The adherence of coagulase-negative staphylococci to smooth surfaces was assayed by measuring the optical densities of stained bacterial films adherent to the floors of plastic tissue culture plates. The optical densities correlated with the weight of the adherent bacterial film (r = 0.906; P less than 0.01). The measurements also agreed with visual assessments of bacterial adherence to culture tubes, microtiter plates, and tissue culture plates. Selected clinical strains were passed through a mouse model for foreign body infections and a rat model for catheter-induced endocarditis. The adherence measurements of animal passed strains remained the same as those of the laboratory-maintained parent strain. Spectrophotometric classification of coagulase-negative staphylococci into nonadherent and adherent categories according to these measurements had a sensitivity, specificity, and accuracy of 90.6, 80.8, and 88.4%, respectively. We examined a previously described collection of 127 strains of coagulase-negative staphylococci isolated from an outbreak of intravascular catheter-associated sepsis; strains associated with sepsis were more adherent than blood culture contaminants and cutaneous strains (P less than 0.001). We also examined a collection of 84 strains isolated from pediatric patients with cerebrospinal fluid (CSF) shunts; once again, pathogenic strains were more adherent than were CSF contaminants (P less than 0.01). Finally, we measured the adherence of seven endocarditis strains. As opposed to strains associated with intravascular catheters and CSF shunts, endocarditis strains were less adherent than were saprophytic strains of coagulase-negative staphylococci. The optical densities of bacterial films adherent to plastic tissue culture plates serve as a quantitative model for the study of the adherence of coagulase-negative staphylococci to medical devices, a process which may be important in the pathogenesis of foreign body infections. Images

Adherence of coagulase-negative staphylococci to plastic tissue culture plates: a quantitative model for the adherence of staphylococci to medical devices.

1: Magnetic Particles: Preparation, Properties and Applications: M. Ozaki. 2: Maghemite (gamma-Fe2O3): A Versatile Magnetic Colloidal Material C.J. Serna, M.P. Morales. 3: Dynamics of Adsorption and Oxidation of Organic Molecules on Illuminated Titanium Dioxide Particles Immersed in Water M.A. Blesa, R.J. Candal, S.A. Bilmes. 4: Colloidal Aggregation in Two-Dimensions A. Moncho-Jorda, F. Martinez-Lopez, M.A. Cabrerizo-Vilchez, R. Hidalgo Alvarez, M. Quesada-PMerez. 5: Kinetics of Particle and Protein Adsorption Z. Adamczyk.

Surface and Colloid Science

The process of surface adhesion and biofilm development is a survival strategy employed by virtually all bacteria and refined over millions of years. This process is designed to anchor microorganisms in a nutritionally advantageous environment and to permit their escape to greener pastures when essential growth factors have been exhausted. Bacterial attachment to a surface can be divided into several distinct phases, including primary and reversible adhesion, secondary and irreversible adhesion, and biofilm formation. Each of these phases is ultimately controlled by the expression of one or more gene products. Ultrastructurally, the mature bacterial biofilm resembles an underwater coral reef containing pyramidal or mushroom-shaped microcolonies of organisms embedded within an extracellular glycocalyx, with channels and cavities to allow the exchange of nutrients and waste. The biofilm protects its inhabitants from predators, dehydration, biocides, and other environmental extremes while regulating population growth and diversity through primitive cell signals. From a physiological standpoint, surface-bound bacteria behave quite differently from their planktonic counterparts. Recognizing that bacteria naturally occur as surface-bound and often polymicrobic communities, the practice of performing antimicrobial susceptibility tests using pure cultures and in a planktonic growth mode should be questioned. That this model does not reflect conditions found in nature might help explain the difficulties encountered in the management and treatment of biomedical implant infections.

/pdf/bacterial-adhesion-seen-any-good-biofilms-lately-2f7wm9gh5j.pdf

Bacterial Adhesion: Seen Any Good Biofilms Lately?

Effect of wettability and surface functional groups on protein adsorption and cell adhesion using well-defined mixed self-assembled monolayers.

