Dental Hypotheses

ORIGINAL RESEARCH
Year
: 2021  |  Volume : 12  |  Issue : 2  |  Page : 87--90

Saliva as a Diagnostic Aid in COVID-19: A Boon for Dentistry


Prashant Shetty1, Barkha Udhani1, Saleem D Makandar2, Rabihah Alawi2, Tahir Yusuf Noorani2, Neetu Jha1, Pradeep A Bapna1,  
1 Department of Conservative Dentistry and Endodontics, Pacific Dental College and Hospital, Udaipur, Rajasthan, India
2 School of Dental Sciences, Universiti Sains Malaysia, Health Campus, Kubang Kerian, Kelantan, Malaysia

Correspondence Address:
Saleem D Makandar
School of Dental Sciences, Universiti Sains Malaysia, Health Campus, 16150 Kubang Kerian, Kelantan
Malaysia

Abstract

Introduction: Coronavirus disease 19 (COVID-19) is a highly contagious and virulent infection caused by severe acute respiratory syndrome coronavirus 2. The symptoms arise within 2 to 14 days after the infection. The specimens are collected from the upper respiratory tract through nasopharyngeal and oropharyngeal swab. This sampling requires close contact with COVID-19 patients and may directly cause transmission to health care professionals. Saliva specimens can be collected easily by asking patients to spit into a sterile container. Materials and Methods: In the current study, the selected patients (n = 20) were those who tested positive for COVID-19 and were admitted to the hospital. After getting approval from ethical committee of the hospital, both nasopharyngeal swab specimens and the salivary samples of each patient were collected and tested using standard procedure of real-time polymerase chain reaction. Results: The mean cycle threshold values obtained from both the sampling techniques were correlated. It was seen that there was no significant difference between them. The advantage of using saliva as a specimen is in the overall specimen collection procedure and its cost and time effectiveness. The diagnosis of COVID-19 through a rapid test procedure using salivary samples could be a boon to dentists. Conclusion: This would help in the detection of positive asymptomatic carriers of the virus among the patients who come to seek dental treatment and reduce the risk of infection in the dental office. The results of this study clearly show that the values obtained from the two sampling techniques are closely related, and hence saliva could definitely be considered as a diagnostic aid for COVID-19.



How to cite this article:
Shetty P, Udhani B, Makandar SD, Alawi R, Noorani TY, Jha N, Bapna PA. Saliva as a Diagnostic Aid in COVID-19: A Boon for Dentistry.Dent Hypotheses 2021;12:87-90


How to cite this URL:
Shetty P, Udhani B, Makandar SD, Alawi R, Noorani TY, Jha N, Bapna PA. Saliva as a Diagnostic Aid in COVID-19: A Boon for Dentistry. Dent Hypotheses [serial online] 2021 [cited 2021 Dec 6 ];12:87-90
Available from: http://www.dentalhypotheses.com/text.asp?2021/12/2/87/322520


Full Text



 Introduction



The coronavirus disease 19 (COVID-19) is a highly contagious and virulent infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which emerged in Wuhan, China and spread around the world. The source of origin and transfer to humans is not known; however, the rapid human to human transmission has been fatally harmful on the worldwide population.[1]

The SARS-CoV-2 is a member of the β group of coronaviruses and infects the upper respiratory tract of humans. The presentation of the illness ranges from mild to severe. SARS-CoV-2 propagates through RNA replication using RNA-dependent RNA polymerase enzyme and undergoes slow mutation, which poses a challenge for its treatment and control. The symptoms normally arise within 2 to 14 days after the infection. The common signs are sore throat, high fever, dry coughing, fatigue, muscle pain, sneezing, and other respiratory problems. Some cases may manifest as pneumonia and serious respiratory distress syndrome.[2]

The laboratory diagnosis of SARS-CoV-2 is confirmed by nucleic acid amplification tests such as real time reverse transcription-polymerase chain reaction (RT-PCR). The specimens are collected from the upper respiratory tract through nasopharyngeal and oropharyngeal swab or wash in ambulatory patients and from lower respiratory tract through sputum (if generated) and/or bronchoalveolar lavage.[3] The sampling requires close contact with COVID-19 patients and may directly cause transmission to health care professionals.[4],[5] The collection of these nasopharyngeal or oropharyngeal specimens may cause discomfort and bleeding in some patients, especially ones with bleeding disorders. Several studies have shown that saliva has a high concordance rate of over 90% with nasopharyngeal specimens in the detection of respiratory viruses.[6] Saliva specimens can be collected easily by asking patients to spit into a sterile container. This can greatly minimize the chance of exposing health care workers to COVID-19.[7]

In a dental setup, procedures involving the generation of aerosols cause the spread of virus into the surroundings. The transmission may also occur via indirect contact from contaminated surfaces. The standard infection control protocols may not be sufficient enough to prevent the spread of COVID-19, especially when patients are still in incubation period, are asymptomatic, and are unaware of their infection.[8] Saliva can prove to be a diagnostic tool for the preliminary testing of such asymptomatic cases prior to any dental procedures since its sampling is much easier and it is both time and cost-effective as compared to the standard nasopharyngeal swab sampling.[6]

The rationale for the current study would be to reduce the overall cost of the COVID-19 testing and to take salivary markers as an important venture in doing so. The aim of this study is to co-relate the RT-PCR results obtained from saliva and nasopharyngeal swab so as to see if saliva can be used as a diagnostic aid in future COVID testings. The null hypothesis for the present study is that there is a marked difference in the RT-PCR values obtained from saliva and nasopharyngeal swab sampling techniques.

