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Objectives As part of an active MRSA surveillance programme in our neonatal ICU, we identified nares surveillance cultures from two infants that displayed heterogeneity in methicillin resistance between isolated subclones that lacked mecA and mecC. Methods The underlying mechanism for the modified Staphylococcus aureus (MODSA) methicillin-resistance phenotype was investigated by WGS. Results Comparison of finished-quality genomes of four MODSA and four MSSA subclones demonstrated that the resistance changes were associated with unique truncating mutations in the gene encoding the cyclic diadenosine monophosphate phosphodiesterase enzyme GdpP or a non-synonymous substitution in the gene encoding PBP2. Conclusions These two cases highlight the difficulty in identifying non-mecA, non-mecC-mediated MRSA isolates in the clinical microbiology laboratory, which leads to difficulties in implementing appropriate therapy and infection control measures.

The COVID-19 pandemic has affected millions of people, including hundreds of deaths. The search for adequate treatments and interventions that influence poor prognostic factors and reduce mortality has led to excessive use of antibiotics based on the possible existence of bacterial co-infection. However, there is no evidence to justify the systematic use of antimicrobials in COVID-19. The recommendations seek to provide knowledge regarding treatment; standardizing a management algorithm requires validation in clinical trials and studies of greater methodological rigor.

Rickets is a metabolic bone disease associated with failure of endochondral ossification and impaired osteoid mineralization in growing animals. As a consequence, affected individuals can develop gross and microscopic bone malformations. The most common causes of rickets in domestic species include vitamin D and phosphorus deficiency. Rickets has been described in multiple species; however, comprehensive postmortem characterizations with confirmatory histopathology in equids have not been published. A 6-mo-old, Thoroughbred-cross foal was diagnosed with rickets based on gross autopsy findings and microscopic examination of the ribs and long bones. Grossly, all costochondral junctions of the ribs were enlarged with a “rachitic rosary” appearance, and there were multiple fracture calluses in the rib bodies. Epiphyses and metaphyses of the long bones appeared widened on sagittal section, and their physes were irregularly thickened. Histologically, there were poorly organized columns of hypertrophic chondrocytes within the physes of affected bones, islands of chondrocytes embedded within the primary and secondary spongiosa, and faintly eosinophilic seams of poorly mineralized osteoid within the bone trabeculae. Areas of focally increased osteoclastic activity were observed in some of the sections, perhaps pointing to a more complex metabolic bone disease in a growing animal. Low serum concentrations of calcium and 25-hydroxyvitamin D were detected in an antemortem sample. The pathogenesis of these imbalances was not definitively established, but lack of sunlight exposure, low concentration of vitamin D precursors in the diet (perhaps secondary to malnutrition), or both, were suspected; a genetic basis cannot be ruled out.

SARS-Cov-2 (severe acute respiratory disease coronavirus 2), which causes Coronavirus Disease 2019 (COVID19) was first detected in China in late 2019 and has since then caused a global pandemic. While molecular assays to directly detect the viral genetic material are available for the diagnosis of acute infection, we currently lack serological assays suitable to specifically detect SARS-CoV-2 antibodies. Here we describe serological enzyme-linked immunosorbent assays (ELISA) that we developed using recombinant antigens derived from the spike protein of SARS-CoV-2. Using negative control samples representing pre-COVID 19 background immunity in the general adult population as well as samples from COVID19 patients, we demonstrate that these assays are sensitive and specific, allowing for screening and identification of COVID19 seroconverters using human plasma/serum as early as two days post COVID19 symptoms onset. Importantly, these assays do not require handling of infectious virus, can be adjusted to detect different antibody types and are amendable to scaling. Such serological assays are of critical importance to determine seroprevalence in a given population, define previous exposure and identify highly reactive human donors for the generation of convalescent serum as therapeutic. Sensitive and specific identification of coronavirus SARS-Cov-2 antibody titers may, in the future, also support screening of health care workers to identify those who are already immune and can be deployed to care for infected patients minimizing the risk of viral spread to colleagues and other patients.

