In vitro quantitative adherence of bacteria to intravascular catheters

Adapting standard techniques, a simple in vitro system was devised to compare quantitative bacterial adherence to iv catheters of different compositions. Upon brief immersion of catheters in suspensions of Staphylococcus aureus, coagulase-negative staphylococci, and Escherichia coli, organisms adhered to catheter surfaces. After overnight growth in broth, organisms remained adherent and formed colonies, as shown by light and scanning electron microscopy. In addition, quantitative adherence using a blood agar roll technique, expressed as bacteria per square centimeter of catheter surface area per 10(6) colonies per milliliter inoculum, was calculated. Adherence was greater on polyvinylchloride (PVC) catheters (geometric mean 342) than on Teflon catheters (geometric mean 49.6) for coagulase-negative staphylococci (P less than 0.005). Also, the number of coagulase-negative staphylococci adherent to PVC catheters was significantly greater than for E. coli (geometric mean 70.6) at analogous inocula (P less than 0.02). Differences in bacterial adherence to the surface of iv devices may be important in the pathogenesis of catheter-associated infections. This in vitro method could prove useful in testing bacterial adherence properties of newly developed catheter materials, and allow development of catheters less prone to be associated with bacterial adherence and catheter-related infections.     

Cathétérisme veineux périphérique: influence de la composition du cathéter dans l''apparition de thrombophlébites

Infusion thrombophlebitis is a common troublesome complication of intravenous therapy. This study compared peripheral intravenous Teflon and Vialon catheters. The incidence of phlebitis, bacterial adherence and mechanical resistance (distortion) were assessed on 170 catheters, 85 of each type. The Vialon catheter resulted in less phlebitis than the Teflon one (18 vs. 35; p less than 0.01). During the period 49 to 72 h after the insertion of the catheter, the risk of phlebitis in the Teflon group was twice that in the Vialon group. The study of bacterial adherence using a semi-quantitative culture method demonstrated that 9.0% of the catheters were infected with Staphylococcus epidermidis. There was no statistically significant difference between the two groups (5.7% Vialon group vs. 12.5% Teflon group). The Teflon catheters were much more distorted than vialon catheters: 1.7% vs. 55.7% in the macroscopic study; 1.75% vs. 8.2% in the microscopic study. As Vialon softens at body temperature, it would seem likely that it generates a lesser degree of endothelial injury, explaining the lower rate of phlebitis with Vialon catheters.     

Bacterial adhesion to cerebrospinal fluid shunts

Bacterial adherence to cerebrospinal fluid (CSF) shunts was analyzed in vivo and in vitro. Scanning electron micrographs (SEM's) of catheters removed from pediatric patients with shunts infected by Staphylococcus aureus or Klebsiella pneumoniae revealed numerous bacterial cells and microcolonies, leukocytes, and erythrocytes attached to the CSF catheters' inner walls, as well as the existence of surface irregularities, such as fissures, rugosities, and holes. Permeability analyses and SEM's demonstrated that catheters develop physical alterations over the period of implantation. Different bacterial strains presented a different in vitro adherence to CSF shunts, suggesting that this attachment may be affected by specific properties of the outer structures of each strain. The attachment of microbial pathogens to CSF shunts seems to contribute to the persistence of bacterial cells within a catheter and the onset of recurrent shunt infection. This study demonstrated that some bacteria can remain attached within shunts in vitro despite a CSF flow at rates up to 200 times higher than those normally demonstrated in vivo. Furthermore, surface irregularities found throughout this study may help to anchor and hide bacterial microcolonies. Based on these findings, it seems advisable to remove an infected shunt and to replace it with a new one after proper antimicrobial therapy, in order to prevent recurrent infections.     

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 and in vivo efficacy of a rifampin-loaded silicone catheter for the prevention of CSF shunt infections

