Is parotid saliva sterile on entry to the oral cavity?

Abstract

Conclusion: The present study indicates that parotid saliva is sterile on entry to the oral cavity.

Objectives: The objective was to investigate if parotid saliva is sterile on entry to the oral cavity and, thus, prior to contamination by oral bacteria.

Method: Forty healthy volunteers were included in sterile parotid saliva collection. Parotid saliva was collected using a sterile Lashley cup, placed over the papilla of the Stensen´s duct, as well as sterile tubes and syringes for collection. All collections were followed by collection of a positive control sample where some of the sterile obtained parotid saliva had been exposed to the contralateral mucosal membranes. All samples parotid saliva, as well as the positive controls, were cultivated, and 10 randomly selected parotid saliva samples underwent polymerase chain reaction (PCR) analyses.

Results: In 33 of 40 parotid saliva samples there were no cultivable bacteria, whereas bacteria were cultivated in all positive control samples. In eight of 10 PCR samples no bacterial DNA was detected. The most frequent bacteria in the remaining non-sterile parotid saliva samples and positive control samples were non-haemolytical streptococci and the coagulase negative staphylococci.

Keywords:

• Bacteria
• humans
• microbiology
• salivary glands
• salivary gland stones
• sialolithiasis

Acknowledgements

The authors wish to thank the staff at the Department of Clinical Microbiology at Rigshospitalet in Copenhagen for help and assistance during the study.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Ethical approval

The authors assert that all procedures contributing to this work comply with the ethical standards of the relevant national and institutional guidelines on human experimentation (Ethical Committees for the Capital Region of Denmark: registration number: H-4-2011-022, issued May 2, 2011) and with the Helsinki Declaration of 1975, as revised in 2008. The experiment was carried out in a hospital setting and all participants gave their written consent prior to inclusion. All data was anonymized and the participants acknowledged that they could not be identified.

Additional information

Funding

This work was supported by: The Research Foundation at Nordsjaellands University Hospital; grant number [E2012]; Inge & Per Refshall´s Research Grant number [2016-1840/68KBN]; The Novo Nordisk Foundation supported HKJ as a clinical research stipend.