Citric acid treatment of severe electric burns complicated by multiple antibiotic resistant Pseudomonas aeruginosa

The efficacy and safety of acids as topical antimicrobial agents: a review

OBJECTIVE

Infected wounds, refractory to conventional therapy, are a major burden on the healthcare system. Available data show that many commonly used antiseptic agents may be toxic to the cells involved in the healing process and may affect the normal tissue repair. The topical use of different acids to control wound infections effectively and promote healing is well known. The present review aims to summarise the safety and efficacy of various acids as topical agents for treating wound infections.

METHOD

A literature search was performed in PubMed and manually from other sources (cross references and journal sites).

RESULTS

We reviewed 116 articles, from which data from 86 relevant articles were analysed. The studies showed that various organic acids were clinically effective in treating wound infections.

CONCLUSION

This study found that various organic acids can act as a substitute for antiseptics to control wound infections refractory to conventional antibiotic therapy and local wound care. Various organic acids differ in efficacy, safety and limitations as topical agents to control wound infections and promote healing. Some acids deliver better results than others, particularly in those cases in which antibiotics and routine antiseptic agents yield little lasting success, especially in controlling hospital strains with multiple antibiotic resistance. Among topically used acids, citric acid and acetic acid are associated with better results.

The Acid-Buffered Engineered Gel Promotes In Vitro Cutaneous Healing and Fights Resistant Bacteria in Wounds

Background: Treatment of cutaneous wound infections is becoming a major clinical challenge due to the growing problem of antimicrobial resistance associated with existing wound treatments. Two prevalent pathogens in wound infections, Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa), continue to present a serious challenge, underscoring the critical need for new therapeutic alternatives. Methods: Novel alginate acid-buffered gels (ABF-1, ABF-2, and ABF-3) were developed using a combination of organic acids in various concentrations and buffered at a pH of 4.5. The acid-buffering capacity of the gels was evaluated against sodium hydroxide solution and simulated wound fluid (SWF) at different wound pHs, mimicking infected and non-infected wound environments. The in vitro antibacterial activity was assessed against resistant bacterial strains (Gram-positive and Gram-negative) using a microdilution method and wound biofilm assay. The rheological properties and cell viability of the gels were evaluated and the gel showing positive cell viability was further investigated for healing ability using an in vitro wound scratch assay. Results: The gels showed promising in vitro antibacterial activity against Staphylococcus epidermidis, S. aureus, and P. aeruginosa. Gels with higher acid concentrations (ABF-1 and ABF-2) were highly effective in reducing the bacterial load in chronic biofilms of S. aureus and P. aeruginosa, while the gel with a lower acid concentration (ABF-3) showed positive effects on the viability of skin cells (over 80% cells viable) and for promoting wound closure. All three gels demonstrated excellent acid-buffering capabilities. Conclusions: The acid-buffered gels demonstrate promising in vitro antibacterial effects, indicating their potential for enhancing wound healing.

High-Intensity Blue Light (450-460 nm) Phototherapy for Pseudomonas aeruginosa-Infected Wounds

Background: Nosocomial wound infection with Pseudomonas aeruginosa (PA) is a serious complication often responsible for the septic mortality of burn patients. Objective: High-intensity antimicrobial blue light (aBL) treatment may represent an alternative therapy for PA infections and will be investigated in this study. Methods: Antibacterial effects of a light-emitting diode array (450-460 nm; 300 mW/cm2; 15/30 min; 270/540 J/cm2) against PA were determined by suspension assay, biofilm assay, and a human skin wound model and compared with 15-min topically applied 3% citric acid (CA) and wound irrigation solution (Prontosan®; PRT). Results: aBL reduced the bacterial number [2.51-3.56 log10 colony-forming unit (CFU)/mL], whereas PRT or CA treatment achieved a 4.64 or 6.60 log10 CFU/mL reduction in suspension assays. aBL reduced biofilm formation by 60-66%. PRT or CA treatment showed reductions by 25% or 13%. Here, aBL reduced bacterial number in biofilms (1.30-1.64 log10 CFU), but to a lower extend than PRT (2.41 log10 CFU) or CA (2.48 log10 CFU). In the wound skin model, aBL (2.21-2.33 log10 CFU) showed a bacterial reduction of the same magnitude as PRT (2.26 log10 CFU) and CA (2.30 log10 CFU). Conclusions: aBL showed a significant antibacterial efficacy against PA and biofilm formation in a short time. However, a clinical application of aBL in wound therapy requires effective active skin cooling and eye protection, which in turn may limit clinical implementation.

