In vitro adherence of bacteria to prosthetic grafting materials

Adherence of bacteria to prosthetic grafting material is thought to play an important role in the ultimate development of prosthetic infections. To evaluate the role of bacterial adherence in the initiation and colonization of prosthetic materials, Proplast II, Gore-Tex, and silicone were evaluated for adherence of Escherichia coli and Staphylococcus aureus. Bacteria were radio labeled and incubated with the study material. Adherence was determined by scintillation. Adherence to Proplast II and Gore-Tex reached a maximum at approximately 45 minutes of incubation and demonstrated a detachment phenomenon with E. coli. Similar results were noted with S. aureus, but with a maximal attachment at approximately 30 minutes. Interestingly, bacterial attachment to silicone continued to increase throughout the time of the incubation. In addition, adherence of S. aureus was at a faster rate than E. coli. Attachment of bacteria is a multifactorial process. However, the PTFE graft demonstrates a slower rate of attachment, lower total number of attached bacteria, and faster detachment. The importance of this phenomenon may help explain the foreign body effect of increased susceptibility to infection of foreign materials.     

In vitro adherence of bacteria to sutures in cardiac surgery

The adherence of bacteria to sutures used in cardiac surgery was studied by in vitro quantitative determination with [3H]-leucine-labeled Staphylococcus epidermidis, Staphylococcus aureus and Streptococcus sanguis. The adherence per unit area for staphylococci was least for monofilament polypropylene (Prolene), 3 times higher (p less than 0.05) for braided polyester (Mersiline) and greatest (10 times, p less than 0.005) for braided polyester sutures coated with polybutylate (Ethibond). Mean values for the adherence of streptococci were low for all the sutures. Sutures pretreated with human plasma showed a 12-37% increase in bacterial adherence. The cell surface hydrophobicity, surface charge and the haemagglutinating property of bacteria did not correlate with their adherence property. In view of these observations, it is suggested that: (a) the preferential adherence of staphylococci to intra-cardiac sutures may be one of the explanations for its being the commonest cause of early prosthetic valve endocarditis, (b) there is a need for a careful selection of sutures used in cardiac surgery and (c) the described in vitro assay for bacterial adherence may be used for monitoring the development of better designed sutures and the effect of incorporation of antibiotics in the sutures.     

Influence of surface morphology on in vitro bacterial adherence to central venous catheters

The detailed surface topography of five poly-urethane centralvenous catheters (CVC) (Hydrocath, Deltacath, Certofix trio,Arrow-Howes and Multicath three) was examined by scanning electronmicroscopy and laser profilometry. The results were correlatedwith the ability of Staphylococcus epidermidis to adhere toeach CVC. Hydrocath CVC had the smoothest surface, as determinedby profile peak values of 0.17 µm (Ra) and 0.94 µm(Rz). These CVC also had the lowest number ofstaphylo-cocciadhering to the surface. In contrast, Certofix trio CVC hadan irregular surface (Ra 1.29µm and Rz 6.35 µm)which was confirmed by scanning electron microscopy. These latterCVC had significantly more bacteria colonizing their surfacecompared with Hydrocath and Arrow-Howes CVC (P < 0.01). Theresults suggest that a CVC with a smooth surface, absent ofsurface defects, may reduce the risk of colonization with bacteriaand therefore subsequent sepsis. (Br. J. Anaesth. 1994; 72:587–591)     

Bacterial adherence to Foley urinary catheters

Bacterial adherence to the surfaces of indwelling urethral (Foley) catheters is briefly reviewed. In addition, crystal adhesion to the catheters is described. Using scanning electron microscopy, micro-organisms including fungi and crystals are frequently observed in association with fibrillar material. Based on our study using the immunofluorescence method, some of the fibrillar material is considered to be fibrin. On the surfaces of catheters, especially those indwelling for long periods, microorganisms are often embedded in biofilms, which are composed of an amorphous matrix. Urease-producing bacteria adherent to the catheters are considered to play an important role in the formation of the calculous encrustation.     

