Staphylococcal Biofilm Research Articles

Biofilm Formation and Antibiotic Resistance of S. aureus Strains isolated from Chronic Traumatic Wounds

Staphylococcal biofilms are the prominent cause of chronic wound infection and antibiotic resistance. It acts as a reservoir for bacteria, making wound healing difficult. Biofilm infections increase the hospital stays and cost to the patients. The current study explores the phenotypic and genotypic detection of S. aureus biofilm from chronic traumatic wounds and their association with antibiotic resistance. A prospective observational study was conducted from April 2020 to March 2021. S. aureus isolates were identified by the MALDI-TOF. Antibiotic susceptibility was determined by VITEK 2. Biofilm production detected by tissue culture plate method and associated ica genes were diagnosed through multiplex PCR. Overall, 67 isolates were investigated. The frequency of biofilm production in S. aureus was 73.1%, and most of the isolates were moderate biofilm producers (38.8%). The presence of intracellular adhesion (ica) operon among these isolates was 85.7% and also significantly associated with the strength of biofilm mass formation. Ica A was the predominant biofilm-producing gene (42.9%). Biofilm producing Methicillin-resistant S. aureus were as high as 75%, and multidrug resistant strains were significantly associated with biofilm formation. But frequency of ica genes were noted more in Methicillin sensitive S. aureus (65.2%). High frequency of biofilm in S. aureus of isolates was responsible for the development of chronic non-healing traumatic wounds. Biofilm-producing isolates showed greater multidrug-resistance. Phenotypically MRSA expressed more biofilm, but ica operon was documented in MSSA. It emphasized the further need for ica independent pathway exploration for MRSA biofilm synthesis.

Submicron topography design for controlling staphylococcal bacterial adhesion and biofilm formation.

Surface topography modification with nano- or micro-textured structures has been an efficient approach to inhibit microbial adhesion and biofilm formation and thereby to prevent biomaterial-associated infection without modification of surface chemistry/bulk properties of materials and without causing antibiotic resistance. This manuscript focuses on submicron-textured patterns with ordered arrays of pillars on polyurethane (PU) biomaterial surfaces in an effort to understand the effects of surface pillar features and surface properties on adhesion and colonization responses of two staphylococcal strains. Five submicron patterns with a variety of pillar dimensions were designed and fabricated on PU film surfaces and bacterial adhesion and biofilm formation of Staphylococcal strains (Staphylococcus epidermidis RP62A and Staphylococcus aureus Newman D2C) were characterized. Results show that all submicron textured surface significantly reduced bacterial adhesion and inhibited biofilm formation, and bacterial adhesion linearly decreased with the reduction in top surface area fraction. Surface wettability did not show a linear correlation with bacterial adhesion, suggesting that surface contact area dominates bacterial adhesion. From this, it appears that the design of textured patterns should minimize surface area fraction to reduce the bacterial interaction with surfaces but in a way that ensures the mechanical strength of pillars in order to avoid collapse. These findings may provide a rationale for design of polymer surfaces for antifouling medical devices.

Rational Design of Polyphosphorylcholine‐Based Micelles for Superior Anti‐Biofilm Activity

AbstractIt's a great challenge to completely eradicate the bacteria in biofilms by antimicrobials, since the cells are wrapped in the dense extracellular polymeric substances. Herein, in order to deliver antibacterial agents into staphylococcal biofilms and to kill the bacteria in the biofilms, an amphiphilic polymer with tertiary amine groups, poly(2‐methacryloyloyethyl phosphorylcholine)‐b‐poly {α‐[4‐(diethylamino)methyl‐1,2,3‐triazol]‐caprolactone‐co‐caprolactone} (PMPC‐PDCL) is synthesized, and its micelles are used as carriers for a model antimicrobial triclosan (TCS) to research the effect of polymeric components on antibiofilm. Polycaprolactone‐b‐poly(2‐methacryloyloxyethyl phosphorylcholine) (PMPC‐PCL) and poly(ethylene glycol)‐b‐polycaprolactone (PEG‐PCL) are designed as contrast materials. The results demonstrate that PMPC‐PDCL micelles possess the highest drug loading, and the accumulative TCS release rate of PMPC‐PDCL/TCS micelles at pH 5.5+lipase is highest. The minimum bactericidal concentration value of PMPC‐PDCL/TCS micelles is 64 µg mL−1. According to the confocal laser scanning microscopy, the penetration effect of PMPC‐PDCL micelles is the best, followed by PMPC‐PCL and PEG‐PCL micelles. PMPC‐PDCL/TCS micelles display excellent anti‐biofilm both on account of their outstanding penetration effect and drug release behavior in acidic and lipase environments. Thus, PMPC‐PDCL micelles can be used as carriers to deliver the antibacterial agents into biofilms, which has important significance to cure diseases caused by bacterial infection.