The Antimicrobial Efficacy of Topically Applied Mafenide Acetate, Citric Acid and Wound Irrigation Solutions Lavanox and Prontosan against Pseudomonas aeruginosa

Since burn wound infections caused by Pseudomonas aeruginosa (PA) lead to major complications and sepsis, this study evaluates the antimicrobial efficacy of the wound irrigation solutions Prontosan (PRT), Lavanox (LAV), citric acid (CA) and mafenide acetate (MA) using microbiology assays and an ex vivo skin wound model. In suspension assays, all the solutions showed significant reductions in bacterial number (log10 reduction: CA 5.77; LAV 4.91; PRT 4.74; MA 1.23). The biofilm assay revealed that PRT and LAV reduced biofilm formation by ~25% after a 15 min treatment, while PRT was most effective after a 24 h treatment (~68%). The number of PA in biofilms measured directly after a 15 min treatment was reduced most effectively with CA and LAV (log10 reductions ~2.5), whereas after a 24 h treatment, all solutions achieved only 1.36-1.65 log10 reductions. In the skin wound model, PRT and LAV provided the highest bacterial reduction after a 15 min treatment (log10 reduction 1.8-1.9), while MA was more effective after a 22 h treatment (log10 reduction 3.6). The results demonstrated the antimicrobial efficacy of all solutions against PA. Further investigation is needed to explore the potential clinical applications of a combination or alternating use of these solutions for infection prophylaxis and treatment of wound infections caused by PA.

Can Cold Atmospheric Plasma Be Used for Infection Control in Burns? A Preclinical Evaluation

Wound infection with Pseudomonas aeruginosa (PA) is a serious complication and is responsible for higher rates of mortality in burn patients. Because of the resistance of PA to many antibiotics and antiseptics, an effective treatment is difficult. As a possible alternative, cold atmospheric plasma (CAP) can be considered for treatment, as antibacterial effects are known from some types of CAP. Hence, we preclinically tested the CAP device PlasmaOne and found that CAP was effective against PA in various test systems. CAP induced an accumulation of nitrite, nitrate, and hydrogen peroxide, combined with a decrease in pH in agar and solutions, which could be responsible for the antibacterial effects. In an ex vivo contamination wound model using human skin, a reduction in microbial load of about 1 log₁₀ level was observed after 5 min of CAP treatment as well as an inhibition of biofilm formation. However, the efficacy of CAP was significantly lower when compared with commonly used antibacterial wound irrigation solutions. Nevertheless, a clinical use of CAP in the treatment of burn wounds is conceivable on account of the potential resistance of PA to common wound irrigation solutions and the possible wound healing-promoting effects of CAP.

Phototherapy of Pseudomonas aeruginosa-Infected Wounds: Preclinical Evaluation of Antimicrobial Blue Light (450-460 nm) Using In Vitro Assays and a Human Wound Skin Model