Summary Infection of cerebrospinal fluid (CSF) shunts is one of the major complications associated with their use and is usually managed by shunt removal, temporary insertion of an external drainage and implantation of a new shunt system. We have evaluated the efficacy of a rifampin-loaded silicone ventricular catheter to prevent bacterial colonization and infection in vitro and in an animal model.On the basis of an incorporation process a rifampin-loaded catheter was developed which is capable of releasing rifampin in bacteriocidal concentrations for 60 days and more. In a stationary bacterial adherence assay usingS. epidermidis as test strain, the colonization resistance of the device was demonstrated.To assess the capability of the catheter to prevent CSF shunt infections, a rabbit model was developed which allowed the establishment of a reliable and reproducible CSF infection by implantation of silicone catheters into the ventricle and inoculatingS. epidermidis (minimal dose 10⁶ cfu) orS. aureus (minimal dose 10³ cfu). Rifampinloaded catheters (12 animals inoculated with S. epidermidis, 8 animals inoculated with S. aureus) were compared with non-loaded (14 animals inoculated with S. epidermidis, 19 animals inoculated with S. aureus) control catheters, and infection was documented by clinical, microbiological and histological methods.In contrast to the control group, none of the animals with rifampin-loaded catheters showed clinical signs of infection. Furthermore, in none of the materials obtained after sacrifice of the animals (catheter, brain tissue, CSF, blood) could the infecting bacteria be cultured, whereas in materials from animals with the unloaded catheter the infecting strains could always be cultured from the catheter and from surrounding brain tissue. The histological examination of catheter-adjacent tissue supported these findings.We conclude that a rifampin-loaded silicone ventricular catheter is capable of completely preventing bacterial colonization and infection by staphylococci as the main causative organisms in CSF shunt infections and should be further evaluated in clinical trials.     

The influence of flushing epidural catheters before use on detection of intravenous placement: an in vitro and in vivo study

Undetected intravenous placement of epidural catheters is rare but potentially fatal and no perfect identification method exists. Epidural catheters may be flushed before insertion to identify faulty epidural catheters, or to prime the system with local anaesthetic. We hypothesised that flushing epidural catheters before insertion may delay the detection of intravenous placement. We investigated our theory using both in vitro and in vivo models. The in vitro component examined flowrates in flushed and unflushed epidural catheters, using conditions designed to mimic epidural venous pressure. The in vivo component examined the flow within flushed and unflushed epidural catheters inserted into the forearm veins of 20 anaesthetised patients, using a randomised crossover design. The end-point utilised for both components was the time taken for frank blood to reach the 20 cm mark on the epidural catheter. Blood flow to the 20 cm mark on the epidural catheter was significantly faster in the unflushed catheters than the flushed catheters, both in vitro and in vivo (in vitro, unflushed median = 18.6 s (range: 18.0 to 20.5 s), flushed 37.6 s (32.6 to 91.2 s), P = 0.0009; in vivo, unflushed 9.2 seconds (range 5.0 to 35.3 s), flushed 19.2 s (10.6 to 47.4 s), P = 0.003 in vivo). Flushed catheters also demonstrated a greater variability in the range of flowrates. Flushing epidural catheters before insertion may delay the detection of intravenous placement.     

Serum dependent variability in the adherence of tumour cells to surgical sutures

Five commonly used surgical sutures were tested for their abilities to adhere tumour cells by an in vitro adherence assay. Adherence was quantified in vitro using radiolabelled tumour cells after standard incubation with a set length of the differing sutures. Tumour cells consistently adhered least to Prolene. All suture materials tested adhered significantly more tumour cells than Prolene (P less than 0.002 for chromic and less than 0.0001 for nylon, silk and Vicryl when compared with Prolene, with increasing cell numbers adhering to the sutures tested in that order). These differences in adherence were dependent upon an as yet unidentified macromolecule(s) in serum. All of the suture materials supported tumour growth in vivo after pre-incubation with tumour cells. Rapidity of in vivo tumour growth, however, correlated well with the in vitro tumour adherence characteristics of the different suture materials. The clinical significance of these findings is discussed.     

Reduction of bacterial adherence to catheter surface with heparin

Despite many advances in catheter design and use, the most common cause of hospital-acquired infections is catheterization of the urinary tract. In the present investigation the adherence of bacteria to catheters coated with heparin was studied. Since heparin itself does not coat the plastic catheter surface, a complex of heparin with tridodecylmethylammonium chloride (TDMAC) was used which results in hydrophobic association of hydrocarbon chains of the TDMAC with the catheter leaving the quaternary ammonium moiety of TDMAC exposed to the surface forming ionic bonds with the highly anionic sulfate groups of heparin. Coating latex catheter material with TDMAC without heparin resulted in 3.6-fold higher adherence whereas coating with the TDMAC-heparin complex reduced adherence to less than 10% of control untreated latex. TDMAC-heparin also significantly reduced bacterial adherence to teflon coated latex (Bardex) and vinyl catheter material. Less than 30% of the original heparin was removed after wash periods of up to one week. These results indicate that TDMAC-heparin coating of urethral catheters reduces bacterial adherence and thereby may delay the acquisition of catheter associated urinary tract infection.     