The Triprenylated Anthranoid Ferruginin A, a Promising Scaffold for the Development of Novel Antibiotics against Gram-Positive Bacteria.

In today’s post-antibiotic era, the search for new antimicrobial compounds is of major importance and nature represents one of the primary sources of bioactive molecules. In this work, through a cheminformatics approach, we clustered an in-house library of natural products and their derivatives based on a combination of fingerprints and substructure search. We identified the prenylated emodine-type anthranoid ferruginin A as a novel antimicrobial compound. We tested its ability to inhibit and kill a panel of Gram-positive and Gram-negative bacteria, and compared its activity with that of two analogues, vismione B and ferruanthrone. Furthermore, the capability of these three anthranoids to disrupt staphylococcal biofilm was investigated, as well as their effect on the viability of human keratinocytes. Ferruginin A showed a potent activity against both the planktonic and biofilm forms of Gram-positive bacteria (i.e., Staphylococcus aureus and S. epidermidis) and had the best therapeutic index compared to vismione B and ferruanthrone. In conclusion, ferruginin A represents a promising scaffold for the further development of valuable antimicrobial agents.

Biofilm Propensity of Staphylococcus Aureus Skin Isolates Is Associated With Increased Atopic Dermatitis Severity and Barrier Dysfunction in the MPAACH Pediatric Cohort

Atopic dermatitis (AD) patients are commonly colonized with Staphylococcus aureus, and staphylococcal biofilms have been described in adult AD lesions. The commensal Staphylococcus epidermidis can antagonize S aureus, but its role in AD is unclear. These investigators sought to characterize S aureus and S epidermidis colonization and biofilm propensity and determine their association with AD severity, barrier function, and epidermal gene expression in an early-life cohort of children with AD.The Mechanisms of Progression of Atopic Dermatitis to Asthma in Children (MPAACH) cohort consists of children aged 1 to 2 years in the greater Cincinnati, Ohio area with either physician-diagnosed AD or a positive parental response to all 3 questions on the Children’s Eczema Questionnaire.A total of 500 children are being enrolled. The current study was focused on the first 400 MPAACH participants. Demographic, environmental, asthma trigger, and personal and family allergy and asthma history data were compiled. AD severity was documented with the Scoring of Atopic Dermatitis scale. Topical medications were withheld the night before the visit. The biofilm propensity of staphylococcal isolates was assessed by crystal violet assays. Gene expression of filaggrin and antimicrobial alarmins S100A8 and S100A9 were measured in keratinocyte RNA extracted from skin tape strips. Staphylococcal biofilms were visualized with scanning electron microscopy.Among the entire 400 children, 26.5% had positive cultures for S aureus, whereas 71% were positive for S epidermidis. A total of 62% of staphylococcal isolates formed moderate or strong biofilms, whereas 68% of those co-colonized with both staphylococcal species exhibited strains that formed cooperative mixed-species biofilms. Scanning electron microscopy verified presence of biofilms. S aureus strains showing higher relative biofilm propensity compared with S epidermidis were associated with increased AD severity and increased lesional and nonlesional transepidermal water loss. Biofilm propensity was associated with decreased FLG expression, which otherwise encodes filaggrin, a structural protein essential to prevent water loss.Collectively, these data suggest that, although S. aureus colonization is associated with increased AD severity, it is the ability of S. aureus to form strong biofilms and the balance between biofilm-forming S. aureus and S epidermidis strains that are particularly important factors affecting AD severity and barrier dysfunction.Biofilms are important in many complex disease processes, and atopic dermatitis appears to be no exception. Whether through genetic (eg, allergy and filaggrin mutations), environmental, or other factors, the altered skin barrier predisposes to S aureus colonization. This jibes with the common clinical observation that acute AD flares are often responsive to a course of both systemic and topical antistaphylococcal therapy while aggressively employing moisturizing measures.

