The Correlation between Clumping Factor A Gene Expression in Biofilm Formation and Antibiotic Resistance Among Staphylococcus aureus Isolated from Urine Samples of Imam Khomeini Hospital, Tehran

Staphylococcus aureus causes problems in hospitals and it has emerged as a serious agent acquired from the environment in recent years. One of the capabilities of S. aureus is the formation of biofilms, in which bacteria can exchange antibiotic-resistance genes among themselves and increase the virulence of other strains of this species (S. aureus). A surface protein attached to the cell wall in S. aureus clumping factor A is a virulence factor in various staphylococcal infections.

In this study, after the Urea Analysis (UA) test, the urea culture test was applied to the blood agar and Baird-Parker Agar culture media from the infectious urine samples in Imam Hospital, Tehran, to identify S. aureus isolates. Finally, a molecular method was used for the confirmation of identified isolates. The microliter plate method was performed to determine the biofilm formation ability. The disk diffusion method was also used for profiling the antibiotic resistance of the isolates.

In the results of this study, 45 out of 160 urinary clinical samples were positive for S. aureus, among which 42 isolates expressed the clfA gene. Moreover, 39 isolates had the ability to form biofilms in vitro. Among these 42 isolates, the highest (88%) and the lowest (16%) rates of antibiotic resistance were observed against penicillin and cefoxitin, respectively. Data analysis with SPSS software and chi-square indicated a significant relationship between gene expression and biofilm production with antibiotic resistance (P < 0.05).

The resistance of S. aureus bacteria is increasing strongly due to the repeated use of antibiotics such as beta-lactams, especially in respiratory infections and pharyngitis. Moreover, biofilm formation and virulence factors, such as clfA and clfB, cause concerns to the World Health Organization for treatment, especially for people with sepsis or toxemia.