Abstract

In human medicine, it has been estimated that 65% of nosocomial infections are biofilm associated, loading the health care system enormous costs. These biofilm infections are 10 to 1000 times more resistant to the effects of antimicrobial agents. This study aimed at showing the difference between patients with catheter associated urinary tract infection (CAUTI) and those with non catheter associated (UTI) in terms of the type of isolated pathogens, antibiotic susceptibility of isolated pathogens, detection of their ability to form biofilm, and comparing (antibiotic susceptibility of sessile cells) minimal biofilm eradication concentration (MBEC) and (their planktonic counterpart) minimal inhibitory concentration (MIC) for biofilm forming bacteria. The most frequently isolated micro-organisms were Escherichia coli (31.7%) followed by Klebsiella (15%); Staphylococcus aureus; coagulase negative Staphylococcus (CoNS); Enterococcus (11.7%); Proteus (10%); Pseudomonas (6.7%) and the least common was Enterobacter (1.7%). In the catheterized patients, 13 isolates out of thirty bacterial isolates (43.3%) were biofilm forming and 17 isolates (56.7%) were non biofilm forming, while in the non catheterized patients, 9 isolates out of thirty bacterial isolates (30%) were biofilm forming and 21 isolates (70%) were non biofilm forming. Antibiotic sensitivity of the isolated pathogens was done using disc diffusion method which showed that Imipenem and Amikacin were most effective antibiotics against gram-negative isolates while for gram positive isolates, Vancomycin and Ciprofloxacin were most effective. There was no statistical difference between the two groups regarding the isolated pathogens or the antibiotic susceptibility pattern. For the biofilm forming isolates, antibiotic susceptibility of sessile cells MBEC were tested and compared to the MIC of their planktonic counterpart. For gram negative isolates, Amikacin and Imipenem were used and for gram positive isolates, Ciprofloxacin and Vancomycin were used. The difference between MBEC and MIC for tested strain was statistically significant. Therefore, researches on easier methods for diagnosing and quantifying biofilm infection would surely help the fight against biofilm formation. Also for certain infection such as CAUTI, it is advised to test antimicrobial susceptibility in biofilm form MBEC.

Key words: Urinary tract infection, Biofilm.