The Current Knowledge on the Pathogenesis of Tissue and Medical Device-Related Biofilm Infections

Efficacy of sodium hypochlorite in overcoming antimicrobial resistance and eradicating biofilms in clinical pathogens from pressure ulcers

Sodium hypochlorite (NaOCl) is widely recognized for its broad-spectrum antimicrobial efficacy in skin wound care. This study investigates the effectiveness of NaOCl against a range of bacterial and fungal isolates from pressure ulcer (PU) patients. We analyzed 20 bacterial isolates from PU patients, comprising carbapenem-resistant Klebsiella pneumoniae (CRKP), multidrug-resistant Acinetobacter baumannii (MDRAB), methicillin-resistant Staphylococcus aureus (MRSA), methicillin-susceptible Staphylococcus aureus (MSSA), along with 5 Candida albicans isolates. Antibiotic resistance profiles were determined using standard susceptibility testing. Whole-genome sequencing (WGS) was employed to identify antimicrobial resistance genes (ARGs) and disinfectant resistance genes (DRGs). Genetic determinants of biofilm formation were also assessed. The antimicrobial activity of NaOCl was evaluated by determining the minimum inhibitory concentration (MIC) and the minimal biofilm eradication concentration (MBEC) for both planktonic and biofilm-associated cells. CRKP and MDRAB showed resistance to fluoroquinolones and carbapenems, while MRSA exhibited resistance to β-lactams and levofloxacin. MSSA displayed a comparatively lower resistance profile. WGS identified significant numbers of ARGs in CRKP and MDRAB, with fewer DRGs compared to MRSA and MSSA. All isolates possessed genes associated with fimbriae production and adhesion, correlating with pronounced biofilm biomass production. NaOCl demonstrated substantial antimicrobial activity against both planktonic cells and biofilms. The MIC90 for planktonic bacterial cells was 0.125 mg/mL, and the MBEC90 ranged from 0.225 to 0.5 mg/mL. For planktonic C. albicans, the MIC90 was 0.150 mg/mL, and the MBEC90 was 0.250 mg/mL. These results highlight the challenge in treating biofilm-associated infections and underscore the potential of NaOCl as a robust antimicrobial agent against difficult-to-treat biofilm infections at concentrations lower than those typically found in commercial disinfectants.

FTY720 Reduces the Biomass of Biofilms in Pseudomonas aeruginosa in a Dose-Dependent Manner

Pseudomonas aeruginosa, a nosocomial pathogen, has strong biofilm capabilities, representing the main source of infection in the human body. Repurposing existing drugs has been explored as an alternative strategy to combat emerging antibiotic-resistant pathogens. Fingolimod hydrochloride (FTY720), an immunomodulatory drug for multiple sclerosis, has shown promising antimicrobial effects against some ESKAPE pathogens. Therefore, the effects of FTY720 on the biofilm capabilities of Pseudomonas aeruginosa were investigated in this study. It was determined that FTY720 inhibited the growth of P. aeruginosa PAO1 at 100 µM. The significant reduction in PAO1 cell viability was observed to be dose-dependent. Additional cytotoxicity analysis on human cell lines showed that FTY720 significantly reduced viabilities at sub-inhibitory concentrations of 25-50 µM. Microtiter assays and confocal analysis confirmed reductions in biofilm mass and thickness and the cell survivability ratio in the presence of FTY720. Similarly, virulence production and biofilm-related gene expression (rhlA, rhlB, pilA, pilI, fliC, fliD and algR) were determined. The results demonstrate that pigment production was affected and quantitative real-time PCR analysis showed a variable degree of reduced gene expression in response to FTY720 at 12.5-50 µM. These findings suggest that FTY720 could be repurposed as an alternative antibiofilm agent against Pseudomonas aeruginosa.

Medical Device-Associated Infections Caused by Biofilm-Forming Microbial Pathogens and Controlling Strategies

