COVID-19 clinical and laboratory diagnosis overview

Background

COVID-19 was identified in Wuhan, China, in December 2019, and rapidly spread worldwide, being declared global pandemic on the 11th of March 2020. Since its emergence, COVID-19 has raised global concerns associated with drastic measures that were never adopted in any previous outbreak, to contain the situation as early as possible.

Main body

The 2019 novel corona virus (2019-nCoV) or SARS-CoV-2 is the causative agent of COVID-19. 2019-nCoV genetic sequence was rapidly identified within few days since the first reported cases and RT-PCR kits became available for COVID-19 diagnosis. However, RT-PCR diagnosis carries a risk of false-negative results; therefore, additional serologic tests are needed. In this review, we summarize the clinical scenario that raises suspicion of COVID-19 and available laboratory diagnostics.

Conclusion

The most important approach in the battle against COVID-19 is rapid diagnosis of suspicious cases, timely therapeutic intervention and isolation to avoid community spread. Diagnosis depends mainly on PCR testing and serological tests. However, even in the context of negative lab test results and clinical suspicion of COVID-19 infection, clinical decision should be based on clinical suspicion.

Communications with lab and POCT users

POCT (Point of Care Test) or (Point of Care Testing) has been widely used, as it can provide quick results to be acted upon immediately by the clinician. However, POCT devices do not always have the same accuracy and precision as Lab equipment. Laboratorians need to be much better at communicating what is being done in the “lab” and how that relates to what the clinicians are doing with the results of the tests they order.

Multiple electrolyte imbalances and mixed acid-base disorder posing a diagnostic dilemma: a case report

Background

In clinical practice, both the history and laboratory testing are paramount to making an accurate diagnosis. Situations in which laboratory findings and patient history are not congruent pose a diagnostic dilemma. We report a case of a young woman presenting with a myriad of electrolyte and acid-base disorders. Difficulty in reaching a unifying diagnosis persisted due to discordant patient history. We believe this case shows that lab findings will clearly portray the problems a patient has and should be given more credence in a case where the history is discordant with lab findings.

Case presentation

A 28-year-old Hispanic American woman presented to the emergency room of our institution with a complaint of painless and sudden onset of stiffness in her upper and lower limbs. Associated weakness worse in the distal limbs was also reported. She experienced shortness of breath with minimal exertion, diaphoresis, and anxiety. Her vital signs revealed tachycardia without corresponding fever. She was conscious, oriented, and alert. Her physical exam revealed dry mucous membranes and warm extremities. She denied recent consumption of a large carbohydrate meal, diarrhea, vomiting, use of laxatives, and use of alcohol or recreational drugs. She vaguely described two previous similar episodes in the last 7 months that spontaneously resolved. Her medical history was significant only for hypothyroidism treated with daily levothyroxine tablets. Laboratory analysis revealed the following abnormalities: an elevated anion gap with significant lactate, hypokalemia, hypomagnesemia, elevated mean corpuscular volume, elevated mean cell hemoglobin, and elevated liver enzymes with aspartate aminotransferase/alanine aminotransferase ratio > 2. She was hydrated with balanced crystalloids, and her electrolyte deficiencies corrected. The etiology of her multiple electrolyte abnormalities was unclear because alcohol use was vehemently denied. Extensive evaluation for causes of electrolyte disorder was undertaken, which was unrevealing. On further interrogation, she admitted to recent alcohol intoxication and several episodes of vomiting before presentation. She was advised to refrain from alcohol use and discharged afterward.

Conclusion

Both patient history and laboratory analysis have a role in identifying and confirming a diagnosis. In cases in which laboratory tests are incongruous with reported history, making a unifying diagnosis can be challenging or delayed. The importance of taking a comprehensive history cannot be overemphasized, but history provided by patients may be prone to intentional or unintentional distortion, whereas laboratory findings are more objective. The case presented underscores why the lab findings should be given credence in cases in which there is discordance between lab results and the provided patient history.

