Gram Positive Cocci | Staphylococcus | Staph. aureus, Staph. epidermidis, Staph. saprophyticus |

By Dr. Umair Khan (MBBS, FCPS)
#microbiology #microbiome #bacteria #bacteriology #viralvideo #trending #staphylococcus #staph #quick #revision #exam #preparation #concept
Gram-positive cocci:
Staph. aureus
- Golden-yellow pigmentation
- Coagulase-positive (can clot blood)
- Catalase-positive (can break down hydrogen peroxide)
- Pathogenic (can cause severe infections)
- Can produce toxins and cause:
- Abscesses
- Pneumonia
- Sepsis
- Food poisoning
- Often resistant to antibiotics (e.g., MRSA - Methicillin-resistant Staphylococcus aureus)
Staph. epidermidis
- White or cream-colored
- Coagulase-negative
- Catalase-positive
- Non-pathogenic (commensal on skin and mucous membranes)
- Can cause infections in:
- Immunocompromised individuals
- Those with prosthetic devices (e.g., joint replacements, catheters)
- Typically sensitive to antibiotics
Staph. saprophyticus
- White or cream-colored
- Coagulase-negative
- Catalase-positive
- Found in urinary tract and genital area
- Can cause:
- Urinary tract infections (UTIs)
- Cystitis (bladder infections)
- Pyelonephritis (kidney infections)
- Typically sensitive to antibiotics
All three:
- Are Gram-positive cocci
- Are non-motile (don't move)
- Have a peptidoglycan cell wall
- Are facultative anaerobes (can grow with or without oxygen)
The three Gram-positive cocci can be abbreviated as:
- Staph. aureus (Staphylococcus aureus)
- Staph. epidermidis (Staphylococcus epidermidis)
- Staph. saprophyticus (Staphylococcus saprophyticus)
This is a common way to abbreviate the names of these bacteria in medical and scientific notation. The "Staph." prefix indicates that it belongs to the Staphylococcus genus.
- Staph. aureus
- Golden-yellow pigmentation
- Coagulase-positive
- Catalase-positive
- Pathogenic
- Staph. epidermidis
- White or cream-colored
- Coagulase-negative
- Catalase-positive
- Non-pathogenic, commensal
- Staph. saprophyticus
- White or cream-colored
- Coagulase-negative
- Catalase-positive
- Found in urinary tract and genital area, can cause UTIs