Hospital-acquired infections, also known as nosocomial infections, include bloodstream infections, surgical site infections, skin and soft tissue infections, respiratory tract infections, and urinary tract infections. According to reports, Gram-positive and Gram-negative pathogenic bacteria account for up to 70% of nosocomial infections in intensive care unit (ICU) patients. Biofilm production is a main virulence mechanism and a distinguishing feature of bacterial pathogens. Most bacterial pathogens develop biofilms at the solid-liquid and air-liquid interfaces. An essential requirement for biofilm production is the presence of a conditioning film. A conditioning film provides the first surface on which bacteria can adhere and fosters the growth of biofilms by creating a favorable environment. The conditioning film improves microbial adherence by delivering chemical signals or generating microenvironments. Microorganisms use this coating as a nutrient source. The film gathers both inorganic and organic substances from its surroundings, or these substances are generated by microbes in the film. These nutrients boost the initial growth of the adhering bacteria and facilitate biofilm formation by acting as a food source. Coatings with combined antibacterial efficacy and antifouling properties provide further benefits by preventing dead cells and debris from adhering to the surfaces. In the present review, we address numerous pathogenic microbes that form biofilms on the surfaces of biomedical devices. In addition, we explore several efficient smart antiadhesive coatings on the surfaces of biomedical device-relevant materials that manage nosocomial infections caused by biofilm-forming microbial pathogens.

Anti-infective management of infected skin ulcers

Infected skin ulcers represent a frequent and intricate clinical challenge, necessitating prompt and comprehensive multidisciplinary interventions to avert complications. Anti-infective therapy constitutes a cornerstone in the therapeutic paradigm. This manuscript delineates our approach to anti-infective management of infected ulcers, encompassing insights into clinical classifications, diagnostic features, exampless of early clinical decision-making in anti-infective treatment, comprehensive evaluation of infectious diseases encompassing host clinical considerations and potential interventions, determination of antibiotic therapy duration, methodologies for assessing clinical response, identification of potential causes for lack of clinical response, as well as strategies for outpatient parenteral antibiotic therapy and a diagnostic and therapeutic algorithm.

Clinical Outcome of Patients with Escherichia coli Isolated from Catheter Lumens and/or Peripheral Blood Cultures: A Retrospective Analysis

BACKGROUND

Escherichia coli commonly causes catheter-related bloodstream infection (C-RBSI) in specific populations. The differential time to positivity (DTTP) technique is the recommended conservative procedure for diagnosing C-RBSIs.

METHODS

We conducted a retrospective study of episodes in which E. coli was isolated from catheter lumens obtained using the DTTP technique. Microbiological and clinical data were obtained based on the DTTP technique as either catheter colonization, C-RBSI, or non-C-RBSI.

RESULTS

A total of 89 catheter blood cultures were included, classified as follows: catheter colonization, 33.7%; C-RBSI, 9.0%; and non-C-RBSI, 57.3%. Only 15.7% of the catheters were withdrawn, with no positive catheter-tip cultures. We found no statistically significant differences in catheter type, antibiotic treatment, or clinical outcome among the groups, except for the frequency of catheter lock therapy or in the frequency of successful treatment. Mortality was associated with C-RBSI in only one patient.

CONCLUSION

E. coli bacteremia diagnosed by the DTTP technique was classified as non-catheter-related in most patients. As the majority of the catheters were retained, E. coli bacteremia could not be microbiologically confirmed as catheter-related by the catheter-tip culture. Future studies are needed to assess the profitability of the DTTP technique for diagnosing E. coli C-RBSIs.

Biofilm-Related Infections in Healthcare: Moving towards New Horizons

In this Special Issue, titled "Biofilm-Related Infections in Healthcare", we have reported considerable progress in understanding the physiology and pathology of biofilms [...].

Modulating the skin mycobiome-bacteriome and treating seborrheic dermatitis with a probiotic-enriched oily suspension

Seborrheic dermatitis (SD) affects 2-5% of the global population, with imbalances in the skin microbiome implicated in its development. This study assessed the impact of an oily suspension containing Lactobacillus crispatus P17631 and Lacticaseibacillus paracasei I1688 (termed EUTOPLAC) on SD symptoms and the skin mycobiome-bacteriome modulation. 25 SD patients were treated with EUTOPLAC for a week. Symptom severity and skin mycobiome-bacteriome changes were measured at the start of the treatment (T0), after seven days (T8), and three weeks post-treatment (T28). Results indicated symptom improvement post-EUTOPLAC, with notable reductions in the Malassezia genus. Concurrently, bacterial shifts were observed, including a decrease in Staphylococcus and an increase in Lactobacillus and Lacticaseibacillus. Network analysis highlighted post-EUTOPLAC instability in fungal and bacterial interactions, with increased negative correlations between Malassezia and Lactobacillus and Lacticaseibacillus genera. The study suggests EUTOPLAC's potential as a targeted SD treatment, reducing symptoms and modulating the mycobiome-bacteriome composition.