 Materials and Methods



Ethical approval was obtained from the ethical committee of the hospital. Twenty patients were enrolled in the study. Quantitative test of COVID-19 RNA was done by standard procedure on real-time polymerase chain reaction (PCR). The selected patients were those who tested positive for COVID-19 and were admitted to the hospital. Nasal specimens were collected on the day of hospitalization. Nasal swab was collected using polyester flocked swabs.[9] Saliva specimens were collected by the patients themselves. Saliva was collected by asking the patient to cough out saliva from throat into a sterile container on the second day of hospitalization between 8 and 10 am in the morning to minimalize the influence of circadian rhythms on the results of salivary biochemical determinations.[10] Each collected sample was inserted into individual tubes containing 2 mL of the virus transport medium. The collected salivary specimens were immersed in ice bath to prevent degradation of biologically important salivary analytes.

Both samples were tested using standard procedure on real-time PCR. In-house one-step real-time Quantitative reverse transcription PCR (RT-qPCR) assay targeting the S gene of 2019-nCoV was performed using QuantiNova SYBR Green RT-PCR Kit (Qiagen) in a LightCycler 480 Real-Time PCR System (Roche).[11]

 Results



Interpretation of the test was carried out by calculating the cycle threshold (Ct) value, which normally ranges from 15 to 40 cycles.[12],[13],[14] Lower the Ct value, the higher is the viral load (inversely proportional relationship). According to latest centers for disease control and prevention (CDC) guidelines, Ct cutoff of more than 33 is not considered as infective as it is extremely difficult to detect any live virus in a sample above the threshold of 33 cycles. The results obtained from the two sampling techniques were compared using the paired t test.

The PCR values of each patient obtained from both the sampling techniques are given in [Table 1]. The mean Ct values obtained from both the sampling techniques and their correlation are shown in [Table 2]. It can be seen that there is no significant difference between them, thus disproving the null hypothesis.{Table 1}{Table 2}

[Figure 1] shows the close co-relation between the PCR values obtained from nasal swabs and that obtained from salivary specimen. It can be seen that the two graphs run very close to each other. The graph obtained from that of salivary samples has shown equal, slightly greater, or slightly lesser PCR values presenting a close co-relation of viral load in saliva with that of nasopharyngeal swab specimen.{Figure 1}

 Discussion



COVID-19 poses a real challenge for the dentists and the working of the dental setup, mostly because of the large number of asymptomatic cases. These apparently alright asymptomatic patients are carriers of the infection and can lead to the spread of the virus among the working dentists, the helping staff at the dental office, and other patients as well.[15]

The route of transmission as discussed is either through the direct contact transmission from cough or sneeze droplets or through indirect transmission from touching of contaminated surfaces. The dental office carries a very high risk of infection as there is risk of transmission from saliva or blood or from touching contaminated instruments or surrounding surfaces. The aerosols contaminated with the patient’s saliva or blood can spread into the air from the use of airotors, scalers, and so on.[16] The virus deposited on the surrounding surfaces from the contaminated aerosols can persist for about 9 days.[17]

The cost of COVID-19 testing in India ranges from about 2000 to 4500 Indian rupees. The testing of every patient is not cost-effective and not feasible because of the large population density of the country. The same cannot be practiced in the dental office with every patient. This is where saliva as a diagnostic tool can come in handy to dentists.

The authors agree that diagnostic gold standard for COVID-19 is through nasopharyngeal swab sampling. However, saliva matches to about 90% of the nasopharygeal specimens in terms of microbial and viral content.[6] Moreover, the advantage of using saliva as a specimen lies in the overall specimen collection procedure and the cost and time effectiveness of the same.[7] The diagnosis of COVID-19 through a rapid test procedure using salivary samples could be a boon to dentists. To gain more evidence for the same, the results obtained from both nasal and salivary samples were compared in this study.

The present study co-related the Ct values obtained from specimens of nasal swab and salivary sample of each patient.[18] It was found that there was no significant difference in the mean Ct­ values of the two sampling techniques used [Table 2]. This further strengthens the plea of considering saliva as a major diagnostic aid for COVID-19.

