Characterisation of the internal and external surfaces of four types of Foley catheter using SEM and profilometry

Differences in Bacterial Colonization and Biofilm Formation Property of Uropathogens between the Two most Commonly used Indwelling Urinary Catheters

INTRODUCTION

Catheter Associated Urinary Tract Infections (CAUTI) are one of the most common cause of nosocomial infections. Many bacterial species show biofilm production, which provides survival benefit to them by providing protection from environmental stresses and causing decreased susceptibility to antimicrobial agents. Two most common types of catheters used in our setup are pure silicone catheter and silicone coated latex catheter. The advantage of pure silicone catheter for long term catheterization is well established. But there is still a controversy about any advantage of the silicone catheter regarding bacterial colonization rates and their biofilm production property.

AIMS

The aim of our study was to compare the bacterial colonization and the biofilm formation property of the colonizing bacteria in patients with indwelling pure silicone and silicone coated latex catheters.

MATERIALS AND METHODS

This prospective observational study was conducted in the Urology Department of our institute. Patients who needed catheterization for more than 5 days during the period July 2015 to January 2016 and had sterile precatheterisation urine were included in the study. Patients were grouped into 2 groups of 50 patients each, Group A with the pure silicone catheter and Group B with the silicone coated latex catheter. Urine culture was done on the 6(th) day of indwelling urinary catheter drainage. If growth was detected, then that bacterium was tested for biofilm production property by tissue culture plate method.

STATISTICAL ANALYSIS

Statistical analyses were performed using the Statistical Package for the Social Science Version 22 (SPSS-22).

RESULTS

After 5 days of indwelling catheterization, the pure silicone catheter had significantly less bacterial colonization than the silicone coated latex catheter (p-value=0.03) and the biofilm forming property of colonizing bacteria was also significantly less in the pure silicone catheter as compared to the silicone coated latex catheter (p-value=0.02). There were no significant differences in the colonizing bacteria in the 2 groups. In both the groups the most common bacteria were Escherichia coli.

CONCLUSION

The pure silicone catheter is advantageous over the silicone coated latex catheter in terms of incidence of bacterial colonization as well as the biofilm formation and hence in the management of CAUTI.

The pathogenesis of catheter-associated urinary tract infection

Catheter-associated urinary tract infection (CAUTI) remains one of the most common types of hospital-acquired infections. Further progress in the prevention of CAUTI requires a better understanding of its pathogenesis. Bacteria may enter the bladder through contamination of the tip during insertion with the flora of the distal urethra or from bacteria ascending the outside or the inside of the catheter. Residual urine in the bladder of catheterised patients increases the risk of bacteriuria. During the process of infection, bacteria need first to adhere to the epithelial cells of the urinary tract and/or the surface of the catheter. They will then develop into biofilms on the catheter surface and are resistant to the immune system and antibiotics. Catheters by themselves may cause immediate physical damage to the bladder epithelium; they may be toxic and also cause inflammation. Bacteria can also damage the epithelium and cause inflammation and the combination of both may be synergistic in producing symptoms in the patient. Most episodes of catheter-associated bacteriuria are asymptomatic but it is not known why some patients are symptomatic and others are not. Further research into the pathogenesis of CAUTI needs to be carried out. A suggestion for the prevention of CAUTI is the use of catheters with an additional eye-hole beneath the balloon to prevent residual urine in the bladder or to remove the tip and balloon altogether, with the additional benefit of having no tip to cause damage or inflammation to the bladder epithelium.