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Staphylococcus aureus
Published in Firza Alexander Gronthoud, Practical Clinical Microbiology and Infectious Diseases, 2020
Staphylococcus aureus grows aerobically and anaerobically and produces β-haemolytic colonies with a yellow pigment. Mannitol salt agar is a selective medium for S. aureus containing a high salt concentration. Coagulase testing used to be the main test to differentiate between S. aureus and coagulase-negative staphylococci, but nowadays MALDI-TOF MS is increasingly being used as it provides a rapid and accurate identification within 5 minutes.
Staphylococcus aureus
Published in Peter M. Lydyard, Michael F. Cole, John Holton, William L. Irving, Nino Porakishvili, Pradhib Venkatesan, Katherine N. Ward, Case Studies in Infectious Disease, 2010
Peter M. Lydyard, Michael F. Cole, John Holton, William L. Irving, Nino Porakishvili, Pradhib Venkatesan, Katherine N. Ward
Culture: S. aureus and other staphylococci grow well on blood agar after 24–48 hours of incubation at 37°C. Staphylococci are facultative anaerobes. Colonies of S. aureus are large, smooth, glossy domes with an entire edge. If held at room temperature the colonies will change color from white to a golden yellow (ergo – S. aureus, the golden staphylococcus). Almost all strains of S. aureus are β-hemolytic due to their secretion of cytotoxins (Figure 9). Mannitol-salt agar containing 7.5% sodium chloride and mannitol as the carbon source is a useful selective and differential medium to recover staphylococci from clinical specimens, for example skin, that contain a mixed microbiota. Most bacteria other than staphylococci are inhibited by this concentration of NaCl and S. aureus can ferment mannitol whereas most other staphylococcal species cannot. Incorporation of the pH indicator, phenol red, reveals colonies fermenting mannitol because acid produced by the colony changes the color of the agar from pink to yellow (Figure 10).
Mild magnetic hyperthermia is synergistic with an antibiotic treatment against dual species biofilms consisting of S. aureus and P. aeruginosa by enhancing metabolic activity
Published in International Journal of Hyperthermia, 2023
Layla A. Almutairi, Bing Yu, Eric Dyne, Alhussain A. Ojaym, Min-Ho Kim
The dual species biofilm formed by S. aureus and P. aeruginosa were established using a static model described previously with some modifications [21,22]. Bacteria suspensions of stationary phase growth of P. aeruginosa and S. aureus were diluted in sterile phosphate buffer solution (PBS) at final concentrations (1x103 - 1x106 CFU/mL) in each tube. The diluted solution was then mixed at a varying density between P. aeruginosa and S. aureus (1:1, 1:10, 1:100, and 1:1000) and 2 μL of the mixed suspension was inoculated on to a 6 mm diameter of polycarbonate membrane filter (0.2 μm pore size, GE). The filter was incubated on TSA plate and incubated at 37 °C for 48 h. After the culture, for subsequent CFU counting on selective agar media, the biofilm matrix was disrupted through vortexing (at 900 rpm) followed by sonication in a sonication bath (Branson Ultrasonic bath) for 5 min. The Mannitol salt agar and Triclosan agar were used as a selective agent for S. aureus and P. aeruginosa, respectively (Figure S1A).
Association of Staphylococcus nasal colonization and HIV in end-stage renal failure patients undergoing peritoneal dialysis
Published in Renal Failure, 2019
Kwazi C. Z. Ndlovu, Khine Swe Swe-Han, Alain Assounga
Swabbing of the anterior nasal vestibules with sterile swabs (Amies Agar Gel-No Charcoal Transport System; Copan Italia SpA, Brescia, Italy) was performed monthly by a research nurse, and the swabs were transported to the laboratory for processing. Colistin-nalidixic agar and mannitol salt agar media were used for the cultures. The CAPD nurse took PD effluent specimens for white blood cell (WBC) counts and culture when the patients’ clinical presentations suggested peritonitis, and they were transported to the NHLS microbiology department in sterile specimen bottles for processing. The PD effluent WBC counts were determined using a 40× microscope objective lens. The culturing was done on chocolate, blood agar, and brain-heart infusion broth. A Vitek® 2 system (bioMérieux, France) was used for identification and antibiotic susceptibility testing of the nasal swab and PD effluent specimens.
Sabinene suppresses growth, biofilm formation, and adhesion of Streptococcus mutans by inhibiting cariogenic virulence factors
Published in Journal of Oral Microbiology, 2019
Bog-Im Park, Beom-Su Kim, Kang-Ju Kim, Yong-Ouk You
The effect of sabinene on bacterial adherence was determined using hydroxyapatite beads (Bio-Rad, Hercules, CA.). In brief, S. mutans in BHI was diluted to approximately 108 CFU/mL. About 30 μg of hydroxyapatite beads [12] were coated with human mixed saliva for 1 h. The saliva-coated hydroxyapatite beads (S-HAs) were rinsed thrice with 10 mM potassium phosphate buffer (pH 7.0) and immersed in bacterial suspension solutions (1 × 107 CFU/mL) with various concentrations of sabinene. The mixtures were gently agitated for 90 min at 37°C to facilitate bacterial adhesion. After incubation, S-HAs were washed and transferred to potassium phosphate buffer in a new tube. The bacteria that adhered to S-HAs were dispersed by sonication (50 W for 30 s), and the supernatants were diluted and spread on mannitol salt agar plates supplemented with 3.2 mg/mL bacitracin. The bacterial colonies were counted after 48 h.