The associations between bacteria, fungi and biofilm production in patients with recurrent tonsillitis and healthy controls

Microorganisms within biofilms are resistant to host defenses and antibiotics. The presence of bacterial biofilms within the tissue and crypts of inflamed tonsils may explain the chronic and recurrent characteristics of some forms of tonsillitis. Research objectives are to establish possible associations between identified bacteria, fungi and biofilm production in patients diagnosed with recurrent tonsillitis (RT) as well as in healthy individuals. During prospective controlled study material from tonsillar crypts was obtained for microbiological testing from healthy individuals and patients with RT. Identification of microorganisms was performed using MALDI–TOF mass spectrometry. Microtiter-plate method was used for the in vitro cultivation and quantification of bacterial biofilms. The optical density of the adherent biofilm layer formed in microtiter-plate was measured using microtiter-plate reader. Pearson Chi-Square (χ2) and Fisher’s exact test was used to determine associations between the variables. There was a significant association between Gr + bacteria and biofilm formation in healthy controls (n=91) (Pearson χ2 test, χ = 61.733, p<0.001), patients with RT (n=99) (Pearson χ2 test, χ = 40.932, p<0.001), patients with exacerbated RT (n=29) (Fisher`s exact test, p<0.001). There was no significant association between Gr - bacteria and biofilm formation in healthy controls (n=91) (Pearson χ2 test, p=0.808), patients with RT (n=99) (Pearson χ2 test, p=0.227), patients with exacerbated RT (n=29) (Fisher`s exact test, p>0.999). There was no significant association between fungi and biofilm formation in healthy controls (n=91) (Fisher`s exact test, p=0.473), patients with RT (n=99) (Fisher`s exact test, p>0.999), patients with exacerbated RT(n=29) (Fisher`s exact test, p=0.215). If Gr + bacteria had been detected in tonsillar crypts of healthy individuals or patients with RT most likely a biofilm was present. On the other hand, if Gr- bacteria or fungi had been detected in the same patient group, most likely a biofilm was not present.