In vitro additive effects of dalbavancin and rifampicin against biofilm of Staphylococcus aureus

Dalbavancin is a novel glycopeptide antibiotic approved for the treatment of acute bacterial skin and skin structure infections (ABSSSIs). It is characterized by a potent activity against numerous Gram-positive pathogens, a long elimination half-life and a favorable safety profile. Most recently, its application for the treatment of periprosthetic joint infections (PJIs) was introduced. The aim of this study was to proof our hypothesis, that dalbavancin shows superior efficacy against staphylococcal biofilms on polyethylene (PE) disk devices compared with vancomycin and additive behavior in combination with rifampicin. Staphylococcus aureus biofilms were formed on PE disk devices for 96 h and subsequently treated with dalbavancin, vancomycin, rifampicin and dalbavancin-rifampicin combination at different concentrations. Quantification of antibacterial activity was determined by counting colony forming units (CFU/ml) after sonification of the PE, serial dilution of the bacterial suspension and plating on agar-plates. Biofilms were additionally life/dead-stained and visualized using fluorescence microscopy. Dalbavancin presented superior anti-biofilm activity compared to vancomycin. Additive effects of the combination dalbavancin and rifampicin were registered. Dalbavancin combined with rifampicin presents promising anti-biofilm activity characteristics in vitro. Further in vivo studies are necessary to establish recommendations for the general use of dalbavancin in the treatment of PJIs.

Screening of Bioactive Metabolites Actinomycetes to Evaluate Potential Sources of Sustainable Marine Natural Products

This study aimed to screen the activity of methanol extract of sponge-derived actinomycetes as an anti-biofilm and antibacterial agent to Staphylococcus aureus. Nine actinomycetes isolates were selected from the UPT LTSIT deposit. S. aureus was obtained from the skin of patients at Abdul Moeloek General Hospital. An antibiotic susceptibility test was performed by the disk diffusion method. Biofilm formation of S. aureus was tested using the crystal violet method. The viability of pathogenic bacteria was measured using the indicator resazurin. The results of the biofilm formation test in vitro revealed that the organic extracts 33A1T2, 33A2T3, 21A1T11, and 38A1T12 inhibited bacterial growth at 0.5 mg/mL. Meanwhile, 50A2T9, 21A1T11, and 38A1T12 significantly inhibited the formation of staphylococcal biofilm on polystyrene at a concentration of 0.25 mg/mL. This information is very important as a basis for further understanding of the mechanism of action of antibiofilm agents.

An interesting approach for Biofilm disruption by Thermocouple device

Microbial biofilm are an aggregate of microbial population encompassed in a matrix of self secreted extracellular polymeric substances (EPS). In various sectors from human health to industries biofilm bring with it an array of harmful impacts. For instance, biofilm linked diseases like chronic otitis, chronic osteomyelitis, urinary tract infections, cystic fibrosis-associated lung infection etc. cannot be treated with regular antibiotics since profound use of the same have led to the existence of several drug resistant strains. Effective techniques for combating this bacterial biofilm are still a challenging issue to the scientific community. Towards this direction, in the present study efforts have been put to use electric shock generated by a thermocouple device to disrupt bacterial biofilm formation. The uniqueness of the procedure lies with the method of generation of the electric shock, wherein a difference in temperature has been exploited to create the shock. Using this method, electric shocks of 105μV was applied for different durations on bacterial biofilm formed by Pseudomonas sp. and Staphylococcus sp. In each case a difference in response was observed which led to the conclusion that Staphylococcal biofilm as well as Pseudomonal biofilm are susceptible to the electric shocks. Hence, this interesting method of usage of low voltage electric shock could be a potential method to fight against biofilm threats.

Capsicumicine, a New Bioinspired Peptide from Red Peppers Prevents Staphylococcal Biofilm In Vitro and In Vivo via a Matrix Anti-Assembly Mechanism of Action.

