Virus sampling tubes are used for the collection and transport of viral specimens such as novel coronaviruses, influenza viruses, avian influenza (e.g. H7N9), hand, foot and mouth viruses, measles, and specimens of mycoplasma, ureaplasma, and chlamydia.
Storage and transport of viruses and related samples under refrigeration (2~8℃) within 48 hours. Prolonged storage of viruses and related samples in -80℃ environment or liquid nitrogen environment.
Virus sampling tube virus preservation solution mainly consists of: Hank's liquid base, gentamicin, fungal antibiotics, biological buffers and amino acids. It can maintain the virus activity in a wide temperature range, reduce the rate of virus decomposition and enhance the positive rate of virus isolation.
Does a clinician have the problem of a patient with a high suspicion of novel coronavirus pneumonia, but two swab tests are negative for nucleic acid? Or is it a true negative when two swabs are negative, but multiple contacts are diagnosed? Or is it a false negative? How to collect specimens to improve the accuracy of nucleic acid?
Many experts from the practical work of the experience that the nasopharyngeal swab specimens 2019-nCOV nucleic acid detection positive rate than the oropharyngeal swab, the lower respiratory tract collected sputum, alveolar lavage fluid specimens positive rate than the upper respiratory tract of the oral and nasopharyngeal swabs collected specimens (this is also a two-day widely commented on a patient pharyngeal swab specimens three times negative nucleic acid test, admitted to the hospital after the resuscitation process collected alveolar lavage fluid specimens positive nucleic acid (This is also the reason why a patient's pharyngeal swab specimen was negative for nucleic acid three times and the alveolar lavage fluid specimen was positive for nucleic acid during resuscitation after admission to hospital), but sputum and alveolar lavage fluid specimens from the lower respiratory tract are difficult to collect and prone to cause patient ejection resulting in increased risk of infection for the collection operator, so it is generally not recommended (tracheotomy, upper respiratory and machine resuscitation patients are available).
The recently released fifth edition of the "Pneumonia Treatment Protocol for Novel Coronavirus Infection" has updated the specimen collection from "pharyngeal swab" to "nasopharyngeal swab". In order to increase the rate of positive tests, it is recommended to collect multiple specimens from the same patient and combine them for testing. For example, the specimen should be collected from the oropharyngeal swab and the nasopharyngeal swab at the same time, and then sent to the same collection tube. For suspected patients with symptoms of digestive disease, stool or anal swabs should be collected for testing at the same time.
Recently, the main specimen used for nucleic acid testing is the oropharyngeal swab, and the patient is allowed to open his mouth wide and then use the special swab to scrape his pharynx to collect the viral specimens. The result is a negative test result.
We all know that novel coronaviruses are RNA viruses, which are easily degraded by exogenous or cell-destructive RNA enzymes and affect the final detection efficiency. Strictly speaking, specimens should be sent to the laboratory (CDC, hospital laboratory, third-party laboratory) promptly after collection to complete the test as soon as possible. Specimens left at room temperature for too long (a few hours, a dozen hours, more than 20 hours, or longer) may also be the cause of a false negative final test result.
The use of antiviral nucleic acid degradation specimen sampling tubes has recently been proposed, but the number of such products is currently low, the cost is high, and the effectiveness of their practical application needs further evaluation. It is recommended that specimens be sent for testing in a timely manner after collection. If for some reasons specimens cannot be sent for testing or detected in time after collection, they should be stored at 4°C. If specimens cannot be detected within a short period of time, it is recommended to store them at -70°C and avoid repeated freezing and thawing.
