Ulcer bed infection

Formulation of water-soluble Buddleja globosa Hope extracts and characterization of their antimicrobial properties against Pseudomonas aeruginosa

Buddleja globosa Hope (BG) extracts are traditionally used to treat skin and gastric ulcers due to their healing properties. Non-aqueous solvents such as ethanol and DMSO are usually used to extract naturally occurring compounds. However, the cytotoxicity of these solvents and the low water solubility of the extracted compounds can hinder their biomedical applications. To overcome the limited solubility of the BG extracts, we aimed to enhance the solubility by processing a standardized hydroalcoholic extract (BG-126) through spray drying (SD), with and without two solubility enhancers. Spray-dried BG (BG-SD) extracts and spray-dried BG extracts plus polyvinylpyrrolidone (BG-SD PVP) and Soluplus® (BG-SD SP) were developed starting from BG-126 (containing 53% ethanol). These four formulations were characterized by total phenolic content, water solubility at 25°C and 37°C, and antimicrobial properties against Pseudomonas aeruginosa. All the SD formulations presented a solubility that allowed them to reach maximum concentrations of 1,024 μg/ml catechin for BG-SD and 2,048 μg/ml catechin for BG-SD PVP and BG-SD SP for antimicrobial testing. BG-SD showed the highest antimicrobial potency with a minimum inhibitory concentration (MIC) of 512 μg/ml catechin, followed by BG-126 with a MIC of 1,024 μg/ml catechin and SP. BG-126 was also shown to inhibit biofilm formation, as well as the excipients PVP and SP. The spray-dried BG (BG-SD) extract represents a promising natural active component with enhanced antimicrobial properties against P. aeruginosa for further research and the development of novel phytopharmaceuticals.

A Novel In Vitro Method to Assess the Microbial Barrier Function of Tissue Adhesives Using Bioluminescence Imaging Technique

Background. Tissue glues can minimize treatment invasiveness, mitigate the risk of infection, and reduce surgery time; ergo, they have been developed and used in surgical procedures as wound closure devices beside sutures, staples, and metallic grafts. Regardless of their structure or function, tissue glues should show an acceptable microbial barrier function before being used in humans. This study proposes a novel in vitro method using Escherichia coli Lux and bioluminescence imaging technique to assess the microbial barrier function of tissue glues. Different volumes and concentrations of E. coli Lux were applied to precured or cured polyurethane-based tissue glue placed on agar plates. Plates were cultured for 1 h, 24 h, 48 h, and 72 h with bioluminescence signal measurement subsequently. Herein, protocol established a volume of 5 μL of a 1 : 100 dilution of E. coli Lux containing around 2 × 10⁷ CFU/mL as optimal for testing polyurethane-based tissue glue. Measurement of OD_600nm, determination of CFU/mL, and correlation with the bioluminescence measurement in p/s unit resulted in a good correlation between CFU/mL and p/s and demonstrated good reproducibility of our method. In addition, this in vitro method could show that the tested polyurethane-based tissue glue can provide a reasonable barrier against the microbial penetration and act as a bacterial barrier for up to 48 h with no penetration and up to 72 h with a low level of penetration through the material. Overall, we have established a novel, sensitive, and reproducible in vitro method using the bioluminescence imaging technique for testing the microbial barrier function of new tissue glues.

Changes of Mineralogical Properties and Biological Activities of Gypsum and Its Calcined Products with Different Phase Structures

Raw gypsum (RG) and calcined gypsum (CG) are widely used in traditional Chinese medicine (TCM). RG is usually taken orally to resolve heat and diminish inflammation, while CG is only used externally to treat ulcerations and empyrosis. Calcination at different temperatures, three phase CG structures, namely, bassanite, anhydrite III, and anhydrite II, may be generated. We herein investigated the relationship between the phase structure and the efficacy of CG and the optimum phase structure for CG. RG has a compact structure, small pore size, weak anti-inflammatory effect, but no antibacterial effect, and has almost no effect on the repair of scalds. CG150 (bassanite) has a loose texture, large pore size and specific surface area, and certain antibacterial and anti-inflammatory effects, but it has a poor repair effect on scalds. CG750 (anhydrite II) has a compact structure, small pore size and specific surface area, and low antibacterial and anti-inflammatory effects, but it has a certain repair effect on scalds. Only CG350 (anhydrite III) has good performance in texture, pore size, specific surface area, antibacterial, anti-inflammatory, and scald repair. Our research has proved that the mineral properties and biological activities of CG are different due to different phase structures. CG350, namely, anhydrite III, is considered by our research to be the optimal phase structure as CG.

