Clinical characteristics of asymptomatic and symptomatic patients with mild COVID-19

OBJECTIVES

Detailed knowledge on the prevalence of asymptomatic cases of coronavirus disease 2019 (COVID-19) and the clinical characteristics of mild COVID-19 is essential for effective control of the COVID-19 pandemic. We determined the prevalence of asymptomatic cases of COVID-19 and characterized the symptoms of patients with mild COVID-19.

METHODS

Study participants were recruited from a community facility designated for the isolation of patients without moderate-to-severe symptoms of COVID-19 in South Korea. The prevalence of asymptomatic patients at admission and the detailed symptoms of mild COVID-19 were evaluated through a questionnaire-based survey. Diagnosis of COVID-19 was confirmed by real-time RT-PCR.

RESULTS

Of the 213 individuals with COVID-19, 41 (19.2%) were asymptomatic until admission. Among the remaining patients with mild COVID-19, the most common symptom was cough (40.1%; 69/172), followed by hyposmia (39.5%; 68/172) and sputum (39.5%; 68/172). Of the 68 individuals with hyposmia, 61 (90%) had accompanying symptoms such as hypogeusia, nasal congestion or rhinorrhoea. Fever (>37.5°C) was only observed in 20 (11.6%) individuals.

CONCLUSIONS

As much as one-fifth of individuals with COVID-19 remained asymptomatic from exposure to admission. Hyposmia was quite frequent among individuals with mild COVID-19, but fever was not. Social distancing should be strongly implemented to prevent disease transmission from asymptomatic individuals or those with mild and inconspicuous symptoms.

Enhanced antimicrobial stewardship based on rapid phenotypic antimicrobial susceptibility testing for bacteraemia in patients with haematological malignancies: a randomized controlled trial

OBJECTIVES

Recently, rapid phenotypic antimicrobial susceptibility testing (AST) based on microscopic imaging analysis has been developed. The aim of this study was to determine whether implementation of antimicrobial stewardship programmes (ASP) based on rapid phenotypic AST can increase the proportion of patients with haematological malignancies who receive optimal targeted antibiotics during early periods of bacteraemia.

METHODS

This randomized controlled trial enrolled patients with haematological malignancies and at least one positive blood culture. Patients were randomly assigned 1:1 to conventional (n = 60) or rapid phenotypic (n = 56) AST. The primary outcome was the proportion of patients receiving optimal targeted antibiotics 72 hr after blood collection for culture.

RESULTS

The percentage receiving optimal targeted antibiotics at 72 hr was significantly higher in the rapid phenotypic AST group (45/56, 80.4%) than in conventional AST group (34/60, 56.7%) (relative risk (RR) 1.42, 95% confidence interval (CI) 1.09-1.83). The percentage receiving unnecessary broad-spectrum antibiotics at 72 hr was significantly lower (7/26, 12.5% vs 18/60, 30.0%; RR 0.42, 95% CI 0.19-0.92) and the mean time to optimal targeted antibiotic treatment was significantly shorter (38.1, standard deviation (SD) 38.2 vs 72.8, SD 93.0 hr; p < 0.001) in the rapid phenotypic AST group. The mean time from blood collection to the AST result was significantly shorter in the rapid phenotypic AST group (48.3, SD 17.6 vs 83.1, SD 22.2 hr).

DISCUSSION

ASP based on rapid phenotypic AST can rapidly optimize antibiotic treatment for bacteraemia in patients with haematological malignancy. Rapid phenotypic AST can improve antimicrobial stewardship in immunocompromised patients.

Fabrication of Two-Dimensional and Three-Dimensional High-Resolution Binder-Free Graphene Circuits Using a Microfluidic Approach for Sensor Applications

In this study, a simple microfluidic method, which can be universally applied to different rigid or flexible substrates, was developed to fabricate high-resolution, conductive, two-dimensional and three-dimensional microstructured graphene-based electronic circuits. The method involves controlled and selective filling of microchannels on substrate surfaces with a conductive binder-free graphene nanoplatelet (GNP) solution. The ethanol-thermal reaction of GNP solution at low temperatures (∼75 °C) prior to microchannel filling (preheating) can further reduce the GNP andprovide a homogeneous GNP solution, which in turn enhances conductivity, reduces sheet resistance (∼0.05 kΩ sq^-1), enables room-temperature fabrication, and eliminates harsh postprocessing, which makes this fabrication technique compatible with degradable substrates. This method can also be used in combination with 3D printing to fabricate 3D circuits. The feature sizes of the graphene patterns can range from a few micrometers (down to ∼15 μm in width and ∼5 μm in depth) to a few millimeters and use very small amounts of GNP solution (∼2.5 mg of graphene to obtain ∼0.1 kΩ sq^-1 of sheet resistance for 1 cm²). This microfluidic approach can also be implemented using other conductive liquids, such as conductive graphene-silver solutions. This technology has the potential to pave the way for low-cost, disposable, and biodegradable circuits for a range of electronic applications including near-field communication antennas and pressure or strain sensors.