Background. Healthcare-associated infections pose a potentially fatal threat to patients worldwide and Staphylococcus aureus is one of the most common causes of healthcare-associated infections. S. aureus is a common commensal pathogen and a frequent cause of bacteremia, with studies demonstrating that nasal and blood isolates from single patients match more than 80% of the time. Here we report on a contemporary collection of colonizing isolates from those with methicillin-resistant S. aureus (MRSA) bloodstream infections to evaluate the diversity within hosts, and detail the clinical features associated with concomitant nasal colonization.Methods. Swabs of the bilateral anterior nares were obtained from patients diagnosed with MRSA bacteremia. A single colony culture from the blood and an average of 6 colonies from the nares were evaluated for MRSA growth. For the nares cultures, we typed multiple isolates for staphylococcal protein A (spa) and derived the clonal complexes. Demographic and clinical data were obtained retrospectively from the electronic medical record system and analysed using univariate and multivariable regression models.Results. Over an 11-month period, 68 patients were diagnosed with MRSA bloodstream infection, 53 were swabbed, and 37 (70%) were colonized with MRSA in the anterior nares. We performed molecular typing on 210 nasal colonies. Spa types and clonal complexes found in the blood were also detected in the nares in 95% of the cases. We also found that 11% of patients carried more than one clone of MRSA in the nares. Male sex and history of prior hospitalization within the past 90 days increased odds for MRSA colonization. Conclusion. The molecular epidemiological landscape of colonization in the setting of invasive disease is diverse and defining the interplay between colonization and invasive disease is critical to combating invasive MRSA disease.

We investigated the genetic diversity and phylogenetic structure of Webster’s salamander (Plethodon websteri), an understudied species of conservation concern and one of the first morphologically cryptic salamander species described solely on the basis of molecular techniques. Using a combination of mitochondrial and microsatellite data, we discovered significant genetic differentiation across the known distribution (ɸST > 0.868 and FST = 0.261−0.652, p

In this study we profiled vaccine-induced polyclonal antibodies as well as plasmablast derived mAbs from individuals who received SARS-CoV-2 spike mRNA vaccine. Polyclonal antibody responses in vaccinees were robust and comparable to or exceeded those seen after natural infection. However, the ratio of binding to neutralizing antibodies after vaccination was greater than that after natural infection and, at the monoclonal level, we found that the majority of vaccine-induced antibodies did not have neutralizing activity. We also found a co-dominance of mAbs targeting the NTD and RBD of SARS-CoV-2 spike and an original antigenic-sin like backboost to seasonal human coronaviruses OC43 and HKU1. Neutralizing activity of NTD mAbs but not RBD mAbs against a clinical viral isolate carrying E484K as well as extensive changes in the NTD was abolished, suggesting that a proportion of vaccine induced RBD binding antibodies may provide substantial protection against viral variants carrying single E484K RBD mutations., An analysis of mRNA vaccine-induced polyclonal antibodies and plasmablast derived monoclonal antibodies from individuals vaccinated against SARS-CoV-2 identifies a high proportion of non-neutralizing antibodies, the induction of cross-reactive antibodies to seasonal coronaviruses and also maps the regions in the spike protein that are targeted, even among viral variants.

Active surveillance in our neonatal intensive care unit identified Staphylococcus aureus cultures from two infants with heterogeneity in methicillin resistance between isolated subclones lacking mecA and mecC. Whole-genome analysis of 4 modified (MODSA) and 4 methicillin-susceptible (MSSA) subclones for each culture identified either truncating mutations in the cyclic diadenosine monophosphate phosphodiesterase enzyme (GdpP), or a nonsynonymous substitution in penicillin binding protein 2 (PBP2). These cases highlight the difficulty in identifying non-mecA/non-mecC-mediated methicillin-resistance in clinical laboratories.