Objective: To determine effective treatment strategies against bacterial infections of burn wounds with Pseudomonas aeruginosa, we tested different treatment regimens with antibacterial blue light (BL). Background: Infections of burn wounds are serious complications and require effective and pathogen-specific therapy. Hereby, infections caused by P. aeruginosa pose a particular challenge in clinical practice due to its resistance to many antibiotics and topical antiseptics. Methods: LED-based light sources (450-460 nm) with different intensities and treatment times were used. Antibacterial effects against P. aeruginosa were determined by colony-forming unit (CFU) assays, human skin wound models, and fluorescence imaging. Results: In suspension assays, BL (2 h, 40 mW/cm², 288 J/cm²) reduced bacterial number (>5 log₁₀ CFU/mL). Applying 144 J/cm², using 40 mW/cm² for 1 h was more effective (>4 log₁₀ CFU) than using 20 mW/cm² for 2 h (>1.5 log₁₀ CFU). BL with low irradiance (24 h, 3.5 mW/cm², 300 J/cm²) only revealed bacterial reduction in thin bacteria-containing medium layers. In infected in vitro skin wounds only BL irradiation (2 h, 40 mW/cm², 288 J/cm²) exerted a significant antimicrobial efficacy (2.94 log₁₀ CFU/mL). Conclusions: BL treatment may be an effective therapy for P. aeruginosa-infected wounds to avoid radical surgical debridement. However, a significant antibacterial efficacy can only be achieved with higher irradiances and longer treatment times (min. 40 mW/cm²; >1 h), which cannot be easily integrated into regular clinical treatment protocols, for example, during a dressing change. Further studies are necessary to establish BL therapy for infected burns among tissue compatibility and interactions with previous therapeutic agents.

Impact of Carbon Source Supplementations on Pseudomonas aeruginosa Physiology

Pseudomonas aeruginosa is an opportunistic pathogen highly resistant to a wide range of antimicrobial agents, making its infections very difficult to treat. Since microorganisms need to perpetually adapt to their surrounding environment, understanding the effect of carbon sources on P. aeruginosa physiology is therefore essential to avoid increasing drug-resistance and better fight this pathogen. By a global proteomic approach and phenotypic assays, we investigated the impact of various carbon source supplementations (glucose, glutamate, succinate, and citrate) on the physiology of the P. aeruginosa PA14 strain. A total of 581 proteins were identified as differentially expressed in the 4 conditions. Most of them were more abundant in citrate supplementation and were involved in virulence, motility, biofilm development, and antibiotic resistance. Phenotypic assays were performed to check these hypotheses. By coupling all this data, we highlight the importance of the environment in which the bacterium evolves on its metabolism, and thus the necessity to better understand the metabolic pathways implied in its adaptative response according to the nutrient availability.

Acetic acid dressings: Finding the Holy Grail for infected wound management

Background

Wounds have since long, contributed majorly to the health-care burden. Infected long-standing non-healing wounds place many demands on the treating surgeon and are devastating for the patients physically, nutritionally, vocationally, financially, psychologically and socially. Acetic acid has long been included among agents used in the treatment of infected wounds. In this study, we have evaluated the use of acetic acid for topical application in the treatment of infected wounds.

Materials and Methods

A total of 100 patients with infected wounds were treated with topical application of 1% acetic acid as dressing material after appropriate cleaning. A specimen of wound swab was collected before first application and further on days 3, 7, 10 and 14. Daily dressings of wounds were done similarly. Minimum inhibitory concentration (MIC) of acetic acid against various organisms isolated was determined.

Results

The patients treated ranged between 9 and 60 years, with the mean age 33 years. Nearly 70% of patients were male. Aetiologies of wounds: infective 35, diabetic 25, trauma 20, burns 10, venous ulcers 5 and infected graft donor site 5. Various microorganisms isolated include Pseudomonas aeruginosa (40%), Staphylococcus aureus (2%), Acinetobacter (12%), Escherichia Coli (5%), Proteus mirabilis (3%), Klebsiella (18%), methicillin-resistant S. aureus (10%), Streptococcus (2%) and Enterococcus (1%), Citrobacter (1%). Few wounds (6%) also isolated fungi. About 28%, 64% and 8% of patients isolated no growth on culture after 7, 14 and 21 days, respectively. MIC of all isolated organisms was ≤0.5%.

Conclusion

pH of the wound environment plays a pivotal role in wound healing. Acetic acid with concentration of 1% has shown to be efficacious against wide range of bacteria as well as fungi, simultaneously accelerating wound healing. Acetic acid is non-toxic, inexpensive, easily available and efficient topical agent for effective elimination of wound infections caused due to multi-drug resistant, large variety of bacteria and fungus.

