Saliva is the Key Element for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Mass Screening.

Since December 2019, the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a global pandemic. At present, confirmed patients are the main source of infection, while a number of studies have indicated that asymptomatic carriers also have the ability to spread the virus. As of September 29, 2020, as the first country to report coronavirus disease 2019 (COVID-19), China has 375 asymptomatic infections according to the National Health Commission of China. Asymptomatic carriers have become the current focus of global epidemic prevention and control efforts. The present review article provides a brief introduction on the clinical characteristics and infectivity of asymptomatic carriers, and makes suggestions for the identification of asymptomatic carriers.

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Clinical characteristics and infectivity of asymptomatic carriers of SARS‑CoV‑2 (Review)

In this study, we re-assessed the criteria defined by the radiological society of North America (RSNA) to determine novel radiological findings helping the physicians differentiating COVID-19 from pulmonary contusion.All trauma patients with blunt chest wall trauma and subsequent pulmonary contusion, COVID-19-related signs and symptoms before the trauma were enrolled in this retrospective study from February to May 2020. Included patients (Group P) were then classified into two groups based on polymerase chain reaction tests (Group Pa for positive patients and Pb for negative ones). Moreover, 44 patients from the pre-pandemic period (Group PP) were enrolled. They were matched to Group P regarding age, sex, and trauma-related scores. Two radiologists blindly reviewed the CT images of all enrolled patients according to criteria defined by the RSNA criteria. The radiological findings were compared between Group P and Group PP; statistically significant ones were re-evaluated between Group Pa and Group Pb thereafter. Finally, the sensitivity and specificity of each significant findings were calculated. The Chi-square test was used to compare the radiological findings between Group P and Group PP.In the Group PP, 73.7% of all ground-glass opacities (GGOs) and 80% of all multiple bilateral GGOs were detected (p < 0.001 and p = 0.25, respectively). Single bilateral GGOs were only seen among the Group PP. The Chi-square tests showed that the prevalence of diffused GGOs, multiple unilateral GGOs, multiple consolidations, and multiple bilateral consolidations were significantly higher in the Group P (p = 0.001, 0.01, 0.003, and 0.003, respectively). However, GGOs with irregular borders and single consolidations were more significant among the Group PP (p = 0.01 and 0.003, respectively). Of note, reticular distortions and subpleural spares were exclusively detected in the Group PP.We concluded that the criteria set by RSNA for the diagnosis of COVID-19 are not appropriate in trauma patients. The clinical signs and symptoms are not always useful either. The presence of multiple unilateral GGOs, diffused GGOs, and multiple bilateral consolidations favor COVID-19 with 88%, 97.62%, and 77.7% diagnostic accuracy. 

https://doi.org/10.1016/j.cjtee.2022.01.004

Comparison of chest CT scan findings between COVID-19 and pulmonary contusion in trauma patients based on RSNA criteria: Established novel criteria for trauma victims

Factors associated with SARS-CoV-2 infection amongst healthcare workers in a COVID-19 designated hospital.

The coronavirus disease 2019 (COVID-19) pandemic has caused and is still causing tremendous morbidity, mortality, and damage to our societies. The disease course of COVID-19 can be unpredictable ranging from asymptomatic infections to multi-organ failure and death. Transmission of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) from an asymptomatic infected individual to others has been observed early in the pandemic. Asymptomatic individuals have been shown to have quantitative SARS-CoV-2 viral loads, there may or may not be radiological and/or laboratory abnormalities. No antiviral therapy has been approved for the treatment of asymptomatic SARS-CoV2- infection. The management of asymptomatic individuals at home requires that the person can be monitored for any signs and symptoms of deterioration and that the requirements for infection prevention and control measures can be fulfilled. It is crucial to properly diagnose and manage asymptomatic COVID-19 cases with effective testing, contact tracing, quarantine, and isolation strategies. Preventing asymptomatic SARS-CoV-2 infections that have a major role in the unhindered transmission of the virus is a milestone to take control of the pandemic. Vaccination has been proven to be the crucial pillar for preventing asymptomatic infections and real-life data will continue to exhibit the effects of community vaccination in breaking the transmission chain of SARS-CoV-2 infections.

Characteristics and management of asymptomatic SARS-CoV-2 infections.

