The New Strategy for Studying Drug-Delivery Systems with Prolonged Release: Seven-Day In Vitro Antibacterial Action

Abstract

The new method of antibacterial-drug-activity investigation in vitro is proposed as a powerful strategy for understanding how carriers affect drug action during long periods (7 days). In this paper, we observed fluoroquinolone moxifloxacin (MF) antibacterial-efficiency in non-covalent complexes, with the sulfobutyl ether derivative of β-cyclodextrin (SCD) and its polymer (SCDpol). We conducted in vitro studies on two Escherichia coli strains that differed in surface morphology. It was found that MF loses its antibacterial action after 3–4 days in liquid media, whereas the inclusion of the drug in SCD led to the increase of MF antibacterial activity by up to 1.4 times within 1–5 days of the experiment. In the case of MF-SCDpol, we observed a 12-fold increase in the MF action, and a tendency to prolonged antibacterial activity. We visualized this phenomenon (the state of bacteria, cell membrane, and surface morphology) during MF and MF-carrier exposure by TEM. SCD and SCDpol did not change the drug’s mechanism of action. Particle adsorption on cells was the crucial factor for determining the observed effects. The proteinaceous fimbriae on the bacteria surface gave a 2-fold increase of the drug carrier adsorption, hence the strains with fimbriae are more preferable for the proposed treatment. Furthermore, the approach to visualize the CD polymer adsorption on bacteria via TEM is suggested. We hope that the proposed comprehensive method will be useful for the studies of drug-delivery systems to uncover long-term antibacterial action.

Cyclodextrins and Their Polymers Affect Human Serum Albumin’s Interaction with Drugs Used in the Treatment of Pulmonary Infections

“…We determined the minimum inhibition concentration (MIC) by the agar well diffusion method [ 25 , 26 , 27 ]. The cell’s suspension (overnight Escherichia coli ATCC 25,922 (grown in Luria Bertuni medium for 12 h)) was diluted to 0.5 McFarland standard.…”

Conjugates of Chitosan with β-Cyclodextrins as Promising Carriers for the Delivery of Levofloxacin: Spectral and Microbiological Studies

“…CDs is proven to be nontoxic in vitro [ 30 ], while unmodified chitosan, according to the literature data, possesses antibacterial activity against fungi, Gram-positive bacteria, and Gram-negative bacteria [ 43 , 44 ]. The modification of amino groups by CDs can change chitosan’s antibacterial properties: with the increase of immobilized CDs content, the polymer’s antibacterial properties decrease [ 45 ].…”

“…Escherichia coli ATCC 25,922 and Bacillus subtilis ATCC 6633 were cultured in Luria Bertuni liquid growth medium for 12 h. These cultures were used for minimum inhibition concentration (MIC) determination. The agar well diffusion method was performed as a standard approach for the determination of the drug form’s MIC in vitro [ 29 , 30 ]. Briefly, four wells were cut in the agar by a sterile plastic pipette tip after the distribution of overnight culture over the agar surface.…”

Encapsulation of Ciprofloxacin into a Cyclodextrin Polymer Matrix: The Complex Formation with Human Serum Albumin and In Vitro Studies

“…The overnight culture (Luria Bertuni medium, pH 7.4) was diluted to match the 0.5 McFarland standard [27,28]. After the distribution of bacteria on Petri dishes, 4 wells were cut using 1 mL of sterile plastic [15,[29][30][31]. A total of 50 µL of each sample was put into wells: sterile buffer as a negative control, CF, CF+MCD, MAX, HSA−CF, HSA−(MCD+CF) or HSA−MAX (C CF = 0.2, 0.3 and 0.5 µg/mL for E. coli ATCC 25922 and C CF = 0.4, 0.6 and 0.8 µg/mL for B. subtilis ATCC 6633).…”

“…Antibacterial Activity of CF's Drug Forms in the Presence of HSA We used Gram-positive Bacillus subtilis and Gram-negative Escherichia coli to investigate the effect of CF's carrier and HSA's presence on the drug's antibacterial properties. We performed a rapid and reliable agar-well diffusion test to determine minimum inhibition concentrations (MIC) [15,[29][30][31].…”