Antibiotic Choice: The Synergistic Effect of Single vs Dual Antibiotics

Efficacy comparison of antibiotic bone cement-coated implants and external fixations for treating infected bone defects

PURPOSE

This study aimed to investigate the clinical efficacy of antibiotic bone cement-coated implants compared with external fixations for treating infected bone defects.

METHODS

We retrospectively enrolled 119 patients with infected bone defects in our hospital from January 2010 to June 2021, of which 56 were treated with antibiotic bone cement-coated implants and 63 were with external fixation.

RESULTS

The pre-operative and post-operative haematological indexes were tested to assess the infection control; the post-operative CRP level in the internal fixation group was lower than that in the external fixation group. No statistical significance was found in the rate of infection recurrence, loosening and rupture of the fixation, and amputation between the two groups. Twelve patients in the external fixation group had pin tract infection. In the evaluation of the Paley score scale, bone healing aspect revealed no significant difference between the two groups, while in the limb function aspect, antibiotic cement-coated implant group showed a much better score than the external fixation group (P = 0.002). The anxiety evaluation scale result also showed lower score in the antibiotic cement implant group (P < 0.001).

CONCLUSIONS

Compared with external fixation, antibiotic bone cement-coated implant had the same effect on controlling infection and was more effective in recovering limb function and mental health in the first-stage treatment of infected bone defects after debridement.

ZIF@VO2 as an Intelligent Nano-Reactor for On-Demand Angiogenesis and Disinfection

Absent angiogenesis and bacterial infection are two major challenges that simultaneously delay the repair of injured tissues and organs. However, most current therapeutic systems deliver therapeutic cues in a separate and inaccurate manner which stimulates angiogenesis or inhibits infection leading to limited repair and side effects. Advanced therapeutic systems capable of providing accurate angiogenic stimulation and anti-infection signals in response to the changing microenvironment are urgently needed. Herein, a nano-reactor (ZFVO) involving zeolitic imidazolate framework-67 (ZIF-67)-deposited hollow vanadium oxide (VO₂ ) is developed to intelligently execute pro-angiogenesis and/or disinfection via the responsive release of cobalt ions and hydroxyl radicals to the injury and infection sites, respectively. ZFVO nano-reactor demonstrates a novel strategy for constructing drug-free nano-platforms with a hierarchical structure which has potential for the accurate treatment of trauma and orthopedic diseases.

Microplastics accumulation in mangroves increasing the resistance of its colonization Vibrio and Shewanella

The enrichment of various pollutants in mangrove has attracted widespread attention. Especially, microplastics accumulation in mangrove may provide a more challenging ecological colonization site by enriching pollutants, thus affecting the change of microplastics antibiotic resistance and increasing the risk of antibiotic failure. Herein, the antibiotic-resistant of microplastics and sediment from mangrove were investigated. The results show that isolates are mainly colonized by Vibrio parahemolyticus (V. parahemolyticus), Vibrio alginolyticus (V. alginolyticus), and Shewanella. 100% mangrove microplastics isolates are resistant to chloramphenicol, cefazolin, and tetracycline, especially amoxicillin clavulanate and ampicillin. Meanwhile, the multiple antibiotics resistance (MAR) indexes of V. parahaemolyticus, Shewanella, and V. alginolyticus in mangrove microplastics are 0.72, 0.77, and 0.77, respectively, which are far higher than the MAR index standard (0.2) and that of mangrove sediment isolates. Furthermore, compared with V. parahaemolyticus isolated from the same mangrove microplastics, Shewanella and V. alginolyticus show stronger drug resistance. It should be noted that there is a closely related relationship between the type of microplastics and the antibiotics resistance of isolated bacteria. For the antibiotics sensitivity test of norfloxacin, streptomycin, amoxicillin, and chloramphenicol, V. parahaemolyticus have the lower antibiotics resistance than that of V. alginolyticus isolated from the same mangrove microplastics. However, Vibrio isolated from PE has stronger antibiotics resistance. Results reveal that mangrove may be one of the potential risks for emergence and spread of bacterial antibiotics-resistant and multidrug-resistant, and microplastic biofilms may act as promoters of bacterial antibiotic resistance.

The Functional Significance of Hydrophobic Residue Distribution in Bacterial Beta-Barrel Transmembrane Proteins

β-barrel membrane proteins have several important biological functions, including transporting water and solutes across the membrane. They are active in the highly hydrophobic environment of the lipid membrane, as opposed to soluble proteins, which function in a more polar, aqueous environment. Globular soluble proteins typically have a hydrophobic core and a polar surface that interacts favorably with water. In the fuzzy oil drop (FOD) model, this distribution is represented by the 3D Gauss function (3DG). In contrast, membrane proteins expose hydrophobic residues on the surface, and, in the case of ion channels, the polar residues face inwards towards a central pore. The distribution of hydrophobic residues in membrane proteins can be characterized by means of 1–3DG, a complementary 3D Gauss function. Such an analysis was carried out on the transmembrane proteins of bacteria, which, despite the considerable similarities of their super-secondary structure (β-barrel), have highly differentiated properties in terms of stabilization based on hydrophobic interactions. The biological activity and substrate specificity of these proteins are determined by the distribution of the polar and nonpolar amino acids. The present analysis allowed us to compare the ways in which the different proteins interact with antibiotics and helped us understand their relative importance in the development of the resistance mechanism. We showed that beta barrel membrane proteins with a hydrophobic core interact less strongly with the molecules they transport.

A pH-sensitive oxidized-dextran based double drug-loaded hydrogel with high antibacterial properties

Delayed healing or non-healing of wounds caused by bacterial infection is still a difficult medical problem. Nowadays, the topical application of antibiotics is a common treatment for infections. However, subinhibitory concentrations or high dose of antibiotics leads to the antibacterial effect counterproductive. So it's necessary to put forward an on-demand drug delivery to solve this tough issue. In this paper, a pH-responsive hydrogel was prepared by oxidized dextran (Dex-CHO), sulfadiazine (SD) and tobramycin (TOB). The hydrogel was designed by the environment in the early immature stage of biofilm (pH 5.0). Schiff bases can release drugs in slightly acidic environment. The hydrogel showed injectable, pH-sensitive drug release, and great biocompatibility. Released SD and TOB exhibited a synergistic effect therefore the hydrogel showed high antibacterial activity. This study provides an easy and promising strategy to develop smart hydrogels that aim at topical administration of antibiotics and come up with a new treatment of local bacterial infections.