Table of Contents
What is the scientific name of this organism (no citation is necessary but the name must be in the correct format – check your notes to ensure you use the correct format)?
Staphylococcus aureus
Use the categories below to list the proper taxa for the organism
Phylum/Division: Firmicutes
Class: Bacilli
Order: Bacillales
Family: Staphylococcaceae (Keene, 2012).
You are handed two slides that have been prepared with your organism. One has been properly Gram stained and the other has been properly Acid-Fast stained.
Describe the appearance of this organism on the slide that has been Gram stained, including morphology. Support your description with cited information from your references.
Staphylococcus aureus is a gram positive bacterium (Tortora, Funke & Case, 2016). When examining the slide, this organism appears in clusters of purplish grape-shaped colonies (Chan & Bourke, 2006).
Describe the appearance of this organism on a slide that has been Acid-Fast stained. Support your description with cited information from your references.
Staphylococcus aureus is considered a non-acid fast cocci. In a petri dish subjected to acid fast stain, the organism forms cocci shaped bacteria juxtaposed above small pink bacilli belonging to Mycobacterium stegmatis (Chan & Bourke, 2006). The S. aureus becomes darker because it retains the primary dye.
What type of metabolism does this organism utilize to generate ATP (aerobic respiration, anaerobic respiration, fermentation, etc)?
Staphylococcus aureus is a facultative anaerobe. They can either live in an environment rich in oxygen or one that contains minimal oxygen (Chan & Bourke, 2006).
(4 pt) 7. What are the virulence factors associated with this organism (toxins, intracellular growth, capsule, antibiotic resistance, etc.. Include information how these factors contribute to the organism’s ability to cause disease?
The convenience of numerous virulence factors makes it easy for Staphylococcus aureus to cause infections. These factors function in a myriad of ways including invasion of the immune system, avoidance of any action from the immune system and increasing toxicity (Chan & Bourke, 2006). One of the most effective virulence factors is surface or antigen proteins. These proteins are anchored covalently on the peptidoglycan molecules and they help the organism attach itself onto wounds and other surfaces (Keene, 2012). This tenacity is important in the survival of the organism. The organism also contains exotoxins and enzymes that convert the nutrients in the host into food for the bacteria. By feeding on the host’s nutrients, Staphylococcus aureus produces toxins which cause disease.
Staphylococcus aureus also contains capsules on the surface. These help the organism survive in harsh environments where it causes infections. Endotoxins are present within most organisms and it also aides the survival of the organism (Tortoraet al., 2016). Apparently, an endotoxin is a lipopolysaccharide that prevents any drug going past the peptidoglycan layer (Keene, 2012). Genetic virulence factors present in Staphylococcus aureus through horizontal gene transfer. This is a common virulence factor that is transferred through the F-pilus. It helps an organism in gaining antibiotic resistance.
- Chan, V., & Bourke, S. (2006) Bacterial genomes and infectious diseases. Totowa, NJ: Humana Press.
- Keene, C. (2012). Paradigms of pathogenesis: Targeting the mobile genetic elements of disease. Frontiers in Cellular and Infection Microbiology, 2, 161.
- Tortora, G.J., Funke, B.R., & Case, C.L. (2016). Microbiology: An Introduction. Boston. Pearson.