The Antibacterial Activity of Acetic Acid against Biofilm-Producing Pathogens of Relevance to Burns Patients.

INTRODUCTION: Localised infections, and burn wound sepsis are key concerns in the treatment of burns patients, and prevention of colonisation largely relies on biocides. Acetic acid has been shown to have good antibacterial activity against various planktonic organisms, however data is limited on efficacy, and few studies have been performed on biofilms. OBJECTIVES: We sought to investigate the antibacterial activity of acetic acid against important burn wound colonising organisms growing planktonically and as biofilms. METHODS: Laboratory experiments were performed to test the ability of acetic acid to inhibit growth of pathogens, inhibit the formation of biofilms, and eradicate pre-formed biofilms. RESULTS: Twenty-nine isolates of common wound-infecting pathogens were tested. Acetic acid was antibacterial against planktonic growth, with an minimum inhibitory concentration of 0.16-0.31% for all isolates, and was also able to prevent formation of biofilms (at 0.31%). Eradication of mature biofilms was observed for all isolates after three hours of exposure. CONCLUSIONS: This study provides evidence that acetic acid can inhibit growth of key burn wound pathogens when used at very dilute concentrations. Owing to current concerns of the reducing efficacy of systemic antibiotics, this novel biocide application offers great promise as a cheap and effective measure to treat infections in burns patients.

Antimicrobial dressings: Comparison of the ability of a panel of dressings to prevent biofilm formation by key burn wound pathogens.

UNLABELLED: Antimicrobial medicated dressings (AMD) are often used to reduce bacterial infection of burns and other wounds. However, there is limited literature regarding comparative efficacies to inform effective clinical decision making. OBJECTIVES: Following on from a previous study where we demonstrated good antibiofilm properties of acetic acid (AA), we assessed and compared the in vitro anti-biofilm activity of a range of AMDs and non-AMDs to AA. METHODS: Laboratory experiments determined the ability of a range of eleven commercial AMD, two nAMD, and AA, to prevent the formation of biofilms of a panel of four isolates of Pseudomonas aeruginosa and Acinetobacter baumannii. RESULTS: There is a large variation in ability of different dressings to inhibit biofilm formation, seen between dressings that contain the same, and those that contain other antimicrobial agents. The best performing AMD were Mepilex(®) Ag and Acticoat. AA consistently prevented biofilm formation. CONCLUSIONS: Large variation exists in the ability of AMD to prevent biofilm formation and colonisation of wounds. A standardised in vitro methodology should be developed for external parties to examine and compare the efficacies of commercially available AMDs, along with robust clinical randomised controlled trials. This is essential for informed clinical decision-making and optimal patient management.

Use of UV-C radiation to disinfect non-critical patient care items: a laboratory assessment of the Nanoclave Cabinet.

BACKGROUND: The near-patient environment is often heavily contaminated, yet the decontamination of near-patient surfaces and equipment is often poor. The Nanoclave Cabinet produces large amounts of ultraviolet-C (UV-C) radiation (53 W/m2) and is designed to rapidly disinfect individual items of clinical equipment. Controlled laboratory studies were conducted to assess its ability to eradicate a range of potential pathogens including Clostridium difficile spores and Adenovirus from different types of surface. METHODS: Each test surface was inoculated with known levels of vegetative bacteria (10(6) cfu/cm(2)), C. difficile spores (10(2)-10(6) cfu/cm(2)) or Adenovirus (10(9) viral genomes), placed in the Nanoclave Cabinet and exposed for up to 6 minutes to the UV-C light source. Survival of bacterial contaminants was determined via conventional cultivation techniques. Degradation of viral DNA was determined via PCR. Results were compared to the number of colonies or level of DNA recovered from non-exposed control surfaces. Experiments were repeated to incorporate organic soils and to compare the efficacy of the Nanoclave Cabinet to that of antimicrobial wipes. RESULTS: After exposing 8 common non-critical patient care items to two 30-second UV-C irradiation cycles, bacterial numbers on 40 of 51 target sites were consistently reduced to below detectable levels (≥ 4.7 log10 reduction). Bacterial load was reduced but still persisted on other sites. Objects that proved difficult to disinfect using the Nanoclave Cabinet (e.g. blood pressure cuff) were also difficult to disinfect using antimicrobial wipes. The efficacy of the Nanoclave Cabinet was not affected by the presence of organic soils. Clostridium difficile spores were more resistant to UV-C irradiation than vegetative bacteria. However, two 60-second irradiation cycles were sufficient to reduce the number of surface-associated spores from 10(3) cfu/cm(2) to below detectable levels. A 3 log10 reduction in detectable Adenovirus DNA was achieved within 3 minutes; after 6 minutes, viral DNA was undetectable. CONCLUSION: The results of this study suggest that the Nanoclave Cabinet can provide rapid and effective disinfection of some patient-related equipment. However, laboratory studies do not necessarily replicate 'in-use' conditions and further tests are required to assess the usability, acceptability and relative performance of the Nanoclave Cabinet when used in situ.

