Activity of multipurpose contact lens solutions against Staphylococcus aureus, Pseudomonas aeruginosa, Serratia marcescens and Candida albicans biofilms.

INTRODUCTION: The use of contact lenses has progressively increased around the world, thereby increasing the risk of complications. The most serious complication is microbial keratitis (corneal infection) that can progress to a corneal ulcer. METHODS: Fourteen multipurpose contact lens solutions were tested on mature biofilms comprising Staphylococcus aureus, Pseudomonas aeruginosa, Serratia marcescens and Candida albicans, using the minimum disinfection times recommended by the manufacturers. The biofilm was induced in the lens case, and 24 h later, the solutions were added. Activity against planktonic and sessile cells was evaluated and quantified as colony forming units per millilitre. The minimum concentration for biofilm eradication was defined as a 99.9% reduction in viable cells. RESULTS: Although most solutions exhibited activity against planktonic cells, only five of the 14 solutions produced a significant reduction in the S. marcescens biofilm. No solution achieved the minimal biofilm eradication of S. aureus, P. aeruginosa and C. albicans. CONCLUSION: Multipurpose contact lens solutions provide greater bactericidal and/or fungicidal activity on planktonic cells than biofilms. The minimal eradication biofilm concentration was only achieved for S. marcescens.

A carbapenem-resistant Acinetobacter baumannii outbreak associated with a polymyxin shortage during the COVID pandemic: an in vitro and biofilm analysis of synergy between meropenem, gentamicin and sulbactam.

BACKGROUND: During the COVID-19 pandemic, the burden of nosocomial infections caused by MDR pathogens has caused a shortage of polymyxins. Thus, we evaluated the in vitro synergism and antibiofilm activity of antimicrobial combinations and propose a test kit for synergism against carbapenem-resistant Acinetobacter baumannii (CRAB). METHODS: Fifty-six CRAB isolates were tested for synergy between meropenem, gentamicin and ampicillin/sulbactam. MICs were determined by broth microdilution. Synergism was tested using chequerboard analysis, followed by a time-kill curve. Additionally, minimum biofilm eradication concentration was determined and the antibiofilm activity of the combinations was evaluated by MTT assay and biomass reduction. A test kit was developed for routine laboratory testing to detect synergism. RESULTS: All CRAB isolates were resistant to gentamicin and ampicillin/sulbactam. Chequerboard synergism occurred against 75% of the isolates. Meropenem + ampicillin/sulbactam was the most frequent combination with synergism (69%), followed by ampicillin/sulbactam + gentamicin (64%) and meropenem + gentamicin (51%). All combinations presented only bacteriostatic activity and no bactericidal or antibiofilm effects. The routine laboratory test showed 100% accuracy compared with other in vitro assays. CONCLUSIONS: Our study demonstrates the potential role of antibiotic combinations against planktonic bacteria. In vitro synergism is possible and can be an alternative treatment for patients with CRAB infection during a polymyxin shortage.

Liposomal drug delivery systems for the treatment of leishmaniasis.

Human le ishmaniasis is a vector-borne, neglected infectious disease that is widely distributed in America, Africa, Europe, and Asia. Current therapy is based on old and toxic drugs, including antimonials, aminoglycosides, and amphotericin. As a neglected disease, investment in the development of new therapeutic molecules is scarce. Considering these aspects, the optimization of treatment through novel delivery systems for current therapeutic agents is an attractive alternative. The encapsulation into liposomes of drugs used in treating leishmaniasis increases the concentration of these molecules in macrophages, which may not only increase the chance of cure but also expand their therapeutic spectrum to include resistant Leishmania, as well as reducing toxicity since the drug is less exposed to healthy cells. The classical example is the liposomal formulation of amphotericin B, a well-established therapeutic option that uses liposomes to decrease the progression of renal failure in patients. However, loading other leishmanicidal drugs into liposomes, such as pentavalent antimonials, presents an opportunity for innovative and cheaper therapeutic options for the treatment of human leishmaniasis. This review aims to discuss liposomes as a drug delivery system for leishmanicidal drugs.

