Comparison of in vitro encrustation on silicone and hydrogel-coated latex catheters

Mid-shaft sections of 100% silicone (Bardex) and hydrogel-coated latex (Biocath) catheters were subjected to controlled in vitro encrustation conditions for periods of up to 18 weeks. There was no significant difference in the quantities of encrusting deposits formed on these two materials during the course of the experiment.     

Cytotoxicity of latex urinary catheters

After an epidemic of severe urethral strictures in cardiac surgery patients, all brand latex catheters marketed in Finland were investigated for cellular toxicity with eluates made from the catheters. Four of the seven brands, including the one involved in the stricture cases, showed marked cytotoxicity and inhibited almost all cell growth in various human cell cultures when a 30% catheter eluate was used. DNA histograms of cells cultured with toxic catheter eluate showed inhibition of DNA synthesis. Silicone catheters did not influence cell growth, which correlates with the finding that no new stricture cases were seen after the latex catheters were replaced with silicone ones. Attention is paid to the facts that international standards regarding urethral catheter toxicity are lacking and that catheter quality control is insufficient.     

导尿管毒性的实验研究

导尿管的毒性物质是引起尿道感染和狭窄的重要因素之一。为进一步明确各种材料制成的导尿管的毒性大小，应用细胞培养的方法检测了７种导尿管毒性提取物对体外培养的鼠成纤维细胞（Ｌ９２９）摄入Ｈ＾３－标记胸腺嘧啶核苷（Ｈ＾３－ＴＤＲ）的抑制情况，并比较其毒性大小，结果表明：硅胶导尿管毒性很小，硅处理乳胶、塑料导尿管毒性中等，橡胶尤其是白橡胶导尿管具有较大的毒性。提示临床选用导尿管应考虑到导尿管的毒性，尽量选用     

Toxicity testing of urinary catheters

The tissue toxicity of 23 urinary catheter batches (6 latex and 2 non-latex brands) was tested in vitro and in vivo. In vitro, a human T-cell leukemia line (JM) was cultured in the presence of different concentrations of eluates made from the catheters. The cytotoxicity of the eluates was assessed from their ability to inhibit DNA synthesis measured by incorporation of 3H-thymidine. In vivo, two methods were used. Strips of catheters were implanted into the rabbit dorsal muscle and pieces of catheters were implanted into the rat peritoneal cavity. After four days, the foreign body reaction, type of inflammation and necrosis were quantified macroscopically and by light microscopy. The results of the in vitro cytotoxicity test were correlated with those of in vivo methods. The rat peritoneal implantation test correlated better with the cell culture test (P less than 0.01) than with the rabbit muscle implantation test (P less than 0.05). Based on the clinical experience of urethral stricture complications caused by urinary catheters, catheters yielding eluate which at 30% dilution inhibited 50% DNA synthesis were regarded as toxic. According to this, the rabbit muscle implantation test was not reliable in testing the tissue toxicity of urinary catheters, while the cell culture test was quantitative and seemed to correlate with both the rat peritoneal implantation test and with the clinical complications observed.     

Cytotoxicity assessment of latex urinary catheters on cultured human urothelial cells

PURPOSE: To study the toxicity of latex urinary catheters on cultured human urothelial cells (HUC). MATERIALS AND METHODS: We exposed monolayers of HUC (well characterized for their proliferation, qualitative evaluation and quantitative measurement of cytokeratins) to either pure or diluted liquid latex extracts, obtained under standard conditions or by direct contact with materials. RESULTS: The latex urinary catheter appears to be highly toxic since cell viability and metabolic activity were about 10% of those of negative controls for original extracts. Concerning direct contact, latex reduced cell viability, metabolic activity and cell proliferation of HUC on days 1, 3 and 8. CONCLUSION: The high toxicity of latex on HUC is confirmed for extracts and direct contact. Therefore, it should no longer be used for urinary catheters.     

Comparison of two different cell culture methods in evaluation of biocompatibility of latex urinary catheters

Summary International biocompatibility standards for urinary catheters have not yet been set. The used in vivo animal tests earlier have been shown to be insensitive and expensive. The present study compared the sensitivity and other properties of two in vitro cell culture methods, the reference method of the British Standards Institution (BSI) [2] and the thymidine incorporation method DNA synthesis inhibition test, [7]. The cell culture toxicities of thirty-seven latex catheters were measured and 84.8% of the catheters tested passed the BSI reference test while 94.6% passed the thymidine incorporation test. The overall batch-to-batch correlation was poor (p > 0.05), but within brands the correlation was better. This is obviously to be explained by the differences the characteristics of the tests and/or the chemical composition of the catheters. The thymidine incorporation test is easier to perform, requires less manpower, and is therefore less liable to subjective interpretations than the BSI test. The biocompatibility toxicity limits for latex urinary catheters need to be tightened. Our experience in this study indicates that the thymidine incorporation test or tests similar to it, which can be highly automated can be recommended for biocompatbility screening in large series, and BSI reference test can be used additionally in unclear cases.     