Adherence of bacteria to urinary catheters

Summary The adherence of ³H-labelled gram-negative bacilli to different urinary catheter materials was studied using an in vitro method. Adherence was found to be significantly less to siliconised rubber than to pure latex or teflon coated rubber. Adherence was altered by variations in incubation pH, time, and bacterial concentration; however, incubation temperature did not affect results. Adherence of bacteria to urinary tract catheters may be part of the pathogenesis of certain catheter-related infections. However, in the absence of controlled clinical studies the significance of these findings remains to be determined.     

In vitro particulate adherence to fibronectin: correlation with in vivo particulate adherence to sites of bladder injury.

This study examined the role of fibronectin in promoting particulate attachment to sites of urothelial injury. Variables influencing adherence of the rat transitional carcinoma cell line 4909 and "non-cellular" styrene-divinylbenzene microspheres to fibronectin were studied in an in vitro system. A soluble synthetic peptide fragment (Gly-Arg-Gly-Asp-Ser [GRGDS]) duplicating the receptor binding domain of fibronectin (RGD) was used to determine whether cell adherence could be inhibited by fibronectin receptor blockade. In vitro findings were correlated with an in vivo assay of both cellular and non-cellular particulate adherence to injured urothelium. Time, plated cell density, substrate concentration, GRGDS concentration, and cell viability, were all found to be significant independent variables influencing in vitro cellular adherence (p less than 0.0001). Receptor blockade with GRGDS significantly decreased in vitro tumor cell adherence to fibronectin. In vitro microsphere binding increased as a direct function of fibronectin concentration but was not time dependent (p less than 0.0001 and p = 0.14 for fibronectin concentration and time respectively). The in vivo adherence of both tumor cells and microspheres was significantly increased in injured bladders compared to controls (p less than 0.01). Receptor blockade with GRGDS failed to inhibit in vivo cell adherence to sites of urothelial injury. Microspheres proved to be competitive inhibitors of cellular adherence in competitive binding assays. In vitro microsphere binding demonstrated a pH dependence with maximal binding at pH 7.2. These data suggest that in vitro tumor cell adherence to fibronectin differs from in vivo tumor cell adherence to sites of urothelial injury. Manipulations which inhibit in vitro adherence, specifically fibronectin receptor blockade and cell death, fail to effect in vivo binding to the extreme that non-cellular particulate appears to bind to the same site, and with similar affinity, as cellular particles.     

Increased resistance of bacteria after adherence to polymethyl methacrylate. An in vitro study.

The pathobiology of total joint prosthesis infection was investigated in vitro. Discs of polymethylmethacrylate (PMMA) were exposed to a suspension containing cells of 10(8) per mL Staphylococcus epidermidis E-46. After 12 hours, exposed discs were rinsed with phosphate-buffered saline and placed in brain heart infusion broth containing antibiotics (2.5 mg per mL of Cephaloridine). After gentle shaking for 24 hours at 37 degrees C, the bacteria on the PMMA surface were detached and washed with phosphate-buffered saline to remove the antibiotics. Compared with the free bacteria which were detached from the PMMA by sonication immediately after exposure to the antibiotic solution, those allowed to remain adhered to the PMMA surface were more resistant to antibiotics. Scanning electron microscopy showed accumulation of bacteria surrounded by slime on PMMA discs exposed for 12 hours. Our results indicate that resistance of bacteria to antibiotics is increased after adherence to the biomaterial and formation of a slime layer.     

Bacterial and crystal adherence to the surfaces of indwelling urethral catheters

Bacterial and crystal adherence to the surfaces of indwelling urethral catheters was investigated by scanning electron microscopy and immunofluorescence method in relation to microbiological examination. Gram-negative bacteria were isolated more frequently than gram-positive bacteria in urine and catheter cultures. Microorganisms and crystals frequently were associated with fibrillar material, some of which was considered to be fibrin. On the surfaces of catheters indwelling for more than 1 week bacteria often were embedded in an amorphous matrix. It was believed that the thick coherent matrix adherent to the catheter served as a protected reservoir of microorganisms that persisted despite antimicrobial chemotherapy. Additionally, urease-producing bacteria attached to the catheter could have an important role in the development of calculous incrustation.     

