Abstract

       Background and Objective: the Formation of urinary infection by uropathogenic E.coli needs   numerous virulence factors and biofilm formation is among these factors. Bacteria that form biofilms express phenotype traits that appear according to the bacteria type. Cellulose is an important compound on the outside of E.coli causing bacterial cell-cell reactions and connection to nonliving surfaces. Curli pili cause the reaction between cell-cell and surface-cell in biofilms and lead to bacteria aggregation. Microorganisms’ ability to form biofilm on a surface depends on the surface nature and its conditions. This study aimed at determining the production ability of cellulose polysaccharide and curli pili in UPEC strains, and its correlation with formation and intensity of biofilm.

       Methods: In this study carried out to compare the ability of cellulose and pili curli production ability in  40 uropathogenic E.coli isolates ,by morphotype  method in Congo Red medium (CR), each isolate was incubated at 37 ^oC, for 24 hours. After 24 hours, all colonies’ morphology characteristics were studied

     Results: It was shown that 67.5% of strains produced cellulose and 72.5% produced curli pili. In addition, 92.6% and 89% of isolates that produce cellulose and curli, respectively, had a moderate to strong biofilm. Moreover, it was shown that there is a significant correlation between cellulose and / or curli pili production with biofilm intensity.

       Conclusion: About 70% of E.coli isolates from patients' urine are able to produce cellulose or curli pili; therefore, it can be concluded that the production of these two combinations is effective in amount and intensity of biofilm formation.

       Keywords: Escherichia coli; Cellulose Polysaccharide; Curli Pili; Biofilm.

ABSTRACT

         Background and Objective: Biofilms are community of bacteria that attach to inanimate surfaces or living tissues via production of extracellular polymers and exopolysaccharide matrix. Microbial biofilms on various surfaces of the hospital environment are considered as a reservoir of infection spread. The present study aimed to evaluate the disinfecting effect of benzalkonium chloride on some bacterial isolates causing nosocomial infections.

       Methods: First, 13 isolates from four bacteria including Pseudomonas aeruginosa, Staphylococcus aureus, Acinetobacter and Enterobacter were obtained from Microbiology Laboratory of Al-Zahra Hospital in Isfahan, Iran. The samples were transferred to Microbiology Laboratory of Faculty of Veterinary Medicine of Shahrekord University for testing. Evaluation of biofilm formation and determination of minimum inhibitory concentration (MIC) of the disinfectant and effect of the disinfectant on planktonic growth and biofilm formation were performed.

        Results: All bacterial isolates (52 cases) produced biofilm. Mean MIC of benzalkonium chloride for P. aeruginosa, S. aureus, Enterobacter and Acinetobacter was 0.14, 0.2, 0.18, 0.17 g/ml, respectively. Planktonic growth of all four bacteria was inhibited at concentrations of 2MIC, MIC and 1/2MIC. Biofilm was not produced in MIC and 2MIC concentrations, and biofilm formation capability increased by reducing the concentration of benzalkonium chloride.

          Conclusion: The results show that the use of appropriate concentration of benzalkonium chloride can prevent the growth of different bacterial species, but sub-MIC dose of this disinfectant may stimulate biofilm formation.

            Keywords: Biofilm, Benzalkonium Chloride, Pseudomonas Aeruginosa, Staphylococcus Aureus, Enterobacter, Acinetobacter.

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.

ABSTRACT
        Background and Objectives: Several virulence factors are involved in the pathogenesis of Staphylococcus aureus. Surface proteins such as collagen binding proteins (Cna) and fibronectin-binding proteins (FnBP) are important factors in adhesion and invasion of S. aureus. The aim of this study was to evaluate the frequency of adherence genes cna, fnbA and fnbB S. aureus isolates from traditional cheese.
        Methods: All 22 isolates tested were identified as S. aureus. The isolates were tested for the presence of adherence genes cna, fnbA and fnbB using specific primers in polymerase chain reaction assay. 
        Results: Six isolates (27.27%) were positive for the can gene. Of the 22 isolates studied, one isolate was positive for fnbA and one was positive for the fnbB. Co-presence of the genes examined was not observed in any of the isolates.
        Conclusion: The results indicate the weak biofilm formation ability of the S. aureus isolates from traditional cheese.
        Keywords: Staphylococcus aureus, Biofilm, Genes, Cheese. 

          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.

ABSTRACT
           Background and Objectives: Candida albicans is one of the most common fungal pathogens that can form biofilm, particularly on surface of medical devices. In recent years, C. albicans has shown increased resistance to antifungal agents. In this experimental study, we aimed to study effects of superparamagnetic iron oxide nanoparticles (Fe₃O₄ nanoparticles or SPION) on biofilm formation by C. albicans.
           Methods: First, the SPION were synthesized by chemical co-precipitation. The formation of nanoparticles was confirmed by Fourier-transform infrared spectroscopy and X-ray diffraction. Minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of SPION were determined. Then, antibiofilm effects of the nanoparticles were investigated by enzyme-linked immunosorbent assay. Finally, data were analyzed using SPSS 22.0 at significance level of 0.05.
           Results: According to the results of X-ray diffraction, the SPION had a mean diameter of about 70 nm. MIC and MFC values of SPION against C. albicans were 100 ppm and 200 ppm which reduced biofilm formation by 87.2% and 100%, respectively. SPION showed significant inhibitory effects on C. albicans growth and biofilm formation.
           Conclusion: Based on the findings, SPION may be considered as a novel family of fungicidal compounds. However, further studies are necessary to evaluate the safety of these nanoparticles for treatment of fungal infections in humans.
           Keywords: Candida albicans; Biofilms; SPION; Nanoparticles.

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.