Unveiling biological activities of biosynthesized starch/silver-selenium nanocomposite using Cladosporium cladosporioides CBS 174.62.

BACKGROUND AND OBJECTIVES: Microbial cells capability to tolerate the effect of various antimicrobial classes represent a major worldwide health concern. The flexible and multi-components nanocomposites have enhanced physicochemical characters with several improved properties. Thus, different biological activities of biosynthesized starch/silver-selenium nanocomposite (St/Ag-Se NC) were assessed. METHODOLOGY: The St/Ag-Se NC was biosynthesized using Cladosporium cladosporioides CBS 174.62 (C. cladosporioides) strain. The shape and average particle size were investigated using scanning electron microscope (SEM) and high-resolution transmission electron microscope (HR-TEM), respectively. On the other hand, the St/Ag-Se NC effect on two cancer cell lines and red blood cells (RBCs) was evaluated and its hydrogen peroxide (H2O2) scavenging effect was assessed. Moreover, its effects on various microbial species in both planktonic and biofilm growth forms were examined. RESULTS: The St/Ag-Se NC was successfully biosynthesized with oval and spherical shape and a mean particle diameter of 67.87 nm as confirmed by the HR-TEM analysis. St/Ag-Se NC showed promising anticancer activity toward human colorectal carcinoma (HCT-116) and human breast cancer (MCF-7) cell lines where IC50 were 21.37 and 19.98 µg/ml, respectively. Similarly, little effect on RBCs was observed with low nanocomposite concentration. As well, the highest nanocomposite H2O2 scavenging activity (42.84%) was recorded at a concentration of 2 mg/ml. Additionally, Staphylococcus epidermidis (S. epidermidis) ATCC 12,228 and Candida albicans (C. albicans) ATCC 10,231 were the highly affected bacterial and fungal strains with minimum inhibitory concentrations (MICs) of 18.75 and 50 µg/ml, respectively. Moreover, the noticeable effect of St/Ag-Se NC on microbial biofilm was concentration dependent. A high biofilm suppression percentage, 87.5% and 68.05%, were recorded with S. epidermidis and Staphylococcus aureus (S. aureus) when exposed to 1 mg/ml and 0.5 mg/ml, respectively. CONCLUSION: The biosynthesized St/Ag-Se NC showed excellent antioxidant activity, haemocompatibility, and anti-proliferative effect at low concentrations. Also, it exhibited promising antimicrobial and antibiofilm activities.

PCR-based RFLP and ERIC-PCR patterns of Helicobacter pylori strains linked to multidrug resistance in Egypt.

H. pylori infects approximately 50% of the world's population that causes chronic gastritis, and may lead to peptic ulcer disease (PUD). H. pylori-induced chronic infections are associated with gastric adenocarcinoma and low-grade gastric lymphoma. In Egypt, H. pylori strains are widespread and became resistant to antimicrobial agents, thus advanced typing methods are needed to differentiate infectious strains that are resistant to antibiotics, and therefore earlier prognosis and infection control. The main objectives were (i) to determine susceptibility of infectious H. pylori strains to some antimicrobial agents that are currently used in eradication therapy in Egypt; (ii) to identify diverse strains commonly detected in the gastrointestinal (GIT) endoscopy units in Egypt through phenotypic and genotypic analyses. In this observational study we isolated 167 isolates from 232 gastric biopsies (antrum and corpus) of patients who were admitted to the upper GIT endoscopy units in five governmental Egyptian hospitals. Antimicrobial susceptibility patterns were investigated using Kirby Bauer disc diffusion and agar dilution Minimum Inhibitory Concentrations (MICs) methods. Phenotypic characterization was based on biotyping and antibiogram typing techniques. Genotypic characterization was carried out using PCR-based Restriction Fragment Length Polymorphism (RFLP) and Enterobacterial Repetitive Intergenic Consensus (ERIC)-PCR analyses. H. pylori isolates were highly resistant to diverse antimicrobial agents including Metronidazole, Fluoroquinolones, Macrolides, Amoxycillin, Tetracycline and Gentamicin. Two factors contributed to the increased resistance of H. pylori to the conventional therapy seen in Egypt: (i) Metronidazole and Amoxycillin are inexpensive and available drugs being abused by patients; (ii) the regional prescribing practice of Macrolids commonly used to treat upper respiratory and urinary tract infections. Five different biotypes were identified depending on the ability of the isolates to synthesize different enzymes. Nine antibiogram types were identified. PCR-RFLP analysis revealed fifteen different fingerprints while ERIC-PCR revealed 22 fingerprints. Biotyping alone or in combination with antibiogram typing are highly useful molecular tools in the prognosis of strain relatedness. PCR-RFLP and ERIC-PCR acquired good discriminatory power for identifying H. pylori infectious sub-types.