Superspreaders are critical infectious resources in multiple infectious diseases. They can be asymptomatic or present mild symptoms but can transmit pathogens to susceptible populations, leading to severe symptoms, and even death. Early identification of this population is extremely important to inhibit the spread of infectious diseases. Right now, the whole global world is suffering from a devastating infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In this article, a superspreader cluster event in coronavirus disease 2019 (COVID-19) was identified by tracking contacting histories of infected patients. This cluster was found to be originated from an asymptomatic SARS-CoV-2 carrier, which resulted in 13 secondary cases getting infected. All the secondary patients presented with non-typical symptoms of COVID-19, such as fever, dry cough, and myalgia, one of which died of respiratory failure at the end. From this cluster, we learn that people with older ages, low immunity, multiple underlying diseases, especially pulmonary diseases, can contribute to a poor prognosis. Thus, asymptomatic superspreaders of COVID-19 can be extremely dangerous and must be handled time-efficiently.

Unclear but present danger: An asymptomatic SARS-CoV-2 carrier.

The prevalence and transmission of mobile colistin resistance (mcr) genes have led to a severe threat to humans and animals. Escherichia fergusonii is an emerging pathogen which is closely related to a variety of diseases. However, the report of mcr genes harboring E. fergusonii is still rare. One study in Brazil reported the E. fergusonii isolates with IncHI2-type plasmids harboring mcr-1. A Chinese study reported two strains carrying mcr-1 gene with the same plasmid type IncI2. Here, we identified two strains of E. fergusonii carrying mcr-1 gene from farm environments with IncX4-type and IncI2-type plasmids, respectively. To our best knowledge, this is the first report about mcr-1 gene located on IncX4-type plasmid in E. fergusonii. We investigate the resistance mechanism of colistin-resistant Escherichia fergusonii strains 6S41-1 and 5ZF15-2-1 and elucidate the genetic context of plasmids carrying mcr-1 genes. In addition, we also investigated chromosomal mutations mediated colistin resistance in these two strains. Species identification was performed using MALDI-TOF MS and 16S rRNA gene sequencing. The detection of mcr-1 gene was determined by PCR and Sanger sequencing. S1-pulsed-field gel electrophoresis (PFGE), Southern blotting, antimicrobial susceptibility testing, conjugation experiments, complete genome sequencing, and core genome analysis were conducted to investigate the characteristics of isolates harboring mcr-1. The mcr-1 genes on two strains were both plasmids encoded and the typical IS26-parA-mcr-1-pap2 cassette was identified in p6S41-1 while a nikA-nikB-mcr-1 locus sites on the conjugative plasmid p5ZF15-2-1. In addition, Core genome analysis reveals that E. fergusonii 6S41-1 and 5ZF15-2-1 have close genetic relationships. The mcr-1 gene is located on conjugative IncI2-type plasmid p5ZF15-2-1, which provides support for its further transmission. In addition, there’s the possibility of mcr-1 spreading to humans through farm environments and thereby threatening public health. Therefore, continuous monitoring and investigations of mcr-1 among Enterobacteriaceae in farm environments are necessary to control the spread.

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Genomic Characterization of Two Escherichia fergusonii Isolates Harboring mcr-1 Gene From Farm Environment

Mobile colistin resistance (mcr) genes represent an emerging threat to public health. Reports on the prevalence, antimicrobial profiles, and clonality of MCR-9-producing Enterobacter cloacae complex (ECC) isolates on a national scale in China are limited. We screened 3,373 samples from humans, animals, and the environment and identified eleven MCR-9-positive ECC isolates. We further investigated their susceptibility, epidemiology, plasmid profiles, genetic features, and virulence potential. Ten strains were isolated from severe bloodstream infection cases, especially three of them were recovered from neonatal sepsis. Enterobacter hormaechei was the most predominant species among the MCR-9-producing ECC population. Moreover, the co-existence of MCR-9, CTX-M, and SHV-12 encoding genes in MCR-9-positive isolates was globally observed. Notably, mcr-9 was mainly carried by IncHI2 plasmids, and we found a novel ~187 kb IncFII plasmid harboring mcr-9, with low similarity with known plasmids. In summary, our study presented genomic insights into genetic characteristics of MCR-9-producing ECC isolates retrieved from human, animal, and environment samples with one health perspective. This study is the first to reveal NDM-1- and MCR-9-co-producing ECC from neonatal sepsis in China. Our data highlights the risk for the hidden spread of the mcr-9 colistin resistance gene.