Ultrastructural study of microbiologic colonization of urinary catheters

We examined ten urinary catheters, associated with catheter-related urinary tract infections, by scanning and transmission electron microscopy to study the morphology of bacterial adherence. We confirmed that the bacteria associated with catheter-associated urinary tract infections grow in glycocalyx-enclosed microcolonies in a biofilm on the catheter surface. The bacterial populations demonstrated a heterogeneity that was not evident from the culture results, and it was demonstrated that only a small proportion of the microorganisms, including fungi, identified morphologically by scanning or transmission electron microscopy are recovered by routine culture methods. The persistence of the bacterial pathogens in catheter-associated infection, even in the face of antibiotic treatment, may be attributed to their adherent mode of growth in protected biofilms and their production of extensive enveloping anionic glycocalyces.     

Biomechanical performance of silicone and latex external condom catheters

Standard in vivo biomechanical performance tests and a pilot clinical study of latex external condom catheters (ECCs) and silicone ECCs demonstrated the superior performance of the silicone ECC over that of the latex ECC. The silicone ECC has a self-adhesive that binds more securely to human skin than the self-adhesive of latex ECC. In addition, the moisture vapor transmission through silicone is significantly greater than through latex. The aggressive self-adhesive of the silicone ECC significantly reduced ECC catheter pop-off compared to that of latex ECC. Silicone ECC removal can be facilitated by the application of a warm, wet cloth to the exterior surface of the silicone ECC, which significantly reduces its self-adhesive force. Constant, gentle traction is then applied to the silicone catheter outlet end to achieve atraumatic silicone ECC removal. On the basis of the results of these standardized tests and pilot study, the silicone ECC is recommended for incontinent men without obstructive uropathy.     

Removal of retained urinary catheters

In a 1-year register, retained urinary catheters were encountered on 23 occasions. In vitro tests showed that 2 ml of ether or chloroform injected through the inflation channel of catheter balloons caused disruption within a few seconds but liquid paraffin took over 20 min, leaving an unacceptable amount of debris. A new method of removal using diagnostic ultrasound to identify the balloon of the retained catheter is described, together with suggestions for removal of retained catheters occurring under different circumstances.     

Gender differences and bleeding complications after PCI on first and second generation DES

Background. The aim of this study was to evaluate gender differences in the long-term clinical outcomes and safety of patients treated with first- and second generation DES. Methods. The Katowice–Zabrze Registry included 1916 consecutive patients treated with either first or second generation DES. We evaluated major adverse cardiac and cerebrovascular events (MACCE) [composite of death, myocardial infarction (MI), stroke and target vessel revascularization (TVR)] at 12-month follow-up. Safety end point was bleeding complications and stent thrombosis. Results. Registry included [unstable angina (UA) 1500(78%), non-ST-segment elevation myocardial infarction (NSTEMI) 285 (15%), ST-segment elevation myocardial infarction/left bundle branch block (STEMI/LBBB) 131 (7%)]. There were 35.5% females and 64.5% males. Women were older and had higher prevalence of comorbidities. Males more often had multivessel disease and higher Syntax score when comparable to females. We did not observed difference in acute and subacute stent thrombosis in our data, however, females had more in-hospital bleeding complications. Univariable Cox regression analysis revealed that women had similar outcomes when compared to men in terms of a risk of death, MI, TVR, stroke and MACCE at 1-year follow-up. There were no differences between males and females in MACCE when first- and second generation DES were analyzed separately. Conclusion. Despite higher risk profile, women treated with DES have similar outcomes as males in 1-year follow-up. However there is, an increased risk of in-hospital bleedings in women.     

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.     

Prospective study of individuals with long-term urinary catheters colonized with Proteus species

OBJECTIVES: To characterize the variability in the times catheters take to block with encrustation in patients who have Proteus in their urinary flora, and to identify factors responsible for modulating the rate of catheter encrustation and blockage. PATIENTS AND METHODS: Twenty patients were followed prospectively for > or = 12 weeks, with a bacteriological analysis on weekly urine samples. The pH of the voided urine samples and the pH at which crystals formed in them (the nucleation pH) were determined. Catheters were collected and examined for bacterial biofilm and crystal deposition. RESULTS: The time that catheters took to block was 2-98 days. The mean pH of the urine voided by patients designated as slow encrusters (6.9) was not significantly different (P = 0.237) from that of rapid encrusters (7.2). However, patients whose catheters took longer to block had a significantly higher mean nucleation pH (8.1 vs 7.3, P = 0.002) and significantly higher mean safety margin between their nucleation pH and voided pH (1.17 pH units vs 0.13, P = 0.003). CONCLUSION: The variation in the rate of catheter encrustation between individuals infected with Proteus is a function of the difference between the voided pH and the nucleation pH of their urine. The value of nucleation pH of an individual's urine varies widely, suggesting it should be possible to devise strategies to increase this value and thus reduce the rate of encrustation in those with urinary tract colonization by urease-positive bacteria.     