Guidelines (2008) for the prophylaxis and treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections in the United Kingdom.

These evidence-based guidelines are an updated version of those published in 2006. They have been produced after a literature review of the treatment and prophylaxis of methicillin-resistant Staphylococcus aureus (MRSA). The guidelines aim to complement those recently published for the antibiotic treatment of common and emerging community-onset MRSA infections in the UK. The guidelines have reviewed and updated, where appropriate, previous recommendations, taking into account any changes in the UK epidemiology of MRSA, ongoing national surveillance data and the value of new antistaphylococcal agents licensed for use in UK practice. Emerging therapies that have not been licensed for UK use are not reviewed, but their future potential role has been mentioned where deemed appropriate. Recommendations are given for the treatment of common infections caused by MRSA, elimination of MRSA from carriage sites and prophylaxis of surgical site infection.

Rapid detection of extended-spectrum beta-lactamase-producing Gram-negative bacilli in blood cultures.

OBJECTIVES: Conventional detection of extended-spectrum beta-lactamase (ESBL) producers in blood cultures usually requires overnight incubation. This could delay the prescribing of appropriate therapy. We evaluated whether the chromogenic cephalosporin HMRZ-86, which is hydrolysed by ESBLs, could be used for the rapid detection of ESBL producers directly in blood culture broths. METHODS: The HMRZ-86 test was first applied to broth cultures of isolates producing known beta-lactamases. A colour change indicating hydrolysis, which was inhibited by clavulanic acid, was taken as an indication of ESBL production. A similar method was used for testing blood culture supernatants and broth subcultures of blood cultures. RESULTS: The HMRZ-86 test detected all the ESBL producers among 83 clinical isolates and control strains. Only one false positive was seen. The usefulness of HMRZ-86 for the direct testing of blood culture broths was limited by the presence of lysed blood. However, by using a 2 h broth subculture of the blood culture broths, the HMRZ-86 test was able to detect all those blood cultures containing an ESBL producer. No false positive or negative tests occurred according to the results of our standard phenotypic tests. CONCLUSIONS: The HMRZ-86 test is a simple and rapid method that can be used for detecting ESBL producers in blood cultures.

Tigecycline: the answer to beta-lactam and fluoroquinolone resistance?

Patients with serious bacterial infections such as intra-abdominal infections and complicated skin and soft tissue infections are often treated empirically because a delay in appropriate initial antimicrobial therapy has been shown to significantly increase morbidity and mortality. Furthermore, pathogens that have developed resistance to mainstay therapeutic options are increasing in prevalence making these infections a challenge for physicians. Treatment guidelines for surgical and intra-abdominal infections recommend selection of an agent or a combination of agents with activity to cover both Gram-positive, Gram-negative organisms and anaerobes. Recommended agents include second-generation cephalosporins with anaerobic coverage, beta-lactam/beta-lactamase inhibitor agents, fluoroquinolone/metronidazole combinations and carbapenems. However, the effectiveness of these agents has come into question as once susceptible organisms are now showing signs of resistance to such antimicrobial therapies. Alternative agents specifically designed to overcome mechanisms of microbial resistance have been sought. The result of that search has been the development of a new class of antimicrobials termed glycylcyclines. The first of these novel antibacterials is tigecycline, with a broad spectrum of activity that includes coverage against vancomycin-resistant enterococci, methicillin-resistant S. aureus, and many species of multidrug-resistant Gram-negative bacteria. Tigecycline also has activity against most penicillin-susceptible and resistant Gram-positive organisms. Clinical trial experience with tigecycline has shown it to be at least as effective as current recommended regimens for the treatment of intra-abdominal infections and complicated skin and soft tissue infections. This new agent thus holds promise as an alternative to the beta-lactams and fluoroquinolones for the initial empiric treatment of serious bacterial infections.

Guidelines for the prophylaxis and treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections in the UK.

These evidence-based guidelines have been produced after a literature review of the treatment and prophylaxis of methicillin-resistant Staphylococcus aureus (MRSA) infection. The guidelines were further informed by antibiotic susceptibility data on MRSA from the UK. Recommendations are given for the treatment of common infections caused by MRSA, elimination of MRSA from carriage sites and prophylaxis of surgical site infection. There are several antibiotics currently available that are suitable for use in the management of this problem and potentially useful new agents are continuing to emerge.