Synergistic Impacts of Organic Acids and pH on Growth of Pseudomonas aeruginosa: A Comparison of Parametric and Bayesian Non-parametric Methods to Model Growth

Different weak organic acids have significant potential as topical treatments for wounds infected by opportunistic pathogens that are recalcitrant to standard treatments. These acids have long been used as bacteriostatic compounds in the food industry, and in some cases are already being used in the clinic. The effects of different organic acids vary with pH, concentration, and the specific organic acid used, but no studies to date on any opportunistic pathogens have examined the detailed interactions between these key variables in a controlled and systematic way. We have therefore comprehensively evaluated the effects of several different weak organic acids on growth of the opportunistic pathogen Pseudomonas aeruginosa. We used a semi-automated plate reader to generate growth profiles for two different strains (model laboratory strain PAO1 and clinical isolate PA1054 from a hospital burns unit) in a range of organic acids at different concentrations and pH, with a high level of replication for a total of 162,960 data points. We then compared two different modeling approaches for the interpretation of this time-resolved dataset: parametric logistic regression (with or without a component to include lag phase) vs. non-parametric Gaussian process (GP) regression. Because GP makes no prior assumptions about the nature of the growth, this method proved to be superior in cases where growth did not follow a standard sigmoid functional form, as is common when bacteria grow under stress. Acetic, propionic and butyric acids were all more detrimental to growth than the other acids tested, and although PA1054 grew better than PAO1 under non-stress conditions, this difference largely disappeared as the levels of stress increased. As expected from knowledge of how organic acids behave, their effect was significantly enhanced in combination with low pH, with this interaction being greatest in the case of propionic acid. Our approach lends itself to the characterization of combinatorial interactions between stressors, especially in cases where their impacts on growth render logistic growth models unsuitable.

Topical use of citric acid for wound bed preparation

Wound bed preparation is the management of a wound in order to accelerate endogenous healing or to facilitate the effectiveness of split-skin grafting. The formation of a healthy wound bed is a prerequisite to the use of advanced wound care products. Unless this is achieved, even the most sophisticated and expensive materials are unlikely to function correctly. An attempt has been made to use 3% citric acid ointment for wound bed preparation to prepare wound for grafting in five cases of wounds with large raw areas infected with multiple antibiotic-resistant bacteria.

Assessment of the effectiveness of silver-coated dressing, chlorhexidine acetate (0.5%), citric acid (3%), and silver sulfadiazine (1%) for topical antibacterial effects against the multi-drug resistant Pseudomonas aeruginosa infecting full-skin thickness burn wounds on rats

The aim of this study was to compare the effects of four different topical antimicrobial dressings on a multi-drug resistant Pseudomonas aeruginosa contaminated full-thickness burn wound rat model. A total of 40 adult male Wistar albino rats were used. The control group (group 1), silver sulfadiazine (1%) group 2, chlorhexidine acetate (0.5%) group 3, citric acid (3%) group 4, and silver-coated dressing group 5 were compared to assess the antibacterial effects of a daily application to a 30% full-skin thickness burn wound seeded 10 minutes earlier with 10(8) CFU (colony forming unit)/0.5 mL of a multi-drug resistant Pseudomonas aeruginosa strain. Five groups (1 control group and 4 treatment groups) were compared. The administration of third-degree burns to all rats was confirmed based on histopathologic data. The tissue cultures from groups 2 and 5 exhibited significant differences compared to those of the other 3 groups, whereas no significant differences were observed between groups 1, 3, and 4. The effectiveness of the treatments was as follows: 1% silver sulfadiazine > silver-coated dressing > 3% citric acid > 0.5% chlorhexidine acetate > control group. Our results supported the efficacy of topical therapy by silver sulfadiazine and silver-coated dressing on infections caused by multi-drug resistant Pseudomonas spp.

