Correlation Analysis Between Biofilm, Colony Counting And Bladder Irrigation Frequency, Catheter Replacement Timing

Objectives1. To determine the rate of Catheter-associated Urinary Tract Infection(CAUTI) forpatients in Intensive Care Unit (ICU) and the distribution pattern of bacteria byurinalysis and urine culture.2. To investigate the clinical risk factors of Urinary Tract Infection (UTI).3. To determine the pattern and number of colony-forming bacteria in the inner side ofcatheter, by catheter sample analysis and colony counting after urine culture.4. To observe biofilm formation at the catheter inner side by Scanning ElectronicMicroscope (SEM) imaging.5. To study the efficacy of bladder irrigation and catheter replacement in circumventingurinary tract infection and biofilm formation, providing a scientific insight for furtherclinical work.Methods1. We admitted the patients who met the preset criteria in ICU from March to December in2013into our study. These patients were divided into four groups according tofrequency of bladder irrigations and catheter replacement: Group A1，1irrigation and1catheter replacement every week(A1,n=36); Group A2,1irrigation every two weeksand1catheter replacement a week(A2, n=40); Group B1, replacing the catheter once aweek with no irrigation(B1, n=38); Group B2, replacing the catheter every two weekswith no irrigation(B2, n=43).2. After catheterization, urine sample was obtained from a sterile mid-catheter aspiratewith a syringe every seven day, for urinalysis and urine culture. The catheter tip with2cm catheter distal to the catheter balloon was removed and cut into halves by sterilescissors, half of which is used for bacterial culture, colony counting, and the other halffor scanning electron microscope imaging. Aseptic principles are adhered to during allthe procedures above.Results1. The study included157male (110,70.06%) and female (47,29.94%) patients (>18yearsof age) who were catheterized for more than7days in ICU, among which,110patients(70.06%) were from Neurosurgery ICU,21patients (13.38%) from Neurology ICU,12patients (7.64%) from gastroenterology ICU,10patients (6.73%) fromanesthesiology ICU,4patients (2.55%) from respiration ICU. It was shown that66patients suffer from severe traumatic brain injury,46cases from cerebral hemorrhage,15patients from cerebral infarction,30patients from other conditions, such asencephalitis, intestinal obstruction, peritonitis, severe pneumonia, etc. The averagecatheter placement span was15.10±8.24days.2. The urine culture results showed that there were a total of9types and59strains ofurinary tract colony-forming bacteria. The predominant Gram-Negative bacterialstrains were Escherichia coli (25.42%), the predominant Gram-Positive bacterialstrains were Enterococcus faecalis (22.03%), while the predominant fungus wereCandida albicans (16.94%). There was no significant distribution difference betweenthe four groups (P＞0.05). The4strains of the Escherichia coli with Extended Spectrum Beta-Lactamases were all resistant to cefuroxime, ceftriaxone, ceftazidimeand ciprofloxacin.3. The urinary tract infection results showed that11of36patients (30.56%) out of A1group acquired UTI, while the UTI rate was15of40patients (37.50%) for A2group,12of38patients (31.58%) for B1group, and15of43patients(34.88%) for B2grouprespectively, but there was no statistical significance (P＞0.05). So the bladderirrigation and catheter replacement had no effect on infection-positive rate (P＞0.05).4. The Logistic regression analysis showed that females have a higher risk of UTI andurine output more than3000ml was a protective factor.5. The inner side of catheter culture results showed that there were a total of82strains ofcatheter colony-forming bacteria, of which the predominant bacterial strain for Grampositive, Gram negative, and fungus were escherichia coli (26.83%), Enterococcusfaecalis (24.39%) and Candida albicans (15.85%) respectively. There was nosignificant distribution difference among the four groups (P＞0.05).6. The catheter culture results showed that16of36catheters (44.44%) out of A1groupacquired culture positive, while the positive rate was21of40catheters (52.50%) forA2group,16of38catheters (42.11%) for B1group, and19of43catheters (41.18%)for B2group respectively, but there also was no statistical significance (P＞0.05). Sothe bladder irrigation and catheter replacement had no effect on catheter-positive rate(P＞0.05).7. The Kruskal-Wallis rank sum test suggested that there is no significant difference ofinner face bacteria counting between all the groups（P＞0.05）.8. The Kruskal-Wallis rank sum test showed that there were no significant effects ofbiofilm formation among the four groups（P＞0.05）by scanning electron microscopy.9. Among all the colony-forming bacteria, the gram-positive cocci are more likely toadhere to the inside catheter to form a biofilm.10. When the urine quantitation of gram-positive cocci is over10000/μl, biofilm could befound at the inside of the catheter for all the samples. Conclusions1. The present pattern of urinary tract infection in our hospital has not changed greatly,with the predominant breeds as Escherichia coli, Enterococcus faecalis and Candidaalbians.2. Bladder irrigation cannot reduce the incidence of CAUTI, and cannot effectivelyinhibit the bacterial colonization of inside catheter and prevent the formation ofbiofilm.3. For critically ill patients, we suggested keeping the24h urine output over3000mL toreduce the incidence of UTI.4. Female patients were more likely to acquired the UTI, especially associated withdiabetes.5. Critically ill patients who indwelling catheter do not need replace the catheter within2weeks, but when bacterial counting in urinary sediment≥10000/μl we must replacethe catheter.