ABSTRACT
        Background and Objectives: Biofilm is a population of bacteria growing on a surface and enclosed in an exopolysaccharides matrix, which increases resistance to antimicrobial agents and immune response. Uropathogenic Escherichia coli (UPEC) are biofilm-forming bacteria and the most common cause of urinary tract infections (UTIs). This study evaluated the effect of different concentrations of glucose, NaCl, blood, serum and urine on biofilm formation and antigen 43 (Ag43) gene expression, as a main gene involved in biofilm formation.
        Methods: Among E. coli isolates from patients with UTI, four extended-spectrum beta-lactamase (ESBL) and non-ESBL strains, and a standard UPEC strain were selected. Biofilm formation of the strains in brain heart infusion (BHI) broth with different concentrations of glucose, NaCl, sheep blood, serum and human urine was evaluated using microplate method and crystal violet staining. Ag43 gene expression was investigated using Real-Time polymerase chain reaction, SYBR Green dye, and specific primers.
           Results: Presence of glucose at all concentrations reduced biofilm formation. Presence of 1% NaCl, 1% sheep blood, 10% bovine serum, and 5% urine significantly increased biofilm formation. Expression of Ag43 by the strains grown under 1% glucose, 1% NaCl, 1% sheep blood, 10% bovine serum and 5% urine decreased.
         Conclusion: All environmental factors other than glucose may increase biofilm formation of E. coli at different concentrations. This is not affected by factors such as isolation from inpatient or outpatients and type of strains (ESBL or non-ESBL). Contrary to our expectations, Ag43 expression is independent of environmental factors and decreases even under the most suitable concentrations.
          Keywords: Biofilms, Uropathogenic Escherichia coli, UTI, Antigen 43, Real-Time PCR.

          Background and Objectives: Staphylococcus aureus is a common cause of nosocomial infections. The ability of S. aureus to form biofilm and acquire antimicrobial resistance has made this organism a major health problem. In this study, we investigate the biofilm-forming ability of S. aureus isolates from clinical samples.
          Methods: Sixty S. aureus isolates from clinical specimens were collected from the 5th Azar Hospital of Gorgan (Iran) in 2018. The isolates were identified using conventional methods including Gram staining and biochemical tests (catalase and coagulase). Biofilm formation by S. aureus isolates was evaluated using a microplate-based method.
          Results: Of 60 S. aureus isolates, 47 (78.3%) strains were identified as biofilm-forming and 13 (21.7%) strains were non-biofilm-forming.
          Conclusion: The high prevalence of biofilm-producing S. aureus isolates in the 5^th Azar hospital of Gorgan could pose a major health challenge with serious consequences for hospitalized patients. Therefore, it is crucial to disinfect and sterilize hospital surfaces and equipment effectively to minimize the risk of contamination and spread of bacteria in the hospital settings.
          Keywords: Biofilms, Staphylococcus aureus, sample.

Background: Staphylococcus aureus is one of the most common agents of nosocomial infection worldwide. Methicillin-resistant and biofilm-associated infections of this bacterium have become a clinical concern in patients. This research aimed to identify biofilm-forming ability and accessory gene regulator (Agr) - specific group of clinical isolates of methicillin-resistant S. aureus (MRSA) in Northern Iran.
Methods: In 2021, a total of 200 clinical isolates were identified as S. aureus by biochemical tests. The disk diffusion method was used to examine the antibiotic resistance of isolates and the microplate method was applied to investigate the biofilm production capability. In addition, the PCR method was used to determine the frequency of biofilm-associated genes and Agr typing of MRSA isolates. P £ 0.05 was considered significant.
Results: Overall, 62.5% of isolates were methicillin-resistant and 75% were multiple antibiotic-resistant. Biofilm-forming ability was detected in 99 (79.2%) methicillin-resistant isolates in which icaA and icaD were found in 85% and 78% of biofilm-producing isolates, respectively. Type 1 of the Agr gene was the most common type among methicillin-resistant isolates. The frequency of biofilm-associated genes showed a significant association with MDR phenotype and the presence of Agr locus (P £ 0.05).
Conclusion: The present findings indicate a high frequency of biofilm and antibacterial resistance in methicillin-resistant S. aureus isolates in Guilan Province. These findings suggest reliable and rapid identification of biofilm-forming MRSA strains to prevent the spread of these bacteria.