Blighted Gotham Deaths caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in New York City (NYC) during the spring of 2020 have vastly exceeded those reported in China and many other countries. What were the early events that led to such a severe outbreak? Gonzalez-Reiche et al. sampled some of the early patients seeking assistance in February and March of 2020 at the Mount Sinai Health System. Phylogenetic analysis of virus sequences in these people, who were drawn from across NYC, showed that the virus had been independently introduced many times from Europe and elsewhere in the United States. Subsequent clusters of community transmission occurred. The focus of infection in NYC is a marker of the role this city plays as a two-way hub for human movement. Science this issue p. 297

The world-class Pueblo Viejo Au deposit in the central Dominican Republic is one of the largest high-sulfidation epithermal Au deposits globally, with past production plus resources and reserves of 41.7 million ounces (Moz) in the Moore and Monte Negro deposits. Mineralization occurs within a 2- × 2-km Early Cretaceous volcano-sedimentary basin filled with felsic volcanic and volcaniclastic rocks, interlayered carbonaceous sedimentary units, and underlying andesitic flows and tuffs. The volcanic stratigraphy was developed during a period of tholeiitic magmatism that transitioned to calc-alkaline magmatism at the time of emplacement of the late- to postmineral Monte Negro dike (~109 Ma). Additional geologic controls to mineralization include high-angle, NE- and NW-faulting, phreatomagmatic breccias, and possible volcanic domes. Mineralization is present across the stratigraphic sequence, with mineralization at Moore dominantly hosted within quartz-bearing volcaniclastic rocks and overlying carbonaceous sedimentary units, whereas that at Monte Negro is in the andesitic sequence as well as overlying epiclastic and sedimentary units. Alteration at the shallowest level is dominated by quartz-pyrophyllite, whereas alunite alteration defines the deep roots to the ore-forming environment. Mineralization comprises early disseminated-type and late veins filled with pyrite ± sphalerite. Hypogene ore is refractory in nature, with Au in solid solution or as mineral inclusions within arsenian pyrite. Re-Os ages of 113.4 ± 2.6 Ma for auriferous pyrite along with new geologic observations appear to confirm an Early Cretaceous age for mineralization, although Re-Os enargite ages suggest the possibility of a second mineralization event in the Eocene.

Background Fear of autism has led to a decline in childhood-immunization uptake and to a resurgence of preventable infectious diseases. Identifying characteristics of parents who believe in a causal role of vaccines for autism spectrum disorder (ASD) in their child may help targeting educational activities and improve adherence to the immunization schedule. Objectives To compare caregivers of children with ASD who agree or disagree that vaccines play an etiological role in autism for 1) socio-demographics characteristics and 2) developmental and clinical profiles of their children. Methods Data from 16,525 participants with ASD under age 18 were obtained from SPARK, a national research cohort started in 2016. Caregivers completed questionnaires at registration that included questions on beliefs about the etiologic role of childhood immunizations and other factors in ASD. Data were available about family socio-demographic characteristics, first symptoms of autism, developmental regression, co-occurring psychiatric disorders, seizures, and current levels of functioning. Results Participants with ASD were 80.4% male with a mean age of 8.1 years (SD = 4.1). Overall, 16.5% of caregivers endorsed immunizations as perceived causes of autism. Compared to caregivers who disagreed with vaccines as a cause for ASD, those who believed in vaccine causation came disproportionately from ethnic minority, less educated, and less wealthy backgrounds. More often their children had experienced developmental regression involving language and other skills, were diagnosed earlier, had lost skills during the second year of life, and had worse language, adaptive, and cognitive outcomes. Conclusion One in six caregivers who participate in a national research cohort believe that child immunizations could be a cause of autism in their child. Parent social background (non-White, less educated) and child developmental features (regression in second year, poorer language skills, and worse adaptive outcomes) index caregivers who are more likely to harbor these beliefs and could benefit from targeted educational activities.

