Eradication of Biofilms on Catheters: Potentials of Tamarix ericoides Rottl. Bark Coating in Preventing Catheter-Associated Urinary Tract Infections (CAUTIs)

Catheter-associated urinary tract infections (CAUTIs) cause serious complications among hospitalized patients due to biofilm-forming microorganisms which make treatment ineffective by forming antibiotic-resistant strains. As most CAUTI-causing bacterial pathogens have already developed multidrug resistance, there is an urgent need for alternative antibacterial agents to prevent biofilms on catheter surfaces. As a trial to find out such a potential agent of natural origin, the bark of <i>Tamarix ericoides</i> Rottl., a little-known plant from the Tamaricaceae family, was examined for its antibacterial and antibiofilm activities against one of the major, virulent, CAUTI-causing bacterial pathogens: <i>Enterococcus faecalis</i>. The methanolic <i>T. ericoides</i> bark extract was analyzed for its antibacterial activity using the well diffusion method and microdilution method. Killing kinetics were calculated using time-kill assay, and the ability of biofilm formation and its eradication upon treatment with the <i>T. ericoides</i> bark extract was studied by crystal violet assay. GC-MS analysis was performed to understand the phytochemical presence in the extract. A in vitro bladder model study was performed using extract-coated catheters against <i>E. faecalis</i>, and the effect was visualized using CLSM. The changes in the cell morphology of the bacterium after treatment with the <i>T. ericoides</i> bark extract were observed using SEM. The biocompatibility of the extract towards L₉₂₉ cells was studied by MTT assay. The anti-<i>E. faecalis</i> activity of the extract-coated catheter tube was quantified by viable cell count method, which exposed 20% of growth after five days of contact with <i>E. faecalis</i>. The anti-adhesive property of the <i>T. ericoides</i> bark extract was studied using CLSM. The extract showed potential antibacterial activity, and the lowest inhibitory concentration needed to inhibit the growth of <i>E. faecalis</i> was found to be 2 mg/mL. The GC-MS analysis of the methanolic fractions of the <i>T. ericoides</i> bark extract revealed the presence of major phytochemicals, such as diethyl phthalate, pentadecanoic acid, methyl 6,11-octadecadienoate, cyclopropaneoctanoic acid, 2-[(2-pentylcyclopropyl) methyl]-, methyl ester, erythro-7,8-bromochlorodisparlure, etc., that could be responsible for the antibacterial activity against <i>E. faecalis.</i> The killing kinetics of the extract against <i>E. faecalis</i> was calculated and the extract showed promising antibiofilm activity on polystyrene surfaces. The <i>T. ericoides</i> bark extract effectively reduced the <i>E. faecalis</i> mature biofilms by 75%, 82%, and 83% after treatment with 1X MIC (2 mg/mL), 2X MIC (4 mg/mL), and 3X MIC (6 mg/mL) concentrations, respectively, which was further confirmed by SEM analysis. The anti-adhesive property of the <i>T. ericoides</i> bark extract studied using CLSM revealed a reduction in the biofilm thickness, and the FDA and PI combination revealed the death of 80% of the cells on the extract-coated catheter tube. In addition, SEM analysis showed extensive damage to the <i>E. faecalis</i> cells after the <i>T. ericoides</i> bark extract treatment, and it was not cytotoxic. Hence, after further studies, <i>T. ericoides</i> bark extract with potential antibacterial, antibiofilm, and anti-adhesive activities can be developed as an alternative agent for treating CAUTIs.