Water soluble macromers are modified by addition of free radical polymerizable groups, such as those containing a carbon-carbon double or triple bond, which can be polymerized under mild conditions to encapsulate tissues, cells, or biologically active materials. The polymeric materials are particularly useful as tissue adhesives, coatings for tissue lumens including blood vessels, coatings for cells such as islets of Langerhans, coatings, plugs, supports or substrates for contact with biological materials such as the body, and as drug delivery devices for biologically active molecules.

Gels for encapsulation of biological materials

https://ris.utwente.nl/ws/files/6880554/Wachem87adhesion.pdf

Adhesion of cultured human endothelial cells onto methacrylate polymers with varying surface wettability and charge

Summary: The adhesion of two Staphylococcus epidermidis strains and one Staphylococcus saprophyticus strain on to poly(tetrafluorethylene-co-hexafluorpropylene) (FEP)-fluorocarbon and cellulose acetate was studied in vitro. Both S. epidermidis strains showed a more hydrophobic character than the encapsulated S. saprophyticus as determined by the bacterial affinity towards xylene. Staphylococcus epidermidis showed a significantly higher adhesion on to the hydrophobic FEP than S. saprophyticus. The adhesion of staphylococci on to the more hydrophilic cellulose acetate was always low. Treatment of S. epidermidis with pepsin or extraction with aqueous phenol yielded cells with a decreased hydrophobicity, which resulted in a decreased adhesion on to FEP. Cells with a decreased hydrophobicity showed a lower rate of reaggregation in suspension. The hydrophobicity and the adhesion on to FEP of S. epidermidis were not affected by exposure to a subminimal inhibitory concentration of penicillin. The strong interaction between S. epidermidis and FEP, which appeared not to be influenced by the age or the metabolic stage of the bacteria, is mainly caused by hydrophobic bonding.

/pdf/adhesion-of-coagulase-negative-staphylococci-to-biomaterials-44pcwcxsys.pdf

Adhesion of coagulase-negative staphylococci to biomaterials

Adhesion of coagulasef-negative staphylococci (CNS) was studied onto a homologous series of methacrylate polymers and copolymers. The materials varied in wettability (contact angles) and were either positively or negatively charged (zetapotential). Bacterial adhesion experiments performed in a parallel-plate perfusion system showed that positively charged TMAEMA-Cl copolymers significantly promoted the adhesion of CNS as compared with all other methacrylate (co)polymers tested. The bacterial adhesion rates onto the positively charged surfaces are diffusion-controlled, whereas those onto the surfaces with a negative zeta-potential are more surface-reaction-controlled due to the presence of a potential energy barrier. The bacterial adhesion rates onto various poly (alkyl methacrylates) were similar. The number of adhering bacteria onto the negatively charged MMA/MAA copolymer did not differ from that onto pMMA, indicating that sufficient sites on the copolymer surface with the same potential energy barrier as that on pMMA, were available for adhesion. Decreasing rates of adhesion of CNS were observed onto MMA/HEMA copolymers with increasing HEMA content coinciding with increasing hydrophilicity. Low plateau values for the bacterial adhesion were observed on 50MMA/50HEMA, pHEMA, and 85HEMA/15MAA, indicating that the adhesion onto these materials was reversible. Four CNS strains with different surface characteristics all showed higher numbers of adhering bacteria onto 85MMA/15TMAEMA-Cl than onto 85MMA/15MAA and pMMA.

/pdf/adhesion-of-coagulase-negative-staphylococci-to-methacrylate-ya0t9gi5wk.pdf

Adhesion of coagulase-negative staphylococci to methacrylate polymers and copolymers