The Hatillo Limestone and the underlying Los Ranchos Formation are exposed over an east-west distance of 100 km in the eastern Dominican Republic. The lowermost portion of the Hatillo Limestone in the Pueblo Viejo district contains a Late Lower Albian fossil assemblage including corals and rudist bivalves indicative of a near-shore reef environment. Diamond drilling in the Pueblo Viejo district and exposures in the open pits show that the Hatillo Limestone conformably overlies the Early Cretaceous Los Ranchos Formation. Volcanogenic massive sulfide beds, exposed in the Moore pit, provide evidence for an Early Cretaceous, syn-mineralization paleosurface. Altered and mineralized clasts in the epiclastic, sedimentary host-rock section at the Pueblo Viejo mine indicate that the ore deposits were open to erosion during hydrothermal alteration and mineralization. The Hatillo Limestone did not overlie the ore deposits during the mineralizing event and, consequently, could not have acted as an impermeable cap to ascending hydrothermal fluids. Intra-oceanic island arc volcanism (Los Ranchos Formation) overlapped at the Aptian–Albian boundary (112 Ma) with a marginal fringing reef (basal Hatillo Limestone). The marginal reef gradually gave way to deeper-water facies as Hatillo Limestone deposition progressed through the middle Albian. Low-angle reverse faulting, penetrative deformation, and metamorphic recrystallization affected the Hatillo Limestone as well as the Los Ranchos and Maimón formations during the Late Cretaceous. Deformation intensity and metamorphic grade progressed from incipient metamorphism in the Pueblo Viejo district to schists in the Maimón Formation to amphibolite near a faulted contact with the Loma Caribe peridotite.

Background Staphylococcus aureus is a common commensal pathogen and a frequent cause of bacteremia, with nasal and blood isolates from single patients matching >80% of the time. Based on our prior work on paired single-patient isolates,1 our aim was to collect a contemporary set of colonizing isolates from those with methicillin-resistant S. aureus (MRSA) bloodstream infections (BSIs), evaluate the within-host diversity by whole-genome sequencing (WGS), and detail the clinical features linked to colonization. Methods Adult patients with MRSA BSIs were screened for MRSA in the anterior nares from July 2018 to March 2019. Blood isolates underwent WGS, and spa and agr function screens were performed on three unique nasal isolates per patient. Clinical data from the electronic medical records underwent uni- and multivariate analyses on clinical features and outcomes. Results Of 55 unique patients with MRSA BSIs, screening of 45 subjects revealed that 67% were colonized with MRSA. The majority (64%) were males, 32% had prior colonization, and the most common infection sources were vascular access (27%), skin (24%), and unknown (24%). For those with nasal colonization, blood isolates were composed of 57% clonal complex (CC)5/t002, 33% CC8/t008, and 10% other. 81% of nasal isolates matched the blood, with 20% of nasal isolates harboring diverse spa types and 23% carried agr mutants. During this time frame, WGS found one transmission event involving a colonized subject. Colonization was associated with male gender (OR=4.52 95% CI [1.05–19.49]; P = 0.04) and prior hospital admission within the last 3 months (OR=6.12 95% CI [1.44–26.09]; P = 0.01) in multivariate analysis, with no differences in outcomes. Conclusion Colonization is an important component of invasive MRSA disease, and we found high rates of colonization with a predominance of the CC5. We also noted significant diversity and high proportion of agr mutants. At-risk groups included males and those with prior hospitalization. Combined molecular and clinical analyses can define the intrahost and interhost transmission dynamics of MRSA, and enables the development of targeted approaches in order to curtail disease. 1. Altman, D. R. et al. Genome Plasticity of agr-defective Staphylococcus aureus during clinical infection. Infect. Immun.(2018). Disclosures All authors: No reported disclosures.

