Kinetics and morphology of polymicrobial biofilm formation on polypropylene mesh

The Infected Polypropylene Mesh: When Does Biofilm Form and Which Antiseptic Solution Most Effectively Removes It?

BACKGROUND

Polypropylene (PPE) mesh is commonly utilized to reconstruct catastrophic extensor mechanism disruptions in revision total knee arthroplasty. Unfortunately, these procedures are associated with a high rate of periprosthetic joint infection. The purpose of the current study was to: 1) visualize and quantify the progression of bacterial biofilm growth on PPE-mesh; and 2) determine which antiseptic solutions effectively remove viable bacteria.

METHODS

Knitted PPE mesh samples were cultured with either methicillin-sensitive Staphylococcus aureus (MSSA) or Escherichia coli (E. coli) for 7 days, with regular quantification of colony forming units (CFUs) and visualization using scanning electron microscopy to identify maturity. Immature (24 hour) and mature (72 hour) biofilm was treated with one of 5 commercial antiseptics for 3 minutes. A 0.05% chlorhexidine gluconate, a surfactant-based formulation of ethanol, acetic acid, sodium acetate, benzalkonium chloride, diluted povidone-iodine (0.35%), undiluted (10%) povidone-iodine, and 1:1 combination of 10% povidone-iodine and 3% hydrogen peroxide. A 3-log reduction in CFUs compared to saline was considered clinically meaningful.

RESULTS

The CFU counts plateaued, indicating maturity, at 72 hours for both MSSA and E. coli. The scanning electron microscopy confirmed confluent biofilm formation after 72 hours. The 10% povidone-iodine was clinically effective against all MSSA biofilms and immature E. coli biofilms. The 10% povidone-iodine with hydrogen peroxide was effective in all conditions. Only 10% povidone iodine formulations produced significantly (P < .0083) reduced CFU counts against mature biofilms.

CONCLUSIONS

Bacteria rapidly form biofilm on PPE mesh. Mesh contamination can be catastrophic, and clinicians should consider utilizing an antiseptic solution at the conclusion of mesh implantation. Undiluted povidone-iodine with hydrogen peroxide should be considered when attempting to salvage infected PPE mesh.

Limited Durability of Extensor Mechanism Reconstruction Following Total Knee Arthroplasty: Mesh and Allograft Show Equivalent Outcomes at Five-Year Follow-Up

BACKGROUND

Extensor mechanism disruption is a challenging complication following total knee arthroplasty. The purpose of this study was to compare outcomes between patients who received mesh versus allograft extensor mechanism reconstruction.

METHODS

All patients who underwent extensor mechanism reconstruction at a single institution were screened. Demographic and surgical variables were recorded, including technique (ie, synthetic mesh versus allograft reconstruction). Patients were assessed for preoperative and postoperative extensor lag, revision, and duration of follow-up. Analyses, including Kaplan-Meier survivorships, were performed to compare mesh to allograft reconstruction. In total, 50 extensor mechanism reconstructions (30 mesh and 20 allograft) were conducted between January 1st, 2001, and December 31st, 2022.

RESULTS

There were no differences between the cohorts with respect to revision (26.7 [8 of 30] versus 35.0% [7 of 20], P = .680) or failure defined as above knee amputation or fusion (6.7 [2 of 30] versus 5.0% [1 of 20], P = .808). There were also no differences in time to reoperation (average 27 months [range, 6.7 to 58.8] versus 29 months [range, 1.2 to 84.9], P = .910) or in postoperative extensor lag among patients who did not undergo a reoperation (13 [0 to 50] versus 11° [0 to 30], P = .921). The estimated 5-year Kaplan-Meier survival with extensor mechanism revision as the endpoint was similar between the 2 groups (52.1, 95% confidence interval [CI] = 25.4 to 73.3 versus 55.0%, 95% CI = 23.0 to 78.4%, P = .990).

CONCLUSIONS

The purpose of this study was to present the findings of a large cohort of patients who required extensor mechanism reconstruction. Regardless of the reconstruction type, the 5-year outcomes of patients requiring extensor mechanism reconstruction are suboptimal.