Adherence of microorganisms to breast prostheses: an in vitro study

The quantitative and morphological characteristics of microbial adherence of four organisms--Staphylococcus epidermidis, S. aureus, Escherichia coli and Candida albicans--to the surfaces of different breast prostheses were observed. Semiquantitative adherence studies based on a modification of Maki's roll culture technique even after short contact times showed (1) increased microbial adherence at higher concentrations of the organisms and (2) differences in adherence properties between gram-positive bacteria and other organisms tested, noted also at lower organism concentrations. Scanning electron microscopy (SEM) to identify microorganisms on foam-covered prostheses, however, revealed organisms in the interstitial spaces that were not recovered by the plating technique. Other features on SEM were extracellular "slime" produced by S. epidermidis, which appears to act as a cement by which bacteria are held against prosthetic surfaces. These in-vitro findings suggest that brief exposure of the prostheses to a few organisms, particularly gram-positive bacteria, at the time of implantation would be sufficient inoculum for bacterial adherence to prosthetic surfaces.     

The 'no-touch' method of intermittent urinary catheter insertion: can it reduce the risk of bacteria entering the bladder?

OBJECTIVE: This in vitro model was designed to determine whether using a no-touch method for catheter preparation and insertion would affect the degree of contamination transmitted to intermittent urinary catheters. SETTING: Northview Laboratories, Northbrook, IL 60062, USA. METHODS: This was a parallel experimental study conducted in vitro at an independent testing laboratory under Good Manufacturing Practices. Six different models of intermittent urinary catheter were tested in triplicate, in accordance with the manufacturer's Instructions For Use (IFU). Gloved hands were contaminated with a known amount of Staphylococcus aureus or Escherichia coli, preparation for insertion was mimicked according to the manufacturer's IFU. The number of bacteria transferred to the catheter was then quantified using a validated technique. The null hypothesis tested was that the bacterial contamination resulting from handling would be the same for all of the catheters. The primary outcome measure was the amount of bacteria, expressed as colony forming units (CFU), recovered from the catheters. The catheter wrappers were sampled to confirm that active transfer of microorganisms had taken place and nonhandled samples served as the negative controls. RESULTS: For both test organisms, the number of bacteria recovered from the catheters was significantly lower (P < 0.05) for the catheters featuring the no-touch design (approximately 5 CFU/plate versus 2.1 x 10(2) to 4.4 x 10(2) for the traditional hydrophilic catheters). The bacterial recovery from those catheters with the no-touch design often fell below the nominal detection limit. CONCLUSION: The results of this study allow the null hypothesis to be rejected; it can be concluded that the no-touch method provides a significant benefit in reducing the potential for external contamination of an intermittent urinary catheter. This result supports the recent recommendations for aseptic intermittent catheterization promoted within the guidelines issued by the European Association of Urologists (EAU).     

Catheter-related sepsis in patients on intravenous nutrition: a prospective study of quantitative catheter cultures and guidewire changes for suspected sepsis

One hundred and ninety-five central venous catheters used for intravenous nutrition in 113 patients were studied prospectively. Catheter-related sepsis (CRS), defined by recovery of the same organism from the catheter tip and peripheral blood cultures, occurred with only 3.3 per cent of catheters or 2.3 per 1000 days of therapy. In contrast, CRS was suspected with 30 per cent of catheters and catheter contamination occurred in 37 per cent. Contamination was defined by a positive catheter tip culture without recovery of the same organism from the blood. CRS was present in 4 of 12 cases (33 per cent) with greater than 1000 colony forming units on the catheter tip but in only 2 of 54 (4 per cent) with fewer organisms. Thirty-eight cases suspected of having CRS were randomized to have catheter removal and later replacement, or replacement over a guidewire. There were no significant differences in the catheter contamination rate but there were significantly fewer problems of insertion in the guidewire group. However, transfer of Klebsiella sp., during the guidewire procedure, resulted in subsequent sepsis in one case. It is concluded that replacement of catheters over a guidewire is a safe and convenient way of establishing whether sepsis is catheter-related. Because organisms may be transferred, the procedure is not an appropriate treatment for catheter-related sepsis.     

