Diagnostic Indexes of a Rapid IgG/IgM Combined Antibody Test for SARS-CoV-2

[Abstract]O_ST_ABSObjectiveC_ST_ABSCoronavirus disease 2019 (COVID-19) has become pandemic in the world. The need for IgG-IgM combined antibody test is booming, but data on diagnostic indexes evaluation was inadequate. The aim of this study was to evaluate diagnostic indexes of a rapid IgG-IgM combined antibody test for SARS-CoV-2. MethodsA total of 179 patients were enrolled. Serum were collected for IgG-IgM combined antibody test and corresponding nasal and pharyngeal swab specimens were collected for SARS-CoV-2 RT-PCR. According to SARS-CoV-2 RT-PCR results, patients under study were categorized as PCR positive group in 90 patients and PCR negative group in 89 patients. Results1. Of the 90 PCR positive samples, 77 were tested positive by SARS-CoV-2 IgG-IgM test kit, yielding a sensitivity of 85.6%. Meanwhile, of the 89 PCR negative sample, 8 samples were detected positive, resulting in a specificity of 91%. Positive predictive value, negative predictive value and accuracy of this test kit was 95.1%, 82.7%, and 88.3%, respectively. Kappa efficiency between IgG/IgM test kit and RT-PCR were 0.75. 2. Accuracy in mild/common and severe/critical subgroup were 73.9% and 97.7%, respectively. Accuracy in clinical confirmed, suspected cases and other disease subgroups were 70%, 60%, and 100%, respectively. 3. Patients were further divided into 0 - 7, 8 - 15 and >= 16 groups according to the time from illness onset to sample collection. Sensitivity, specificity and accuracy in these three groups were 18.8%, 77.8% and 40%; 100%, 50% and 87.5%; 100%, 64.3%, and 93.9, respectively. ConclusionThe sensitivity and specificity of this ease-of-use IgG/IgM combined test kit were adequate, plus short turnaround time, no specific requirements for additional equipment or skilled technicians, all of these collectively contributed to its competence for mass testing. At the current stage, it cannot take the place of SARA-CoV-2 nucleic acid RT-PCR, but can be served as a complementary option for RT-PCR. The combination of RT-PCR and IgG-IgM combined test kit could provide further insight into SARS-CoV-2 infection diagnosis.

Detectable serum SARS-CoV-2 viral load (RNAaemia) is closely associated with drastically elevated interleukin 6 (IL-6) level in critically ill COVID-19 patients

BackgroundAlthough the SARS-CoV-2 viral load detection of respiratory specimen has been widely used for novel coronavirus disease (COVID-19) diagnosis, it is undeniable that serum SARS-CoV-2 nucleic acid (RNAaemia) could be detected in a fraction of the COVID-19 patients. However, it is not clear that if the incidence of RNAaemia could be correlated with the occurrence of cytokine storm or with the specific class of patients. MethodsThis study enrolled 48 patients with COVID-19 admitted to the General Hospital of Central Theater Command, PLA, a designated hospital in Wuhan, China. The patients were divided into three groups according to the Diagnosis and Treatment of New Coronavirus Pneumonia (version 6) published by the National Health Commission of China. The clinical and laboratory data were collected. The serum viral load detection and serum IL-6 levels were determined. Except for routine statistical analysis, Generalized Linear Models (GLMs) analysis was used to establish a patient status prediction model based on real-time RT-PCR Ct value. FindingsThe Result showed that cases with RNAaemia were exclusively confirmed in critically ill patients group and appeared to reflect the illness severity. Further more, the inflammatory cytokine IL-6 levels were significantly elevated in critically ill patients, which is almost 10-folds higher than those in other patients. More importantly, the extremely high IL-6 level was closely correlated with the incidence of RNAaemia (R=0.902) and the vital signs of COVID-19 patients (R= -0.682). InterpretationSerum SARS-CoV-2 viral load (RNAaemia) is strongly associated with cytokine storm and can be used to predict the poor prognosis of COVID-19 patients. Moreover, our results strongly suggest that cytokine IL-6 should be considered as a therapeutic target in critically ill patients with excessive inflammatory response.

Lymphopenia predicts disease severity of COVID-19: a descriptive and predictive study

BackgroundCoronavirus disease-2019 (COVID-19) is a rapidly escalating epidemic caused by SARS-CoV-2. Identification of a simple and effective indicator to assess disease severity and prognosis is urgently needed. MethodsDynamic changes of blood lymphocyte percentage (LYM%) in 15 death cases, 15 severe cases as well as 40 moderate cases of COVID-19 patients were retrospectively analyzed. A Time-LYM% model (TLM) was established according to the descriptive studies and was validated in 92 hospitalized cases. ResultsResults from death and severe cases showed that LYM% in blood tests were inversely associated with the severity and prognosis of COVID-19. LYM% in moderate type of patients with COVID-19 remained higher than 20% 10-12 days after symptom onset. In contrast, LYM% was lower than 20% in severe cases. However, LYM% in severe cases was higher than 5% 17-19 days after the onset of the disease, while it fell below 5% in death cases. Accordingly, we established a Time-LYM% model (TLM), which was validated as an independent criterion of disease classification in another 92 hospitalized patients with COVID-19. ConclusionLymphopenia can be used as an indicator of disease severity and prognosis of COVID-19 patients. TLM is worth of application in the clinical practice.