Enterococci facilitate polymicrobial infections

Enterococci are ubiquitous members of the gut microbiota in human beings and animals and are among the most important nosocomial organisms. Due to their opportunistic pathogenicity, enterococci are referred to as pathobionts and play decisive roles in a diverse array of polymicrobial infections. Enterococci can promote the colonization, pathogenesis, and persistence of various pathogens, compromise the efficacy of drugs, and pose a severe threat to public health. Most current treatments tend to focus on the sole pathogenic bacteria, with insufficient attention to the driving role of enterococci. In this review, we summarize the characteristics of enterococci in infections, the factors facilitating their outgrowth, as well as the sites and types of enterococci-associated polymicrobial infections. We present an overview of the underlying mechanisms of enterococci-mediated pathogenesis in polymicrobial infections. Furthermore, we discuss alternative strategies and potential intervention approaches to restrict such infections, shedding light on the discovery and development of new therapies against polymicrobial infections.

Killing of a Multispecies Biofilm Using Gram-Negative and Gram-Positive Targeted Antibiotic Released from High Purity Calcium Sulfate Beads

BACKGROUND

Multispecies biofilm orthopedic infections are more challenging to treat than mono-species infections. In this in-vitro study, we aimed to determine if a multispecies biofilm, consisting of Gram positive and negative species with different antibiotic susceptibilities could be treated more effectively using high purity antibiotic-loaded calcium sulfate beads (HP-ALCSB) containing vancomycin (VAN) and tobramycin (TOB) in combination than alone.

METHODS

Three sets of species pairs from bioluminescent strains of Pseudomonas aeruginosa (PA) and Staphylococcus aureus (SA) and clinical isolates, Enterococcus faecalis (EF) and Enterobacter cloacae were screened for compatibility. PA + EF developed intermixed biofilms with similar cell concentrations and so were grown on 316L stainless steel coupons for 72 h or as 24 h agar lawn biofilms and then treated with HP-ALCSBs with single or combination antibiotics and assessed by viable count or bioluminescence and light imaging to distinguish each species. Replica plating was used to assess viability.

RESULTS

The VAN + TOB bead significantly reduced the PA + EF biofilm CFU and reduced the concentration of surviving antibiotic tolerant variants by 50% compared to single antibiotics.

CONCLUSIONS

The combination of Gram-negative and positive targeted antibiotics released from HP-ALCSBs may be more effective in treating multispecies biofilms than monotherapy alone.

Antibiofilm Activities of Cinnamaldehyde Analogs against Uropathogenic Escherichia coli and Staphylococcus aureus

Bacterial biofilm formation is a major cause of drug resistance and bacterial persistence; thus, controlling pathogenic biofilms is an important component of strategies targeting infectious bacterial diseases. Cinnamaldehyde (CNMA) has broad-spectrum antimicrobial and antibiofilm activities. In this study, we investigated the antibiofilm effects of ten CNMA derivatives and trans-CNMA against Gram-negative uropathogenic Escherichia coli (UPEC) and Gram-positive Staphylococcus aureus. Among the CNMA analogs tested, 4-nitrocinnamaldehyde (4-nitroCNMA) showed antibacterial and antibiofilm activities against UPEC and S. aureus with minimum inhibitory concentrations (MICs) for cell growth of 100 µg/mL, which were much more active than those of trans-CNMA. 4-NitroCNMA inhibited UPEC swimming motility, and both trans-CNMA and 4-nitroCNMA reduced extracellular polymeric substance production by UPEC. Furthermore, 4-nitroCNMA inhibited the formation of mixed UPEC/S. aureus biofilms. Collectively, our observations indicate that trans-CNMA and 4-nitroCNMA potently inhibit biofilm formation by UPEC and S. aureus. We suggest efforts be made to determine the therapeutic scope of CNMA analogs, as our results suggest CNMA derivatives have potential therapeutic use for biofilm-associated diseases.