The site of origin of the intravascular electrocardiogram recorded from multiorificed intravascular catheters

Successful retrieval of venous air emboli via central venous catheters requires accurate placement of the distal tip of the catheter. The distal tip of single-orificed central venous catheters can be precisely located using intravenous electrocardiography (IVECG). However, the site of origin of the IVECG complex with multiorificed central venous catheters is not well known. In this study, the site of origin of the IVECG complex deriving from the wire within a multiorificed Arrow Antecubital Central Venous Catheterization Kit, the same Arrow catheter type without wire, and a multiorificed Cook Bunegin-Albin CVP Kit was determined in ten anesthetized dogs. The IVECG was found to originate from the distal portion of the Arrow wire whether the distal tip of the wire was within the distal segment of the Arrow multiorificed catheter, at the tip of the catheter, or protruding several cm from the tip of the catheter. When the Arrow multiorificed catheter (without wire) was used to determine the IVECG, the mean site of origin of the IVECG was 1.7 +/- 1.2 cm (mean +/- SD) proximal to the distal catheter tip. When the Cook multiorificed catheter (without wire) was used to determine the IVECG, the mean site of origin of the IVECG was 2.5 +/- 0.6 cm proximal to the distal catheter tip. Knowledge of the site of origin of the IVECG with the Arrow and Cook multiorificed catheters should permit the distal tips of these catheters to be placed in locations where efficient retrieval of venous air emboli is likely.     

In vitro evaluation of percutaneous drainage catheters: Flow related to connections and liquid characteristics

Purpose

To evaluate the effect of catheter connections on drainage catheters’ flow rate.

In vitro and in vivo adherence of uropathogenic Escherichia coli strains

Twenty-eight Escherichia coli strains isolated from the urine of patients with urinary tract infections were assayed for fimbrial type, in vitro capacity to agglutinate guinea pig red blood cells, and in vivo adherence to rat bladder uroepithelium. A direct correlation was found between hemagglutinating capacity and in vivo adherence. Strains with both Type 1 and P fimbriae showed the greatest adherence in vivo. Of the 28 strains, seven did not manifest either Type 1 or P fimbriae but agglutinated red blood cells and did adhere in vivo. In studies on bacterial adherence and urinary tract infections, both in vivo and in vitro studies may contribute to understanding the relevance of bacterial adhesins in initiating urinary tract infections.     

Colonization of intravascular catheters in the intensive care unit

A prospective study of intravascular catheters (arterial, Swan-Ganz, and central venous) in two hospitals with similar intensive care units revealed an overall 25 percent colonization rate (more than 15 colony counts). Arterial catheters had the lowest colonization rate and central venous catheters had the highest. Arterial, Swan-Ganz, and central venous catheters are possible sources of nosocomial infections and septicemia. They should be inserted only when necessary. A critical review of our data and the literature suggests that future studies should examine the potential benefits of assiduous insertion technique, improved dressing care, intravascular delivery systems, and the choice of catheter.     

Prevention of Staphylococcus aureus biofilm on dialysis catheters and adherence to human cells

BACKGROUND: Dialysis patients, often carriers of Staphylococcus aureus in their nares, are at high risk of S. aureus infections. METHODS: We examined whether RNAIII inhibiting peptide (RIP), which interferes with quorum sensing mechanisms, reduces adherence of S. aureus to host cells and to dialysis catheter polymers in vitro. Adherence was tested by spectroscopy using safranin staining, by confocal scanning laser microscopy and by atomic force microscopy. RESULTS: RIP inhibited bacterial adherence to HaCat and HEp-2 cells and reduced adherence and biofilm formation not only on polystyrene, but also on both polyurethane- and silicone-made dialysis catheters, with a preponderant effect on silicone, to which bacteria were more adherent. CONCLUSION: RIP opens a new perspective in anti-S. aureus prophylaxis, particularly in dialysis patients.