Distribution and change of antimicrobial resistance of common pathogenic bacteria from geriatric ward / 中国感染控制杂志

Objective To analyze the distribution and change of antimicrobial resistance of common pathogenic bacteria from geriatric ward,and provide reference for rational use of antimicrobial agents.Methods Specimens from hospitalized patients in a geriatric ward from 2009 to 2013 were analyzed,the isolated pathogenic bacteria and antimicrobial resistance of bacteria were analyzed statistically.Results From 2009 to 2013,a total of 7 426 patho-genic bacteria were isolated,the percentage of gram-negative bacilli,gram-positive cocci,and fungi were 90.96%(n=6 755),7.23%(n =537),and 1 .81 % (n = 134),respectively.The top 5 detected bacteria were Pseudomonas aeruginosa (39.16%),Escherichia coli (16.47%),Stenotrophomonas maltophilia (10.65%),Klebsiella pneu-moniae (7.22%),and Acinetobacter baumannii (6.21 %),these strains were mainly isolated from sputum (94.15%,n =5 573 ).Resistance rates of Acinetobacter baumannii to all detected antimicrobial agents,Pseudo-monas aeruginosa to 8 kinds of common antimicrobial agents (piperacillin / tazobactam,ceftazidime,aztreonam, imipenem,et al),Escherichia coli to 5 kinds of common antimicrobial agents (piperacillin/ tazobactam,cefopera-zone/sulbactam,aztreonam,levofloxacin,and ciprofloxacin),and Stenotrophomonas maltophilia to ceftazidime and levofloxacin all showed an increased tendency (all P 0.05).Conclusion The major pathogenic bacteria isolated from geriatric ward is Pseudomonas aeruginosa ,which is highly resistant to multiple antimicrobial agents, antimicrobial agents should be chosen based on antimicrobial susceptibility testing results.

Constitute and antifungal susceptibility of Candida spp . causing blood-stream infection / 中国感染控制杂志

Objective To analyze the constitute and antifungal susceptibility of Candida spp . causing bloodstream infection in a hospital,so as to provide evidence for the prevention and treatment of bloodstream infection caused by Candida spp .Methods Candida spp . isolated from blood specimens of clinical patients in a hospital between 2009 and 2013 were analyzed retrospectively,the high risk factors for Candida bloodstream infection were analyzed. Results A total of 42 isolates of Candida spp . were isolated from blood specimens of 42 patients between 2009 and 2013,the major was Candida parapsilosis (C.parapsilosis ,n =20,47.62%),followed by C.albicans (n =16, 38.10%),C.tropicalis (n=4,9.52%),and C.glabrata(n=2,4.76%).Candida spp .were mainly distributed in emergency intensive care unit(n=11),departments of urologic surgery (n=9)and cardiothoracic surgery(n=8). The venous catheters of 37 patients(88.10%)were isolated the same Candida spp . as blood culture,the average time from indwelling venous catheters to positive culture of blood and catheters were 31 .47 and 33.18 days respec-tively;the percentage of positive culture for blood and catheters both increased with the prolongation of catheteriza-tion (both P < 0.001 ).Susceptibility rates of Candida spp . to fluconazole and voriconazole were 75.00% -100.00%,to amphotericin B were all 100.00%,to itraconazole varied significantly with different species (0 -87.50%).Conclusion The major Candida strains causing bloodstream infection in this hospital is C.parapsilosis , and is related to the use of intravenous catheters,susceptibility rates to fluconazole,amphotericin B,and voricon-azole are all high.

Comparison of Two Kinds of Automated Microbial Identification System Used in the Identification of Brucella / 现代检验医学杂志

Objective To compare Vitek2 Compact and Walkaway 40 in the identification of Brucella.Methods Used Vitek2 Compact and Walkaway 40 automated microbial identification system to identify clinical isolates and compared with the de-tection of 16S rRNA gene sequences analysis.Results The clinical isolates was identified as Bergeyella zoohelcum or Moraxella by Walkaway 40 and as Brucella melitensis by Vitek2 Compact.16S RNA sequence analysis of the isolate,the se-quence was identical to the sequences of 16S rRNA of Brucella,which excluded the possibility of B.zoohelam and Moraxel-la .Determined that the isolate was B.melitensis.Conclusion Vitek 2 Compact can accurately identified Brucella.Use molec-ular methods to corroborate when the isolates was identified as Brucella by Vitek 2 Compact,this method can greatly im-prove the detection rate of brucellosis and reduce the possibility of misdiagnosis.Walkaway 40 cannot accurately identified Brucella,Misidentification of Brucella can result in wrong treatment of the patient and let the staff in the risk of laboratory-acquired infection.Recommend laboratory should be cautious reporting in the identified B.zoohelam or Moraxella by Walk-away 40 and use Vitek2 Compact or molecular methods for review.