Collagen matrices are preserved following decellularization of a bovine bone scaffold.

The decellularization of bovine bone has emerged as a strategy for the repair, replacement, and regeneration of bone defects. To evaluate the effects of a new protocol of bone decellularization and its impact on the structure and collagen scaffold. Cancellous bone from bovine femur was dissected in fragments and decellularized based on protocol of multiple steps. The residual protein levels, histological, morphometric, and scanning electronic microscopy analyses were carried out to evaluate the effects of decellularization and the impact on the structure and collagen scaffold. A cytotoxicity assay was performed. Residual protein analysis showed an important removal of bone marrow components and cell debris from the bone. Sections revealed that collagen fibers presented integrity and absence of cells in the decellularized bone. Sirius Red-stained sections of collagen fiber collagen matrix were maintained after decellularization. Scanning electron microscopy revealed that the main bone structure, despite being irregular, was maintained in both groups, with no significant visual differences between the surface characteristics according to the groups. Decellularized bovine bone demonstrated a degree of toxicity of 3, indicating moderate reactivity. The present data demonstrate that the main bone structure was maintained. Additionally, the chemical and physical treatments were able to remove cellular debris, and extracellular matrix architecture and collagen were preserved. However, the tissue showed moderate toxicity.

Disinfection protocol for human musculoskeletal allografts in tissue banking using hydrogen peroxide 30.

Musculoskeletal allografts are used in reconstructive procedures, however, the risk of contamination with potential pathogens is possible, and safe transplantation requires multiple processing considerations. Hydrogen peroxide (H2O2) has commonly been used in bone washing because it can remove donor cells and eliminate antigens, pathogens, or cytotoxic agents from the matrix. The aim of this study was to evaluate the quantitative activity of H2O2 in a model of bone contamination with a high bacterial load to define the bioburden reduction. Twelve bone disc models were artificially contaminated with Staphylococcus aureus. The bones were treated with a washing process composed by antibiotics, 30% hydrogen peroxide, and 70% alcohol. Tryptic Soy Agar plates were directly inoculated with 100µL of each step of the washing process and colonies were counted in CFU/mL. Scanning electron microscopy was used for bone structural analysis before and after the washing process. After antibiotics, there was a drop of less than 1 log for cancellous bone and almost 1 log for cortical bone. However, after H2O2, there as a drop of 3 logs for cortical (p = 0.007), and 2 logs for cancellous bone (p = 0.063). The use of alcohol did not change the bioburden following H2O2 in cancellous and cortical bone. Despite the important drop of bacterial load, H2O2 was not enough to completely eradicate bacterial with this model of bioburden. H2O2 is useful in decontamination, but antibiotics have little activity, and alcohol is useless. The process is useful in decontamination up to 3 logs of bioburden.

Antimicrobial Treatment of Staphylococcus aureus Biofilms.

Staphylococcus aureus is a microorganism frequently associated with implant-related infections, owing to its ability to produce biofilms. These infections are difficult to treat because antimicrobials must cross the biofilm to effectively inhibit bacterial growth. Although some antibiotics can penetrate the biofilm and reduce the bacterial load, it is important to understand that the results of routine sensitivity tests are not always valid for interpreting the activity of different drugs. In this review, a broad discussion on the genes involved in biofilm formation, quorum sensing, and antimicrobial activity in monotherapy and combination therapy is presented that should benefit researchers engaged in optimizing the treatment of infections associated with S. aureus biofilms.

Evaluation of silver nanoparticle-impregnated PMMA loaded with vancomycin or gentamicin against bacterial biofilm formation.

