22Coronavirus disease-19 (COVID19), the novel respiratory illness caused by severe acute 23 respiratory syndrome coronavirus 2 (SARS-CoV-2), is associated with severe morbidity and 24 mortality. The rollout of diagnostic testing in the United States was slow, leading to numerous 25 cases that were not tested for SARS-CoV-2 in February and March 2020, necessitating the use 26 of serological testing to determine past infections. Here, we evaluated the Abbott SARS-CoV-2 27IgG test for detection of anti-SARS-CoV-2 IgG antibodies by testing 3 distinct patient 28 populations. We tested 1,020 serum specimens collected prior to SARS-CoV-2 circulation in the 29United States and found one false positive, indicating a specificity of 99.90%. We tested 125 30 patients who tested RT-PCR positive for SARS-CoV-2 for which 689 excess serum specimens 31 were available and found sensitivity reached 100% at day 17 after symptom onset and day 13 32 after PCR positivity. Alternative index value thresholds for positivity resulted in 100% sensitivity 33 and 100% specificity in this cohort. We tested 4,856 individuals from Boise, Idaho collected over 34 one week in April 2020 as part of the Crush the Curve initiative and detected 87 positives for a 35 positivity rate of 1.79%. These data demonstrate excellent analytical performance of the Abbott 36 SARS-CoV-2 IgG test as well as the limited circulation of the virus in the western United States. 37We expect the availability of high-quality serological testing will be a key tool in the fight 38 against SARS-CoV-2. 39 40 41 on June 9, 2020 by guest

Legionella pneumophila is an intracellular pathogen responsible for Legionnaires' disease. This bacterium uses the Dot/Icm type IV secretion system to inject a large number of bacterial proteins into host cells to facilitate the biogenesis of a phagosome permissive for its intracellular growth. Like many highly adapted intravacuolar pathogens, L. pneumophila is able to maintain a neutral pH in the lumen of its phagosome, particularly in the early phase of infection. However, in all cases, the molecular mechanisms underlying this observation remain unknown. In this report, we describe the identification and characterization of a Legionella protein termed SidK that specifically targets host v-ATPase, the multi-subunit machinery primarily responsible for organelle acidification in eukaryotic cells. Our results indicate that after being injected into infected cells by the Dot/Icm secretion system, SidK interacts with VatA, a key component of the proton pump. Such binding leads to the inhibition of ATP hydrolysis and proton translocation. When delivered into macrophages, SidK inhibits vacuole acidification and impairs the ability of the cells to digest non-pathogenic E. coli. We also show that a domain located in the N-terminal portion of SidK is responsible for its interactions with VatA. Furthermore, expression of sidK is highly induced when bacteria begin to enter new growth cycle, correlating well with the potential temporal requirement of its activity during infection. Our results indicate that direct targeting of v-ATPase by secreted proteins constitutes a virulence strategy for L. pneumophila, a vacuolar pathogen of macrophages and amoebae.

Nonselected and natural populations of Escherichia coli from 12 animal sources and humans were examined for the presence and types of 14 tetracycline resistance determinants. Of 1,263 unique E. coli isolates from humans, pigs, chickens, turkeys, sheep, cows, goats, cats, dogs, horses, geese, ducks, and deer, 31% were highly resistant to tetracycline. More than 78, 47, and 41% of the E. coli isolates from pigs, chickens, and turkeys were resistant or highly resistant to tetracycline, respectively. Tetracycline MICs for 61, 29, and 29% of E. coli isolates from pig, chickens, and turkeys, respectively, were >233 g/ml. Muliplex PCR analyses indicated that 97% of these strains contained at least 1 of 14 tetracycline resistance genes [tetA, tetB, tetC, tetD, tetE, tetG, tetK, tetL, tetM, tetO, tetS, tetA(P), tetQ, and tetX] examined. While the most common genes found in these isolates were tetB (63%) and tetA (35%), tetC, tetD, and tetM were also found. E. coli isolates from pigs and chickens were the only strains to have tetM. To our knowledge, this represents the first report of tetM in E. coli.

A B S T R A C TLower respiratory infections remain one of the top global causes of death and the emergence of new diseases continues to be a concern. In the first two decades of the 21st century, we have born witness to the emergence of newly recognized coronaviruses that have rapidly spread around the globe, including severe acute respiratory syndrome virus (SARS) and Middle Eastern respiratory syndrome virus (MERS). We have also experienced the emergence of a novel H1N1 pandemic influenza strain in 2009 that caused substantial morbidity and mortality around the world and has transitioned into a seasonal strain. Although we perhaps most frequently think of viruses when discussing emerging respiratory infections, bacteria have not been left out of the mix, as we have witnessed an increase in the number of infections from Legionella spp. since the organisms' initial discovery in 1976. Here, we explore the basic epidemiology, clinical presentation, histopathology, and clinical laboratory diagnosis of these four pathogens and emphasize themes in humans' evolving relationship with our natural environment that have contributed to the infectious burden. Histology alone is rarely diagnostic for these infections, but has been crucial to bettering our understanding of these diseases. Together, we rely on the diagnostic acumen of pathologists to identify the clinicopathologic features that raise the suspicion of these diseases and lead to the early control of the spread in our populations. (A. Bryan). Seminars in DiagnosticPathology 36 (2019) 152-159 0740-2570/