Microbiology of secondary infections in Buruli ulcer lesions; implications for therapeutic interventions

Background

Buruli ulcer (BU) is a skin disease caused by Mycobacterium ulcerans and is the second most common mycobacterial disease after tuberculosis in Ghana and Côte d’Ivoire. M. ulcerans produces mycolactone, an immunosuppressant macrolide toxin, responsible for the characteristic painless nature of the infection. Secondary infection of ulcers before, during and after treatment has been associated with delayed wound healing and resistance to streptomycin and rifampicin. However, not much is known of the bacteria causing these infections as well as antimicrobial drugs for treating the secondary microorganism. This study sought to identify secondary microbial infections in BU lesions and to determine their levels of antibiotic resistance due to the prolonged antibiotic therapy required for Buruli ulcer.

Results

Swabs from fifty-one suspected BU cases were sampled in the Amansie Central District from St. Peters Hospital (Jacobu) and through an active case surveillance. Forty of the samples were M. ulcerans (BU) positive. Secondary bacteria were identified in all sampled lesions (N = 51). The predominant bacteria identified in both BU and Non-BU groups were Staphylococci spp and Bacilli spp. The most diverse secondary bacteria were detected among BU patients who were not yet on antibiotic treatment. Fungal species identified were Candida spp, Penicillium spp and Trichodema spp. Selected secondary bacteria isolates were all susceptible to clarithromycin and amikacin among both BU and Non-BU patients. Majority, however, had high resistance to streptomycin.

Conclusions

Microorganisms other than M. ulcerans colonize and proliferate on BU lesions. Secondary microorganisms of BU wounds were mainly Staphylococcus spp, Bacillus spp and Pseudomonas spp. These secondary microorganisms were less predominant in BU patients under treatment compared to those without treatment. The delay in healing that are experienced by some BU patients could be as a result of these bacteria and fungi colonizing and proliferating in BU lesions. Clarithromycin and amikacin are likely suitable drugs for clearance of secondary infection of Buruli ulcer.

Effects of Silver Nanoparticles on Burn Wound Healing in a Mouse Model

Healing of injuries caused by exposure to heat has been discussed in many studies, although a few drugs have been shown to produce satisfactory results. In this study, 100 healthy mice randomly allocated into four categories (each = 25 mice) were analyzed. A deep second-degree burn on the back of each mouse was created. The burns were dressed daily with either AgNPs or silver sulfadiazine over 28 days of treatment. Safety evaluation of the AgNP treatment was performed by measuring the deposition rate of silver in the liver, brain, and kidney of treated mice. In the murine burn model, the speed of wound healing and the antibacterial effect of AgNPs were better than those in the silver sulfadiazine group. Burn wounds treated with SSD appeared to display a greater degree of inflammation as notable by the three clinical signs of the inflammatory process such as redness and swelling which appeared to be less after wounds treated with AgNPs. Also, AgNP treatment modified leukocytic infiltration and reduced collagen degeneration in treated mice and enhanced healing processes that were confirmed by morphological and histological investigations. Beside the potential significant effects of AgNPs on reduction of some microorganism counts that routinely isolated from burn wounds included aerobic organisms as Staphylococcus aureus and Escherichia coli when compared to both SSD and control groups. The deposition kinetics of AgNPs revealed lower distribution in the liver, brain, and kidney than that in silver sulfadiazine-treated mice with respect to both SSD and control groups.

The diagnosis of infection in chronic leg ulcers: A narrative review on clinical practice

This literature review aimed to provide a narrative review of evidence on validity of clinical and microbial indicators of infection and to gain insights into the diagnosis of infection in chronic leg ulcers (CLUs). A search was conducted in Cinahl, Medline, the Cochrane Library databases, Embase, Web of Science, ScienceDirect, Pubmed, PsycINFO, ProQuest dissertations, and Google Scholar from January 1990 to July 2017. The inclusion criteria were original studies, systematic reviews, and consensus documents focused on "infection" in CLUs, English language, clinical and community settings, and human. The reviewed studies were inconsistent in criteria for infection between investigated wound types and lack of specificity regarding wound types. There were few studies investigating the criteria for diagnosis of infection in leg ulcers. The identification of leg ulcer infection still remains problematic and relies on out-of-date and not uniform evidence. Literature in this area was mostly limited to level III and IV evidence based on The Australian National Health and Medical Research Council Levels of Evidence, or expert opinion. This literature review showed seven clinical signs and symptoms that could be diagnostic for infection in CLUs, including: new, increased, or altered ulcer pain; malodour; increased ulcer area; wound breakdown, delayed or non-healing; and erythema and increased local temperature, whilst the microbial indicators used to diagnose infected leg ulcers were varied and regarded as less important.

