Individualized antibiotic strategies

Double-Network Hydrogel with Strengthened Mechanical Property for Controllable Release of Antibacterial Peptide

Developing double-network (DN) hydrogels with high mechanical properties and antibacterial efficacy to combat multidrug-resistant bacterial infections and serve as scaffolds for cell culture still remains an ongoing challenge. In this study, an ion-responsive antibacterial peptide (AMP) (C16-WIIIKKK, termed as IK7) was synergistically combined with a photoresponsive gelatin methacryloyl (GelMA) polymer to fabricate a biocompatible DN hydrogel. The GelMA-IK7 DN hydrogel showed enhanced mechanical properties in contrast to the individual IK7 and GelMA hydrogels and demonstrated substantial antibacterial efficacy. Further investigations revealed that the DN hydrogel effectively inhibited bacterial growth by the controlled and sustained release of the IK7 peptide. In addition, the formation of the DN hydrogel was also found to protect AMP IK7 from rapid degradation by proteinase K. Our findings suggested that the developed GelMA-IK7 DN hydrogel holds great potential for next-generation antibacterial hydrogels for three-dimensional cell culture and tissue regeneration.

The Recent Progress of the Cellulose-Based Antibacterial Hydrogel

Cellulose-based antibacterial hydrogel has good biocompatibility, antibacterial performance, biodegradability, and other characteristics. It can be very compatible with human tissues and degradation, while its good water absorption and moisturizing properties can effectively absorb wound exudates, keep the wound moist, and promote wound healing. In this paper, the structural properties, and physical and chemical cross-linking preparation methods of cellulose-based antibacterial hydrogels were discussed in detail, and the application of cellulose-based hydrogels in the antibacterial field was deeply studied. In general, cellulose-based antibacterial hydrogels, as a new type of biomaterial, have shown good potential in antimicrobial properties and have been widely used. However, there are still some challenges, such as optimizing the preparation process and performance parameters, improving the antibacterial and physical properties, broadening the application range, and evaluating safety. However, with the deepening of research and technological progress, it is believed that cellulose-based antibacterial hydrogels will be applied and developed in more fields in the future.

Advances in preparation and application of antibacterial hydrogels

Bacterial infections, especially those caused by drug-resistant bacteria, have seriously threatened human life and health. There is urgent to develop new antibacterial agents to reduce the problem of antibiotics. Biomedical materials with good antimicrobial properties have been widely used in antibacterial applications. Among them, hydrogels have become the focus of research in the field of biomedical materials due to their unique three-dimensional network structure, high hydrophilicity, and good biocompatibility. In this review, the latest research progresses about hydrogels in recent years were summarized, mainly including the preparation methods of hydrogels and their antibacterial applications. According to their different antibacterial mechanisms, several representative antibacterial hydrogels were introduced, such as antibiotics loaded hydrogels, antibiotic-free hydrogels including metal-based hydrogels, antibacterial peptide and antibacterial polymers, stimuli-responsive smart hydrogels, and light-mediated hydrogels. In addition, we also discussed the applications and challenges of antibacterial hydrogels in biomedicine, which are expected to provide new directions and ideas for the application of hydrogels in clinical antibacterial therapy.

Functionalization and Antibacterial Applications of Cellulose-Based Composite Hydrogels

Pathogens, especially drug-resistant pathogens caused by the abuse of antibiotics, have become a major threat to human health and public health safety. The exploitation and application of new antibacterial agents is extremely urgent. As a natural biopolymer, cellulose has recently attracted much attention due to its excellent hydrophilicity, economy, biocompatibility, and biodegradability. In particular, the preparation of cellulose-based hydrogels with excellent structure and properties from cellulose and its derivatives has received increasing attention thanks to the existence of abundant hydrophilic functional groups (such as hydroxyl, carboxy, and aldehyde groups) within cellulose and its derivatives. The cellulose-based hydrogels have broad application prospects in antibacterial-related biomedical fields. The latest advances of preparation and antibacterial application of cellulose-based hydrogels has been reviewed, with a focus on the antibacterial applications of composite hydrogels formed from cellulose and metal nanoparticles; metal oxide nanoparticles; antibiotics; polymers; and plant extracts. In addition, the antibacterial mechanism and antibacterial characteristics of different cellulose-based antibacterial hydrogels were also summarized. Furthermore, the prospects and challenges of cellulose-based antibacterial hydrogels in biomedical applications were also discussed.

