.

OBJECTIVES: Critically ill patients requiring extracorporeal membrane oxygenation (ECMO) frequently require interhospital transfer to a center that has ECMO capabilities. Patients receiving ECMO were evaluated to determine whether interhospital transfer was a risk factor for subsequent development of a nosocomial infection. DESIGN: Retrospective cohort study. SETTING: A 425-bed academic tertiary-care hospital. PATIENTS: All adult patients who received ECMO for >48 hours between May 2012 and May 2020. METHODS: The rate of nosocomial infections for patients receiving ECMO was compared between patients who were cannulated at the ECMO center and patients who were cannulated at a hospital without ECMO capabilities and transported to the ECMO center for further care. Additionally, time to infection, organisms responsible for infection, and site of infection were compared. RESULTS: In total, 123 patients were included in analysis. For the primary outcome of nosocomial infection, there was no difference in number of infections per 1,000 ECMO days (25.4 vs 29.4; P = .03) by univariate analysis. By Cox proportional hazard analysis, transport was not significantly associated with increased infections (hazard ratio, 1.7; 95% confidence interval, 0.8-4.2; P = .20). CONCLUSION: In this study, we did not identify an increased risk of nosocomial infection during subsequent hospitalization. Further studies are needed to identify sources of nosocomial infection in this high-risk population.

An RNA Interference (RNAi) Toolkit and Its Utility for Functional Genetic Analysis of Leishmania (Viannia).

RNA interference (RNAi) is a powerful tool whose efficacy against a broad range of targets enables functional genetic tests individually or systematically. However, the RNAi pathway has been lost in evolution by a variety of eukaryotes including most Leishmania sp. RNAi was retained in species of the Leishmania subgenus Viannia, and here we describe the development, optimization, and application of RNAi tools to the study of L. (Viannia) braziliensis (Lbr). We developed vectors facilitating generation of long-hairpin or "stem-loop" (StL) RNAi knockdown constructs, using GatewayTM site-specific recombinase technology. A survey of applications of RNAi in L. braziliensis included genes interspersed within multigene tandem arrays such as quinonoid dihydropteridine reductase (QDPR), a potential target or modulator of antifolate sensitivity. Other tests include genes involved in cell differentiation and amastigote proliferation (A600), and essential genes of the intraflagellar transport (IFT) pathway. We tested a range of stem lengths targeting the L. braziliensis hypoxanthine-guanine phosphoribosyl transferase (HGPRT) and reporter firefly luciferase (LUC) genes and found that the efficacy of RNAi increased with stem length, and fell off greatly below about 128 nt. We used the StL length dependency to establish a useful 'hypomorphic' approach not possible with other gene ablation strategies, with shorter IFT140 stems yielding viable cells with compromised flagellar morphology. We showed that co-selection for RNAi against adenine phosphoryl transferase (APRT1) using 4-aminopyrazolpyrimidine (APP) could increase the efficacy of RNAi against reporter constructs, a finding that may facilitate improvements in future work. Thus, for many genes, RNAi provides a useful tool for studying Leishmania gene function with some unique advantages.

Response to a Serogroup B Meningococcal Disease Case Among Military Trainees.

We describe the public health response to a military trainee who developed serogroup B meningococcal disease while sharing underwater breathing equipment. Despite high transmission risk, with rapid isolation and postexposure prophylaxis administration, there were no secondary cases. This case supports carefully weighing serogroup B meningococcal vaccination in high-risk settings.

Effect of Arrival Quarantine on Subsequent COVID-19 Testing in a Cohort of Military Basic Trainees.

INTRODUCTION: Basic Military Training at Joint Base San Antonio-Lackland implemented several sequential non-pharmaceutical interventions in response to coronavirus disease-2019 (COVID-19). One measure, arrival quarantine, has not been studied as a modern military disease prevention strategy. This study aimed to determine the effect of a 14-day arrival quarantine on symptomatic COVID-19 testing. MATERIAL AND METHODS: A retrospective cohort study compared symptomatic COVID-19 testing among all trainees who entered Basic Military Training between March 17, 2020, and April 17, 2020, before the implementation of universal arrival COVID-19 testing, during their first 2 weeks in arrival quarantine compared to the rest of their training. Furthermore, symptomatic COVID-19 testing in the last 5 weeks of training in those who completed arrival quarantine was compared to testing in the last 5 weeks for trainees who arrived between February 16, 2020, and March 16, 2020, and did not undergo arrival quarantine. Nominal variables were compared by chi-square test, and continuous variables were compared by Mann-Whitney U test. This study was approved as a public health surveillance project by the 59th Medical Wing Institutional Review Board. RESULTS: Five thousand five hundred and seventy-six trainees started training between February 16, 2020, and April 17, 2020, with 2,573 trainees undergoing an arrival quarantine compared to 3,003 trainees who did not. Trainees who underwent arrival quarantine had higher rates of COVID-19 testing while in arrival quarantine (10.5 tests per 1,000 trainee-weeks vs. 2.3, P ≤ .001) and higher rates of concomitant influenza testing (74% vs. 38%, P = .001) compared to after they completed quarantine. Trainees that completed quarantine had less symptomatic COVID-19 testing after day 14 of training (2.3 tests per 1,000 trainee-weeks vs. 14.3, P ≤ .001) and influenza testing (38% vs. 74%, P = .001) compared to trainees that did not undergo arrival quarantine. CONCLUSION: Arrival quarantine appears to be an effective non-pharmaceutical intervention associated with fewer symptomatic COVID-19 tests, especially after completion of quarantine.