Cellulitis in Venous Leg Ulcers Treated with a Hydrocolloid Dressing

Objective:

To evaluate the development of cellulitis in patients with venous leg ulcers in relation to colonizing or infecting microorganisms and principles of ulcer dressing.

Design:

Patients were prospectively randomized to either a routine leg ulcer dressing principle or hydrocolloid dressing (HCD).

Setting:

Tertiary care university hospital.

Patients:

Fifty-seven consecutive patients followed for at least 6 months.

Main outcome measures:

Development of cellulitis related to isolation of microorganisms and the ulcer dressing principle.

Results:

Development of cellulitis was only correlated to the isolation of haemolytic streptococci, predominantly belonging to Lancefield group G (2 p < 0.01). Staphylococcus aureus and Pseudomonas aeruginosa did not contribute to the development of cellulitis. One infection per 198 days was found in patients treated with HCD compared with one infection per 290 days in patients treated with chlorhexidine ointment with a vehicle of carbowax polyethylene glycol (not statistically different).

Conclusions:

Hydrocolloid dressing treatment was safe. Cellulitis was caused by haemolytic streptococci.

Venous Leg Ulcer Healing: A Randomized Prospective Study of Long-Stretch versus Short-Stretch Compression Bandages

Objective:

To compare the efficacy of a long-stretch bandage with that of a short-stretch compression bandage.

Design:

Prospective evaluation of healing of venous leg ulcers in blindly randomized groups of patients.

Setting:

Bispebjerg Hospital, Copenhagen, Denmark.

Patients:

Forty-three patients with venous leg ulcers were included. Forty legs in 40 patients were evaluated at 1 month (34 patients), 6 months (32 patients) or 12 months (27 patients).

Interventions:

Both types of bandage were used at a width of 10 cm and applied using the same spiral bandaging technique.

Main outcome measures:

Ulcer healing and ulcer area reduction.

Results:

Healed ulcers after 1 month were observed in 27% of the long-stretch group and in 5% of the short-stretch group ( p = 0.15); after 6 months the corresponding figures were 50% and 36% ( p = 0.49) and after 12 months 71% and 30% ( p = 0.06). Using life-table analysis the predicted healing rate in the long-stretch group after 12 months was 81% and for the short-stretch group 31% ( p = 0.03). The mean of relative ulcer areas at 1 month was 0.45 for the long-stretch group and 0.72 for the short-stretch group ( p = 0.07), at 6 months the corresponding figures were 0.81 and 0.60 ( p = 0.25) and at 12 months 0.25 and 0.95 ( p = 0.01).

Conclusions:

The present study appears to indicate a Positive influence of the elasticity of a compression bandage on venous ulcer healing.

Assessment of bacterial infection in chronic wounds in the elderly: biopsy versus VERSAJET

AIM

The aim of this study was to evaluate the hydro-surgery VERSAJET system as a suitable alternative to the traditional invasive tissue sampling technique in detecting bacteria and their load in chronic wounds in the elderly.

MATERIALS AND METHODS

To investigate and evaluate bacterial incidence and load in chronic wounds, we simultaneously performed on 19 affected patients a deep tissue biopsy and tissue collections by the VERSAJET hydro-surgical system. After local cleaning and anesthesia, a deep biopsy was performed with a punch of 3-4 mm in diameter. Subsequently, three tissue samples were collected by the VERSAJET system: one from the first washing in order to investigate the superficial contamination; one from the second washing to investigate deep tissue infection investigation and one from the third washing as a control procedure. After treatment, all tissue samples were cultured in vitro for diagnostic and micro-biological assessment.