Quorum Sensing in Gram-Negative Bacteria: Strategies to Overcome Antibiotic Resistance in Ocular Infections

Truly miraculous medications and antibiotics have helped save untold millions of lives. Antibiotic resistance, however, is a significant issue related to health that jeopardizes the effectiveness of antibiotics and could harm everyone's health. Bacteria, not humans or animals, become antibiotic-resistant. Bacteria use quorum-sensing communication routes to manage an assortment of physiological exercises. Quorum sensing is significant for appropriate biofilm development. Antibiotic resistance occurs when bacteria establish a biofilm on a surface, shielding them from the effects of infection-fighting drugs. Acylated homoserine lactones are used as autoinducers by gram-negative microscopic organisms to impart. However, antibiotic resistance among ocular pathogens is increasing worldwide. Bacteria are a significant contributor to ocular infections around the world. Gram-negative microscopic organisms are dangerous to ophthalmic tissues. This review highlights the use of elective drug targets and treatments, for example, combinational treatment, to vanquish antibiotic-resistant bacteria. Also, it briefly portrays anti-biotic resistance brought about by gram-negative bacteria and approaches to overcome resistance with the help of quorum sensing inhibitors and nanotechnology as a promising medication conveyance approach to give insurance of anti-microbials and improve pathways for the administration of inhibitors of quorum sensing with a blend of anti-microbials to explicit target destinations and penetration through biofilms for treatment of ocular infections. It centres on the methodologies to sidestep the confinements of ocular anti-biotic delivery with new visual innovation.

Effect of florfenicol on Piscirickettsia salmonis biofilm formed in materials used in salmonid nets, nylon and high-density polyethylene

Piscirickettsiosis is the most prevalent bacterial disease affecting seawater salmon in Chilean salmon industry. Antibiotic therapy is the first alternative to counteract infections caused by Piscirickettsia salmonis. The presence of bacterial biofilms on materials commonly used in salmon farming may be critical for understanding the bacterial persistence in the environment. In the present study, the CDC Biofilm Reactor® was used to investigate the effect of sub- and over-MIC of florfenicol on both the pre-formed biofilm and the biofilm formation by P. salmonis under the antibiotic stimuli on Nylon and high-density polyethylene (HDPE) surfaces. This study demonstrated that FLO, at sub- and over-MIC doses, decreases biofilm-embedded live bacteria in the P. salmonis isolates evaluated. However, it was shown that in the P. salmonis Ps007 strain the presence of sub-MIC of FLO reduced its biofilm formation on HDPE surfaces; however, biofilm persists on Nylon surfaces. These results demonstrated that P. salmonis isolates behave differently against FLO and also, depending on the surface materials. Therefore, it remains a challenge to find an effective strategy to control the biofilm formation of P. salmonis, and certainly other marine pathogens that affect the sustainability of the Chilean salmon industry.

Novel Antibacterial Agents SAAP-148 and Halicin Combat Gram-Negative Bacteria Colonizing Catheters

The antibiotic management of catheter-related infections (CRIs) often fails owing to the emergence of antimicrobial-resistant strains and/or biofilm/persister apparitions. Thus, we investigated the efficacy of two novel antimicrobial agents, i.e., the synthetic peptide SAAP-148 and the novel antibiotic halicin, against Gram-negative bacteria (GNB) colonizing catheters. The antibacterial, anti-biofilm, and anti-persister activities of both agents were evaluated against Acinetobacter baumannii, Escherichia coli, and Klebsiella pneumoniae strains. The enrolled strains were isolated from catheters and selected based on their resistance to at least three antibiotic classes and biofilm formation potential. Furthermore, the hemolysis and endotoxin neutralization abilities of these agents were explored. The bactericidal activity of both agents was reduced in urine and plasma as compared to buffered saline. In a dose-dependent manner, SAAP-148 and halicin reduced bacterial counts in 24 h preformed biofilms on silicone elastomer discs and eliminated persisters originating from antibiotic-exposed mature 7-day biofilms, with halicin being less effective than SAAP-148. Importantly, SAAP-148 and halicin acted synergistically on E. coli and K. pneumoniae biofilms but not on A. baumannii biofilms. The peptide, but not halicin, decreased the production of IL-12p40 upon exposure to UV-killed bacteria. This preliminary study showed that SAAP-148 and halicin alone/in combination are promising candidates to fight GNB colonizing catheters.