Antibiofilm and Antimicrobial Activities of Chloroindoles Against Uropathogenic Escherichia coli

Uropathogenic Escherichia coli (UPEC) is a nosocomial pathogen associated with urinary tract infections and expresses several virulence factors that cause recurring infections and cystitis of the bladder, which can lead to pyelonephritis. UPEC uses different types of extracellular appendages like fimbriae and pili that aid colonization and adherence to bladder epithelium and can form persistent biofilm-like bacterial communities that aid its survival after the deployment of host immune responses. We investigated the antibiofilm, antimicrobial, and antivirulence properties of three indole derivatives namely, 4-chloroindole, 5-chloroindole, and 5-chloro 2-methyl indole. All the three chloroindoles had MICs of 75 μg/ml and inhibited biofilm formation by an average of 67% at 20 μg/ml. In addition, they inhibited swarming and swimming motilities, which are essential for dissemination from bacterial communities and colonization, reduced cell surface hydrophobicity, and inhibited indole production and curli formation. Gene expression analysis showed all three chloroindoles significantly downregulated the expressions of virulence genes associated with adhesion, stress regulation, and toxin production. A 3D-QSAR analysis revealed substitutions at the fourth and fifth positions of the indole moiety favored antimicrobial activity. Furthermore, these chloroindoles potently inhibited biofilm formation in other nosocomial pathogens and polymicrobial consortia.

Foodborne ESKAPE Biofilms and Antimicrobial Resistance: lessons Learned from Clinical Isolates

The ESKAPE pathogens (Enterococcus spp., Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) are identified to be multidrug-resistant (MDR), extensively drug-resistant (XDR), and pan drug-resistant (PDR); thereby, imposing severe challenges in the treatment of associated infections. ESKAPE pathogens colonize on various biotic and abiotic surfaces; biofilms formed by these pathogens are a potential source for food contamination. Moreover, biofilms play a pivotal role in the development of antimicrobial-resistant (AMR) strains. Hence, the frequent isolation of antimicrobial-resistant ESKAPE pathogens from food products across the globe imposes a threat to public health. A comprehensive understanding of the adhesion signaling involved in the polymicrobial and single-species biofilm will assist in developing alternative preservation techniques and novel therapeutic strategies to combat ESKAPE pathogens. The review provides a comprehensive overview of the signaling mechanisms that prevail in the ESKAPE pathogens for adhesion to abiotic and biotic surfaces and molecular mechanisms associated with poly-microbial biofilm-assisted AMR in ESKAPE.

Removal of Mixed-Species Biofilms Developed on Food Contact Surfaces with a Mixture of Enzymes and Chemical Agents

Sanicip Bio Control (SBC) is a novel product developed in Mexico for biofilms’ removal. The aims of this study were to evaluate (i) the removal of mixed-species biofilms by enzymatic (protease and α-amylase, 180 MWU/g) and chemical treatments (30 mL/L SBC, and 200 mg/L peracetic acid, PAA) and (ii) their effectiveness against planktonic cells. Mixed-species biofilms were developed on stainless steel (SS) and polypropylene B (PP) in whole milk (WM), tryptic soy broth (TSB) with meat extract (TSB+ME), and TSB with chicken egg yolk (TSB+EY) to simulate the food processing environment. On SS, all biofilms were removed after treatments, except the enzymatic treatment that only reduced 1–2 log₁₀ CFU/cm², whereas on PP, the reductions ranged between 0.59 and 5.21 log₁₀ CFU/cm², being the biofilms developed in TSB+EY being resistant to the cleaning and disinfecting process. Higher reductions in microbial load on PP were reached using enzymes, SBC, and PAA. The employed planktonic cells were markedly more sensitive to PAA and SBC than were the sessile cells. In conclusion, biofilm removal from SS can be achieved with SBC, enzymes, or PAA. It is important to note that the biofilm removal was strongly affected by the food contact surfaces (FCSs) and surrounding media.

Biofilm and its implications postfracture fixation: All I need to know

Biofilm represents an organized multicellular community of bacteria having a complex 3D structure, formed by bacterial cells and their self-produced extracellular matrix. It usually attaches to any foreign body or fixation implant. It acts as a physical protective barrier of the bacteria from the penetration of antibodies, bacteriophages, granulocytes and biocides, antiseptics, and antibiotics. Biofilm-related infections will increase in the near future. This group of surgical site infections is the most difficult to diagnose, to suppress, to eradicate, and in general to manage. Multispecialty teams involved in all stages of care are an effective way to improve results and save resources and time for the benefit of patients and the health system. Significant steps have occurred recently in the prevention and development of clever tools that we can employ in this everlasting fight with the bacteria. Herein, we attempt to describe the nature and role of the "biofilm" to the specific clinical setting of surgical site infections in the field of orthopaedic trauma surgery.

