Virulence Factors of Staphylococcus aureus in the Pathogenesis of Endocarditis A Comparative Study of Clinical Isolates

We used a murine model of acute, posttraumatic osteomyelitis to evaluate the virulence of two divergentStaphylococcus aureusclinical isolates (the USA300 strain LAC and the USA200 strain UAMS-1) and their isogenicsarAmutants. The results confirmed that both strains caused comparable degrees of osteolysis and reactive new bone formation in the acute phase of osteomyelitis. Conditioned medium (CM) from stationary-phase cultures of both strains was cytotoxic to cells of established cell lines (MC3TC-E1 and RAW 264.7 cells), primary murine calvarial osteoblasts, and bone marrow-derived osteoclasts. Both the cytotoxicity of CM and the reactive changes in bone were significantly reduced in the isogenicsarAmutants. These results confirm thatsarAis required for the production and/or accumulation of extracellular virulence factors that limit osteoblast and osteoclast viability and that thereby promote bone destruction and reactive bone formation during the acute phase ofS. aureusosteomyelitis. Proteomic analysis confirmed the reduced accumulation of multiple extracellular proteins in the LAC and UAMS-1sarAmutants. Included among these were the alpha class of phenol-soluble modulins (PSMs), which were previously implicated as important determinants of osteoblast cytotoxicity and bone destruction and repair processes in osteomyelitis. Mutation of the corresponding operon reduced the cytotoxicity of CM from both UAMS-1 and LAC cultures for osteoblasts and osteoclasts. It also significantly reduced both reactive bone formation and cortical bone destruction by CM from LAC cultures. However, this was not true for CM from cultures of a UAMS-1psmαmutant, thereby suggesting the involvement of additional virulence factors in such strains that remain to be identified.

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EVALUATION OF ANTIBACTERIAL ACTIVITY OF SILVER NANOPARTICLES AGAINST METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS AND DETECTION OF VIRULENCE FACTORS - NUCLEASE, PHOSPHATASE, AND BIO FILM PRODUCTION

Asian Journal of Pharmaceutical and Clinical Research ◽

10.22159/ajpcr.2018.v11i5.24097 ◽

2018 ◽

Vol 11 (5) ◽

pp. 224 ◽

Cited By ~ 1

Author(s):

Manipriya B ◽

Tasneem Banu ◽

Prem Kumar L ◽

Kalyani M

Keyword(s):

Staphylococcus Aureus ◽

Silver Nanoparticles ◽

Antibacterial Activity ◽

Virulence Factors ◽

Bactericidal Activity ◽

Methicillin Resistant Staphylococcus Aureus ◽

Nano Particles ◽

Clinical Isolates ◽

Ag Nps ◽

Methicillin Resistant

Objective: To determine the virulence factors-biofilm, nuclease and phosphatase production in Staphylococcus aureus isolates. To determine the effect of silver nano particles and antibiotics on MRSA by MIC determination and kirby baeur method respectively and finally to compare antibacterial activity of silver nano particles and antibiotics.Methods: In the present study, we explore the antibacterial activity of silver nanoparticles (Ag-NPs) dispersion (10 nm) against reference strain and clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA). We evaluated the antibacterial activity of Ag-NPs against MRSA isolated from patients in Saveetha Medical College and Hospital, a tertiary care centre in Chennai, Tamil Nadu. The bactericidal activity of different concentrations of Ag-NPs (200, 100, 50, 25, 12.5, 6.25, 3.125, and 1.5625 μg/ml) was tested by determining MIC using microbroth dilution and MBC by agar dilution methods.. In addition, the virulence factors phosphatase, nuclease, and biofilm production were tested.Result: The values of minimal inhibitory concentration and minimal bactericidal concentration of Ag-NPs against all clinical isolates of MRSA and a single of S. aureus were found in the range of 12.5–50 μg/ml and 12.5–25 μg/ml, respectively, indicating very good bactericidal activity. Ag-NPs with the highest concentration showed almost no growth for up to 16 h representing a bactericidal effect at this concentration. Effect was proportional to dose since 50.0 μg/ml was the most effective dose since the bacterial population did not recover and 12.5 μg/ml was the least effective. All the MRSA isolates were positive for the virulence factors.Conclusion: The study result suggests that Ag-NPs could be used as an effective alternative antibacterial agent.

