The potential for developing new antimicrobial resistance from the use of medical devices containing chlorhexidine, minocycline, rifampicin and their combinations: a systematic review

Novel dalbavancin-PLLA implant coating prevents hematogenous Staphylococcus aureus infection in a minimally invasive mouse tail vein model

Infective/bacterial endocarditis is a rare but life-threatening disease with a hospital mortality rate of 22.7% and a 1-year mortality rate of 40%. Therefore, continued research efforts to develop efficient anti-infective implant materials are of the utmost importance. Equally important is the development of test systems that allow the performance of new materials to be comprehensively evaluated. In this study, a novel antibacterial coating based on dalbavancin was tested in comparison to rifampicin/minocycline, and the suitability of a recently developed mouse tail vein model for testing the implant coatings was validated. Small polymeric stent grafts coated with a poly-L-lactic acid (PLLA) layer and incorporated antibiotics were colonized with Staphylococcus (S.) aureus before implantation into the tail vein of mice. The main assessment criteria were the hematogenous spread of the bacteria and the local tissue reaction to the contaminated implant. For this purpose, colony-forming units (CFU) in the blood, spleen and kidneys were determined. Tail cross sections were prepared for histological analysis, and plasma cytokine levels and expression values of inflammation-associated genes were examined. Both antibiotic coatings performed excellently, preventing the onset of infection. The present study expands the range of available methods for testing the anti-infectivity of cardiovascular implants, and the spectrum of agents for effective surface coating.

Chlorhexidine Mucoadhesive Buccal Tablets: The Impact of Formulation Design on Drug Delivery and Release Kinetics Using Conventional and Novel Dissolution Methods

Oropharyngeal candidiasis (OPC) is a mucosal infection caused by Candida spp., and it is common among the immunocompromised. This condition is mainly treated using oral antifungals. Chlorhexidine (CHD) is a fungicidal and is available as a mouth wash and oral gel. It is used as an adjuvant in the treatment of OPC due to the low residence time of the current formulations. In this study, its activity was tested against C. albicans biofilm and biocompatibility with the HEK293 human cell line. Then, it was formulated as mucoadhesive hydrogel buccal tablets to extend its activity. Different ratios of hydroxypropyl methylcellulose (HPMC), poloxamer 407 (P407), and three different types of polyols were used to prepare the tablets, which were then investigated for their physicochemical properties, ex vivo mucoadhesion, drug release profiles, and the kinetics of drug release. The release was performed using Apparatus I and a controlled flow rate (CFR) method. The results show that CHD is biocompatible and effective against Candida biofilm at a concentration of 20 µg/mL. No drug excipient interaction was observed through differential scanning calorimetry (DSC) and Fourier-transform infrared spectroscopy (FTIR). The increase in P407 and polyol ratios showed a decrease in the swelling index and an increase in CHD in vitro release. The release of CHD from the selected formulations was 86-92%. The results suggest that chlorhexidine tablets are a possible candidate for the treatment of oropharyngeal candidiasis.

Bacterial antibiotic resistance development and mutagenesis following exposure to subinhibitory concentrations of fluoroquinolones in vitro: a systematic review of the literature

BACKGROUND

Understanding social and scientific drivers of antibiotic resistance is critical to help preserve antibiotic efficacy. These drivers include exposure to subinhibitory antibiotic concentrations in the environment and clinic.

OBJECTIVES

To summarize and quantify the relationship between subinhibitory fluoroquinolone exposure and antibiotic resistance and mutagenesis to better understand resistance patterns and mechanisms.

METHODS

Following PRISMA guidelines, PubMed, Web of Science and Embase were searched for primary in vitro experimental studies on subinhibitory fluoroquinolone exposure and bacterial antibiotic resistance and mutagenesis, from earliest available dates through to 2018 without language limitation. A specifically developed non-weighted tool was used to assess risk of bias.

RESULTS

Evidence from 62 eligible studies showed that subinhibitory fluoroquinolone exposure results in increased resistance to the selecting fluoroquinolone. Most increases in MIC were low (median minimum of 3.7-fold and median maximum of 32-fold) and may not be considered clinically relevant. Mechanistically, resistance is partly explained by target mutations but also changes in drug efflux. Collaterally, resistance to other fluoroquinolones and unrelated antibiotic classes also develops. The mean ± SD quality score for all studies was 2.6 ± 1.8 with a range of 0 (highest score) to 7 (lowest score).

CONCLUSIONS

Low and moderate levels of resistance and efflux changes can create an opportunity for higher-level resistance or MDR. Future studies, to elucidate the genetic regulation of specific resistance mechanisms, and increased policies, including surveillance of low-level resistance changes or genomic surveillance of efflux pump genes and regulators, could serve as a predictor of MDR development.