Biofilm formation: mechanistic insights and therapeutic targets

Biofilms are complex multicellular communities formed by bacteria, and their extracellular polymeric substances are observed as surface-attached or non-surface-attached aggregates. Many types of bacterial species found in living hosts or environments can form biofilms. These include pathogenic bacteria such as Pseudomonas, which can act as persistent infectious hosts and are responsible for a wide range of chronic diseases as well as the emergence of antibiotic resistance, thereby making them difficult to eliminate. Pseudomonas aeruginosa has emerged as a model organism for studying biofilm formation. In addition, other Pseudomonas utilize biofilm formation in plant colonization and environmental persistence. Biofilms are effective in aiding bacterial colonization, enhancing bacterial resistance to antimicrobial substances and host immune responses, and facilitating cell‒cell signalling exchanges between community bacteria. The lack of antibiotics targeting biofilms in the drug discovery process indicates the need to design new biofilm inhibitors as antimicrobial drugs using various strategies and targeting different stages of biofilm formation. Growing strategies that have been developed to combat biofilm formation include targeting bacterial enzymes, as well as those involved in the quorum sensing and adhesion pathways. In this review, with Pseudomonas as the primary subject of study, we review and discuss the mechanisms of bacterial biofilm formation and current therapeutic approaches, emphasizing the clinical issues associated with biofilm infections and focusing on current and emerging antibiotic biofilm strategies.

Culture Shock: An Investigation into the Tolerance of Pathogenic Biofilms to Antiseptics in Environments Resembling the Chronic Wound Milieu

Credible assessment methods must be applied to evaluate antiseptics' in vitro activity reliably. Studies indicate that the medium for biofilm culturing should resemble the conditions present at the site of infection. We cultured S. aureus, S. epidermidis, P. aeruginosa, C. albicans, and E. coli biofilms in IVWM (In Vitro Wound Milieu)-the medium reflecting wound milieu-and were compared to the ones cultured in the laboratory microbiological Mueller-Hinton (MH) medium. We analyzed and compared crucial biofilm characteristics and treated microbes with polyhexamethylene biguanide hydrochloride (PHMB), povidone-iodine (PVP-I), and super-oxidized solution with hypochlorites (SOHs). Biofilm biomass of S. aureus and S. epidermidis was higher in IVWM than in MH medium. Microbes cultured in IVWM exhibited greater metabolic activity and thickness than in MH medium. Biofilm of the majority of microbial species was more resistant to PHMB and PVP-I in the IVWM than in the MH medium. P. aeruginosa displayed a two-fold lower MBEC value of PHMB in the IVWM than in the MH medium. PHMB was more effective in the IVWM than in the MH medium against S. aureus biofilm cultured on a biocellulose carrier (instead of polystyrene). The applied improvement of the standard in vitro methodology allows us to predict the effects of treatment of non-healing wounds with specific antiseptics.

Understanding the diagnosis of catheter-related bloodstream infection: real-time monitoring of biofilm growth dynamics using time-lapse optical microscopy

Background

The differential time to positivity (DTTP) technique is recommended for the conservative diagnosis of catheter-related bloodstream infection (C-RBSI). The technique is based on a 120-minute difference between microbial growth in blood drawn through the catheter and blood drawn through a peripheral vein. However, this cut-off has failed to confirm C-RBSI caused by Candida spp. and Staphylococcus aureus.

Objective

We hypothesized that the biofilm of both microorganisms disperses faster than that of other microorganisms and that microbial load is rapidly equalized between catheter and peripheral blood. Therefore, our aim was to compare the biofilm dynamics of various microorganisms.

Methods

Biofilm of ATCC strains of methicillin-resistant Staphylococcus epidermidis, methicillin-susceptible S. aureus, Enterococcus faecalis, Escherichia coli and Candida albicans was grown on silicon disks and analyzed using time-lapse optical microscopy. The time-lapse images of biofilms were processed using ImageJ2 software. Cell dispersal time and biofilm thickness were calculated.

Results

The mean (standard deviation) dispersal time in C. albicans and S. aureus biofilms was at least nearly 3 hours lower than in biofilm of S. epidermidis, and at least 15 minutes than in E. faecalis and E. coli biofilms.

Conclusion

Our findings could explain why early dissemination of cells in C. albicans and S. aureus prevents us from confirming or ruling out the catheter as the source of the bloodstream infection using the cut-off of 120 minutes in the DTTP technique. In addition, DTTP may not be sufficiently reliable for E. coli since their dispersion time is less than the cut-off of 120 minutes.

