Understanding biofilm in practice: a global survey of health professionals

Breaking membrane barriers to neutralize E. coli and K. pneumoniae virulence with PEGylated branched polyethylenimine

Bacterial infections caused by Gram-negative pathogens, such as those in the family Enterobacteriaceae, are among the most difficult to treat because effective therapeutic options are either very limited or non-existent. This raises serious concern regarding the emergence and spread of multi-drug resistant (MDR) pathogens in the community setting; and thus, creates the need for discovery efforts and/or early-stage development of novel therapies for infections. Our work is directed towards branched polyethylenimine (BPEI) modified with polyethylene glycol (PEG) as a strategy for targeting virulence from Gram-negative bacterial pathogens. Here, we neutralize lipopolysaccharide (LPS) as a barrier to the influx of antibiotics. Data demonstrate that the β-lactam antibiotic oxacillin, generally regarded as ineffective against Gram-negative bacteria, can be potentiated by 600 Da BPEI to kill some Escherichia coli and some Klebsiella pneumoniae. Modification of 600 Da BPEI with polyethylene glycol (PEG) could increase drug safety and improves potentiation activity. The ability to use the Gram-positive agent, oxacillin, against Gram-negative pathogens could expand the capability to deliver effective treatments that simplify, reduce, or eliminate some complicated treatment regimens.

Diagnosis and treatment of infected wounds: A multi-centre audit of current clinical practice across the UK, Ireland and Scandinavia

AIMS AND OBJECTIVES

Surveillance of wound infection including signs of infection alongside antimicrobial usage (types, duration, frequency) can highlight knowledge gaps and inconsistencies. This manuscript aims to highlight these, identify and inform opportunities for practice improvement and to show impact of infection management practice may be having on the issue of antimicrobial resistance.

BACKGROUND

Infected wounds pose challenges to healthcare professionals. Balancing risk of wound deterioration and progression to systemic infection with appropriate use of antimicrobials is necessary to minimise development of resistance.

METHODS

Analysis consisted of a practice survey of 9661 wounds across 70 community sites over a period of one week. Data were collected from projects between 2017 and 2020. The form was available to providers within the UK, Ireland, Norway, Denmark, Sweden and Finland. EQUATOR research guidelines were followed; STROBE checklist for observational research reporting was completed.

RESULTS

Infection rates of 8.9% were reported from wounds assessed. These data indicate inconsistencies with diagnosis across practice with non-specialists more likely to be unsure of wound infection. Greater confidence in infection identification was observed as number of signs increased. Inconsistencies were also observed in appropriate treatment; antimicrobials were used in 35% of wounds considered not infected and not used in 41% of wounds that were identified as infected.

CONCLUSIONS

This investigation of infection management practice of over 9000 wounds provides an insight into diagnosis and treatment of infection. Inconsistencies in diagnosis and treatment of wound infections reported highlight the need for increased education, awareness of diagnosis and treatment of infection.

RELEVANCE TO CLINICAL PRACTICE

Variability in management of infected wounds highlights opportunities to aid more effective diagnosis and treatment of infected wounds. Incorporation of support tools or evidence-based pathways into practice may enhance confidence in management of local infection, balanced with appropriate use, potentially minimising resistance and improving outcomes.

An overview of the prevention and management of wound infection

A wound can be defined as infected when the presence and subsequent proliferation of microorganisms leads to a local or systemic response in an individual. Wound infection is associated with delayed healing, wound chronicity, increased risk of hospital admission, loss of limb or digit and increased healthcare costs. The presence of biofilm is also recognised as a challenge in infected wounds and is associated with chronicity and delays in healing. Identifying and managing wound infection early can contribute to faster wound healing, thus reducing the risk of negative outcomes. This article details the pathophysiology, risk factors and signs and symptoms of wound infection. It also outlines various prevention and management options for wound infection.

Frequency of sharp wound debridement in the management of diabetes-related foot ulcers: exploring current practice

Background

Conservative sharp wound debridement (CSWD) is fundamental to wound bed preparation. Evidence-based practice guidelines strongly recommend frequent CSWD of diabetes-related foot ulcers (DFU) based on expert opinion and observational studies which suggest that more frequent debridement is associated with better healing outcomes.

Aim

To document current practice with regards to CSWD of DFU and whether this is performed at every visit, how often and what factors determine debridement frequency.

Method

Survey data were collected and managed using REDCap electronic data tools, a secure, web-based application. The survey was distributed through podiatry managers and relevant clinical networks between October 2017 and February 2018.

Results

One hundred clinicians opened the survey and seventy-five surveys were completed by n = 53 NSW Health (Australia) employed podiatrists (representing 41% of all NSW Health podiatrists), 11 privately practicing podiatrists, and 11 nurses. Most (n = 47) worked in metropolitan areas versus regional/remote (n = 28). CSWD was the most frequently used debridement method, performed at every visit by most (84%) of podiatrists. Callus, slough and infection presence were the top 3 most important determinants of frequency, with staff time (a limiting factor) ranking 4th. Regional/remote podiatrists practiced less frequent debridement compared with those in metropolitan areas (debridement every 2 weeks or less = 71% regional podiatrists versus 45% metropolitan podiatrists) (p = 0.024).

Conclusion and clinical implications

CSWD was the predominant form of debridement used with debridement occurring at every treatment visit for most of the clinicians surveyed. Debridement frequency was determined by clinical wound indications and staffing resources, with regional/remote podiatrists providing debridement less often than their metropolitan colleagues.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13047-021-00489-1.