Bacterial colonization in hemodialysis temporary dual lumen catheters: a prospective study

AIMS: The use of hemodialysis temporary dual-lumen catheters is often complicated by infections, which may be a significant cause of death among patients with end stage renal disease (ESRD). The aim of this study was to assess the incidence of bacteremia and bacterial colonization related to non-tunneled, non-cuffed, dual-lumen temporary catheters in patients with ESRD submitted to hemodialysis. METHODS: This study included 29 patients with ESRD. After catheter implantation, patients were monitored throughout the period of catheter permanence by means of blood samples collected weekly from a peripheral vein. Bacteria were isolated and identified according to CLSI recommendations. When catheters were removed for any reason, their tips were evaluated microbiologically. RESULTS: A total of 194 blood samples from the 29 patients implanted with 55 catheters were analyzed. Of these, 15.5% (30 samples) demonstrated bacterial growth, principally Staphylococcus epidermidis (64.5%). Twenty patients (68.9%) presented at least one positive blood culture during follow-up. The median time for catheter colonization was 18.5 days (95% CI: 16.8-30.3). Of the 55 catheters implanted, 28 (50.9%) showed bacterial colonization, corresponding to 23.4 episodes/1000 catheter/days and 9.2 episodes of bacteremia /1000 catheter/days. Fifteen of 28 catheter tips analyzed showed bacterial growth (53.5%). In 14 of these (93.3%), there was agreement between the isolates from the catheter tip and blood cultures. Of 24 episodes of positive blood cultures from 20 different patients in 17 episodes (70.8%), the patients showed no clinical signs or symptoms of bacteremia. CONCLUSIONS: The high incidence of catheter colonization, the correlation between blood and catheter tip cultures, and the occurrence of frequent cases of asymptomatic bacteremia justify the proposal of routine peripheral blood collections to monitor patients undergoing hemodialysis with temporary dual-lumen catheters.     

Electrical microcurrent to prevent conditioning film and bacterial adhesion to urological stents

Long-term catheters remain a significant clinical problem in urology due to the high rate of bacterial colonization, infection, and encrustation. Minutes after insertion of a catheter, depositions of host urinary components onto the catheter surface form a conditioning film actively supporting the bacterial adhesion process. We investigated the possibility of reducing or avoiding the buildup of these naturally forming conditioning films and of preventing bacterial adhesion by applying different current densities to platinum electrodes as a possible catheter coating material. In this model we employed a defined environment using artificial urine and Proteus mirabilis. The film formation and desorption was analyzed by highly mass sensitive quartz crystal microbalance and surface sensitive atomic force microscopy. Further, we performed bacterial staining to assess adherence, growth, and survival on the electrodes with different current densities. By applying alternating microcurrent densities on platinum electrodes, we could produce a self regenerative surface which actively removed the conditioning film and significantly reduced bacterial adherence, growth, and survival. The results of this study could easily be adapted to a catheter design for clinical use.     

Efficacy of prior skin puncture in preventing iv catheter damage

The efficacy, with respect to preventing i.v. catheter damage, of creating a skin entry site by first piercing the skin with a large gauge needle through which an over-the-needle teflon catheter is then placed was evaluated. In 50 adult volunteers two 22-gauge i.v. catheters and two 24-gauge catheters were placed through the forearm skin into the subcutaneous tissue. One catheter of each size was placed through an entry site created by piercing the skin with an 18-gauge disposable, stainless steel needle. One catheter of each size was inserted through nearby skin without creation of an entry site. Two to three weeks after insertion all catheters, along with 50 catheters of each size that had not been inserted, were examined under a microscope for evidence of damage. Intravenous catheter damage was more prevalent in the 24-gauge catheters than the 22-gauge catheters (P less than 0.05). No differences in frequency of damage were noted for either gauge catheter inserted through an entry site compared with those inserted without a prior skin puncture. Twenty-four-gauge catheters, but not 22-gauge catheters, placed into the subcutaneous tissue were damaged more frequently than were catheters that had never been inserted (control catheters). This study demonstrated that 24-gauge catheters are more likely to be damaged during insertion into the subcutaneous tissue than are 22-gauge catheters. We also demonstrated that creation of a skin entry site by piercing the epidermis with a needle of larger gauge than the catheter to be placed is not efficacious in preventing intravenous catheter damage during insertion.     

