Erythromycin Formulations—A Journey to Advanced Drug Delivery

Erythromycin (ERY) is a macrolide compound with a broad antimicrobial spectrum which is currently being used to treat a large number of bacterial infections affecting the skin, respiratory tract, intestines, bones and other systems, proving great value from a clinical point of view. It became popular immediately after its discovery in 1952, due to its therapeutic effect against pathogens resistant to other drugs. Despite this major advantage, ERY exhibits several drawbacks, raising serious clinical challenges. Among them, the very low solubility in water and instability under acidic conditions cause a limited efficacy and bioavailability. Apart from this, higher doses promote drug resistance and undesirable effects. In order to overcome these disadvantages, during the past decades, a large variety of ERY formulations, including nanoparticles, have emerged. Despite the interest in ERY-(nano)formulations, a review on them is lacking. Therefore, this work was aimed at reviewing all efforts made to encapsulate ERY in formulations of various chemical compositions, sizes and morphologies. In addition, their preparation/synthesis, physico-chemical properties and performances were carefully analysed. Limitations of these studies, particularly the quantification of ERY, are discussed as well.

Lamprey immunity protein enables early detection and recurrence monitoring for bladder cancer through recognizing Neu5Gc-modified uromodulin glycoprotein in urine

The clinical management of bladder cancer (BCa) is hindered by the lack of reliable biomarkers. We aimed to investigate the potential of lamprey immunity protein (LIP), a lectin that specifically binds to multi-antennary sialylated N-glycolylneuraminic acid (Neu5Gc) structures on UMOD glycoproteins in the urine of BCa patients. Primary BCa patients had higher levels of LIP-bound Neu5Gc in urine than healthy participants and patients receiving postoperative treatment did. In addition, lectin chip assay and mass spectrometry were used to analyze the glycan chain structure, which can recognize the UMOD glycoprotein decorated with multi-antennary sialylated Neu5Gc structures. Furthermore, compared with urine samples from healthy patients (N = 2821, T/C = 0.12 ± 0.09) or benign patients (N = 360, T/C = 0.11 ± 0.08), the range of the urine T/C ratio detected using LIP test paper was 1.97 ± 0.32 in patients with bladder cancer (N = 518) with significant difference (P < 0.0001). Our results indicate that LIP may be a tool for early BCa identification, diagnosis, and monitoring. Neu5Gc-modified UMOD glycoproteins in urine and Neu5Gc-modified N-glycochains and sialyltransferases may function as potential markers in clinical trials.

Nanotargeting of Resistant Infections with a Special Emphasis on the Biofilm Landscape

Bacterial resistance to antimicrobial compounds is a growing concern in medical and public health circles. Overcoming the adaptable and duplicative resistance mechanisms of bacteria requires chemistry-based approaches. Engineered nanoparticles (NPs) now offer unique advantages toward this effort. However, most in situ infections (in humans) occur as attached biofilms enveloped in a protective surrounding matrix of extracellular polymers, where survival of microbial cells is enhanced. This presents special considerations in the design and deployment of antimicrobials. Here, we review recent efforts to combat resistant bacterial strains using NPs and, then, explore how NP surfaces may be specifically engineered to enhance the potency and delivery of antimicrobial compounds. Special NP-engineering challenges in the design of NPs must be overcome to penetrate the inherent protective barriers of the biofilm and to successfully deliver antimicrobials to bacterial cells. Future challenges are discussed in the development of new antibiotics and their mechanisms of action and targeted delivery via NPs.

Pulse Dosing of Antibiotic Enhances Killing of a Staphylococcus aureus Biofilm

Biofilms are highly tolerant to antibiotics and underlie the recalcitrance of many chronic infections. We demonstrate that mature Staphylococcus aureus biofilms can be substantially sensitized to the treatment by pulse dosing of an antibiotic – in this case, oxacillin. Pulse (periodic) dosing was compared to continuous application of antibiotic and was studied in a novel in vitro flow system which allowed for robust biofilm growth and tractable pharmacokinetics of dosing regimens. Our results highlight that a subpopulation of the biofilm survives antibiotic without becoming resistant, a population we refer to as persister bacteria. When oxacillin was continuously present the persister level did not decline, but, importantly, providing correctly timed periodic breaks decreased the surviving population. We found that the length of the periodic break impacted efficacy, and there was an optimal length that sensitized the biofilm to repeat treatment without allowing resistance expansion. Periodic dosing provides a potential simple solution to a complicated problem.