Sumayah Abdulhussien Ibraheem et al. Int. Res. J. Pharm. 2019, 10 (1) 92 INTERNATIONAL RESEARCH JOURNAL OF PHARMACY www.irjponline.com ISSN 2230 – 8407 Research Article ATTENUATION OF GROWTH OF METHICILLIN RESISTANT STAPHYLOCOCCUS AUREUS IN RESPONSE TO SILVER NANOPARTICLES Sumayah Abdulhussien Ibraheem 1 *, Al-keline Haitham Ali Kadhem 1 , Nada H. A. Al-Mudallal 2 , Ihsan Ali Kadhim 3 , Mihaileescu Dan Florin 1 1 Faculty of biology/university Bucharest/ Romania 2 Al Iraqi university college of medicine /medical microbiology department/Baghdad/Iraq 3 Ministry of science and Technology/ Industrial development and research *Corresponding Author Email: sumayahibraheem8@gmail.com Article Received on: 17/12/18 Approved for publication: 02/01/19 DOI: 10.7897/2230-8407.100117 ABSTRACT Nanotechnology is emerging as a new interdisciplinary field combining microbiology, Chemistry, physics, and material science. Recent advances promise developments in the synthesis, modification and practical applications of nanoparticles (NPs). Nanoparticles were excellent antibacterial agents with potential clinical applications. Sliver Nanoparticles have been successfully used in a wide range of applications including wound dressing, protective clothing, antibacterial surfaces, food preservation, and cosmetics as biocidal and disinfecting agents. The aim of this study was to investigate the mechanism of silver nanoparticle action against of methicillin-resistant Staphylococcus aureus. The Gram-positive methicillin-resistant Staphylococcus areas were used to evaluate the antibacterial activities of silver nanoparticles (Ag NPs). The growth rate of methicillin-resistant Staphylococcus aureus was investigated under varying Ag NPs concentrations by scanning electron microscope (SEM) & acridine orange /ethidium bromide (AO-EtBr) staining. The Quantitative Real-time PCR experiment showed that the mecA gene from the bacterial cells treated with Ag-NPs was downregulated compared to that in the untreated cells. Keywords: methicillin-resistant, Staphylococcus aureus, silver nanoparticles, mec A gene INTRODUCTION Nanotechnology can actually be defined as the technology at the dimensions of 1-billionth of a meter. It’s the design, characterization, synthesis and applications of substances, systems, devices and systems via controlling form and size at nanometer scale. This science has a great value of modern research in the major field of biology, chemistry, physics and materials sciences 1 . It is noted that physical and chemical properties change when decrease the particle size to nanoscale 2 . Nanoparticles (NPs) can be classified into different classes based on their properties, shapes or sizes. The different groups include fullerenes, metal NPs, ceramic NPs, and polymeric NPs. NPs possess unique physical and chemical properties due to their high surface area and nanoscale size. Generally, metal nanoparticles can be synthesized and stabilized by chemical, physical and biological methods; the chemical approach, such as electrochemical reduction, photochemical reduction and heat evaporation, the physical methods by either evaporation - condensation method or laser ablation method Living organisms have huge potential for the production of nanoparticles /nanodevices of wide applications 3 . Silver nanoparticles are of hobby due to the precise properties (e.g., Diameter and shape relying optical, electric, and magnetic residences) which may be integrated into antimicrobial applications, biosensor substances, composite fibers, and digital additives Currently most of the applications of the silver nanoparticles are in antibacterial/antifungal agents in in biotechnology and bioengineering, textile, water treatment, and silver-based consumer products 4 . One of the main causes of infection disease is bacteria. Infectious diseases are the leading reason for international morbidity and mortality. The spreading of infectious diseases is an outcomes from alters in human behavior like lifestyles, land use patterns and wrong utilization of anti-microbial medicine that reason changes in microorganism strains Staphylococcus aureus and E. coli are typical reasons of varied humans’ infections. Staphylococcus aureus is a major human pathogen, has a collection of virulence factors and the capability to acquire resistance to most antibiotics 5 . Take into account to be a potential “superbug”, methicillin- resistant Staphylococcus aureus (MRSA) represented one of the main recent infectious pathogens and therefore poses a challenge to hospital infection control 6 . Since the 1960s, methicillin- resistant Staphylococcus aureus (MRSA) has emerged, spread globally and come to be an important reason of bacterial infections in both health-care and community sites 7 . MRSA infection, in otherwise healthy individuals, affects the soft tissues and superficial skin although more serious infections can arise, affecting the deep soft tissues, blood, and bone 8 . MRSA is able to avoid the body’s immune system due to production of biofilm as well as certain toxins 9 . These virulence factors, in combination with multidrug resistance, cause in high morbidity and mortality rates 10 . The mecA gene is a gene found in bacterial cells which allows a bacterium to be resistant to antibiotics such as methicillin, penicillin and other penicillin-like antibiotics. Resistant strains are responsible for many infections originating in hospital. The mecA gene encodes the protein PBP2A (penicillin binding protein 2A). PBP2A has a low affinity for beta-lactam antibiotics such as methicillin and penicillin. This enables transpeptidase activity in the presence of beta-lactams, preventing them from inhibiting cell wall synthesis. The mecA gene is contained on a mobile gene element, called the staphylococcal cassette chromosome mec, from which the gene can undergo horizontal gene transfer and