Biosynthesis of Peptide Hydrogel-Titania Nanoparticle Composites with Antibacterial Properties

The photoantibacterial properties of titania nanoparticles (TiO2NPs) are attracting much interest, but the separation of their suspension limits their application. In this study, the encapsulation of commercial TiO2NPs within self-assembling tripeptide hydrogels to form hgel-TiO2NP composites with significant photoantibacterial properties is reported. The Fmoc-Phe3 hydrogelator was synthesized via an enzymatic method. The resulting composite was characterized with DLS, ζ-potential, SAXS, FESEM-EDS and rheological measurements. Two different concentrations of TiO2NPs were used. The results showed that, by increasing the TiO2NP quantity from 5 to 10 mg, the value of the elastic modulus doubled, while the swelling ratio decreased from 63.6 to 45.5%. The antimicrobial efficacy of hgel-TiO2NPs was tested against a laboratory Staphylococcus aureus (S. aureus) strain and two methicillin-resistant S. aureus (MRSA) clinical isolates. Results highlighted a concentration-dependent superior antibacterial activity of hgel-TiO2NPs over TiO2NPs in the dark and after UV photoactivation. Notably, UV light exposure substantially increased the biocidal action of hgel-TiO2NPs compared to TiO2NPs. Surprisingly, in the absence of UV light, both composites significantly increased S. aureus growth relative to control groups. These findings support the role of hgel-TiO2NPs as promising biocidal agents in clinical and sanitation contexts. However, they also signal concerns about TiO2NP exposure influencing S. aureus virulence.

The effect and mechanism of iodophors on the adhesion and virulence of Staphylococcus aureus biofilms attached to artificial joint materials

BACKGROUND

Iodophors are known to be a treatment for biofilm-related periprosthetic joint infection. However, the efficacy and mechanism of eradicating biofilms from different artificial joint materials after iodophor treatment are unknown. This study was conducted to understand the effect and mechanism of iodophors with respect to the adhesion and virulence of Staphylococcus aureus biofilms attached to artificial joint materials.

METHODS

Biofilms of Staphylococcus aureus strains were grown on titanium alloy, cobalt chromium molybdenum and polyethylene coupons, which are commonly used materials for artificial joints, for 24 h. Afterward, all coupons were divided into experimental and control groups: (1) exposed to a 0.5 ± 0.05% iodophor for 5 min and (2) exposed to phosphate-buffered saline for 5 min. To gauge the level of biofilm, colony forming units (CFU), live/dead staining confocal microscopy and crystal violet staining were used. Meanwhile, the expression of icaACDR and clfA, which are related to virulence and adhesion, was examined in both the experimental and control groups.

RESULTS

A roughly three-log decrease in CFU/cm2 was seen in the viable plate count compared to the control group. Confocal imaging and crystal violet staining verified the CFU data. Moreover, the expression of icaACDR was reduced on three different orthopaedic implant materials, and the expression of clfA was also inhibited on titanium alloy coupons exposed to the iodophor.

CONCLUSIONS

Our results indicated that exposure to an iodophor for 5 min could significantly eliminate biofilms. When Staphylococcus aureus that had adhered to these three materials, which were used for artificial joints, was treated with an iodophor for 5 min, the expression of icaACDR was significantly reduced. This provides strong evidence for clinically clearing periprosthetic joint infections without removing the artificial joints.

How biofilm changes our understanding of cleaning and disinfection

Biofilms are ubiquitous in healthcare settings. By nature, biofilms are less susceptible to antimicrobials and are associated with healthcare-associated infections (HAI). Resistance of biofilm to antimicrobials is multifactorial with the presence of a matrix composed of extracellular polymeric substances and eDNA, being a major contributing factor. The usual multispecies composition of environmental biofilms can also impact on antimicrobial efficacy. In healthcare settings, two main types of biofilms are present: hydrated biofilms, for example, in drains and parts of some medical devices and equipment, and environmental dry biofilms (DSB) on surfaces and possibly in medical devices. Biofilms act as a reservoir for pathogens including multi-drug resistant organisms and their elimination requires different approaches. The control of hydrated (drain) biofilms should be informed by a reduction or elimination of microbial bioburden together with measuring biofilm regrowth time. The control of DSB should be measured by a combination of a reduction or elimination in microbial bioburden on surfaces together with a decrease in bacterial transfer post-intervention. Failure to control biofilms increases the risk for HAI, but biofilms are not solely responsible for disinfection failure or shortcoming. The limited number of standardised biofilm efficacy tests is a hindrance for end users and manufacturers, whilst in Europe there are no approved standard protocols. Education of stakeholders about biofilms and ad hoc efficacy tests, often academic in nature, is thus paramount, to achieve a better control of biofilms in healthcare settings.