Atlantoaxial bands in small breed dogs: influence of external pressure by the endotracheal tube tie

OBJECTIVES

To determine the prevalence of dorsal cervical spinal compression in a population of dogs susceptible to caudal occipital dysplasia. To determine whether endotracheal tube ties iatrogenically alter the dorsal compression ratio in the atlantoaxial region.

MATERIALS AND METHODS

Prospective, randomised, controlled, cross-over, blinded cohort study of dogs weighing <15 kg and presenting for neurologic signs localised to the cervical region. In mid-sagittal T2-weighted MR images, dorsal cervical compression and cerebellar compression were evaluated. Dorsal cervical compression ratios were calculated and compared to determine the effect of the endotracheal tube tie on the atlantoaxial region depending on whether dogs were in extended or flexed neck position.

RESULTS

Prevalence of dorsal cervical spinal compression consistent with an atlantoaxial band was 32/44 (73%) dogs without tie pressure and 37/44 (84%) dogs with tie pressure. Significantly higher compression ratios were found with tie placement over the craniocervical region. Dorsal compression ratios of dogs with cerebellar compression were significantly greater than those without it.

CLINICAL SIGNIFICANCE

The location of the endotracheal tube tie can influence interpretation of MR images of the craniocervical region of small breed dogs. These breeds more often had greater dorsal cervical spinal compression with tie pressure, especially when they had cerebellar compression.

New prebiotic chemistry inspired filter media for stormwater/greywater disinfection

Greywater and stormwater have received significant attention due to increasing water scarcity. Passive filtration such as biofiltration has been a popular treatment method with its low energy input and environmental friendliness. However, pathogen removal capacity needs improvement to achieve safe water quality. In this study, a prebiotic chemistry inspired copolymer based on aminomalononitrile and 3,4,5-trihydroxybenzaldehyde (AMNT30) was introduced to develop antimicrobial media for passive filtration. The AMNT30 polymer provided an adhesive coating on zeolite substrates following a spontaneous polymerisation process at room temperature. AMNT30 coated media were investigated for metal loading capacity, surface morphology, E. coli removal and metal leaching after filtration of different water sources (i.e. stormwater, greywater, and deionised water) at low/high conductivity. The coating enhanced metal ion loading on the surface and demonstrated that >8 log reduction of E. coli can be achieved for silver loaded materials compared to a 1 log reduction for copper loaded materials. The coating also increased the stability of the metals on the media irrespective of inflow characteristics. This study provided the first example using AMNT30 to create antimicrobial water purification media. It is expected that this technology will find applications in the water treatment industry.

S-layer protein-AuNP systems for the colorimetric detection of metal and metalloid ions in water

Bacterial surface layer proteins (S-layer) possess unique binding properties for metal ions. By combining the binding capability of S-layer proteins with the optical properties of gold nanoparticles (AuNP), namely plasmonic resonance, a colorimetric detection system for metal and metalloid ions in water was developed. Eight S-layer proteins from different bacteria species were used for the functionalization of AuNP. The thus developed biohybrid systems, AuNP functionalized with S-layer proteins, were tested with different metal salt solutions, e.g. Indium(III)-chloride, Yttrium(III)-chloride or Nickel(II)-chloride, to determine their selective and sensitive binding to ionic analytes. All tested S-layer proteins displayed unique binding affinities for the different metal ions. For each S-layer and metal ion combination markedly different reaction patterns and differences in concentration range and absorption spectra were detected by UV/vis spectroscopy. In this way, the selective detection of tested metal ions was achieved by differentiated analysis of a colorimetric screening assay of these biohybrid systems. A highly selective and sensitive detection of yttrium ions down to a concentration of 1.67 × 10^-5 mol/l was achieved with S-layer protein SslA functionalized AuNP. The presented biohybrid systems can thus be used as a sensitive and fast sensor system for metal and metalloid ions in aqueous systems.