The indoor-outdoor characteristics of water-soluble ion in PM2.5 in Tianjin wintertime

The indoor and outdoor PM_2.5 mass concentration, water-soluble ion by filter sampler was analyzed on December 3-21, 2015 during wintertime in Tianjin, China. The results indicate that high humidity conditions result in the accumulation of atmospheric pollutants and reduce atmosphere visibility. The I/O ratio for PM_2.5 concentration in dormitory and lab are less than 1 in haze days. Indoor PM_2.5 concentration increases rapidly with outdoor PM_2.5 concentration increasing in haze days. The filtration factors of the dormitory and lab indicate nearly half of the outdoor PM_2.5 enters indoor environment. The human activities in dormitory could cause more the formation of PM_2.5 than those in lab. The concentration of SO₄^2- is the highest ion in water-soluble ion for outdoor PM_2.5. The SO₄^2-, NO₃^-, NH₄⁺, and Cl^- are generated mainly by outdoor sources; however, the Na⁺, Ca²⁺, and Mg²⁺ are generated mainly by indoor sources. The NH₄NO₃, (NH₄)₂SO₄, and NH₄Cl accounts for 20.2~41.8%, 32.0~51.4%, and 6.4~10.6% of the total water-soluble ion in different indoor-outdoor environment. The total secondary aerosols including NH₄NO₃, (NH₄)₂SO₄, and NH₄Cl in PM_2.5 are 28.3, 42.1, 28.2, 31.0, and 33.9% in outdoor environment for haze days, outdoor environment for non-haze days, dormitory for haze days, dormitory for non-haze days, and lab for haze days, respectively.

Comparison of electronic versus paper rubrics to assess patient counseling experiences in a skills-based lab course

BACKGROUND AND PURPOSE

To evaluate an electronic counseling rubric to facilitate timely student feedback and explore differences in student performance, student anxiety, and self-perceived preparedness in a high stakes practical exam when using a paper rubric versus an electronic rubric.

EDUCATIONAL ACTIVITY AND SETTING

Two cohorts of students in the third professional year were evaluated using the same rubric criteria: cohort 1 (n = 97) used traditional paper rubrics and cohort 2 (n = 104) used electronic rubrics. Cohorts were surveyed to measure anxiety and perceived preparedness in patient counseling skills one week prior to a practical exam, and cohort responses were compared. Student practical exam performance was also compared between the two cohorts.

FINDINGS

Results showed no significant relationship between electronic rubric use and student anxiety (p = 0.07) or student exam performance [average score 53.42 points (SD 3.65) and 53.93 points (SD 3.78) in Cohort 1 and Cohort 2, respectively]. Perceived exam preparedness was higher among students using electronic rubrics, with timing of feedback being the mediating process in increasing preparedness (p < 0.01).

DISCUSSION AND SUMMARY

Electronic rubrics resulted in more timely feedback on patient counseling skills, and students felt more prepared for their practical exam. This did not result in a significant difference in practical exam performance between the two cohorts. Additional methods to incorporate electronic rubrics into the course will be explored.

Inhibition of Salmonella by thyme essential oil and its effect on microbiological and sensory properties of minced pork meat packaged under vacuum and modified atmosphere

The antibacterial activity of thyme essential oil (TEO) was evaluated against four serovars of Salmonella (S. Enteritidis, S. Typhimurium, S. Montevideo and S. Infantis), experimentally inoculated (10⁶CFU/g) in minced pork, which was treated with different concentrations of the TEO (0.3%, 0.6% and 0.9%) packaged under vacuum or MAP (30%O₂/50%CO₂/20% N₂) and stored at 3±1°C for 15days. GC-MS analysis of the TEO was performed in order to determine composition, and the predominant constituent was thymol (50.48%), followed by p-cymene and linalool. The minimum inhibitory concentration was determined for each Salmonella serovar studied. Among the tested active compounds, thymol and carvacrol exhibited the greatest inhibitory effect followed by TEO, with minimum inhibitory concentrations of 320 to 640μg/ml. S. Enteritidis was the most sensitive serovar. During the storage period, Salmonella counts in pork were reduced by 1.69-4.05logCFU/g. The influence of TEO on Enterobacteriaceae, lactic acid bacteria and total viable count was determined in control mince with no added Salmonella. The most pronounced antibacterial effect was achieved by the combination MAP and 0.9% TEO. Although the antibacterial activities of all studied concentrations of TEO in pork were evident and significant (P<0.05), sensory analysis showed that 0.3% TEO was the most acceptable to trained panellists.