Hepatitis C virus infection in hemodialyzed patients detected by first and second generation assays.

A prospective study of liver disease has been conducted among patients entering our Dialysis Unit between 1987 and 1990. On entry, 7 patients had a history of blood transfusions but none had clinical or biochemical features of liver disease. During follow-up, 13 further patients were transfused; 1 case developed acute resolving hepatitis B and another acute non-A, non-B hepatitis progressing to chronicity. Eleven other cases showed transient or fluctuating ALT abnormalities. On entry, anti-HCV was negative by both 1st and 2nd generation ELISA assays (Ortho-Diagnostic Systems) in all cases. During follow-up, a positive reaction was detected in 17 cases: 4 patients were positive by both assays and 13 only by 2nd generation test (p less than 0.01). HCV was implicated in 66% of cases with liver disease of the non-A, non-B type and in 50% of transfused as compared to 23% of nontransfused cases (p = n.s.). These findings suggest that HCV could play a major etiological role in liver disease of hemodialysis patients and that anti-C100 reactivity is more affected by immunosuppression associated with chronic uremia.     

Comparison of urethral reaction to full silicone, hydrogen-coated and siliconised latex catheters

Indwelling urinary catheter may induce an inflammatory reaction or even stricture of the urethra. Catheter encrustation and urinary infection are other disadvantages associated with long-term catheterisation. In the present study, 77 male patients were catheterised randomly as part of their normal treatment with 1 of 3 different types of catheter: 22 siliconised latex, 28 hydrogel-coated latex and 27 full silicone catheters. The mean duration of catheterisation was 2.2 days. The urethral inflammatory reaction was assessed from cytological urethral swab specimens. Catheter encrustation was studied using scanning electron microscopic (SEM) analysis. The full silicone catheters induced the mildest degree of inflammation in the urethra, the percentage mean of inflammatory cells in smears being 20%. In both latex catheter groups the value was 36%. Neither the age of the patients nor the duration of catheterisation had any effect on the inflammatory reaction, which was more marked in patients with haemodynamic abnormalities. The hydrogel coating effectively prevented encrustation, while siliconised latex catheters were the least resistant to encrustation. The inflammatory reaction was variable in all patients. The use of urethral catheters should be restricted and suprapubic tubes should be used instead, particularly in patients with shock-like circulatory changes. By developing the biocompatibility and physical properties of urinary catheters, more compatible devices may be manufactured.     

Relationship between urease-producing bacteria, urinary pH and encrustation on indwelling urinary catheters

In 11 patients with long-term indwelling catheters the amount of catheter encrustation and urinary pH were measured and the urine regularly cultured over a prolonged period of time (median of 7 periods of 3 weeks). The mean urinary pH was related to the persistent presence of urease-producing micro-organisms (P. mirabilis) and urinary pH governed the precipitation of catheter encrustation. The critical pH appeared to be around 6.8. In patients with a mean urinary pH below this level the encrustation was minute (less than or equal to 2.9 mg phosphate). In patients with a mean urinary pH above 6.8 it was considerable but with a marked interindividual variation (35.5-138.7 mg phosphate). The composition of the encrustation was also strongly pH-related, with a much higher proportion present as magnesium ammonium phosphate in patients with a mean urinary pH above 6.8. The persistent presence of urease producers was not associated with a high pH or a more pronounced precipitation of phosphate in all patients. The amount of encrustation thus appears to depend not only on the presence of urease-producing micro-organisms but also on individual factors such as urinary composition.     

Spontaneous knotting of urinary catheters: clinical and experimental observations

Urinary catheters are known to spontaneously knot inside the bladder. Approximately 40 cases of this complication have been recorded in the world literature. Clinical observation in 4 children and simulation experiments done using a balloon model are described herein. Risk factors identified in this study includes catheter size less than 10 Fr, overdistended bladder and insertion of more than 10 cm length of catheter inside the bladder. Water-current generated by the flow of urine appears to play an important role in the pathogenesis of catheter knotting.     

Complications of chronic indwelling urinary catheters among male nursing home patients: a prospective study

We studied prospectively the incidence of symptomatic infections of presumed urinary tract origin requiring antimicrobial therapy among 54 male nursing home patients with chronic indwelling bladder catheters. During 514 patient-months at risk there were 106 episodes of symptomatic infection, for an incidence of 0.21 per patient-month at risk. Of the patients 80 per cent had at least 1 episode and 48 per cent had 2 or more. None of the clinical factors we examined, including age, nutritional status, stool incontinence, diabetes mellitus, episodes of catheter blockage and the use of chronic suppressant antimicrobial therapy, was associated with the development of symptomatic infection. Further research on host and pathogen-related factors that increase the risk for symptomatic infection, and improvements in infection control and catheter care protocols are necessary to decrease catheter-associated morbidity among male nursing home patients who must be managed by chronic indwelling catheterization.