Inhibition of bacterial biofilms by the snake venom proteome

Snake venoms possess a range of pharmacological and toxicological activities. Here we evaluated the antibacterial and anti-biofilm activity against methicillin-susceptible and methicillin-resistant Staphylococcus aureus (MSSA and MRSA) of venoms from the Samar spitting cobra Naja samarensis and the Puff adder Bitis arietans. Both venoms prevented biofilm production by pathogenic S. aureus in a growth-independent manner, with the B. arietans venom being most potent. Fractionation showed the active molecule to be heat-labile and >10 kDa in size. Proteomic profiles of N. samarensis venom revealed neurotoxins and cytotoxins, as well as an abundance of serine proteases and three-finger toxins, while serine proteases, metalloproteinases and C-lectin types were abundant in B. arietans venom. These enzymes may have evolved to prevent bacteria colonising the snake venom gland. From a biomedical biotechnology perspective, they have valuable potential for anti-virulence therapy to fight antibiotic resistant microbes.

Microbial Biofilms: Applications, Clinical Consequences, and Alternative Therapies

Biofilms are complex communities of microorganisms that grow on surfaces and are embedded in a matrix of extracellular polymeric substances. These are prevalent in various natural and man-made environments, ranging from industrial settings to medical devices, where they can have both positive and negative impacts. This review explores the diverse applications of microbial biofilms, their clinical consequences, and alternative therapies targeting these resilient structures. We have discussed beneficial applications of microbial biofilms, including their role in wastewater treatment, bioremediation, food industries, agriculture, and biotechnology. Additionally, we have highlighted the mechanisms of biofilm formation and clinical consequences of biofilms in the context of human health. We have also focused on the association of biofilms with antibiotic resistance, chronic infections, and medical device-related infections. To overcome these challenges, alternative therapeutic strategies are explored. The review examines the potential of various antimicrobial agents, such as antimicrobial peptides, quorum-sensing inhibitors, phytoextracts, and nanoparticles, in targeting biofilms. Furthermore, we highlight the future directions for research in this area and the potential of phytotherapy for the prevention and treatment of biofilm-related infections in clinical settings.

Stable Superhydrophobic and Antimicrobial ZnO/Polytetrafluoroethylene Films via Radio Frequency (RF) Magnetron Sputtering

In this study, superhydrophobic ZnO/Polytetrafluoroethylene (ZnO/PTFE) films with water droplet contact angles (CA) observed as high as 165° and water droplet sliding angles of (SA) <1° have been prepared on glass substrates by RF magnetron sputtering. The PTFE was wrapped on a nano-rod made of a ZnO film with superhydrophobic properties while providing excellent UV resistance compared to hexadecyltrimethoxysilane (HDTMS) hydrophobic agents. The upper surface of the rough ZnO film was coated with PTFE, and most of the underlying coating was bare ZnO, which could well make contact with bacteria. For the Gram-negative strain, E. coli, the cell viability count of the ZnO/PTFE sample (3.5 log reduction, 99.96%) was conspicuously lower than that of the ZnO/HDTMS sample (1.2 log reduction, 93.87%) under 1 h illumination of UV light, which showed that the ZnO/PTFE sample has a better photocatalytic property than the ZnO/ HDTMS films. The ZnO/PTFE films also showed good mechanical robustness, which is an important consideration in their widespread real-world adoption.

A review of Spaulding's classification system for effective cleaning, disinfection and sterilization of reusable medical devices: Viewed through a modern-day lens that will inform and enable future sustainability