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Emergence of Neonatal Sepsis Caused by MCR-9- and NDM-1-Co-Producing Enterobacter hormaechei in China

Purpose The frequent and inappropriate use of antibiotics has caused a dramatic rise in the number, species, and degree of multi-drug resistant bacteria, making them more prevalent and difficult to treat. In this context, the aim of the present study was to characterize the OXA-484-producing strains isolated from a perianal swab of a patient by using whole-genome analysis. Patients and Methods In this study, carbapenemase-producing Klebsiella variicola was identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), average nucleotide identity (ANI) and PCR. S1 nuclease pulsed-field gel electrophoresis (S1-PFGE) and Southern blotting were utilized to characterize the plasmid profiles of K. variicola 4717. In particular, WGS was performed to obtain genomic information on this clinical isolate, and assemble all the plasmids of the blaOXA-484-harboring strain. Results The antimicrobial susceptibility pattern of K. variicola 4717 revealed that it was resistant to a range of antibiotics, including aztreonam, imipenem, meropenem, ceftriaxone, cefotaxime, ceftazidime, levofloxacin, ciprofloxacin, piperacillin-tazobactam, methylene-sulfamer oxazole, amoxicillin-clavulanic acid, cefepime, and tigecycline. Its susceptibility to chloromycin was intermediate, while it was still susceptible to amikacin, gentamicin, fosfomycin, and polymyxin B. The presence of two companion plasmids, p4717_1 and p4717_2, together with a plasmid carrying the blaOXA-484 gene was observed. An in-depth investigation of p4717-OXA-484 uncovered that it is an IncX3-type plasmid and shares a similar segment encoded by IS26. Given the similar genetic background, it was conceivable that blaOXA-484 could have developed from blaOXA-181 through a series of mutations. Conclusion Herein, we described the first genome sequence of K. variicola strain harbouring the class D β-actamase blaOXA-484 in an Inc-X3-type plasmid. Our work also uncovered the genetic characterization of K. variicola 4717 and the importance of initiating antimicrobial detection promptly.

https://www.dovepress.com/getfile.php?fileID=88471

Emergence of OXA-484-Producing Klebsiella variicola in China

Abstract Background Despite the global prevalence of Klebsiella pneumoniae Carbapenemase (KPC)-type class A β-lactamases, occurrences of KPC-3-producing isolates in China remain infrequent. This study aims to explore the emergence, antibiotic resistance profiles, and plasmid characteristics of bla KPC-3 -carrying Pseudomonas aeruginosa . Methods Species identification was performed by MALDI-TOF-MS, and antimicrobial resistance genes (ARGs) were identified by polymerase chain reaction (PCR). The characteristics of the target strain were detected by whole-genome sequencing (WGS) and antimicrobial susceptibility testing (AST). Plasmids were analyzed by S1-nuclease pulsed-field gel electrophoresis(S1-PFGE), Southern blotting and transconjugation experiment. Results Five P. aeruginosa strains carrying bla KPC-3 were isolated from two Chinese patients without a history of travelling to endemic areas. All strains belonged to the novel sequence type ST1076. The bla KPC-3 was carried on a 395-kb IncP-2 megaplasmid with a conserved structure (IS 6100 -IS Kpn27 - bla KPC-3 -IS Kpn6 - korC - klcA ), and this genetic sequence was identical to many plasmid-encoded KPC of Pseudomonas species. By further analyzing the genetic context, it was supposed that the original of bla KPC-3 in our work was a series of mutation of bla KPC-2 . Conclusions The emergence of a multidrug resistance IncP-2 megaplasmid and clonal transmission of bla KPC-3 -producing P. aeruginosa in China underlined the crucial need for continuous monitoring of bla KPC-3 for prevention and control of its further dissemination in China. 

Ruishan Liu

Papers

Unclear but present danger: An asymptomatic SARS-CoV-2 carrier.

Genomic Characterization of Two Escherichia fergusonii Isolates Harboring mcr-1 Gene From Farm Environment

Emergence of Neonatal Sepsis Caused by MCR-9- and NDM-1-Co-Producing Enterobacter hormaechei in China

Emergence of OXA-484-Producing Klebsiella variicola in China

Emergence and clonal dissemination of KPC-3-producing Pseudomonas aeruginosa in China with an IncP-2 megaplasmid