ABSTRACTStaphylococci are pathogenic biofilm-forming bacteria and a source of multidrug resistance and/or tolerance causing a broad spectrum of infections. These bacteria are enclosed in a matrix that allows them to colonize medical devices, such as catheters and tissues, and that protects against antibiotics and immune systems. Advances in antibiofilm strategies for targeting this matrix are therefore extremely relevant. Here, we describe the development of the Capsicum pepper bioinspired peptide “capsicumicine.” By using microbiological, microscopic, and nuclear magnetic resonance (NMR) approaches, we demonstrate that capsicumicine strongly prevents methicillin-resistant Staphylococcus epidermidis biofilm via an extracellular “matrix anti-assembly” mechanism of action. The results were confirmed in vivo in a translational preclinical model that mimics medical device-related infection. Since capsicumicine is not cytotoxic, it is a promising candidate for complementary treatment of infectious diseases.IMPORTANCE Pathogenic biofilms are a global health care concern, as they can cause extensive antibiotic resistance, morbidity, mortality, and thereby substantial economic loss. So far, no effective treatments targeting the bacteria in biofilms have been developed. Plants are constantly attacked by a wide range of pathogens and have protective factors, such as peptides, to defend themselves. These peptides are common components in Capsicum baccatum (red pepper). Here, we provide insights into an antibiofilm strategy based on the development of capsicumicine, a natural peptide that strongly controls biofilm formation by Staphylococcus epidermidis, the most prevalent pathogen in device-related infections.

The High Impact of Staphylococcus aureus Biofilm Culture Medium on In Vitro Outcomes of Antimicrobial Activity of Wound Antiseptics and Antibiotic.

The staphylococcal biofilm-based infections of wounds still pose a significant therapeutical challenge. Treated improperly, they increase the risk of limb amputation or even death of the patient. The present algorithms of infected wound treatment include, among others, the application of antiseptic substances. In vitro wound biofilm models are applied in order to scrutinize their activity. In the present work, using a spectrum of techniques, we showed how the change of a single variable (medium composition) in the standard in vitro model translates not only to shift in staphylococcal biofilm features but also to the change of efficacy of clinically applied wound antimicrobials such as octenidine, polyhexamethylene biguanide, chlorhexidine, hypochlorite solutions, and locally applied gentamycin. The data presented in this study may be of a pivotal nature, taking into consideration the fact that results of in vitro analyses are frequently used to propagate application of specific antimicrobials in hospitals and ambulatory care units.

Investigating Extracellular DNA Release in Staphylococcus xylosus Biofilm In Vitro.

Staphylococcus xylosus forms biofilm embedded in an extracellular polymeric matrix. As extracellular DNA (eDNA) resulting from cell lysis has been found in several staphylococcal biofilms, we investigated S. xylosus biofilm in vitro by a microscopic approach and identified the mechanisms involved in cell lysis by a transcriptomic approach. Confocal laser scanning microscopy (CLSM) analyses of the biofilms, together with DNA staining and DNase treatment, revealed that eDNA constituted an important component of the matrix. This eDNA resulted from cell lysis by two mechanisms, overexpression of phage-related genes and of cidABC encoding a holin protein that is an effector of murein hydrolase activity. This lysis might furnish nutrients for the remaining cells as highlighted by genes overexpressed in nucleotide salvage, in amino sugar catabolism and in inorganic ion transports. Several genes involved in DNA/RNA repair and genes encoding proteases and chaperones involved in protein turnover were up-regulated. Furthermore, S. xylosus perceived osmotic and oxidative stresses and responded by up-regulating genes involved in osmoprotectant synthesis and in detoxification. This study provides new insight into the physiology of S. xylosus in biofilm.

Staphylococcal Bacterial Persister Cells, Biofilms, and Intracellular Infection Are Disrupted by JD1, a Membrane-Damaging Small Molecule.