Investigation of synovial fluid induced Staphylococcus aureus aggregate development and its impact on surface attachment and biofilm formation

Periprosthetic joint infections (PJIs) are a devastating complication that occurs in 2% of patients following joint replacement. These infections are costly and difficult to treat, often requiring multiple corrective surgeries and prolonged antimicrobial treatments. The Gram-positive bacterium Staphylococcus aureus is one of the most common causes of PJIs, and it is often resistant to a number of commonly used antimicrobials. This tolerance can be partially attributed to the ability of S. aureus to form biofilms. Biofilms associated with the surface of indwelling medical devices have been observed on components removed during chronic infection, however, the development and localization of biofilms during PJIs remains unclear. Prior studies have demonstrated that synovial fluid, in the joint cavity, promotes the development of bacterial aggregates with many biofilm-like properties, including antibiotic resistance. We anticipate these aggregates have an important role in biofilm formation and antibiotic tolerance during PJIs. Therefore, we sought to determine specifically how synovial fluid promotes aggregate formation and the impact of this process on surface attachment. Using flow cytometry and microscopy, we quantified the aggregation of various clinical S. aureus strains following exposure to purified synovial fluid components. We determined that fibrinogen and fibronectin promoted bacterial aggregation, while cell free DNA, serum albumin, and hyaluronic acid had minimal effect. To determine how synovial fluid mediated aggregation affects surface attachment, we utilized microscopy to measure bacterial attachment. Surprisingly, we found that synovial fluid significantly impeded bacterial surface attachment to a variety of materials. We conclude from this study that fibrinogen and fibronectin in synovial fluid have a crucial role in promoting bacterial aggregation and inhibiting surface adhesion during PJI. Collectively, we propose that synovial fluid may have conflicting protective roles for the host by preventing adhesion to surfaces, but by promoting bacterial aggregation is also contributing to the development of antibiotic tolerance.

Effectiveness of manual versus automated cleaning on Staphylococcus epidermidis biofilm removal from the surface of surgical instruments

BACKGROUND

Biofilm removal is a challenge during surgical instrument processing. We analyzed the time required for Staphylococcus epidermidis to form biofilms on surgical instruments, and how cleaning methods removed them.

METHODS

Different areas (ratchet, shank, and jaw) of straight crile forceps were contaminated by soaking in Tryptic Soy Broth containing 10⁶ colony forming units (CFU)/mL of S epidermidis for 1, 2, 4, 6, 8, and 12 hours. S epidermidis adhesion and removal, after manual or automated ultrasonic cleaning, was evaluated by microbiological culture and scanning electron microscopy.

RESULTS

Microbial load increased with time (10¹-10² CFU/cm² after 1 hour; 10⁴ CFU/cm² after 12 hours). Exopolysaccharide was detected after 2 hours and gradually increased thereafter. Bacterial load was reduced by 1-2 log₁₀ after manual cleaning and 1-3 log₁₀ after automated cleaning, but biofilms were not completely eliminated. In general, bacterial load was lower in shank fragments. This difference was significant at 6 hours.

CONCLUSIONS

Rapid adhesion of S epidermidis and exopolysaccharide formation was observed on surgical instruments. Automated cleaning was more effective than manual cleaning, but neither method removed biofilms completely. The precleaning conditions and the forceps design are critical factors in processing quality.