Balloon embolectomy catheter-induced arterial injury: a comparison of four catheters

This study compared four brands of balloon embolectomy catheters with respect to their mechanical characteristics and the histologic responses they elicit. Seventy-two 4F Becton-Dickinson, Edwards, Electro-Catheter, and Shiley catheters were studied. In vitro studies of penetration forces demonstrated that the forces required for arterial puncture were greatest for Shiley (295 +/- 22 gm) and least for Edwards catheter tips (217 +/- 11 gm) (p less than 0.05). This indicates that the Shiley catheter is least likely to puncture vessels in patients. Studies of balloon eccentricity showed that none of the balloons distended with excessive eccentricity. Studies of balloon emptying time demonstrated that the silicon Becton-Dickinson balloon required more than two times as long (5.7 +/- 1.2 seconds) as all other balloons to empty. Balloon emptying time reflects the ability of the surgeon to rapidly adapt the balloon to changing vessel diameter in patients. Shear forces were studied in cylindrical segments of arteries in vitro. Initial shear forces were significantly different among all catheters, Becton-Dickinson greater than Edwards greater than Shiley greater than Electro-Catheter (p less than 0.05). In contrast, during catheter withdrawal dynamic shear forces were similar among the four brands of catheters. Balloon embolectomies were performed in vivo in the common carotid and common femoral arteries in 18 anesthetized dogs. Histologic examinations of the vessels exposed to 50, 100, and 200 gm shear forces showed that myointimal hyperplasia increased with rising shear forces for all catheters (p less than 0.05), but that there were no differences in the degree of myointimal hyperplasia elicited by the different brands of catheters.(ABSTRACT TRUNCATED AT 250 WORDS)     

Exit of catheter lock solutions from double lumen acute haemodialysis catheters--an in vitro study.

BACKGROUND: Double lumen dialysis catheters are routinely heparin or citrate 'locked' to maintain patency. Heparin lock-related bleeding episodes and antibiotic lock-related toxicity have been reported. The aim of this study is to quantify the amount of leak during 'lock' procedures and to compare leakage for different double lumen dialysis catheters. METHODS: In an experimental, in vitro study at a University research laboratory, five different double lumen dialysis catheters were tested using three different lock volumes. RESULTS: Using the catheter flush volume, leak ratios for Flexxicon II 15 cm and 20 cm catheters were greater than that seen in the Arrow 16 cm catheter (P < 0.05). Using 20% less than the catheter flush volume, the Flexxicon II 20 cm catheter had greater leak than the Duo-flow 15 and 20 cm catheters and Arrow 16 cm catheter (P < 0.05). The Flexxicon II 15 cm catheter had greater leak than the Duo-flow 15 cm and Duo-flow 20 cm catheters with 20% less locking volume (P < 0.05). Using 20% greater than the catheter flush volume, the Duo-flow 20 cm catheter had significantly less leak ratio than the Flexxicon II 20 cm catheter (P < 0.05). There were no other significant differences in leak ratios between the catheters. CONCLUSION: All double lumen dialysis catheters we tested have a substantial amount of leak even when the catheter 'lock' volumes were used, and leak ratio increases significantly with 20% overfill. There is a leak even when using 20% less 'lock' volume. The amount of leak can be clinically important and may explain the reports of bleeding episodes after heparin lock and antibiotic toxicity after antibiotic and anticoagulant combination lock. Some devices have lower leak ratios than others, likely related to catheter design.     

Intravenous glutamine or short-chain fatty acids reduce central venous catheter infection in a model of total parenteral nutrition

BACKGROUND/PURPOSE: In children receiving total parenteral nutrition (TPN) translocated enteric organisms are a possible cause of central venous catheter infection. The aim of this study was to determine the relationship between gut mucosal atrophy, bacterial translocation, and catheter sepsis in rats receiving TPN alone or supplemented with intravenous short chain fatty acids (SCFA) or glutamine. METHODS: Mature Wistar rats were studied. Groups 2 to 5 had a central venous catheter inserted. Group 1 (n = 12) had enteral feeds only, group 2 (n = 14) had enteral feeds and intravenous saline, group 3 (n = 15) had TPN only, group 4 (n = 13) had TPN with SCFA, and group 5 (n = 15) had TPN with glutamine. At 1 week, blood, tissue, and catheter specimens were obtained for culture and mucosal morphometry. RESULTS: Villus height and crypt depth were reduced significantly in group 3 compared with group 1 (P < .05). Glutamine and SCFA significantly ameliorated the mucosal atrophy. Significant bacterial translocation and catheter infection occurred in group 3. Reduced translocation with SCFA was not significant, but catheter infection was (P < .05). Glutamine significantly reduced translocation and catheter infection. CONCLUSIONS: There is an association between bacterial translocation and central venous catheter infection. The risk of catheter infection is reduced by supplementing TPN with SCFA or glutamine.     

