High prevalence of antibiotic resistance of Streptococcus species in saliva from non-hospitalized adults – a pilot study

Background: Antibiotic resistance (AR) is a recognized threat to global human health. However, the prevalence of AR in healthy adults is not well described. The present observational pilot study aimed to uncover the potential of using saliva samples for screening for antibiotic resistance. Methodology: A laboratory protocol was developed for screening of AR in saliva samples, which was tested and validated using saliva samples collected from 100 study participants. The risk of AR was analyzed with descriptive statistics and evaluated using a risk-factor profile based on information on antibiotic usage within the last 12 months, education level and origin of birth. Results: AR was identified in 43 (48%) saliva samples, out of which 60,0% and 17,1% of resistant strains displayed resistance to clindamycin and penicillin, respectively. Streptococcus salivarius and Streptococcus parasanguinis were most often identified with AR (51,4% of all cases). The risk of AR was not associated with self-perceived oral or general health, antibiotic use within the latest 12 months or any demographic or socioeconomic parameters recorded. The risk-factor profile was observed in 44% in the AR group versus 30% in the non-AR group (p = 0.19). Conclusion: The present study showed that it is possible to perform non-invasive saliva-based screening for AR with a frequency of 48% of the samples, highlighting that saliva samples could be a valuable supplement to current surveillance methodologies for AR in the oral microbiota.