RESULTS

Nineteen patients with chronic wounds of the lower limbs were enrolled from February 2010 to May 2013. Concordance between deep tissue biopsy cultures and tissue cultures collected by the VERSAJET system was examined. The deep tissue biopsy cultures showed complete concordance with the VERSAJET as follows: 2 patients (11%) for the first washing sample; 10 patients (53%) for the second washing sample; 4 patients (21%) for the third washing sample. However, with reference to only aerobic isolated strains, the concordance of the VERSAJET second washing samples cultures with a biopsy of the deep tissue cultures was very high (84%) and fairly high (63%) in the anaerobic isolated strains. The second VERSAJET washing sample cultures seem to have the highest concordance with the biopsy of the deep tissue cultures.

CONCLUSIONS

Tissue biopsy remains the leading technique for detecting bacteria and their load in chronic wounds. However, this study shows that the hydro-surgery VERSAJET system is sufficiently effective in detecting bacteria and their load in chronic wounds and can be a potential alternative to a biopsy. In particular, the second washing sample culture showed the best correlation with the deep tissue biopsy culture. However, further studies are needed in order to modify techniques of tissue collection in the VERSAJET system before drawing any conclusions.

The clinical efficacy of two semi-quantitative wound-swabbing techniques in identifying the causative organism(s) in infected cutaneous wounds

A prospective randomised controlled trial of two paired wound-swabbing techniques (Levine versus Z) was conducted to establish which method was more effective in determining the presence of bacteria in clinically infected wounds. The Levine technique involves rotating the wound swab over a 1-cm(2) area of the wound; the Z technique involves rotating the swab between the fingers in a zigzag fashion across the wound without touching the wound edge. Fifty patients were recruited into the study with acute (42%) and chronic wounds (58%). Overall, the Levine technique detected significantly more organisms than the Z technique (P≤ 0· 001). When acute and chronic wounds were analysed separately, the Levine technique again detected more organisms in both acute (P≤ 0· 001) and chronic wounds (P≤ 0· 001). We conclude that the Levine technique is superior to the Z technique and this result may be because of the Levine technique's ability to express fluid from the wound bed and thereby sampling a greater concentration of microorganisms from both the surface and slightly below the surface of the wound.

Biofilms and bacterial imbalances in chronic wounds: anti-Koch

Microbial imbalances and synergistic relationships between bacteria in medically important biofilms are poorly researched. Consequently, little is known about how synergy between bacteria may increase the net pathogenic effect of a biofilm in many diseases and infections, including chronic wounds. Microbial synergy in chronic wounds may increase virulence and pathogenicity, leading to enhanced tissue degradation, malodour and in some cases, an impairment of the host immune response. Microbial synergy and growth within a biofilm provide a competitive advantage to the microorganisms cohabiting in a wound, thereby promoting their survival and tolerance and resistance to antimicrobial agents. The aim of this article was to provide greater insight into microbial imbalances found within wound biofilms and the significance they may have on non healing and infected wounds. We also present two possible hypotheses which could explain the role microorganisms play in non healing chronic wounds and offer possible strategies for combating harmful and detrimental biofilms.

Wound microbiology and associated approaches to wound management

The majority of dermal wounds are colonized with aerobic and anaerobic microorganisms that originate predominantly from mucosal surfaces such as those of the oral cavity and gut. The role and significance of microorganisms in wound healing has been debated for many years. While some experts consider the microbial density to be critical in predicting wound healing and infection, others consider the types of microorganisms to be of greater importance. However, these and other factors such as microbial synergy, the host immune response, and the quality of tissue must be considered collectively in assessing the probability of infection. Debate also exists regarding the value of wound sampling, the types of wounds that should be sampled, and the sampling technique required to generate the most meaningful data. In the laboratory, consideration must be given to the relevance of culturing polymicrobial specimens, the value in identifying one or more microorganisms, and the microorganisms that should be assayed for antibiotic susceptibility. Although appropriate systemic antibiotics are essential for the treatment of deteriorating, clinically infected wounds, debate exists regarding the relevance and use of antibiotics (systemic or topical) and antiseptics (topical) in the treatment of nonhealing wounds that have no clinical signs of infection. In providing a detailed analysis of wound microbiology, together with current opinion and controversies regarding wound assessment and treatment, this review has attempted to capture and address microbiological aspects that are critical to the successful management of microorganisms in wounds.

Models for use in wound healing research: a survey focusing on in vitro and in vivo adult soft tissue

Many different factors must be considered before selecting a wound healing model to use for a specific study. A wide variety of models have been developed that examine different aspects of the repair response, both in vitro and in vivo. In this review article, we focus on those systems that are most widely used for studies on adult soft tissue healing. Advantages and disadvantages of each are discussed, along with relevant background information to help guide decision-making.