The current study was performed on a very small sample size of only 20 patients, and hence the results obtained in the study cannot be considered an absolute proof. Nevertheless, it is a potential area of further study considering the need of the hour for newer research in COVID-19 diagnosis.[19]

This study creates a spark for future prospects in the research of biomarkers present in the saliva in the diagnosis of various conditions related to periodontitis and cardiovascular diseases. These salivary markers can further be also correlated with their presence in serum. Saliva can also be tested for the presence of immunoglobulins for specific bacteria and the study of their causative disease and severity can be co-related.[20],[21],[22]

 Conclusion



Evidently nasopharyngeal swab specimen remains the gold standard for definitive diagnosis of COVID-19. This study was solely done to focus on the diagnostic value of saliva for the same. This would help in the detection of positive asymptomatic carriers of the virus among the patients who come to seek dental treatment. This would in turn reduce the risk of infection in the dental office and among the working staff. The results of this study clearly show that the values obtained from the two sampling techniques are closely related, and hence saliva could definitely be considered as a diagnostic aid for COVID-19. The biomarkers present in the saliva are potential early detectors of various systemic diseases, such as cardiovascular and endocrinal disorders.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

1Shereen M, Khan S, Kazmi A et al. COVID-19 infection: origin, transmission and characteristics of human coronavirus. J Adv Res 2020;24:91-98.
2Ali I, Alharbi O. COVID-19: Disease, management, treatment and social impact. Sci Total Environ 2020;728:138861.
3Saxena SK. Coronavirus Disease 2019 (COVID-19). In: Medical Virology: from Pathogenesis to Disease Control. New York, USA: Springer Publising Co.; 2020. pp. 95-107.
4Qian Y, Zeng T, Wang H et al. Safety management of nasopharyngeal specimen collection from suspected cases of coronavirus disease2019. Int J Nurs Sci 2020;7:153-6.
5Piras A, Rizzo D, Longoni E et al. Nasopharyngeal swab collection in the suspicion of Covid-19. Am J Otolaryngol 2020;41:102551.
6To K, Yip C, Lai C et al. Saliva as a diagnostic specimen for testing respiratory virus by a point-of-care molecular assay: a diagnostic validity study. Clin Microbiol Infect 2019;25:372-8.
7To K, Tsang O, Yip C et al. Consistent detection of2019 novel coronavirus in saliva. Clin Infect Dis 2020;71:841-3.
8Bhanushali P, Katge F, Deshpande S. COVID-19: changing trends and its impacts on future of dentistry. Int J Dent 2020;2020:1-6.
9Marty FM, Chin K, Verrill KA. How to obtain a nasopharyngeal swab specimen. N Eng J Med 2020;383:e14.
10Bhattarai K, Kim H, Chae H. Compliance with saliva collection protocol in healthy volunteers: strategies for managing risk and errors. Int J Med Sci 2018;15:823-31.
11QuantiNova® SYBR® Green RT-PCR Kit Handbook-Quagen. (2015). https://www.qiagen.com › resources
12Vaerman J, Saussoy P, Ingargiola I. Evolution of real time PCR data. J Biol Regul Homeost Agents 2004;18:212-4.
13Chang M, Hur J, Park D. Interpreting the COVID-19 test results. A Guide for Physiatrics. Am J Phys Med Rehabil 2020; 99:583-5.
14Watson J, Whiting P, Brush J. Interpreting a COVID-19 test results. Brit Med J 2020;369:m1808.
15Ather A, Patel B, Ruparel N et al. Coronavirus disease 19 (COVID-19): Implication for clinical dental care. J Endod 2020;46:584-95.
16Peng X, Xu X, Li Y et al. Transmission routes of 2019-nCoV and controls in dental practice. Int J Oral Sci 2020;12:9.
17Kampf G, Todt D, Pfaender S, Steinmann E. Persistence of coronavirus on inanimate surfaces and their inactivation with biocidal agents. J Hosp Infect 2020; 104:246-51.
18QIAGEN OneStep RT-PCR Handbook. (2012). https://www.qiagen.com › do...PDF
19Silva R, Jardim A, Siqueira W. Coronavirus COVID-19 impacts to dentistry and potential salivary diagnosis. Clin Oral Investig 2020;24:1619-21.
20Isola G, Polizzi A, Patini R, Ferlito S, Alibrandi A, Palazzo G. Association among serum and salivary A. actinomycetemcomitans specific immunoglobulin antibodies and periodontitis. BMC Oral Health 2020; 20:283.
21Isola G, Polizzi A, Iorio-Siciliano V, Alibrandi A, Ramaglia L, Leonardi R. Effectiveness of a nutraceutical agent in the non-surgical periodontal therapy: a randomized, controlled clinical trial. Clin Oral Investig 2021;25:1035-45.
22Isola G, Polizzi A, Alibrandi A, Williams RC, Leonardi R. Independent impact of periodontitis and cardiovascular disease on elevated soluble urokinase-type plasminogen activator receptor (suPAR) levels. J Periodontol 2021 ;92:896-906.