1. Isolation of uropathogenic Escherichia coli (UPEC) and determination of their Antimicrobial sensitivity Patterns.
2. Evaluation of biofilm-forming capacity of UPEC isolates.
3. Assessment of the antibiofilm efficacy of chitosan nanoparticles alone and in combination with ciprofloxacin against UPEC isolates.
4. Examination of the effectiveness of chitosan nanoparticle coating in preventing biofilm formation by UPEC on urinary catheter surfaces.
5. Evaluation of the impact of chitosan nanoparticles on the expression levels of biofilm associated genes in UPEC.

Urinary tract infections (UTIs) remain among the most prevalent bacterial infections globally, causing substantial healthcare burden, with uropathogenic Escherichia coli (UPEC) responsible for the majority of cases in both community and hospital settings. Catheter-associated urinary tract infections (CAUTIs) represent a major proportion of healthcare-associated infections due to bacterial adhesion and biofilm formation on indwelling urinary catheters. Biofilm formation enables microorganisms to attach to abiotic surfaces and produce an extracellular polymeric matrix that enhances bacterial survival under adverse environmental conditions.

Biofilm-associated bacteria exhibit increased resistance to host immune responses and antimicrobial agents, contributing to chronic and recurrent infections. Cells embedded within biofilms may demonstrate markedly elevated antibiotic tolerance compared with planktonic bacteria, limiting therapeutic success. Although systemic antibiotics remain the mainstay of treatment, rising antimicrobial resistance among biofilm forming UPEC strains highlights the need for alternative antibiofilm strategies.

Chitosan, a naturally derived biopolymer, has attracted attention due to its biocompatibility, biodegradability, and intrinsic antimicrobial properties. Chitosan disrupts bacterial membranes and inhibits biofilm matrix formation and surface adhesion. Emerging evidence indicates that chitosan can downregulate biofilm-related gene expression involved in adhesion and extracellular polysaccharide synthesis. Furthermore, nanoparticle formulation enhances chitosan penetration into biofilms and improves antimicrobial efficiency compared with bulk polymer forms. Moreover, chitosan nanoparticles may enhance antibiotic diffusion and demonstrate synergistic antibiofilm activity when combined with ciprofloxacin.

Ciprofloxacin, a fluoroquinolone antibiotic widely used in UTIs, has demonstrated partial inhibition of biofilm formation through interference with bacterial DNA replication, initial bacterial adhesion to surfaces, reduction of expression of biofilm-related genes, quorum-sensing activity and decreases production of extracellular polymeric substances (EPS); however, its efficacy is reduced against mature biofilms. Consequently, chitosan nanoparticles may demonstrate enhanced antibiofilm activity when combined with ciprofloxacin.

Despite promising findings, limited studies have evaluated chitosan nanoparticle coatings on clinically relevant catheter surfaces against UPEC isolates. Therefore, investigating this strategy may offer an effective preventive approach for CAUTIs and support improved infection control practices.

Inclusion Criteria:

• 1. Patients (inpatients or outpatients) clinically diagnosed with urinary tract infection (UTI).

  2. Presence of significant bacteriuria in urine culture (≥10⁵ colony-forming units per milliliter (CFU/mL) for midstream urine, or as clinically indicated).

  3. Isolation of Escherichia coli as the sole or predominant pathogen from urine culture.

  4. Patients of any age and both sexes. 5. Patients who have not received antibiotic therapy within the previous 48-72 hours.

Exclusion Criteria:

• 1. Patients who received systemic antibiotic therapy within the previous 48-72 hours prior to urine sample collection.

  2. Urine cultures showing insignificant bacteriuria (<10⁵ CFU/mL for midstream urine, unless clinically justified).

  3. Polymicrobial growth in urine culture (mixed bacterial growth suggestive of contamination).

  4. Isolation of organisms other than Escherichia coli. 5. Improperly collected, leaking, or contaminated urine samples. 6. Patients unwilling to provide informed consent.

This study will include UTI patients attending Assiut University Hospitals. Urine samples will be collected aseptically for isolation of uropathogenic E. coli. Only patients meeting inclusion criteria and providing consent will be included.