Multi-armed antibiotics for Gram-positive bacteria

Fighting Antibiotic Resistance: Insights Into Human Barriers and New Opportunities: Antibiotic Resistance Constantly Rises With the Development of Human Activities. We discuss Barriers and Opportunities to Get It Under Control

The public health issue of bacterial multi-resistance to antibiotics has gained awareness among the public, researchers, and the pharmaceutical sector. Nevertheless, the spread of antimicrobial resistance has been considerably aggravated by human activities, climate change, and the subsequent increased release of antibiotics, drug-resistant bacteria, and antibiotic resistance genes in the environment. The extensive use of antibiotics for medical and veterinary purposes has not only induced increasing resistance but also other health problems, including negative effects on the patient's microbiome. Preventive strategies, new treatment modalities, and increased surveillance are progressively set up. A comprehensive approach is, however, lacking for urgently tackling this adverse situation. To address this challenge, we discussed here the main causes driving antimicrobial resistance and pollution of the environment by factors favorable to the emergence of drug resistance. We next propose some key priorities for research, prevention, surveillance, and education to supervise an effective clinical and sustainable response.

One-for-All Photoactivatable Manganese-Based Carbon Monoxide-Releasing Molecules (CORMs) for Synergistic Therapy of Mycobacterial Infection

Tuberculosis presents a severe threat to human health. It is of crucial importance to develop novel and effective treatments to combat mycobacterial infections, especially those caused by drug-resistant bacteria. In this study, a tricarbonyl manganese(I) complex (Mn-PTP) was synthesized for the purpose of conducting synergistic therapy against mycobacterial infection. When subjected to white light irradiation, Mn-PTP generated multiple reactive species, including type I/II combined reactive oxygen species (ROS), carbon monoxide (CO), the toxic ligand PTP, and manganese oxides (MnOX) with catalase-like ability. The antibacterial experiment demonstrated that irradiated Mn-PTP exhibited specific antibacterial effects on Mycobacterium smegmatis (M. smegmatis). It was found to cause damage to the bacterial membrane and effectively eradicate biofilms. Moreover, the in vivo experiment revealed that the photoactive Mn-PTP could promote the healing process of M. smegmatis-infected skin wounds. This study pioneers innovative frameworks for developing one-for-all small-molecule pharmaceuticals capable of enabling synergistic therapeutic strategies against mycobacterial infections.

Freeze-Thaw Microfluidic System Produces "Themis" Nanocomplex for Cleaning Persisters-Infected Macrophages and Enhancing Uninfected Macrophages

Macrophages are the primary effectors against potential pathogen infections. They can be "parasitized" by intracellular bacteria, serving as "accomplices", protecting intracellular bacteria and even switching them to persisters. Here, using a freeze-thaw strategy-based microfluidic chip, a "Themis" nanocomplex (TNC) is created. The TNC consists of Lactobacillus reuteri-derived membrane vesicles, heme, and vancomycin, which cleaned infected macrophages and enhanced uninfected macrophages. In infected macrophages, TNC releases heme that led to the reconstruction of the respiratory chain complexes of intracellular persisters, forcing them to regrow. The revived bacteria produces virulence factors that destroyed host macrophages (accomplices), thereby being externalized and becoming vulnerable to immune responses. In uninfected macrophages, TNC upregulates the TCA cycle and oxidative phosphorylation (OXPHOS), contributing to immunoenhancement. The combined effect of TNC of cleaning the accomplice (infected macrophages) and reinforcing uninfected macrophages provides a promising strategy for intracellular bacterial therapy.

Cyclic peptide conjugated photosensitizer for targeted phototheranostics of gram-negative bacterial infection

Antimicrobial photodynamic therapy (PDT) is a promising alternative to antibiotics for eradicating pathogenic bacterial infections. It holds advantage of not inducing antimicrobial resistance but is limited for the treatment of gram-negative bacterial infection due to the lack of photosensitizer (PS) capable of targeted permeating the outer membrane (OM) of gram-negative bacteria. To facilitate the targeted permeability of PS, cyclic polymyxin b nonapeptide that can specifically bind to the lipopolysaccharide on OM, is conjugated to an FDA approved PS chlorin e6 via variable linkers. Based on structure to activity study, C6pCe6 with aminohexanoic linker and P2pCe6 with amino-3, 6-dioxaoctanoic linker are identified to preferentially image gram-negative bacteria. These two conjugates also exhibit improved aqueous dispersity and enhanced ROS generation, consequently enabled their selective bactericidal activities against gram-negative bacteria upon 660 nm light irradiation. The effective photobactericidal ability of P2pCe6 is further validated on P. aeruginosa infected G. mellonella. Moreover, it is demonstrated to effectively treat the P. aeruginosa infection and accelerate the healing process at the wound site of mouse. Owing to the light irradiation triggered targeted imaging and enhanced bactericidal capacities, P2pCe6 hold great potential to serve as a potent PS for mediating the phototheranostics of gram-negative bacterial infection.

Multi-arming ourselves against drug-resistant bacteria

New classes of antibiotics are desperately needed in our fight against antibiotic-resistant bacterial infections. Jia et al. publish a new "multi-armed" antibiotic scaffold that effectively treats methicillin-resistant Staphylococcus aureus infections in mice. These compounds are structurally unlike pre-clinical or approved antibiotics, and they may hit an "irresistible" target.