Resistance of Synthetic and Biologic Surgical Meshes to Methicillin-Resistant Staphylococcus aureus Biofilm: An In Vitro Investigation

Surgical meshes have become the standard procedure for a variety of surgical applications with 20 million meshes being implanted each year. The popularity of mesh usage among surgeons is backed by the multiple studies that support its functionality as a tool for improving surgical outcomes. However, their use has also been associated with infectious surgical complications and many surgeons have turned to biologic meshes. While there have been several studies investigating synthetic meshes, there is limited data comparing synthetic and biologic meshes in vitro in an infection model. This study evaluates the in vitro susceptibility of both synthetic and biologic meshes to single-species methicillin-resistant Staphylococcus aureus (MRSA) biofilms. This research compares biofilm biomass, average thickness, and coverage between the three meshes through florescent in situ hybridization (FISH), confocal scanning microscopy (CSLM), and image analysis. We also report the varying levels of planktonic and attached bacteria through sonication and cfu counts. While the data illustrates increased biofilm formation on biologic mesh in vitro, the study must further be investigated in vivo to confirm the study observations.

A critical review of the in vitro and in vivo models for the evaluation of anti-infective meshes

BACKGROUND

Infectious complications following mesh implantation for abdominal wall repair appear in 0.7 up to 26.6% of hernia repairs and can have a detrimental impact for the patient. To prevent or to treat mesh-related infection, the scientific community is currently developing a veritable arsenal of antibacterial meshes. The numerous and increasing reports published every year describing new technologies indicate a clear clinical need, and an academic interest in solving this problem. Nevertheless, to really appreciate, to challenge, to compare and to optimize the antibacterial properties of next generation meshes, it is important to know which models are available and to understand them.

PURPOSE

We proposed for the first time, a complete overview focusing only on the in vitro and in vivo models which have been employed specifically in the field of antibacterial meshes for hernia repair.

RESULTS AND CONCLUSION

From this investigation, it is clear that there has been vast progress and breadth in new technologies and models to test them. However, it also shows that standardization or adoption of a more restricted number of models would improve comparability and be a benefit to the field of study.

A Formidable Foe Is Sabotaging Your Results: What You Should Know about Biofilms and Wound Healing

LEARNING OBJECTIVES

After reading this article, the participant should be able to: 1. Describe biofilm pathogenesis as it relates to problem wounds. 2. Understand the preclinical and clinical evidence implicating biofilm in problem wounds. 3. Explain the diagnostic and treatment challenges that biofilms create for problem wounds. 4. Demonstrate a basic understanding of emerging strategies aimed at counteracting these processes.

SUMMARY

Biofilm represents a protected mode of growth for bacteria, allowing them to evade standard diagnostic techniques and avoid eradication by standard therapies. Although only recently discovered, biofilm has existed for millennia and complicates nearly every aspect of medicine. Biofilm impacts wound healing by allowing bacteria to evade immune responses, prolonging inflammation and disabling skin barrier function. It is important to understand why problem wounds persist despite state-of-the-art treatment, why they are difficult to accurately diagnose, and why they recur. The aim of this article is to focus on current gaps in knowledge related to problem wounds, specifically, biofilm infection.

Direct demonstration of bacterial biofilms on prosthetic mesh after ventral herniorrhaphy

BACKGROUND

Prosthetic mesh is employed routinely in the treatment of ventral and parastomal hernias, but its use can lead to major complications, including infection, extrusion, and fistula. Bacterial biofilms have been posited to play a role in mesh-related infection, but although bacteria have been noted to form biofilms on mesh surfaces in vitro, they have never been visualized directly in biofilms on mesh recovered from patients experiencing infectious complications.

METHODS

Five patients who developed complications after ventral hernia repair with prosthetic mesh were operated on again. Explanted mesh was examined for biofilm with confocal laser scanning microscopy (CLSM) and fluorescence in situ hybridization (FISH). In two cases, a novel molecular assay (the Ibis T5000) was used to characterize the biofilm-forming bacteria.

RESULTS

The CLSM examination demonstrated adherent biofilms on mesh surfaces in all five patients. Biofilms also were noted on investing fibrous tissue. The FISH study was able to discriminate between bacterial species in polymicrobial biofilms. In two patients the Ibis T5000 detected more species of constituent biofilm bacteria than did standard culture. Removal of the mesh and reconstruction with autologous tissues or biologic materials resolved the presenting complaints in all cases.

CONCLUSION

Bacterial biofilms should be considered an important contributor to the pathology and complications associated with prosthetic mesh implanted in the abdominal wall. If biofilms are present, complete removal of the mesh and repair of the resulting defect without alloplastic materials is an effective intervention.