Date of Submission

1-2025

Document Type

Thesis

Degree Name

Master of Science in Cellular and Molecular Biology

Department

Biology and Environmental Sciences

Advisor

Eva Sapi, Ph.D.

Committee Member

Alireza G. Senejani, Ph.D.

Committee Member

Anna Kloc, Ph.D.

Keywords

Lyme Disease, Borrelia burgdorferi, Biofilm Formation, Antibiotic Resistance, Crystal Violet Biofilm Assays

MeSH

Lyme Disease, Borrelia burgdorferi, Biofilms, Anti-Bacterial Agents, Gentian Violet

LCSH

Lyme disease, Borrelia burgdorferi, Biofilms, Antibiotics, Gentian violet

Abstract

Lyme disease, caused by the bacterium Borrelia burgdorferi, is the most prevalent tick-borne illness in the United States, with approximately 500,000 annual diagnoses. Despite antibiotic treatment, B. burgdorferi can persist in the host, often leading to relapses. Its treatment is further complicated by this pathogen’s ability to form biofilms, a morphological form that enhances antibiotic resistance and serves as a defense mechanism. Previous studies have shown that established biofilms are highly resistant to eradication, even at high antibiotic concentrations. While recent therapeutic strategies advocate administering antibiotics after a tick bite to prevent B. burgdorferi biofilm formation, supporting research data remain lacking.

This study aimed to evaluate the efficacy of various antibiotics (doxycycline, dapsone, azithromycin, and hygromycin A) in inhibiting biofilm formation in vitro using crystal violet biofilm assays, LIVE/DEAD staining, and subculture assays.

The results showed that doxycycline, the most commonly prescribed antibiotic for Lyme disease, and azithromycin, widely used in Europe, demonstrated limited efficacy both against established biofilms and in preventing biofilm formation. Hygromycin A, a B. burgdorferi-specific antibiotic, showed moderate efficacy as a monotherapy but achieved significant results in dual therapy, particularly when combined with dapsone. The combination of hygromycin A and dapsone reduced biofilm mass by nearly 50% and prevented biofilm recovery in subculture assays.

These findings suggest that antibiotics used for Lyme disease treatment may be inadequate for addressing B. burgdorferi biofilm formation. This research underscores the importance of early, targeted interventions and highlights the potential of non-standard antibiotics and combination therapies as innovative strategies to combat B. burgdorferi biofilm formation. This study adds to the expanding body of research on Lyme disease treatment, highlighting the urgent need for innovative strategies to address the challenges presented by the bacteria’s adaptive defense mechanisms.

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