ABSTRACTRates of antibiotic and multidrug resistance are rapidly rising, leaving fewer options for successful treatment of bacterial infections. In addition to acquiring genetic resistance, many pathogens form persister cells, form biofilms, and/or cause intracellular infections that enable bacteria to withstand antibiotic treatment and serve as a source of recurring infections. JD1 is a small molecule previously shown to kill Gram-negative bacteria under conditions where the outer membrane and/or efflux pumps are disrupted. We show here that JD1 rapidly disrupts membrane potential and kills Gram-positive bacteria. Further investigation revealed that treatment with JD1 disrupts membrane barrier function and causes aberrant membranous structures to form. Additionally, exposure to JD1 reduced the number of Staphylococcus aureus and Staphylococcus epidermidis viable persister cells within broth culture by up to 1,000-fold and reduced the matrix and cell volume of biofilms that had been established for 24 h. Finally, we show that JD1 reduced the number of recoverable methicillin-resistant S. aureus organisms from infected cells. These observations indicate that JD1 inhibits staphylococcal cells in difficult-to-treat growth stages as well as, or better than, current clinical antibiotics. Thus, JD1 shows the importance of testing compounds under conditions that are relevant to infection, demonstrates the utility that membrane-targeting compounds have against multidrug-resistant bacteria, and indicates that small molecules that target bacterial cell membranes may serve as potent broad-spectrum antibacterials.

Dalbavancin.

Dalbavancin is a long-acting antimicrobial agent with an excellent in vitro activity against Gram-positive pathogens, including staphylococcal biofilms. The unusually long terminal half-life ranging from 149 to 250 hours in human subjects, allows a weekly dose. Currently is indicated in acute bacterial skin and skin structure infections (ABSSSIs), but in real-life clinical practice it has already been used successfully and safely in other infections, especially as consolidation therapy.

The Antimicrobial and Antibiofilm In Vitro Activity of Liquid and Vapour Phases of Selected Essential Oils against Staphylococcus aureus.

The high resistance of staphylococcal biofilm against antibiotics and developing resistance against antiseptics induces a search for novel antimicrobial compounds. Due to acknowledged and/or alleged antimicrobial activity of EOs, their application seems to be a promising direction to follow. Nevertheless, the high complexity of EOs composition and differences in laboratory protocols of the antimicrobial activity assessment hinders the exact estimation of EOs effectiveness. To overcome these disadvantages, in the present work we analysed the effectiveness of volatile and liquid forms of seven EOs (derived from thyme, tea tree, basil, rosemary, eucalyptus, lavender, and menthol mint) against 16 staphylococcal biofilm-forming strains using cohesive set of in vitro techniques, including gas chromatography–mass spectrometry, inverted Petri dish, modified disk-diffusion assay, microdilution techniques, antibiofilm dressing activity measurement, AntiBioVol protocol, fluorescence/confocal microscopy, and dynamic light scattering. Depending on the requirements of the technique, EOs were applied in emulsified or non-emulsified form. The obtained results revealed that application of different in vitro techniques allows us to get a comprehensive set of data and to gain insight into the analysed phenomena. In the course of our investigation, liquid and volatile fractions of thyme EO displayed the highest antibiofilm activity. Liquid fractions of rosemary oil were the second most active against S. aureus. Vapour phases of tea tree and lavender oils exhibited the weakest anti-staphylococcal activity. The size of emulsified droplets was the lowest for T-EO and the highest for L-EO. Bearing in mind the limitations of the in vitro study, results from presented analysis may be of pivotal meaning for the potential application of thymol as a antimicrobial agent used to fight against staphylococcal biofilm-based infections.

Non-Antimicrobial Adjuvant Strategies to Tackle Biofilm-Related Staphylococcus aureus Prosthetic Joint Infections.

Staphylococcus aureus frequently causes community- and hospital-acquired infections. S. aureus attachment followed by biofilm formation on tissues and medical devices plays a significant role in the establishment of chronic infections. Staphylococcal biofilms encase bacteria in a matrix and protect the cells from antimicrobials and the immune system, resulting in infections that are highly resistant to treatment. The biology of biofilms is complex and varies between organisms. In this review, we focus our discussion on S. aureus biofilms and describe the stages of their formation. We particularly emphasize genetic and biochemical processes that may be vulnerable to novel treatment approaches. Against this background, we discuss treatment strategies that have been successful in animal models of S. aureus biofilm-related infection and consider their possible use for the prevention and eradication of biofilm-related S. aureus prosthetic joint infection.

Biofilm properties in relation to treatment outcome in patients with first-time periprosthetic hip or knee joint infection.

