Anti-adhesive properties of polytetrafluoroethylene (Gore-Tex) in middle ear surgery. An experimental study

A Glance at Antimicrobial Strategies to Prevent Catheter-Associated Medical Infections

Urinary and intravascular catheters are two of the most used invasive medical devices; however, microbial colonization of catheter surfaces is responsible for most healthcare-associated infections (HAIs). Several antimicrobial-coated catheters are available, but recurrent antibiotic therapy can decrease their potential activity against resistant bacterial strains. The aim of this Review is to question the actual effectiveness of currently used (coated) catheters and describe the progress and promise of alternative antimicrobial coatings. Different strategies have been reviewed with the common goal of preventing biofilm formation on catheters, including release-based approaches using antibiotics, antiseptics, nitric oxide, 5-fluorouracil, and silver as well as contact-killing approaches employing quaternary ammonium compounds, chitosan, antimicrobial peptides, and enzymes. All of these strategies have given proof of antimicrobial efficacy by modifying the physiology of pathogens or disrupting their structural integrity. The aim for synergistic approaches using multitarget processes and the combination of both antifouling and bactericidal properties holds potential for the near future. Despite intensive research in biofilm preventive strategies, laboratorial studies still present some limitations since experimental conditions usually are not the same and also differ from biological conditions encountered when the catheter is inserted in the human body. Consequently, in most cases, the efficacy data obtained from in vitro studies is not properly reflected in the clinical setting. Thus, further well-designed clinical trials and additional cytotoxicity studies are needed to prove the efficacy and safety of the developed antimicrobial strategies in the prevention of biofilm formation at catheter surfaces.

Morphological sequence of Plastipore extrusion in experimental otitis media

OBJECTIVES

Plastipore prostheses are still used by many surgeons, although the functional results are controversial. The aim of this study was the morphological analysis of Plastipore material performance in the middle ear of rats, with special attention to extrusion.

METHODS

Twenty-four Wistar rats were given implants made of commercially available Plastipore and assigned to 3 groups: group A, with implantation in a healthy middle ear; group B, with implantation and cauterization of the nasopharyngeal orifice of the eustachian tube (hypoventilation); and group C, with implantation, cauterization of the eustachian tube, and bacterial inoculation with Pseudomonas aeruginosa.

RESULTS

The pathological study showed in nearly all cases the disintegration of the biomaterial. Adhesion between the biomaterial and bone could be seen in 1 rat from group C (hypoventilation and infection). In group C, the Plastipore was in contact with the tympanic membrane in 1 case and was extruding in 2 animals. Different phases of extrusion were defined. No extrusion was observed in the other groups.

CONCLUSIONS

The sequential stages of Plastipore extrusion are demonstrated. Infection seems to be the most important factor in Plastipore extrusion in our model.

Agarose/collagen composite scaffold as an anti-adhesive sheet

The objective of this work was to find a new material or new technology to achieve satisfactory post-surgery anti-adhesion. An agarose/collagen composite sheet was developed to prevent mesenchymal cells and extracellular matrix from adhering on the lesion site, in which agarose formed uniaxial channels that hindered penetration and intercommunication of cells among pores in a 3D sheet. The tensile strength of the composite sheet in the designed ratio of agarose and collagen was over 17 MPa in dry and 2 MPa in wet, which was suitable and convenient to be sewed or operated on in other general surgery. In vitro and in vivo experimental results showed that fibroblasts, adult-derived adipose stem cells, could not penetrate into the sheet and formed a 3D tissue, and agarose did not degrade in three weeks. The demonstration that this sheet can prevent mesenchymal cells from penetrating in 3D and forming a tissue warrants the agarose-based composite for an anti-adhesive membrane.