Low prevalence (0.13%) of COVID-19 infection in asymptomatic pre-operative/pre-procedure patients at a large, academic medical center informs approaches to perioperative care.

BackgroundThe coronavirus disease 2019 (COVID-19) pandemic has resulted in reduced performance of elective surgeries and procedures at medical centers across the United States. Awareness of the prevalence of asymptomatic disease is critical for guiding safe approaches to operative/procedural services. As COVID-19 polymerase chain reaction (PCR) testing has been limited largely to symptomatic patients, health care workers, or to those in communal care centers, data regarding asymptomatic viral disease carriage are limited.MethodsIn this retrospective observational case series evaluating UCLA Health patients enrolled in pre-operative/pre-procedure protocol COVID-19 reverse transcriptase (RT)-PCR testing between April 7, 2020 and May 21, 2020, we determine the prevalence of COVID-19 infection in asymptomatic patients scheduled for surgeries and procedures.ResultsPrimary outcomes include the prevalence of COVID-19 infection in this asymptomatic population. Secondary data analysis includes overall population testing results and population demographics. Eighteen of 4,751 (0.38%) patients scheduled for upcoming surgeries and high-risk procedures had abnormal (positive/inconclusive) COVID-19 RT-PCR testing results. Six of 18 patients were confirmed asymptomatic and had positive test results. Four of 18 were confirmed asymptomtic and had inconclusive results. Eight of 18 had positive results in the setting of recent symptoms or known COVID-19 infection. The prevalence of asymptomatic COVID-19 infection was 0.13%. More than 90% of patients had residential addresses within a 67-mile geographic radius of our medical center, the median age was 58, and there was equal male/female distribution.ConclusionThese data demonstrating low levels (0.13% prevalence) of COVID-19 infection in an asymptomatic population of patients undergoing scheduled surgeries/procedures in a large urban area have helped to inform perioperative protocols during the COVID-19 pandemic. Testing protocols like ours may prove valuable for other health systems in their approaches to safe procedural practices during COVID-19

Pan genome of the phytoplankton Emiliania underpins its global distribution

Coccolithophores have influenced the global climate for over 200 million years1. These marine phytoplankton can account for 20 per cent of total carbon fixation in some systems2. They form blooms that can occupy hundreds of thousands of square kilometres and are distinguished by their elegantly sculpted calcium carbonate exoskeletons (coccoliths), rendering themvisible fromspace3.Although coccolithophores export carbon in the form of organic matter and calcite to the sea floor, they also release CO2 in the calcification process. Hence, they have a complex influence on the carbon cycle, driving either CO2 production or uptake, sequestration and export to the deep ocean4. Here we report the first haptophyte reference genome, from the coccolithophore Emiliania huxleyi strain CCMP1516, and sequences from 13 additional isolates. Our analyses reveal a pan genome (core genes plus genes distributed variably between strains) probably supported by an atypical complement of repetitive sequence in the genome. Comparisons across strains demonstrate thatE. huxleyi, which has long been considered a single species, harbours extensive genome variability reflected in different metabolic repertoires. Genome variability within this species complex seems to underpin its capacity both to thrive in habitats ranging from the equator to the subarctic and to form large-scale episodic blooms under a wide variety of environmental conditions

Ergot cluster-encoded catalase is required for synthesis of chanoclavine-I in Aspergillus fumigatus

Genes required for ergot alkaloid biosynthesis are clustered in the genomes of several fungi. Several conserved ergot cluster genes have been hypothesized, and in some cases demonstrated, to encode early steps of the pathway shared among fungi that ultimately make different ergot alkaloid end products. The deduced amino acid sequence of one of these conserved genes (easC) indicates a catalase as the product, but a role for a catalase in the ergot alkaloid pathway has not been established. We disrupted easC of Aspergillus fumigatus by homologous recombination with a truncated copy of that gene. The resulting mutant (?easC) failed to produce the ergot alkaloids typically observed in A. fumigatus, including chanoclavine-I, festuclavine, and fumigaclavines B, A, and C. The ?easC mutant instead accumulated N-methyl-4-dimethylallyltryptophan (N-Me-DMAT), an intermediate recently shown to accumulate in Claviceps purpurea strains mutated at ccsA (called easE in A. fumigatus) (Lorenz et al. Appl Environ Microbiol 76:1822–1830, 2010). A ?easE disruption mutant of A. fumigatus also failed to accumulate chanoclavine-I and downstream ergot alkaloids and, instead, accumulated N-Me-DMAT. Feeding chanoclavine-I to the ?easC mutant restored ergot alkaloid production. Complementation of either ?easC or ?easE mutants with the respective wild-type allele also restored ergot alkaloid production. The easC gene was expressed in Escherichia coli, and the protein product displayed in vitro catalase activity with H2O2 but did not act, in isolation, on N-Me-DMAT as substrate. The data indicate that the products of both easC (catalase) and easE (FAD-dependent oxidoreductase) are required for conversion of N-Me-DMAT to chanoclavine-I