Prevention of catheter sepsis by antibiotic bonding

The techniques of antibiotic bonding were applied to the problem of hyperalimentation catheter sepsis. Pretreatment with tridodecylmethylammonium chloride (TDMAC) increased the bonding of 14C-penicillin to polyethylene catheter segments from 3.1 to 212 micrograms/cm and to silicone elastomer catheter segments from 0.09 to 181 micrograms/cm. The elution of the bound ligands from silicone elastomer catheter segments in the presence of plasma was studied. At 2 weeks more than 60% of the bound TDMAC remained adherent to the catheter. The elution of the bonded penicillin from the silicone elastomer catheters was biphasic, initially 95% dissociated after 48 hours of incubation. A bioassay revealed that the dissociated penicillin was bacteriocidal. Polyethylene catheters were placed in the jugular vein of rats and positioned in the right atrium. The catheters were tunneled posteriorly, exited between the forelimb shoulder girdles, and connected to a swivel mechanism. The exit site was inoculated before closure with 1 X 10(8) Staphylococcus aureus. Five days after insertion the catheters were removed via sterile thoracotomy and the tips cultured. Untreated control catheters, catheters treated by antibiotic soaking, and catheters pretreated with TDMAC all had high rates of catheter colonization (60% to 80)%. TDMAC-penicillin-bonded catheters did not become colonized. This difference was significant (p less than 0.005). Antibiotic bonding may prove effective in preventing hyperalimentation catheter sepsis.     

The continuous femoral nerve block catheter for postoperative analgesia: bacterial colonization, infectious rate and adverse effects

We investigated the incidence of bacterial and vascular or neurological complications resulting from femoral nerve catheters used for postoperative analgesia. Patients requiring continuous femoral blockade were consecutively included. Using surgical aseptic procedure, 211 femoral nerve catheters were placed (short-beveled insulated needle, peripheral nerve stimulator). After 48 h, each catheter was removed and semiquantitative bacteriological cultures were performed on each distal catheter tip. Postoperative analgesia and antibiotics were standardized. All complications during the insertion of the catheters and postoperatively (after 48 h and 6 wk) were noted. Few initial complications with no immediate or delayed complications were noted (20 difficult insertions, 3 impossible injections, 3 ineffective catheters, and 12 vascular punctures). After 48 h, 208 catheters were analyzed; 57% had positive bacterial colonization (with a single organism in 53%). The most frequent organisms were Staphylococcus epidermidis (71%), Enterococcus (10%), and Klebsiella (4%). Neither cellulitis nor abscess occurred. Three transitory bacteremias likely related to the catheter occurred. After 6 wk, no septic complications were noted. One femoral paresthesia, partially recovered 1 yr later, was noted. We conclude that the risk of bacterial complications is small with femoral nerve catheters, although the rate of colonization is frequent. IMPLICATIONS: In this prospective study, continuous femoral nerve catheters were effective for postoperative analgesia but had a frequent rate of bacterial catheter colonization. We found no serious infections after short-term (2-day) infusion. Side effects were few, but one nerve injury occurred.     

Adherence of uropathogenic E. coli to differentiated human uroepithelial cells grown in vitro

A quantitative in vitro model to measure E. coli adherence to differentiated human uroepithelial cells has been developed. Primary cultures of uroepithelial cells were initiated from normal ureteral epithelium. Adherence of uropathogenic 3H-labelled Escherichia coli to postconfluent human uroepithelial cells was directly related to the bacteria:epithelial cell ratio during incubation. Bacterial attachment was inhibited either by mannose or by urine containing anti-E. coli antibodies. Transmission electron microscopy showed that epithelial cells differentiated in vitro to resemble normal uroepithelium in vivo. Furthermore, electron microscopy showed specific adherence of bacteria to the glycocalyx of microvilli of the superficial uroepithelial cells in vitro in a manner which closely mimics the in vivo interaction. This model of bacterial adherence permits in vitro analysis of adhesin-receptor interactions between uropathogenic E. coli and a layer of viable uroepithelial cells similar to those lining the bladder.