INTRODUCTION: Bone cement containing vancomycin or gentamicin is a therapeutic strategy for combating orthopedic infections: however, the activity of these antibiotics is narrow. Silver nanoparticles (AgNPs) are nanocomponents with a wide spectrum, including multidrug-resistant bacteria. In the present study, we aimed to evaluate the effect of AgNP-loaded polymethylmethacrylate (PMMA) on biofilm formation by Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus epidermidis. METHODS: The effect of AgNP-loaded PMMA with and without vancomycin or gentamicin on biofilm production was quantitatively analyzed. S. aureus, E. coli, P. aeruginosa, and S. epidermidis were included as biofilm-producing microorganisms in the in vitro model. RESULTS: AgNP-loaded PMMA with antibiotics reduced the number of colony-forming units (CFUs; p<0.001). However, AgNP-loaded PMMA alone did not significantly reduce biofilm formation. CONCLUSION: Our study demonstrated the potential of AgNP-loaded PMMA. Notably, we observed that AgNP-loaded PMMA containing vancomycin or gentamycin exhibited significantly superior efficacy, with satisfactory activity against most biofilm-forming microbial agents examined.

Pathogenesis of the Pseudomonas aeruginosa Biofilm: A Review.

Pseudomonas aeruginosa is associated with several human infections, mainly related to healthcare services. In the hospital, it is associated with resistance to several antibiotics, which poses a great challenge to therapy. However, one of the biggest challenges in treating P. aeruginosa infections is that related to biofilms. The complex structure of the P. aeruginosa biofilm contributes an additional factor to the pathogenicity of this microorganism, leading to therapeutic failure, in addition to escape from the immune system, and generating chronic infections that are difficult to eradicate. In this review, we address several molecular aspects of the pathogenicity of P. aeruginosa biofilms.

Antimicrobial action, cytotoxicity, calcium ion release, and pH variation of a calcium hydroxide-based paste associated with Myracrodruon urundeuva Allemão extract.

The extract of Myracrodruon urundeuva Allemão (aroeira), as a vehicle, associated with calcium hydroxide (CH) paste was evaluated based on cell viability, antimicrobial action, calcium ion release, and pH variation. Calcium hydroxide with propylene glycol was used as control. The pH variation was measured at 3, 24, 72, 168, 140, 360, and 720 h and calcium ion release was measured on days 7, 15, and 30. Cell viability was assessed with NIH/3T3 cells using MTT and crystal violet assays, after 24, 48, and 72 h. Antibacterial activity was determined by the disc diffusion method, while microbial reduction (Enterococcus faecalis) was evaluated using the time-kill test. The CH paste formulated with aroeira showed antibacterial activity against Enterococcus faecalis and further did not interfere with pH, calcium ion release, or cell viability; moreover, the formulation had antimicrobial activity and could serve as a vehicle for CH paste.

Depression and anxiety in hospitalized patients on contact precautions for multidrug-resistant microorganisms.

BACKGROUND: Contact precautions for patients with multidrug-resistant organisms (MDROs) have been associated with adverse effects. The aim of this study was, therefore, to evaluate the level of anxiety and depression through different standardized scales in patients isolated by MDROs. METHODS: This is a case-control study with hospitalized patients on contact precautions for MDROs. A questionnaire survey was conducted to analyse the presence and level of depression and anxiety. A multivariable analysis was performed to define independent questions for anxiety/depression scores to create a short questionnaire facilitating a practical approach to the care of hospitalized patients with MDROs. A receiver operating characteristic (ROC) curve was plotted to determine the diagnostic ability of the simplified score. RESULTS: A total of 141 patients were included in the study, among whom 68 were isolated because of MDRO colonization while 73 were not isolated (control-group). Forty-five (31.9%) patients had some degree of anxiety. Patients in MDRO contact isolation had a higher level of anxiety than those who were not isolated (55.9% vs. 9.6%, p < 0.001). The equation obtained by multivariated analysis allowed for the construction of a score with ROC area of 0.949 and a sensitivity of 91.1%. CONCLUSION: Contact isolation for MDROs is associated with increased depression and anxiety. A simple anxiety score was developed and should be validated for screening.