BackgroundPeriprosthetic joint infections (PJI) are challenging complications following arthroplasty. Staphylococci are a frequent cause of PJI and known biofilm producers. Biofilm formation decreases antimicrobial susceptibility, thereby challenging favourable treatment outcomes. The aims of this study were to characterize the biofilm abilities and antimicrobial susceptibilities of staphylococci causing first-time PJI and correlate them to clinical outcome (infection resolution and recurrence).MethodsReoperations for PJI of the hip or knee between 1st January 2012 to 30th June 2015 performed at the Sahlgrenska University Hospital were identified in a local database. Medical records were reviewed and clinical parameters recorded for patients whose intraoperative bacterial isolates had been stored at the clinical laboratory. Staphylococcal strains isolated from reoperations due to first-time PJI were characterised by their ability to form biofilms using the microtiter plate test. Antimicrobial susceptibility of the strains was determined by minimum inhibitory concentration (MIC) when grown planktonically, and by minimum biofilm eradication concentration (MBEC) when grown as biofilms. MBEC determination was conducted using the Calgary biofilm device (CBD) and a custom-made antimicrobial susceptibility plate containing eight clinically relevant antimicrobial agents.ResultsThe study group included 49 patients (70 bacterial strains) from first-time PJI, whereof 24 (49%) patients had recurrent infection. Strong biofilm production was significantly associated with recurrent infection. Patients infected with strong biofilm producers had a five-fold increased risk for recurrent infection. Strains grown as biofilms were over 8000 times more resistant to antimicrobial agents compared to planktonic cultures. Biofilms were more susceptible to rifampicin compared to other antimicrobials in the assay. Increased biofilm susceptibility (MBEC ​> ​MIC) was observed for the majority of the bacterial strains and antimicrobial agents.ConclusionsStrong biofilm production was significantly associated with increased antimicrobial resistance and PJI recurrence. This underscores the importance of determining biofilm production and susceptibility as part of routine diagnostics in PJI. Strong staphylococcal biofilm production may have implications on therapeutic choices and suggest more extensive surgery. Furthermore, despite the increased biofilm resistance to rifampicin, results from this study support its use in staphylococcal PJI.The Translational Potential of this ArticleLike for many biomaterial-associated infections, staphylococci are a common cause of PJI. Their ability to adhere to surfaces and produce biofilms on medical devices is proposed to play a role. However, clinical studies where biofilm properties are directly linked to patient outcome are scarce. This study demonstrates that the majority of staphylococci isolated from first-time PJI were biofilm producers with increased antimicrobial resistance. Patients suffering an infection caused by a staphylococcal strain with strong biofilm production ability had a five-fold greater risk of recurrent infection. This novel finding suggests the importance of evaluating biofilm production as a diagnostic procedure for the guidance of treatment decisions in PJI.

DNA Polyelectrolyte Multilayer Coatings Are Antifouling and Promote Mammalian Cell Adhesion.

The ability of bacteria to adhere to and form biofilms on implant surfaces is the primary cause of implant failure. Implant-associated infections are difficult to treat, as the biofilm mode of growth protects microorganisms from the host’s immune response and antibiotics. Therefore, modifications of implant surfaces that can prevent or delay bacterial adhesion and biofilm formation are highly desired. In addition, the attachment and spreading of bone cells are required for successful tissue integration in orthopedic and dental applications. We propose that polyanionic DNA with a negatively charged phosphate backbone could provide a dual function to repel bacterial adhesion and support host tissue cell attachment. To this end, we developed polyelectrolyte multilayer coatings using chitosan (CS) and DNA on biomaterial surfaces via a layer-by-layer technique. The assembly of these coatings was characterized. Further, we evaluated staphylococcal adhesion and biofilm growth on the coatings as well as cytotoxicity for osteoblast-like cells (SaOS-2 cells), and we correlated these to the layer structure. The CS-DNA multilayer coatings impaired the biofilm formation of Staphylococcus by ~90% on both PMMA and titanium surfaces. The presence of cationic CS as the top layer did not hinder the bacteria-repelling property of the DNA in the coating. The CS-DNA multilayer coatings demonstrated no cytotoxic effect on SaOS-2 cells. Thus, DNA polyelectrolyte multilayer coatings could reduce infection risk while promoting host tissue cell attachment on medical implants.