Acetic acid treatment of pseudomonal wound infections--a review

PURPOSE

Pseudomonas aeruginosa is a significant cause of burn wound infections and, skin and soft tissue infections. The antiseptic management is an integral part of the management of wound infections and is essential to control wound infection. Although commonly used, concerns have been raised.

RESULTS

Available experimental data suggest that many commonly used antiseptic agents may be toxic to the cells involved in wound healing process and may affect the process of normal tissue repair. In view of this, the present review summarized the various organic acids commonly used as a substitute for antiseptics to control pseudomonal wound infections with special reference to acetic acid and their role in the process of wound healing.

CONCLUSION

Acetic acid is to be kept in mind as one of the alternatives when infection is caused by multiple antibiotic resistant strains of P. aeruginosa. At a time when bacterial resistance to antibiotics is a matter of increasing concern, the value of topical agents such as acetic acid should not be forgotten.

Treatment of lepromatous ulcers using citric acid as a sole antimicrobial agent

A prospective study was carried out to assess the role of citric acid as a sole antimicrobial agent in the management of lepromatous ulcers. Thirty-four known cases of lepromatous ulcers not responding to conventional antibiotic therapies for long duration were investigated for culture and susceptibility studies. Staphylococcus aureus (25·00%) and Klebsiella spp. (23·43%) were found to be the most common isolates. Amikacin (68·75%) and ciprofloxacin (67·18%) were found to be the most effective antimicrobial agents. Topical application of citric acid ointment resulted in complete healing in 25 (73·52%) cases. In eight cases (26·48%), there was elimination of infective agent from ulcer site and formation of healthy granulation, but no complete healing of ulcer was seen. Results indicate that citric acid is the best alternative for the effective management of lepromatous ulcers when other therapies are exhausted.

Simple, effective and affordable approach for the treatment of burns infections

OBJECTIVE

The aim of the present study was to develop a simple and effective treatment modality using citric acid as a sole antimicrobial agent to control infections in burns patients not responding to conventional treatment.

METHODS

Forty-six cases with 5-60% superficial to deep burns in a study group and 20 cases with 10-70% superficial to deep burns in a control group were investigated for culture and susceptibility. The isolates in study group were further tested for susceptibility to citric acid. Three percent citric acid gel was applied to burns wounds in study group; however, the control group received conventional antibiotic therapy and local wound care.

RESULTS

In the control group, Pseudomonas aeruginosa (44.44%) and Staphylococcus aureus (33.33%) were found to be the commonest bacterial isolates and, amikacin and ciprofloxacin (40.74%) were found to be most effective antibacterial agents. In study group, P. aeruginosa (30.48%) and S. aureus (23.17%) were found to be the commonest bacterial isolates. Ceftazidime (52.43%), ciprofloxacin (47.56%) and amikacin (46.34%) were found to be most effective antibacterial agents. Application of citric acid to burn wounds resulted in complete healing in 40 (86.95%) cases in 7-25 applications (P value 0.145); however, in a control group conventional antibiotic therapy and local wound care resulted in complete healing in nine (45%) patients only.

CONCLUSIONS

Citric acid treatment was found effective in the control of burns infections as compared to conventional therapy. Complete healing in 86.95% cases as compared to 45% in a control group indicates that citric acid is nontoxic, economical and quite effective in the management of burns infections.

A simple and effective approach for the treatment of diabetic foot ulcers with different Wagner grades

Diabetic foot infections are the major cause of morbidity. Infection is the common sequel of diabetic foot ulceration that leads to delayed wound healing. These infections are difficult to control. If not addressed well in time, they may lead to amputation of foot. An attempt has been made to develop simple and effective treatment modality by using citric acid as a sole antimicrobial agent to control diabetic foot infections not responding to conventional treatment. Hundred and fifteen cases of diabetic foot ulcers of different Wagner grades infected with a variety of bacteria were investigated for culture and susceptibility, and susceptibility to citric acid. Citric acid gel was applied to ulcer to determine its efficacy in the management of diabetic foot ulcers with different Wagner grades. Citric acid gel was found effective in the control of foot infections; especially in Wagner grades I and II, the success rate was found to be more than 94%. In Wagner grade III also, it was found effective in complete healing of ulcers without deep osteomyelitis. Citric acid treatment is effective in the control of diabetic foot infections and in successful management of diabetic foot ulcers with Wagner grades I and II, and even with Wagner grade III, without deep osteomyelitis.