Despite advances in medicine and innovations in many underpinning fields including disease prevention and control, the Spaulding classification system, originally proposed in 1957, remains widely used for defining the disinfection and sterilization of contaminated re-usable medical devices and surgical instruments. Screening PubMed and Scopus databases using a PRISMA guiding framework generated 272 relevant publications that were used in this review. Findings revealed that there is a need to evolve how medical devices are designed, and processed by cleaning, disinfection (and/or sterilization) to mitigate patient risks, including acquiring an infection. This Spaulding Classification remains in use as it is logical, easily applied and understood by users (microbiologists, epidemiologists, manufacturers, industry) and by regulators. However, substantial changes have occurred over the past 65 years that challenge interpretation and application of this system that includes inter alia emergence of new pathogens (viruses, mycobacteria, protozoa, fungi), a greater understanding of innate and adaptive microbial tolerance to disinfection, toxicity risks, increased number of vulnerable patients and associated patient procedures, and greater complexity in design and use of medical devices. Common cited examples include endoscopes that enable non- or minimal invasive procedures but are highly sophisticated with various types of materials (polymers, electronic components etc), long narrow channels, right angle and heat-sensitive components and various accessories (e.g., values) that can be contaminated with high levels of microbial bioburden and patient tissues after use. Contaminated flexible duodenoscopes have been a source of several significant infection outbreaks, where at least 9 reported cases were caused by multidrug resistant organisms [MDROs] with no obvious breach in processing detected. Despite this, there is evidence of the lack of attention to cleaning and maintenance of these devices and associated equipment. Over the last few decades there is increasing genomic evidence of innate and adaptive resistance to chemical disinfectant methods along with adaptive tolerance to environmental stresses. To reduce these risks, it has been proposed to elevate classification of higher-risk flexible endoscopes (such as duodenoscopes) from semi-critical [contact with mucous membrane and intact skin] to critical use [contact with sterile tissue and blood] that entails a transition to using low-temperature sterilization modalities instead of routinely using high-level disinfection; thus, increasing the margin of safety for endoscope processing. This timely review addresses important issues surrounding use of the Spaulding classification system to meet modern-day needs. It specifically addresses the need for automated, robust cleaning and drying methods combined with using real-time monitoring of device processing. There is a need to understand entire end-to-end processing of devices instead of adopting silo approaches that in the future will be informed by artificial intelligence and deep-learning/machine learning. For example, combinational solutions that address the formation of complex biofilms that harbour pathogenic and opportunistic microorganisms on the surfaces of processed devices. Emerging trends are addressed including future sustainability for the medical devices sector that can be enabled via a new Quintuple Helix Hub approach that combines academia, industry, healthcare, regulators, and society to unlock real world solutions.

Comparison of the Patency and Regenerative Potential of Biodegradable Vascular Prostheses of Different Polymer Compositions in an Ovine Model

The lack of suitable autologous grafts and the impossibility of using synthetic prostheses for small artery reconstruction make it necessary to develop alternative efficient vascular grafts. In this study, we fabricated an electrospun biodegradable poly(ε-caprolactone) (PCL) prosthesis and poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/poly(ε-caprolactone) (PHBV/PCL) prosthesis loaded with iloprost (a prostacyclin analog) as an antithrombotic drug and cationic amphiphile with antibacterial activity. The prostheses were characterized in terms of their drug release, mechanical properties, and hemocompatibility. We then compared the long-term patency and remodeling features of PCL and PHBV/PCL prostheses in a sheep carotid artery interposition model. The research findings verified that the drug coating of both types of prostheses improved their hemocompatibility and tensile strength. The 6-month primary patency of the PCL/Ilo/A prostheses was 50%, while all PHBV/PCL/Ilo/A implants were occluded at the same time point. The PCL/Ilo/A prostheses were completely endothelialized, in contrast to the PHBV/PCL/Ilo/A conduits, which had no endothelial cells on the inner layer. The polymeric material of both prostheses degraded and was replaced with neotissue containing smooth-muscle cells; macrophages; proteins of the extracellular matrix such as type I, III, and IV collagens; and vasa vasorum. Thus, the biodegradable PCL/Ilo/A prostheses demonstrate better regenerative potential than PHBV/PCL-based implants and are more suitable for clinical use.

Beyond the Risk of Biofilms: An Up-and-Coming Battleground of Bacterial Life and Potential Antibiofilm Agents

Microbial pathogens and their virulence factors like biofilms are one of the major factors which influence the disease process and its outcomes. Biofilms are a complex microbial network that is produced by bacteria on any devices and/or biotic surfaces to escape harsh environmental conditions and antimicrobial effects. Due to the natural protective nature of biofilms and the associated multidrug resistance issues, researchers evaluated several natural anti-biofilm agents, including bacteriophages and their derivatives, honey, plant extracts, and surfactants for better destruction of biofilm and planktonic cells. This review discusses some of these natural agents that are being put into practice to prevent biofilm formation. In addition, we highlight bacterial biofilm formation and the mechanism of resistance to antibiotics.