Characterization of biosurfactants derived from probiotic lactic acid bacteria against methicillin-resistant and sensitive Staphylococcus aureus isolates

Metabolites of lactic acid bacteria (LAB) are gaining renewed interest as postbiotics to curb the growth of undesirable microorganisms in food and pharmaceutical industries. The present study was aimed to extract and characterize the biosurfactants (BS) of Lactobacillus acidophilus NCFM and Lacticaseibacillus rhamnosus GG. Acceptable levels of emulsification index and oil displacement ability of cell-free supernatant as well as considerable cell surface hydrophobicity of LGG and NCFM confirmed the BS production. The cell wall-bound and extracellular BS were extracted by solvent extraction method. Chemical group characterization of BS through Fourier-Transform Infrared Spectroscopy specified the amalgamation of carbohydrates, lipids, and proteins in NCFM, whereas only the proteins and carbohydrates in LGG. Gas chromatography-mass spectrometry analysis of BS (NCFM) revealed hexadecanoic acid, 9-octadecenoic acid, and methyl stearate as principal fatty acids. BS showed dose-dependent antibacterial and antibiofilm activities against methicillin-resistant and sensitive staphylococcal isolates. Upon visual inspection through scanning electron microscopy confirmed the cell death via alternations in the cell surface coherence. Overall, our findings suggest that BS from LGG and NCFM may be the potential candidates to abrogate staphylococcal biofilms, and therefore further technology intervention to scale up the production process could be noteworthy.

Staphylococcal Biofilm on the Surface of Catheters: Electron Microscopy Evaluation of the Inhibition of Biofilm Growth by RNAIII Inhibiting Peptide.

Staphylococcus aureus and coagulase-negative staphylococci (CoNS) have become the main causative agents of medical device-related infections due to their biofilm-forming capability, which protects them from the host’s immune system and from the action of antimicrobials. This study evaluated the ability of RNA III inhibiting peptide (RIP) to inhibit biofilm formation in 10 strains isolated from clinical materials, including one S. aureus strain, two S. epidermidis, two S. haemolyticus, two S. lugdunensis, and one isolate each of the following species: S. warneri, S. hominis, and S. saprophyticus. The isolates were selected from a total of 200 strains evaluated regarding phenotypic biofilm production and the presence and expression of the ica operon. The isolates were cultured in trypticase soy broth with 2% glucose in 96-well polystyrene plates containing catheter segments in the presence and absence of RIP. The catheter segments were observed by scanning electron microscopy. The results showed inhibition of biofilm formation in the presence of RIP in all CoNS isolates; however, RIP did not interfere with biofilm formation by S. aureus. RIP is a promising tool that might be used in the future for the prevention of biofilm-related infections caused by CoNS.

Evaluation of Staphylococcus aureus and Candida albicans biofilms adherence to PEEK and titanium-alloy prosthetic spine devices.

Titanium and polyether-ether-ketone (PEEK) interbody cages are commonly used for spine fusion. Few data are known about bacterial and yeast biofilms formation in these implants. The aim of this study was to compare Staphylococcus aureus and Candida albicans biofilm formation in the surface of two different interbody devices used routinely in spine surgery. Six bodies of proof specimens of PEEK and titanium alloy were used for microbiological tests, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Experimental biofilm was produced with Staphylococcus aureus and Candida albicans, followed by quantitative analysis of planktonic cells and sessile cells. The comparison between the medians of biofilm quantification between the two models was performed using the Mann-Whitney test and considered the statistical difference for a p < 0.05. In the S. aureus model, in both planktonic and sessile cell counts, titanium-alloy samples showed lower values for colony forming units per milliliter (UFC/mL) (p < 0.05). The evaluation through the optic density of planktonic and sessile cells showed lower values in the titanium-alloy samples, however, only statistically significant in planktonic cell count (p < 0.05). The count of planktonic yeast cells in PEEK was similar to titanium-alloy samples, while the count of sessile yeast cells in titanium alloy was lower when compared to PEEK (p < 0.05). Titanium-alloy models were associated with less staphylococcal and Candida biofilm formation when compared with PEEK.