Fabrication of High-resolution Graphene-based Flexible Electronics via Polymer Casting

In this study, a novel method based on the transfer of graphene patterns from a rigid or flexible substrate onto a polymeric film surface via solvent casting was developed. The method involves the creation of predetermined graphene patterns on the substrate, casting a polymer solution, and directly transferring the graphene patterns from the substrate to the surface of the target polymer film via a peeling-off method. The feature sizes of the graphene patterns on the final film can vary from a few micrometers (as low as 5 µm) to few millimeters range. This process, applied at room temperature, eliminates the need for harsh post-processing techniques and enables creation of conductive graphene circuits (sheet resistance: ~0.2 kΩ/sq) with high stability (stable after 100 bending and 24 h washing cycles) on various polymeric flexible substrates. Moreover, this approach allows precise control of the substrate properties such as composition, biodegradability, 3D microstructure, pore size, porosity and mechanical properties using different film formation techniques. This approach can also be used to fabricate flexible biointerfaces to control stem cell behavior, such as differentiation and alignment. Overall, this promising approach provides a facile and low-cost method for the fabrication of flexible and stretchable electronic circuits.

Are patients with mild to moderate renal impairment on metformin or other oral anti-hyperglycaemic agents at increased risk of contrast-induced nephropathy and metabolic acidosis after radiocontrast exposure?

AIM

To investigate whether the use of metformin during computed tomography (CT) with radiocontrast agents increases the risk of contrast-induced nephropathy (CIN) and metabolic acidosis after CT in type 2 diabetes patients with mild to moderate renal failure.

MATERIALS AND METHODS

Patient records from January 2015 to December 2017 were reviewed retrospectively. A total of 374 patients were included in the final analysis. Of them, 157 patients received metformin, and 217 patients were taking other oral hypoglycaemic agents (OHAs) during radiocontrast administration.

RESULTS

No significant difference in CIN incidence was observed between the metformin use group and the other OHAs group (p=0.085). Metabolic acidosis after CT was seen in 91 (58%) patients who used metformin and 141 (65%) patients who were taking other OHAs. There was no relationship between metabolic acidosis after CT and the use of metformin (p=0.195). Metabolic acidosis after radiocontrast agent exposure was associated with malignant disease, low serum albumin level, and low serum total CO₂ level at baseline.

CONCLUSION

These data show that other factors, but not metformin use, are associated with metabolic acidosis after radiocontrast agent exposure in patients with reduced renal function. These data support current recommendations that there is no need to discontinue metformin before CT using radiocontrast agents in patients with mild to moderate renal failure.

WP1-17 Risk factors and patterns of progression in a surgical cohort of low grade glioma patients

Objectives

To understand the risk factors for and patterns of progression of low grade glioma (LGG).

Design

Single centre retrospective cohort study.

Subjects

Patients undergoing at least two neurosurgical procedures for LGG, the first being for diffuse LGG (WHO 2). 22 patients included (14M; 8F); mean age at time of first operation 37.7±2.7 years. 20 patients had a Performance Status (PS) 0–1 and 2 patients had a PS 2.

Methods

All patients with LGG diagnosed in between 2009–2018 were retrospectively evaluated. Variables of interest included demographics, staging, performance status, time to re-operation (TTR), extent of resection, molecular genetics (1p19q co-deletion, IDH status). Tumour volumes were estimated from MRI images by the validated ABC/2 equation. Statistical analyses were performed by Stata13.0.

Results

The tumour progressed in WHO grade in 18 patients (WHO grade 3 (n=15); WHO grade 4 (n=3). Mean time to re-operation after the first surgery was 7.0±1.2 years following gross total resection (GTR) and 3.2±0.7 years following subtotal resection (STR). Non-adjusted analysis of risk factors for time to re-operation (TTR) showed absence of 1p19q co-deletion as a risk factor (p=0.021). Adjusted analysis revealed that GTR, 1p19q mutation, PS 0 at 1 st surgery and tumour volumetric change decrease the risk for re-intervention (p<0.05). Chemo-radiotherapy was not associated with TTR.

Conclusions

In our cohort, TTR in LGG was influenced by the amount of initial resection, 1p19q deletion, PS and post-operative volumetric change.