Non-deacetylated poly-N-acetylglucosamine-hyperproducing Staphylococcus aureus undergoes immediate autoaggregation upon vortexing

Biofilms are microbial communities of cells embedded in a matrix of extracellular polymeric substances generated and adhering to each other or to a surface. Cell aggregates formed in the absence of a surface and floating pellicles that form biofilms at the air-liquid interface are also considered to be a type of biofilm. Staphylococcus aureus is a well-known cause of biofilm infections and high-molecular-weight polysaccharides, poly-N-acetylglucosamine (PNAG) is a main constituent of the biofilm. An icaADBC operon comprises major machinery to synthesize and extracellularly secrete PNAG. Extracellular PNAG is partially deacetylated by IcaB deacetylase, and the positively charged PNAG hence interacts with negatively charged cell surface to form the major component of biofilm. We previously reported a new regulator of biofilm (Rob) and demonstrated that Rob binds to a unique 5-bp motif, TATTT, present in intergenic region between icaADBC operon and its repressor gene icaR in Yu et al. The deletion of the 5-bp motif induces excessive adherent biofilm formation. The real function of the 5-bp motif is still unknown. In an attempt to isolate the 5-bp motif deletion mutant, we isolated several non-adherent mutants. They grew normally in turbid broth shaking culture but immediately auto-aggregated upon weak vortexing and sedimented as a lump resulting in a clear supernatant. Whole genome sequencing of the mutants identified they all carried mutations in icaB in addition to deletion of the 5-bp motif. Purification and molecular characterization of auto-aggregating factor in the culture supernatant of the mutant identified that the factor was a massively produced non-deacetylated PNAG. Therefore, we created a double deficient strain of biofilm inhibitory factors (5-bp motif, icaR, rob) and icaB to confirm the aggregation phenomenon. This peculiar phenomenon was only observed in Δ5bpΔicaB double mutant but not in ΔicaR ΔicaB or ΔrobΔicaB mutant. This study explains large amount of extracellularly produced non-deacetylated PNAG by Δ5bpΔicaB double mutation induced rapid auto-aggregation of S. aureus cells by vortexing. This phenomenon indicated that Staphylococcus aureus may form biofilms that do not adhere to solid surfaces and we propose this as a new mechanism of non-adherent biofilm formation of S. aureus.

Homocysteine and Inflammatory Cytokines in the Clinical Assessment of Infection in Venous Leg Ulcers

Inflammation and biofilm-associated infection are common in chronic venous leg ulcers (VU), causing deep pain and delayed healing. Albeit important, clinical markers and laboratory parameters for identifying and monitoring persistent VU infections are limited. This study analyzed 101 patients with infected (IVU) and noninfected VUs (NVU). Clinical data were collected in both groups. The serum homocysteine (Hcys) and inflammatory cytokines from the wound fluid were measured. In addition, microbial identification, antibiotic susceptibility, and biofilm production were examined. IVU were 56 (55.4%) while NVU were 45 (44.5%). IVUs showed a significant increase in the wound's size and depth compared to NVUs. In addition, significantly higher levels of interleukin (IL)-6, IL-10, IL17A, and tumor necrosis factor-alpha (TNF-α) were found in patients with IVUs compared to those with NVUs. Notably, hyperhomocysteinemia (HHcy) was significantly more common in patients with IVUs than NVUs. A total of 89 different pathogens were identified from 56 IVUs. Gram-negative bacteria were 51.7%, while the Gram-positives were 48.3%. At the species level, Staphylococcus aureus was the most common isolate (43.8%), followed by Pseudomonas aeruginosa (18.0%). Multidrug-resistant organisms (MDROs) accounted for 25.8% of the total isolates. Strong biofilm producers (SBPs) (70.8%) were significantly more abundant than weak biofilm producers (WBP) (29.2%) in IVUs. SBPs were present in 97.7% of the IVUs as single or multispecies infections. Specifically, SBPs were 94.9% for S. aureus, 87.5% for P. aeruginosa, and 28.6% for Escherichia coli. In IVU, the tissue microenvironment and biofilm production can support chronic microbial persistence and a most severe clinical outcome even in the presence of an intense immune response, as shown by the high levels of inflammatory molecules. The measurement of local cytokines in combination with systemic homocysteine may offer a novel set of biomarkers for the clinical assessment of IVUs caused by biofilm-producing bacteria.