Background As part of active surveillance in our NICU for methicillin-resistant Staphylococcus aureus (MRSA), two isolates representing modified S. aureus (MODSA), which are Methicillin resistant but lacking mecA or C were identified. Our current microbiology laboratory workflow for screening for MRSA involves plating isolates on chromoID agar (bioMérieux, Marcy-l’Etoile, France) as well as on sheep blood agar (SBA). Β hemolytic colonies on SBA that are catalase and coagulase positive are set up for confirmation and antimicrobial susceptibility testing on the Vitek 2 (bioMérieux, Marcy-l’Etoile, France). Methods These 2 isolates (from Baby 1 and Baby 2) tested positive for green colonies on the chromoagar plates. The Vitek 2 subsequently identified both these isolates as MRSA. However, for research purposes, all positive NICU MRSA isolates are tested via whole-genome sequencing (WGS). Both isolates were identified by WGS as methicillin-susceptible Staphylococcus aureus (MSSA). We subsequently went back and performed additional workup on these isolates. Isolates were plated on SBA and chromagar again and incubated for 24 hours. 2 colonies of different morphologies from the chromagar plates and 3 from the SBA were randomly selected and subcultured to chromagar and SBA for a total of 5 subcultures. Each of the subcultures was tested using staphaurex, mannitol salt agar and the Cepheid Xpert MRSA assay and all were confirmed to be Staphylococcus aureus. Results All 10 isolates tested negative by the Cepheid Xpert MRSA assay for MRSA. Phenotypic testing was set up again for all ten isolates using the vitek GP panel, as well as cefoxitin disk, and oxacillin E test using Mueller–Hinton agar supplemented with 2% NaCl as per CLSI methods. See table attached for results. Conclusion In conclusion, these two cases highlight the difficulty in identifying non-MecA, non-MecC-mediated MRSA isolates in the clinical microbiology laboratory. This is particularly important as more laboratories rely on testing for MecA by PCR for surveillance testing. These 2 cases were further complicated by heterogeneous sub-populations of Staphylococcus aureus. Failure to recognize these variant forms of MRSA can lead to difficulties in implementing appropriate therapy and infection control measures. Improved methodologies are needed. Disclosures All authors: No reported disclosures.

In dynamic analysis, the energy dissipation in a base-isolated building is typically accounted for by allocating damping properties independently to the superstructure and to the isolation system. Rayleigh damping applied to the superstructure component alone is often used to represent the superstructure energy dissipation. At least one study has indicated that when used improperly, superstructure Rayleigh damping leads to excessive damping of the response of a base-isolated structure. As shown here, even when used as recommended for combining subsystems with disparate damping properties, Rayleigh damping results in undesirable suppression of the first mode response. To correct this behavior, stiffness-proportional damping can be used in lieu of Rayleigh damping. Stiffness-proportional damping is demonstrated to negligibly affect the first mode response, yet provide the expected energy dissipation in higher modes.