PEGylation of Polyethylenimine Lowers Acute Toxicity while Retaining Anti-Biofilm and β-Lactam Potentiation Properties against Antibiotic-Resistant Pathogens

Bacterial biofilms, often impenetrable to antibiotic medications, are a leading cause of poor wound healing. The prognosis is worse for wounds with biofilms of antimicrobial-resistant (AMR) bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), methicillin-resistant S. epidermidis (MRSE), and multi-drug resistant Pseudomonas aeruginosa (MDR-PA). Resistance hinders initial treatment of standard-of-care antibiotics. The persistence of MRSA, MRSE, and/or MDR-PA often allows acute infections to become chronic wound infections. The water-soluble hydrophilic properties of low-molecular-weight (600 Da) branched polyethylenimine (600 Da BPEI) enable easy drug delivery to directly attack AMR and biofilms in the wound environment as a topical agent for wound treatment. To mitigate toxicity issues, we have modified 600 Da BPEI with polyethylene glycol (PEG) in a straightforward one-step reaction. The PEG-BPEI molecules disable β-lactam resistance in MRSA, MRSE, and MDR-PA while also having the ability to dissolve established biofilms. PEG-BPEI accomplishes these tasks independently, resulting in a multifunction potentiation agent. We envision wound treatment with antibiotics given topically, orally, or intravenously in which external application of PEG-BPEIs disables biofilms and resistance mechanisms. In the absence of a robust pipeline of new drugs, existing drugs and regimens must be re-evaluated as combination(s) with potentiators. The PEGylation of 600 Da BPEI provides new opportunities to meet this goal with a single compound whose multifunction properties are retained while lowering acute toxicity.

Overcoming Multidrug Resistance and Biofilms of Pseudomonas aeruginosa with a Single Dual-Function Potentiator of β-Lactams

Clinicians prescribe hundreds of millions of β-lactam antibiotics to treat the majority of patients presenting with bacterial infections. Patient outcomes are positive unless resistant bacteria, such as Pseudomonas aeruginosa (P. aeruginosa), are present. P. aeruginosa has both intrinsic and acquired antibiotic resistance, making clinical management of infection a real challenge, particularly when these bacteria are sequestered in biofilms. These problems would be alleviated if, upon the initial presentation of bacterial infection symptoms, clinicians were able to administer an antibiotic that kills both susceptible and otherwise resistant bacteria and eradicates biofilms. As the most common class of antibiotics, β-lactams could be used in a new drug if the leading causes of β-lactam antibiotic resistance, permeation barriers from lipopolysaccharide, efflux pumps, and β-lactamase enzymes, were also defeated. Against P. aeruginosa and their biofilms, the potency of β-lactam antibiotics is restored with 600 Da branched polyethylenimine (600 Da BPEI). Checkerboard assays using microtiter plates demonstrate the potentiation of piperacillin, cefepime, Meropenem, and erythromycin antibiotics. Growth curves demonstrate that only a combination of 600 Da BPEI and piperacillin produces growth inhibition against antibiotic resistant P. aeruginosa. Scanning electron microscopy (SEM) was used to confirm that the combination treatment leads to abnormal P. aeruginosa morphology. Data collected with isothermal titration calorimetry and fluorescence spectroscopy demonstrate a mechanism of action in which potentiation at low concentrations of 600 Da BPEI reduces diffusion barriers from lipopolysaccharides without disrupting the outer membrane itself. Coupled with the ability to overcome a reduction in antibiotic activity created by biofilm exopolymers, targeting anionic sites on lipopolysaccharides and biofilm exopolysaccharides with the same compound provides new opportunities to counter the rise of multidrug-resistant infections.

Improving the quality of clinical research on chronic wound infection treatment: expert-based recommendations

OBJECTIVE:

To produce recommendations for the design of reliable and informative clinical investigations in chronic wound infection.

METHOD:

A multidisciplinary panel of international experts from four countries (Italy, UK, Ireland and the US) were involved in a detailed, semi-structured discussion on how to better select and describe a target population, interventions and outcomes, and which infection-related criteria to apply in order to achieve a high-quality trial. Consent among the experts was measured using the Delphi method and GRADE Working Group suggestions. The project was fully supported by AISLeC 2016 (Italian Nursing Society for Wound Care Study).

RESULTS:

In total, 37 recommendations achieved substantial agreement among the experts; 10 concerned the most appropriate description and selection of a target population, four related to interventions and 15 to outcomes. A further eight statements about critical methodological points were approved.

CONCLUSION:

Developing recommendations in a systematic manner through a representative group of experts could generate tools for improving the design of clinical trials in this challenging area.

The role of the microbiome in nonhealing diabetic wounds

Wound healing is a highly coordinated and complex process, and there can be devastating consequences if it is interrupted. It is believed that, in combination with host factors, microorganisms in a wound bed can not only impair wound healing but can lead to stalled, chronic wounds. It is hypothesized that the wound microbiota persists in chronic wounds as a biofilm, recalcitrant to antibiotic and mechanical intervention. Cultivation-based methods are the gold standard for identification of pathogens residing in wounds. However, these methods are biased against fastidious organisms, and do not capture the full extent of microbial diversity in chronic wounds. Thus, the link between specific microbes and impaired healing remains tenuous. This is partially because local infection and, more specifically, the formation of a biofilm, is difficult to diagnose. This has led to research efforts aimed at understanding if biofilm formation delays healing and leads to persistent and chronic infection. Circumventing challenges associated with culture-based estimations, advances in high-throughput sequencing analysis has revealed that chronic wounds are host to complex, diverse microbiomes comprising multiple species of bacteria and fungi. Here, we discuss how the use of genomic methodologies to study wound microbiomes has advanced the current understanding of infection and biofilm formation in chronic wounds.