Abstract P6-02-08: SUV max of 18F FDG-PET/CT: A predictive factor associated with pathologic complete response in luminal HER2–negative breast cancer patients (receiving neoadjuvant chemotherapy)

Purpose Neoadjuvant chemotherapy (NAC) is considered to be the standard of care for locally advanced breast cancer. When pathological complete response (pCR) is obtained with NAC it is a predictor of better outcome and often used as a surrogate for survival. However, response to NAC of luminal type breast cancer is variable and mostly limited. This study investigated the predictive relevance of several clinicopathological factors, including parameters of 18F FDG-PET/CT, on the pCR to NAC in patients with luminal HER2–negative breast cancer.

Methods From 2009 to 2015, 117 hormone receptor-positive, HER2-negative breast cancer patients who were treated with NAC followed by curative surgery at the Kyungpook National University Hospital (Daegu, Korea) were retrospectively analyzed. pCR was defined as the absence of cancer cells in breast and axillary node. 18F FDG-PET/CT maximum standardized uptake value (SUV max) was measured at baseline. Patients received from 6 to 8 cycles of anthracycline-based and taxane-based NAC.

Results The median age of the patients was 48 years (range-29-68 years). 104 patients (88.9%) were PR-positive, and forty-nine (41.9%) patients showed high ki-67 expression at initial diagnosis. After NAC, nine patients (7.7%) achieved pCR and patients who had high initial SUV max (≥ 9.09) achieved improved pCR rate compared to low initial SUV max (&lt; 9.09) patients (77.8 % vs. 22.2%).

Conclusion In luminal HER2-negative breast cancer, 18F FDG-PET/CT SUV max was useful for predicting pathologic complete response after NAC

Table 1Characteristics of study populationMedian, range48 (29-68)Initial clinical T stage 1 2 3 48 (6.8) 83 (70.9) 19 (16.2) 7 (6.0)Initial clinical N stage 0 1 2 310 (8.5) 49 (41.9) 47 (40.2) 11 (9.4)Initial ER expression Negative (0-2) Weak (3-5) Strong (6-8)8 (6.8) 14 (12) 95 (81.2)Initial PR expression Negative (0-2) Weak (3-5) Strong (6-8)13 (11.1) 20 (17.1) 84 (71.8)Initial Ki-67 expression &lt;14% ≥14% Not assessed55 (47) 49 (41.9) 13 (11.1)Pathologic T stage 0 I II III16 (13.7) 50 (42.7) 42 (35.9) 9 (7.7)Pathologic Stage (AJCC) pCR 1A 1B 2A 2B 3A 3C9 (7.7) 23 (19.7) 7 (6.0) 27 (23.1) 21 (17.9) 23 (19.7) 7 (6.0)Histologic grade 1 2 322 (18.8) 61 (52.1) 14 (12)Nuclear Grade 1 2 316 (13.7) 9 (7.7) 50 942.7)Pathologic complete response Yes9 (7.7)Recurrence18 (15.4)Death10 (8.5)table 2Association between pathologic complete response and clinicopathologic featuresFactorsPathologic CR NoPathologic CR YesP- valueAll patients108 (92.3)9 (7.7) Age &lt;40 40-55 56-7016 (18.2) 54(61.4) 18 (20.5)2 (22.2) 6 (66.7) 1 (11.1)0.789Initial clinical T stage 1 2 3 48 (7.4) 76 (70.4) 7 (6.5) 17 (15.7)0 (0) 7 (77.8) 2 (22.2) 0 (0)0.676Initial ER expression Negative (0-2) Weak (3-5) Strong (6-8)7 (6.5) 12 (11.1) 89 (8.4)1 (11.1) 2 (22.2) 6 (66.7)0.504Initial PR expression Negative (0-2) Weak (3-5) Strong (6-8)11 (10.2) 20 (18.5) 77 (71.3)2 (22.2) 0 (0) 7 (77.8)0.247Initial Ki-67 expression &lt;14% ≥14%52 (54.7) 43 (45.3)3 (33.3) 6 (66.7)0.301SUV max (tumor) &lt; 9.09 ≥ 9.0972 (66.7) 36 (33.3)2 (22.2) 7 (77.8)0.012SUV max (axilla) &lt; 6.08 ≥ 6.0858 (67.4) 28 (32.6)3 (42.9) 4 (57.1)0.228

Citation Format: Lee IH, Lee SJ, Lee J, Lee RK, Jung J, Park H, Lee S-w, Chae YS. SUV max of 18F FDG-PET/CT: A predictive factor associated with pathologic complete response in luminal HER2–negative breast cancer patients (receiving neoadjuvant chemotherapy) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-02-08.