In Vitro Assessment of Biofilm Production, Antibacterial Resistance of , , , and spp. Obtained from Tonsillar Crypts of Healthy Adults.

Background And Objective: Tonsillar crypts can be considered a reservoir for a variety of bacterial species. Some bacterial species can be considered part of the normal oropharyngeal microbiota. The roles of other pathogens, for example, the so-called non-oral and respiratory pathogens , , , and spp., which have strong virulence factors, biofilm production capacity, and the ability to initiate infectious diseases, are unclear. The purpose of this study was to detect the presence of , , , and spp. within the tonsillar crypts of healthy individuals, and to analyze the pathogens' biofilm production and antibacterial resistances.

Results: Only common oropharyngeal microbiota were cultivated from 37 participant samples (40.7%). The most commonly isolated pathogenic bacterium was , which was isolated in 41 (45%) participant samples. was isolated in seven (7.7%) samples, spp. were isolated in five (5.5%) samples, and was isolated in two (2.2%) samples. Biofilm producers predominated among the pathogenic bacteria; 51 strains were biofilm producers, and among them, 31 strains were moderate or strong biofilm producers. The tested , , , and spp. strains were sensitive to commonly used antibiotics (amoxicillin-clavulanic acid, clindamycin, or ciprofloxacin). One of the isolated strains was MRSA.

Conclusions: Biofilm is a commonly observed feature that seems to be a naturally existing form of pathogenic bacteria colonizing human tissue. , , , and spp. occasionally occur in the tonsillar crypts of healthy individuals, and, therefore, it is most likely that , and spp. in opportunistic tonsillar infections originate from the tonsillar crypt microbiota.