A simple and effective approach for the treatment of chronic wound infections caused by multiple antibiotic resistant Escherichia coli

Antimicrobial resistance is a major problem in present-day therapy. Despite the advent of newer antimicrobial agents with a broad spectrum of activity, multiple antibiotic resistant pathogens are difficult to eliminate from infected sites. The present study was carried out to develop an approach, using citric acid as a sole antimicrobial agent, for the treatment of chronic wound infections caused by multiresistant Escherichia coli (MAREC). A total of 34 cases of chronic wound infections yielding MAREC isolates on culture were studied. The antibacterial effect of citric acid against MAREC was evaluated in vitro by broth dilution method. Three percent citric acid gel was applied to each wound once daily until it healed completely. All 34 isolates were inhibited by citric acid with minimum inhibitory concentrations in the range of 1500-2000 microg/ml. Topical application of 3% citric acid to wounds 7-42 times resulted in elimination of MAREC from infected sites and successful healing of wounds in all 34 patients. This treatment modality was simple, reliable, non-toxic and effective. Hence, the use of citric acid for the cost-effective treatment of wound infections caused by MAREC is recommended.

Biofilm reduction by a new burn gel that targets nociception

AIMS

To compare the ability of an amorphous first aid topical gel containing vinegar, citric acid and EDTA (RescuDerm(TM); RESC) and various derivative formulations to eradicate Pseudomonas aeruginosa (PSEUD) and Staphylococcus epidermidis (STAPH) biofilms.

METHODS AND RESULTS

24-h biofilms prepared using the Minimum Biofilm Elimination Concentration (MBEC) Assay System were exposed for 4 or 24 h to the different gel formulations. Citric acid-free, acetic acid-free or acetic acid-free/sodium acetate-supplemented RESC gels reduced PSEUD and STAPH biofilm formation as effectively as RESC. Substituting the weak organic acids with equivalent concentrations of glacial acetic acid reduced the effectiveness of gel against PSEUD and STAPH biofilms by half, but viable bacterial counts still remained below 4 log(10) CFU/peg. Removal of gelling agent and/or EDTA enhanced efficacy against PSEUD but not STAPH biofilms. An acidified placebo gel formulation generated an only marginal bactericidal effect compared to that of RESC.

CONCLUSIONS

RESC is a promising new antimicrobial agent. Its weak organic acid content, rather than merely acidic pH, mediates its considerable in vitro bactericidal efficacy against bacterial biofilms.

SIGNIFICANCE AND IMPACT OF THE STUDY

These data, taken together with the observation that RescuDerm possesses broad in vitro bactericidal activity against other pathogen species, suggest the potential usefulness of this product for controlling biofilm formation on a variety of cutaneous traumatic and surgical wounds.

The efficacy of honey in inhibiting strains of Pseudomonas aeruginosa from infected burns

Because there is no ideal therapy for burns infected with Pseudomonas aeruginosa, there is sufficient need to investigate the efficacy of alternative antipseudomonal interventions. Honey is an ancient wound remedy for which there is modern evidence of efficacy in the treatment of burn wounds, but limited evidence for the effectiveness of its antibacterial activity against Pseudomonas. We tested the sensitivity of 17 strains of P. aeruginosa isolated from infected burns to two honeys with different types of antibacterial activity, a pasture honey and a manuka honey, both with median levels of activity. All strains showed similar sensitivity to honey with minimum inhibitory concentrations below 10% (vol/vol); both honeys maintained bactericidal activity when diluted more than 10-fold. Honey with proven antibacterial activity has the potential to be an effective treatment option for burns infected or at risk of infection with P. aeruginosa.