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 gland stones; salivary glands; sialolithiasis.