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Antibacterial activity of unifloral honeys against clinical isolates of methicillin-resistant Staphylococcus aureus

Planta Medica ◽

10.1055/s-0029-1234974 ◽

2009 ◽

Vol 75 (09) ◽

Author(s):

A Hannan ◽

MB Hussain ◽

M Absar

Keyword(s):

Staphylococcus Aureus ◽

Antibacterial Activity ◽

Methicillin Resistant Staphylococcus Aureus ◽

Clinical Isolates ◽

Methicillin Resistant

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Assessment of the Multifactorial Effect on Antimicrobial Sensitivity in Positive Staphylococcus Aureus Clinical Isolates from Assir Region, Saudi Arabia

Journal of Medicine ◽

10.3329/jom.v13i2.12750 ◽

2012 ◽

Vol 13 (2) ◽

pp. 152-159 ◽

Cited By ~ 2

Author(s):

Nazar M Abdalla ◽

Waleed O Haimour ◽

Amani A Osman ◽

Hassan Abdul Aziz

Keyword(s):

Staphylococcus Aureus ◽

Saudi Arabia ◽

Culture Media ◽

Meca Gene ◽

Laboratory Data ◽

Age Groups ◽

Clinical Isolates ◽

Diabetic Patients ◽

Staph Aureus ◽

Antimicrobial Sensitivity

General objectives: This study aimed at assessment of factors affecting antimicrobial sensitivity in Staphylococcus aureus clinical isolates from Assir region, Saudi Arabia. Materials and Methods: In this study, eighty one patients presented with Staph. aureus infections either nosocomial or community acquired infections were involved by collecting nasal swabs from them at Aseer Central Hospital General Lab. These patients were from all age groups and from males and females during the period of Jan 2011- Jun 2011. These samples were undergone variable laboratory procedures mainly; bactech, culture media, antibiotics sensitivity test using diffusion disc test (MIC) and molecular (PCR) for detection of mec A gene. Clinical and laboratory data were recorded in special formats and analyzed by statistical computer program (SPSS). Results: Showed that; Descriptive and analytical statistical analysis were performed and final results were plotted in tables. In Staph aureus MecA gene positive cases (50) showed: Oxacillin/ Mithicillin, Ciprofloxacin and Fusidin resistant in diabetic patients were 13, 26.0%, 9, 18% and 7, 14% respectively and in non diabetic patients were 37, 74.0%, 22, 44% and 20, 40% respectively. While no sensitivity in diabetic and non diabetic patients using Oxacillin/ Mithicillin. In Staph aureus MecA gene negative cases (31) showed: Oxacillin/ Mithicillin, sensitivity in diabetic patients (5, 16.1%) and in non diabetic were (26, 83.9%). While no resistant in diabetic and non diabetic patients. In Ciprofloxacin and Fusidin resistant in diabetic patients were 1, 3.2% and 1, 3.2% respectively and in non diabetic patients were 12, 38.7% and 7, 22.6%respectively. Erythromycin in Staph aureus ( MecA gene) positive cases (50) showed: resistant in age (0-15) years were (5, 10%), (16-50) years were (16, 32%) and ( 50 years) were (12, 24%). Erythromycin in Staph aureus (MecA gene) negative cases (31) showed: resistant in age (0-15) years were (6, 19.3%), (16-50) years were (5, 16.1%) and ( 50 years) were (3, 9.7%). Conclusion: Drugs resistance is a major progressive multifactorial problem facing the treatment of Staph aureus infections. DOI: http://dx.doi.org/10.3329/jom.v13i2.12750 J Medicine 2012; 13 : 152-159

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