Paeoniflorin Derivative in Paeoniae Radix Aqueous Extract Suppresses Alpha-Toxin of Staphylococcus aureus

The emergence and dissemination of bacterial infections is paralyzing our public health systems worldwide. Worse still, there are no effective antibiotics against bacterial toxins, which facilitate the infection. Natural herbs that target bacterial toxins may be a better choice for therapy of infectious diseases. However, most natural drugs present unknown compositions and unclear mechanisms. Here we demonstrated that the Chinese herb Paeoniae Radix aqueous extract (PRAE) could suppress alpha-toxin (α-toxin) of Staphylococcus aureus. We observed that the paeoniflorin derivative (PRAE-a) derivative in PRAE significantly abolished the hemolytic activity of S. aureus α-toxin. The analyses of high-performance liquid chromatography (HPLC), mass spectrometer (MS), Fourier transform infrared spectrometer (FTIR), and nuclear magnetic resonance (NMR) showed that PRAE-a was a glycoside compound with a paeoniflorin nucleus. We further found that PRAE-a disrupted the pore-forming ability of α-toxin by prevention of the dimer to heptamer. Therefore, PRAE-a proved to be an effective therapy for S. aureus lung infections in mice by inhibiting α-toxin. Collectively, these results highlighted that PRAE-a can be used as an antibacterial agent to attenuate S. aureus virulence by targeting α-toxin.

Individualized antibiotic therapy in the treatment of severe infections

Introduction: Sepsis is a frequent and life-threatening clinical entity and antibiotic treatment is one of the most important interventions, together with source control and hemodynamic resuscitation. Guidelines have highlighted the importance of an early (i.e. within 1-3 h from recognition) and appropriate (i.e. the pathogen is sensitive in vitro to the administered drug) antimicrobial therapy in this setting.Areas covered: Antibiotic therapy should be individualized according to several issues, including early pathogen identification, optimal drug regimens based on pharmacokinetic/pharmacodynamics (PK/PD) and adequate duration using both clinical and biological biomarkers. This narrative review has considered the most relevant studies evaluating these issues.Expert opinion: Rapid identification pathogen resistance profile (i.e. the minimal inhibitory concentration for the available antimicrobials), real-time measurement of drug concentrations with regimen adjustment on MIC and daily measurement of procalcitonin to guide duration of therapy are the main issues to individualize the antibiotic management in critically ill patients.

Control of Gram-negative multi-drug resistant microorganisms in an Italian ICU: Rapid decline as a result of a multifaceted intervention, including conservative use of antibiotics

BACKGROUND

Gram-negative Multi-Drug-Resistant Organisms (GNMDROs) cause an increasing burden of disease in Intensive Care Units (ICUs). We deployed a multifaceted intervention to control selection and transmission of GNMDROs and to estimate at which rate GNMDROs would decline with our interventional bundle.

METHODS

Interventions implemented in 2015: in-ward Antimicrobial-Stewardship-Program for appropriate management of antimicrobial prescription; infection monitoring with nasal/rectal swabs and repeated procalcitonin assays; 24 h microbiological support (since 2016); prevention of catheter-related infections, VAPs and in-ward GNMDROs transmission; education of ICU personnel. In May 2017, epidemiological, clinical and microbiological data were collected and retrospectively analyzed. Rates of resistance in Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii, as well as percentages of resistance among all Gram-negative bacteria were compared during the study period.