The ability of 21 nonencapsulated and 15 encapsulated coagulase-negative staphylococci (CNS) to adhere to xylene in xylene-water emulsions and to fluorinated poly(ethylenepropylene) (FEP) films revealed remarkable differences. Nonencapsulated CNS strains adhered well to FEP, whereas their adherence to xylene ranged widely. Encapsulated strains with low adherence to xylene showed slight adherence to FEP. Encapsulated strains which adhered well to xylene ranged widely in their adherence to FEP. It was concluded that results obtained from the xylene adherence test were not predictive of the adherence of CNS to the hydrophobic FEP surface. The number of nonwashed, slime-producing CNS strains adhering to FEP was similar to that of washed bacteria of the same strains. Bacterial adherence to FEP was decreased when FEP films were exposed to a solution containing extracellular products (EP) obtained from a slime-producing CNS strain. Bacterial adherence to xylene also decreased when the bacterial suspensions contained EP. Apparently, initial adherence of CNS to FEP and xylene is hampered by EP. Nonencapsulated and encapsulated CNS pretreated with proteolytic enzymes failed to adhere to xylene and FEP, indicating that intact surface proteins or constituents associated with surface proteins mediated their adherence to xylene and FEP. Freeze-etch replicas of a CNS strain adhering to FEP showed a smooth, flattened area on the bacterial surface at the contact site of the bacteria with the FEP, indicating that an external layer was present at the bacterial surface.

Cell surface characteristics of coagulase-negative staphylococci and their adherence to fluorinated poly(ethylenepropylene).

Received 20 January 1983 Accepted 23 January 1983 1. INTRODUCTION 2. MATERIALS AND METHODS Infections associated with prosthetic implants or medical devices are most commonly caused by coagulase-negative staphylococci (CNS) [1]. The ability of CNS to produce slime has been sug- gested to play a critical role in the adhesion onto surfaces of implants and medical devices [2] and in the course of medical device-associated infections [3]. Staphylococcus aureus, the pathogenic counter- part of CNS, can be encapsulated [4]. Such strains possessed increased virulence in comparison with their non-encapsulated variant strains [5,6]. Char- acterization of CNS has been advocated [7,8], but no special attention has been given to the presence of a capsule, although encapsulated CNS have been reported [9]. Bacterial adhesion onto surfaces is also regarded to be an important virulence fac- tor [10]. Bacterial interaction with mammalian cells and artificial surfaces is promoted by the hydro- phobicity of the bacterial cell surface [11-13]. After characterization of twenty one CNS, the presence of a capsule and the ability to produce extracellular slime were studied. In addition, the surface hydrophobicity of the strains was mea- sured using a xylene-water system [14]. * Correspondence should be addressed to J. Dankert. 2.1. Bacterial strains and growth conditions 21 CNS strains isolated from open-heart surgery patients and laboratory staff members were classi- fied according to the scheme of Kloos and Schleifer [8] using the API Staph gallery (API Systems S.A., Montalieu Vercieu, France). 7 strains (NCTC) were a gift of Dr. R.R. Marples, Central Public Health Laboratory, Colindale Avenue, London, England. Strains stored at -20°C in skim milk were grown on sheep blood agar plates (Oxoid, Ltd., U.K.) and maintained on nutrient agar slants (Oxoid) at 4°C for 1 month. The strains were cultured in Trypticase soy broth (TSB, BBL Microbiology Systems, Cockeys- ville, MD) for 20 h at 37°C. Late exponential phase cells were obtained by culturing 2 ml of the overnight broth into 100 ml of fresh TSB for 5 h at 37°C in a rotary shaker incubator (New Bruns- wick Sci. Co., New Brunswick, N J) at 90 rev./min. The bacteria were harvested by centrifuging (20000 ×g, 4°C, 10 min; Beckman Instruments Inc., J2-21, Palo Alto, CA), washed three times with phosphate-buffered saline (PBS; 8.1 mM Na2HPO4, 1.5 mM KHzPO4, 140 mM NaC1, 3 mM KC1, pH 7.2) and resuspended in PBS. To determine the effect of glucose depletion, all strains were grown in glucose-free TSB (GF-TSB, BBL). 0378-1097/83/0000-0000/$03.00 © 1983 Federation of European Microbiological Societies

https://ris.utwente.nl/ws/files/6533920/Hogt83encapsulation.pdf

A.H. Hogt

Papers

Adhesion of cultured human endothelial cells onto methacrylate polymers with varying surface wettability and charge

Adhesion of coagulase-negative staphylococci to biomaterials

Adhesion of coagulase-negative staphylococci to methacrylate polymers and copolymers

Cell surface characteristics of coagulase-negative staphylococci and their adherence to fluorinated poly(ethylenepropylene).

Encapsulation, slime production and surface hydrophobicity of coagulase-negative staphylococci