Exam 2 - Clinically Significant Aerobic GPC Flashcards
Name the 4 species of clinically significant aerobic GPC
- Micrococcus species
- Staphylococcus species
- Streptococcus species
- Enterococcus species
Micrococcus:
What are its preferred conditions for thriving?
- Obligate aerobes
- Grow in ambient air
- About 35°-37° C
Micrococcus:
What does it look like, microscopically?
It shows any of the following:
- Pairs
- Tetrads
- Clusters
Micrococcus:
What is its colonial morphology?
- Usually one of these pigments:
# Bright yellow
# Orange
# Pink
# Tan
# White
- Nonhemolytic
- Often has domed top (convex)
- Can resemble Staphylococcus speciesMicrococcus:
What are its key reactions?
- Catalase (+)
- Modified oxidase (+)
- Bacitracin (S)
- Furazolidone (R)
- Lysostaphin (R)
Micrococcus:
Where is it found?
- NF of mucus membranes
- NF of oropharynx
- Also found in environment
Micrococcus:
Where is it NOT found, and why is that important?
- Not often found in clinical specimens
- Important for occasional opportunist or to differentiate from Staphylococcus species
Micrococcus:
What happens when it is found clinically?
- May be immunocompromised patient
- Can cause:
# Pneumonia
# Meningitis
# Endocarditis
Micrococcus:
What is it often seen as?
Seen as HAI with IV’s, CSF shunts
Staphylococcus:
What are its preferred conditions for thriving?
- Most species are facultative anaerobes
- Grow in ambient air
- About 35°-37° C
Staphylococcus:
What does it look like on a Gram stain?
Spherical cells arranged in irregular clusters
Staphylococcus:
What is it a common inhabitant of?
- Skin
- Mucous membranes
Staphylococcus:
What are some general characteristics of the cell?
- Lack spores and flagella
- May have capsules
Staphylococcus aureus:
What is its colonial morphology?
- Colonies usually:
# Large
# Rounded or flat-top
# Opaque
- Beta-hemolytic (clears RBC’s)Staphylococcus aureus:
What kinds of extremes can it withstand?
Withstands:
- High salt
- Extremes in pH
- High temperatures
Staphylococcus aureus:
What media does it grow on?
- PEA
- CNA
- MSA (7.5% NaCl content)
Staphylococcus aureus:
What is its reaction on MSA?
- Yellow
- Mannitol fermenter
Staphylococcus aureus:
What are its key reactions?
- Coagulase (+)
- Catalase (+)
- Thermonuclease (+)
- DNase (+)
Staphylococcus aureus:
What is on its antibiogram?
- Ampicillin (R)
- Penicillin (R)
Staphylococcus aureus:
What are the enzymes produced as defense by the bacterium?
- Coagulase
- Hyaluronidase
- Staphylokinase
- DNase
- Lipase
- Penicillinase
What is this enzyme?
- Coagulates plasma and blood
- Produced by 97% of human isolates
Coagulase
What is this enzyme?
- Catalyzes the breakdown of hyaluronic acid
- Increases tissue permeability to fluids
Hyaluronidase
What is this enzyme?
- Induces fibrinolysis by converting plasminogen to plasmin
Staphylokinase
What is this enzyme?
- Catalyzes breakdown of DNA
- Aids with spread of bacteria through tissues
DNase
What is this enzyme?
- Catalyzes breakdown of lipids
- Aids with spread of bacteria through tissues
Lipase
What is this enzyme?
- Hydrolyzes and inactivates penicillin
Penicillinase
What is associated with toxigenic diseases?
Production of extracellular toxin
Staphylococcus aureus:
What are 3 toxigenic diseases related to it?
- Food poisoning
- TSS (Toxic Shock Syndrome)
- SSS (Scalded Skin Syndrome)
Staphylococcus aureus:
General info concerning Toxic Shock Syndrome
- Toxic Shock Syndrome
- 1st linked to use of ultra-absorbent tampons that bound Mg+ ions and created a favorable environment for increased colonization and growth of vaginal S. aureus and increased TSS toxin production
- Toxin enters bloodstream and causes:
# Fever
# Vomiting
# Organ damage
# Potential fatality
Staphylococcus aureus:
General info concerning Scalded Skin Syndrome
- Caused by exfoliatin toxin
- Results in epidermal layer sloughing off
Staphylococcus aureus:
What do its non-toxigenic diseases do to CF patients?
They cause increased morbidity and mortality in CF patients
Staphylococcus aureus:
What are 6 non-toxigenic diseases related to it?
- Folliculitis
- Cellulitis
- Furuncle (boil)
- Carbuncle
- Impetigo
- Osteomyelitis
What is this non-toxigenic disease?
- Infection of hair follicles
- Pustule develops at base of hair shaft
Folliculitis
What is this non-toxigenic disease?
- Acute infection of skin and soft tissues
- Characterized by localized pain
- Swelling
- Tenderness
- Warmth at site
Cellulitis
What is this non-toxigenic disease?
- Infection of a single hair follicle
- Commonly occur on:
# Buttocks
# Face
# Neck
# Armpits
# Groin - Often seen with community-acquired MRSA, sports-related activities (teammates sharing shower facilities, etc.)
Furuncle (Boil)
What is this non-toxigenic disease?
- Deeper than furuncle
- A group of infected hair follicles in one location
Carbuncle
What is this non-toxigenic disease?
- Most commonly seen in children age 2-5 years old
- Spread by direct person-to-person contact at a break in the skin
- Can be contained with appropriate hygiene
Impetigo
What is this non-toxigenic disease?
- Infection of the bone
Osteomyelitis
See chart on PDF to see key reactions by the other Staphylococcus species
M’kay