RESULTS

Of 668 patients, at least one isolate was obtained from 399 patients. The proportions of patients with infection and with Gram-negative isolates were even across the 5 semesters (p = 0.8). For Klebsiella pneumoniae, the number of strains resistant to carbapenems fell from 94% to 6% (p < 0.001). Significant drops were also observed for Pseudomonas aeruginosa and Acinetobacter baumannii. Percentages of resistance for all Gram-negative isolates fell from 91% to 13% (p < 0.0001). The reduction in antibiotic prescription translated in a considerable reduction of pharmacy costs. Multivariate models confirmed that the hospitalization semester was the most relevant independent predictor of resistance among Gram-negative bacteria.

CONCLUSIONS

Our experience provides further evidence that a multi-faceted intervention, aimed to reduce selection and transmission of GNMDROs with efficient microbiological support, may yield remarkable results in a short time interval.

Design of polymer-based antimicrobial hydrogels through physico-chemical transition

The antimicrobial activity represents a cornerstone in the development of biomaterials: it is a leading request in many areas, including biology, medicine, environment and industry. Over the years, different polymeric scaffolds are proposed as solutions, based on the encapsulation of metal ions/particles, antibacterial agents or antibiotics. However, the compliance with the biocompatibility criteria and the concentration of the active principles to avoid under- and over-dosing are being debated. In this work, we propose the synthesis of a versatile hydrogel using branched polyacrylic acid (carbomer 974P) and aliphatic polyetherdiamine (elastamine®) through physico-chemical transition, able to show its ability to counteract the bacterial growth and infections thanks to the polymers used, that are not subjected to further chemical modifications. In particular, the antimicrobial activity is clearly demonstrated against Staphyloccoccus aureus and Candida albicans, two well-known opportunistic pathogens. Moreover, we discuss the hydrogel use as drug carrier to design a unique device able to combine the antibacterial/antimicrobial properties to the controlled drug delivery, as a promising tool for a wide range of biomedical applications.

Use of microdialysis for the assessment of fluoroquinolone pharmacokinetics in the clinical practice

Antibacterial drugs, including fluoroquinolones, can exert their therapeutic action only with adequate penetration at the infection site. Multiple factors, such as rate of protein binding, drug liposolubility and organ blood-flow all influence ability of antibiotics to penetrate target tissues. Microdialysis is an in vivo sampling technique that has been successfully applied to measure the distribution of fluoroquinolones in the interstitial fluid of different tissues both in animal studies and clinical setting. Tissue concentrations need to be interpreted within the context of the pathogenesis and causative agents implicated in infections. Integration of microdialysis -derived tissue pharmacokinetics with pharmacodynamic data offers crucial information for correlating exposure with antibacterial effect. This review explores these concepts and provides an overview of tissue concentrations of fluoroquinolones derived from microdialysis studies and explores the therapeutic implications of fluoroquinolone distribution at various target tissues.

Management of community-acquired pneumonia in immunocompetent adults: updated Swedish guidelines 2017

Based on expert group work, Swedish recommendations for the management of community-acquired pneumonia in adults are here updated. The management of sepsis-induced hypotension is addressed in detail, including monitoring and parenteral therapy. The importance of respiratory support in cases of acute respiratory failure is emphasized. Treatment with high-flow oxygen and non-invasive ventilation is recommended. The use of statins or steroids in general therapy is not found to be fully supported by evidence. In the management of pleural infection, new data show favourable effects of tissue plasminogen activator and deoxyribonuclease installation. Detailed recommendations for the vaccination of risk groups are afforded.

