Microorganisms. 2021 Feb 18 ;9(2). Epub 2021 Feb 18. PMID: 33670726
In Vitro Effects ofLN66 and Antibiotics Used Alone or in Combination onMature Biofilm.
is a gastrointestinal pathogen with high prevalence that harms human health. Studies have shown thatcan form antibiotic-tolerant biofilms, which may interfere with the efficacy of clinical antibiotic therapy. Probiotics can antagonize planktonic and biofilm pathogen cells and thus may play an auxiliary role inantibiotic therapy. However, the effects of different probiotic strains and antibiotic combinations onbiofilms need to be further investigated. We determined the cell viability ofmature biofilms after treatment withLN66 cell-free supernatant (CFS), clarithromycin (CLR), and levofloxacin (LVX) alone or in combination by the XTT method. Biofilm cells were observed by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Subsequently, protein and polysaccharide concentrations in biofilm extracellular polymeric substances (EPSs) were quantitatively detected by the Bradford method and the phenol-sulfate method. The results showed that LN66 CFS had an eradication effect on maturebiofilm. When used in combination with CLR, LN66 CFS significantly attenuated the eradication effect of CLR on biofilms; in contrast, when used in combination with LVX, LN66 CFS enhanced the disrupting effect of LVX. We speculate that the different effects of CFS and antibiotic combinations on biofilms may be related to changes in the content of proteins and polysaccharides in EPS and that the combination of CFS and CLR might promote the secretion of EPS, while the combination of CFS and LVX might have the opposite effect. Accordingly, we suggest that supplementation withLN66 may provide additional help when therapy involving LVX is used for clinicalbiofilm eradication, whereas it may impair CLR efficacy when therapy involving CLR is used.