Antimicrobial Activity of Nanoemulsion in Combination with Cetylpyridinium Chloride in Multidrug-Resistant Acinetobacter baumannii

Abstract

c Acinetobacter baumannii has emerged as a serious problematic pathogen due to the ever-increasing presence of antibiotic resistance, demonstrating a need for novel, broad-spectrum antimicrobial therapeutic options. Antimicrobial nanoemulsions are emulsified mixtures of detergent, oil, and water (droplet size, 100 to 800 nm) which have broad antimicrobial activity against bacteria, enveloped viruses, and fungi. Here, we screened the antimicrobial activities of five nanoemulsion preparations against four Acinetobacter baumannii isolates to identify the most suitable preparation for further evaluation. Among them, N5, which contains 10% (vol/vol) Triton X-100, 25% (vol/vol) soybean oil, and 1% (wt/vol) cetylpyridinium chloride (CPC), showed the best efficacy against A. baumannii in both its planktonic and biofilm forms and was selected for further study. Our data demonstrate that, while the killing of planktonic forms of A. baumannii was due to the 1% CPC component of our nanoemulsions, the breakdown of biofilms was achieved via the emulsified oil and detergent fractions. Furthermore, we documented the effect of ethanol and NaCl in combination with N5 on planktonic A. baumannii. In killing curves of N5 combined with other agents (ethanol or NaCl), a synergistic effect of a >2-log decrease in CFU/ml was observed. The antibiofilm activity of N5 was confirmed via a cell proliferation test and scanning electron microscopy. The effects of exposure to severe environmental conditions, which simulates the field conditions in Iraq and Afghanistan, were evaluated, and this exposure did not affect the overall antimicrobial activity of N5. These studies lay a solid foundation for the utilization of nanoemulsions against the antibiotic-resistant forms of A. baumannii.

Factors Affecting the Phase Behavior and Antimicrobial Activity of Carvacrol Microemulsions

“…It interacts with the negatively charged cell wall of the microbe by electrostatic attraction allowing the hydrophobic palmitate moiety of CPC to interact with the cell wall resulting in leakage of the cellular components 61 . Previous investigations indicated that CPC at 1.0 in a soybean nano-emulsion can inhibit the planktonic forms of Acinetobacter baumannii 62 . It was also used as antimicrobial and disinfecting agent in many commercially available oral hygiene products 63 and disinfecting soaps.…”

Inhibited biofilm formation and improved antibacterial activity of a novel nanoemulsion against cariogenic Streptococcus mutans in vitro and in vivo

“…8 Many studies have demonstrated the antimicrobial properties of nanoemulsions formulated with antimicrobial substances. 21 Investigations on the use of nanoemulsions as antimicrobial agents were prompted by the development of antimicrobial-resistant strains after the use of existing agents, due to the widespread and sometimes inappropriate use of antibiotics, disinfectants, and antiseptics. Moreover, nanoemulsions are novel water-inoil formulations that are stabilized by adding small amounts of surfactants.…”

Acinetobacter baumannii biofilm resistance mechanisms and prevention and control of progress

“…Ethanol, sodium chloride and soybean oil, cetyl chloride are able to destroy the Acinetobacter baumannii biofilm. [38] Physical methods such as electric current, ultrasonic vibration, high-frequency pulse and heating can destroy the mature Acinetobacter baumannii biofilm to increase the antibiotic sensitivity to bacteria. Low frequency (0.4 MHz) ultrasound can promote the penetration of oxygen molecules and nutrients in the biofilm and accelerate the release of bacterial metabolites, resulting in the recovery of low-metabolizing bacteria and the restoration of sensitivity to antibiotics.…”