The Pueblo Viejo district, located in the Cordillera Central of the Dominican Republic, contains large Au-Ag deposits associated with acid-sulfate alteration within spilites, conglomerates and carbonaceous sedimentary rocks that were deposited in a maar-diatreme complex. Much of the Au mineralization occurs in pyritic, carbonaceous siltstones of the Pueblo Viejo Maar-Diatreme Member of the Cretaceous Los Ranchos Formation. Pyrite is the only Fe-bearing phase in mineralized rock, whereas siderite is the dominant Fe-bearing phase in siltstones distal to mineralization. Disseminated pyrite occurs as framboids, cubes, pyritohedra, concretions and cement. Early framboids occur throughout the district. Au occurs as inclusions in later non-framboid disseminated pyrite (NFDP); an occurrence that is interpreted to be indicative of contemporaneous deposition. Pyrite framboids exhibit a wide range of δ34S cdt -values (−17.5 to +4.8‰) and are interpreted to have formed during biogenic reduction of pore-water sulfate. The NFDP yield restricted δ34S cdt -values ( x = −5.2‰ , s = ±2.4‰ , n = 43) similar to those obtained from later vein pyrite ( x = −6.4‰ , s = ±1.5‰ , n = 12). Alunite and barite have δ34S-values ranging from +18.8 to +21.6‰. The interpretation that the NFDP, vein pyrite, alunite and barite, and possibly even the framboidal pyrite share a common source of igneous sulfur is supported by the δ34S data. Siderite occurs as concretions and cement, contains abundant Mg (Fe0.75Mg0.19Mn0.03Ca0.02CO3) and has δ13C pdb - and δ18O smow -values ranging from −2.5 to +1.1%. and +14.6 to +19.5‰, respectively. These data are consistent with the interpretation that the siderite formed in lacustrine sediments and that the carbonate in the siderite is probably methanogenic, although contributions from oxidation of organic matter during biogenic sulfate reduction, thermal decarboxylation of organic matter, or magmatic vapor cannot be ruled out. Disseminated Au mineralization in the sedimentary rocks formed when a hydrothermal fluid encountered reactive Fe2+ in diagenetic siderite. The ensuing pyrite deposition consumed H2S and destabilized the Au (HS)−2 complex, leading to precipitation of Au. The capacity of the sedimentary rocks to consume H2S and precipitate Au was controlled by the amount of non-pyrite Fe present as siderite. The abundance of siderite was controlled by the extent of pyrite formation during diagenesis.

This study was undertaken to determine the geologic factors that were important in making Pueblo Viejo, which contains over 600,000 kg of gold in relatively high-grade ore, one of the few acid sulfate deposits to be mined economically on a large scale. Orebodies at Pueblo Viejo, including Monte Negro, the focus of this study, are found around a maar-diatreme complex that formed in the upper part of the Lower Cretaceous Los Ranchos Formation. Ore is hosted by spilite, spilite-derived conglomerate, and intramaar carbonaceous sandstone and mudstone. Regional seawater alteration of these rocks was overprinted by two stages of advanced argillic alteration, both of which are associated with precious metals. Stage I produced deep alunite + quartz + pyrite and overlying kaolinite + quartz + pyrite assemblages and deposited gold in association with disseminated pyrite in wall rock. Stage II, which overprinted stage I, produced deep pyrophyllite + or - diaspore and an overlying (recrystallized) silica cap. Pyrite + or - sphalerite + or - enargite veins that probably formed in response to hydrofracturing of the silica cap contain gold grades of as much as 100 ppm. Vein density and assay data show that approximately 60 percent of the gold at Monte Negro is in disseminated stage I ore, with the remainder in stage II veins.Phase equilibria and sulfur isotope thermometry show that stage I alteration took place below 260 degrees C at pH values between 2 and 3. Stage II pyrophyllite + or - diaspore formation occurred above 285 degrees C, from a fluid with an initial pH of 1 to 1.5, while the silica caps formed below 220 degrees C. Geologic constraints indicate that stage I wall-rock gold at Monte Negro was deposited by sulfidation of Fe-rich wall rock, whereas stage II vein-hosted gold could have formed by cooling, boiling, or mixing with overlying ground water. Use of the programs SOLVEQ and CHILLER to evaluate the relative efficiencies of these ore-forming processes confirms that sulfidation was capable of depositing disseminated stage I gold, whereas stage II vein gold was probably deposited by boiling related to pressure release during hydrofracturing and subsequent mixing with ground water.These observations indicate that development of grade and tonnage at Pueblo Viejo was greatly facilitated by (1) the porous-permeable maar-diatreme complex, which hosted large, shallow hydrothermal cells and probably served as a conduit for rising magmatic gases, (2) the presence of iron-rich wall rock, which caused early deposition of "background" disseminated gold by sulfidation, and (3) later hydrothermal activity which formed impermeable silica caps that hydrofractured to create the high-grade vein overprint. Remobilization of stage I background gold into stage II veins might also have been an important factor in upgrading the deposits. Exploration for similar deposits should focus on areas of explosive volcanism in andesitic island arc terranes.