Characterization of biofilm formation and virulence factors of Staphylococcus aureus isolates from paediatric patients in Tehran, Iran.

OBJECTIVES: Staphylococcus aureus can cause several infections. Its capability to form biofilm has been reported to be a vital property involved in the bacteria's pathogenesis. Various genes contributing to biofilm formation have not yet been completely clarified. This study was designed to evaluate the factors influencing adherence and biofilm formation in S. aureus isolated from paediatric patients. MATERIALS AND METHODS: One hundred and ninety-seven S. aureus isolates were obtained from pediatric patients and confirmed with phenotypic and molecular examinations. Antimicrobial susceptibility testing and biofilm formation were evaluated using standard methods. The genes encoding adhesion and virulence factors were investigated by the PCR method. RESULTS: The most efficient antibiotics against S. aureus isolates were vancomycin and linezolid. Approximately, 54.2% of MSSA and 85.6% of MRSA isolates were biofilm producers according to the microtiter test. Our analysis indicated that MRSA isolates are better able to form biofilm compared with MSSA isolates. All isolates harbored clfA, fnbpA, icaA, icaB, icaC, and icaD, while clfB, fnbB, hlg, and pvl were detected in 99.5%, 42.1%, 97.5%, and 5.6% of isolates, respectively. In addition, a significant difference was found in fnhB gene and biofilm formation. CONCLUSION: Our findings showed a significant correlation between mecA and pvl genes and MRSA and biofilm formation in S. aureus isolates. Additionally, this study indicated the significant role of the fnhB gene as a major marker for S. aureus biofilm formation. Therefore, further experiments are warranted to exactly elucidate the function of the fnhB gene in the formation of biofilm.

The roles of programmed death ligand 1 in virus-associated cancers.

Programmed death ligand 1 (PD-L1) is a surface glycoprotein that induces T-cell anergy or apoptosis by binding to PD-1 on activated T and B cells. It is also known as a cluster of differentiation 274 (CD274) or B7 homolog 1 (B7-H1). Suppressing the adaptive arm of the immune system is the critical role of PD-L1.so it prohibits the proliferation of activated T cells and reduces apoptosis in regulatory T cells. When PD-L1 binds to PD-1, it prevents T cells from killing other cells such as cancer cells. Viruses have various strategies to evade from the immune system such as modifying host gene expression or deregulating proteins function. So they can directly or indirectly change the expression of PD-L1. This study proposed to evaluate the effect of viruses on the expression of PD-L1 which leading to uncontrolled cell growth and tumor formation. We have studied serious tumorigenic viruses, including Human Papillomaviruses (HPV), Epstein-Barr viruses (EBV), Human T-cell leukemia viruses type 1 (HTLV-1), Hepatitis B viruses (HBV) and Hepatitis C viruses (HCV). So we surveyed the correlation between the presence of viruses and expression of PD-L1. Most studies showed the PD-L1 overexpression due to viral functions; however, further studies are needed to better understand the role of the PD-1/PD-L1 pathway in virus-associated cancers as a candidate of anti- PD-L1 therapy.

In vitro antibacterial activity of curcumin-meropenem combination against extensively drug-resistant (XDR) bacteria isolated from burn wound infections.

OBJECTIVE: Burn wound infection is a severe complication of thermal injury. Patients with severe burn injuries need urgent care to diminish complications after severe burns. Wound infections are commonly considered one of the most serious burn complications, particularly those that are caused by extensively drug-resistant (XDR) bacteria with few therapeutic choices. The objective of this study was to determine in vitro activity of meropenem and curcumin, alone and in combination, against antibiotic-susceptible Gram-positive, and antibiotic-resistant and antibiotic susceptible gram-negative bacteria isolated from burn wound infections. MATERIALS AND METHODS: The antimicrobial activity of meropenem and curcumin was investigated alone and in combination, against antibiotic-susceptible and antibiotic-resistant bacterial (XDR) strains isolated from burn patients. In addition, the cytotoxic effect of curcumin on human's epithelial cell lines, was determined. RESULTS: In this study, minimum inhibitory concentrations of meropenem decreased considerably in the presence of curcumin (2- to 16-fold reductions), with synergy observed. Curcumin exerted no cytotoxic effect at concentrations 256-512 µg/ml on human epithelial cell lines. CONCLUSION: We suggest that curcumin-antibiotic combinations may provide an alternative approach for treating infections with multidrug-resistant (MDR) and extensively drug-resistant (XDR) bacteria.