Clinical on-site monitoring of ß-lactam antibiotics for a personalized antibiotherapy

An appropriate antibiotherapy is crucial for the safety and recovery of patients. Depending on the clinical conditions of patients, the required dose to effectively eradicate an infection may vary. An inadequate dosing not only reduces the efficacy of the antibiotic, but also promotes the emergence of antimicrobial resistances. Therefore, a personalized therapy is of great interest for improved patients' outcome and will reduce in long-term the prevalence of multidrug-resistances. In this context, on-site monitoring of the antibiotic blood concentration is fundamental to facilitate an individual adjustment of the antibiotherapy. Herein, we present a bioinspired approach for the bedside monitoring of free accessible ß-lactam antibiotics, including penicillins (piperacillin) and cephalosporins (cefuroxime and cefazolin) in untreated plasma samples. The introduced system combines a disposable microfluidic chip with a naturally occurring penicillin-binding protein, resulting in a high-performance platform, capable of gauging very low antibiotic concentrations (less than 6 ng ml^-1) from only 1 µl of serum. The system's applicability to a personalized antibiotherapy was successfully demonstrated by monitoring the pharmacokinetics of patients, treated with ß-lactam antibiotics, undergoing surgery.

Individualized antibiotic therapy in patients with ventilator-associated pneumonia

The optimal duration of the treatment of ventilator-associated pneumonia (VAP) is still the subject of debate. While 1 week treatment has been reported as possibly sufficient, patients generally receive antibiotic therapy for 10 to 14 days. The purpose of our study was to investigate whether length of treatment in patients with VAP can be reduced with an individualized therapeutic strategy. The study was performed prospectively with patients diagnosed with VAP in our hospital's intensive care units between 1 January and 31 December 2015. Duration of antibiotic therapy was determined with 5 day clinical evaluation according to previously established criteria. Patients were divided into two groups depending on length of treatment, short (7-10 days) and long treatment (>10 days). Nineteen patients received 7 to 10 day antibiotic therapy, and 30 received >10 day antibiotic therapy. Demographic and clinical characteristics, Glasgow Coma Scale score, CPIS and the PaO2/FiO2 ratio at the time of diagnosis of VAP were statistically similar between the two groups (P>0.05). A second VAP attack occurred post-treatment in three patients receiving short-term treatment and in four receiving long-term treatment (P=0.561). The numbers of antibiotic-free days were 15.6±6.2 in the short-term treatment group and 8.3±7.5 in the long-term group (P<0.0001). One of the patients receiving short-term treatment died within 28 days after treatment, and four of the patients receiving long-term treatment (P=0.348) did so. The most commonly observed micro-organisms in both groups were Acinetobacterbaumannii and Pseudomonasaeruginosa. Short-term treatment can be administered in cases with early clinical and laboratory response started on VAP treatment by considering individual characteristics and monitoring fever, CPIS, the PaO2/FiO2 ratio, C-reactive protein and procalcitonin values.

Electrophoretic stacking for sensitive determination of antibiotic ceftazidime in human blood and microdialysates from diabetic foot

An electrophoretic stacking method has been developed for monitoring the therapeutic level of the antibiotic ceftazidime in blood plasma and microdialysates taken from peripheral soft tissues of the lower limbs of patients with diabetic foot syndrome. The biological samples are treated by addition of acetonitrile in an amount of 75% v/v and injected into a capillary in a large volume; after turning on the separation voltage, the residual acetonitrile is forced out of the capillary by the application of hydrodynamic pressure. The clinical samples were separated in an optimised background electrolyte composed of 50 mM chloroacetic acid +20% v/v methanol +0.5% v/v INST coating solution. The attained LOD for ceftazidime equalled 0.42 μg mL^-1 (0.8 μM) and the migration time equalled 3.75 min when using a 25 μm capillary with minimum length of 31.5 cm. The separation was controlled by a maximum voltage of +30 kV and the movement of the analyte was accelerated by a pressure of 50 mbar. The RSD values for intra-day repeatability of the migration time and peak area are 0.14% and 3.8%, respectively; the inter-day values equalled 0.25% for the migration time and 7.3% for peak area, respectively. Pharmacological studies revealed that ceftazidime passes from the blood circulation to the peripheral tissues of the lower limbs with an efficiency of 20%. The introduction of CE control of ceftazidime level in diabetic foot represents a very important improvement in achieving the targeted therapeutic effect.