Gram + cocci: Staphylococci Flashcards
1) catalase + producing bacteria and facultatively anaerobic
2) non-motile, non-sporeforming, glucose fermenter
3) normal inhabitant of the skin, mucous membrane and intestine
Staphylococci
What is the family of staphylococci
Staphylococcaceae
Rare strains are fastidious requiring (3)
1) Carbin dioxide
2) hemin
3) menadione for growth
What are exempted staphylococci
1) S. saccharolyticus
2) S. aureus subspecies
3) S. anaerobius (obligate anaerobes, catalase negative)
What is microscopic appearance of to staphylococci?
Spherical cells that appear in clusters, some singly
Culture used on a staphylococci
- BAP - colonies (4-8mm) on agar plate appear creamy, white or light gold
- buttery looking
- others have gray colonies
- B-hemolytic (S. aureus) (complete clear zone)
It uses 0.04 units bacitracin; performed on BAP or MHA
Bacitracin
What is the results of bacitracin for Micrococci and Staphylococci?
Micrococci - susceptible
Staphylococci- resistant
Size of the result of Micrococci in the bacitracin
> or equal to 10 mm zone of inhibition
1) most virulent spp.
2) coagulase +
3) chiefly responsible for the various skin, wound and deep tissue infections due to trauma or abrasion to the skin or mucosal
4) furuncles and impetigo (boils/pigsa)
Staphylococcus aureus
3 types of nasal carriers associated with S. aureus
1) persistent carriers
2) intermittent carriers
3) noncarriers
A nasal carrier that harbor a single strain for a long time
Persistent carriers
A nasal carrier that harbor various strain overtime
Intermittent carriers
A nasal carrier that do not harbor any organism
Noncarriers
Associated diseases and infections in S. aureus (7)
1) toxin-induced disease (SSS or TSS)
2) bacteremia/sepsis
3) UTI
4) acute bacterial endocarditis
5) cutaneous infections
6) osteomyelitis
7) septic arthritis
1) a toxin-induced disease where there is an exfoliative dermatitis
2) primarily in newborns and previously healthy children
Scalded skin syndrome (SSS)
1) a toxin-induced disease that is rare but potentially fatal, multi system disease characterized by a sudden onset of FEVER, CHILLS, VOMITING, DIARRHEA, MUSCLE ACHES and RASH
2) can quickly progress to hypotension and shock
Toxic shock syndrome (TSS)
5 cutaneous infections
1) folliculitis
2) furuncles (boils)
3) carbuncles
4) impetigo
5) purulent abscess
A mild inflammation of hair follicles or sebaceous glands
Folliculitis
1) are large, raised, superficial abscesses
2) can be an extension of folliculitis
Furuncles
1) develop from multiple furuncles which may progress to deeper tissues
2) patients may have fever and chills (systemic infections)
Carbuncles
1) is a superficial cutaneous infection characterized by CRUSTY LESION and VESICLES surrounded by a red border
2) common in children
Impetigo
Secondary to bactemia
Osteomyelitis
An associated disease/infection usually in children
Septic arthritis
Staphylococci patients are ______
Bleeders
12 enzymes and toxins produced by S. aureus
1) coagulase
2) hyaluronidase
3) staphylokinase
4) lipase
5) DNAse and Phosphatase
6) beta-lactamase
7) enterotoxins
8) leukocidin/Panton-Valentine Leukocidin
9) hemolysin
10) exfoliatin A and B/Epidermolytic toxin A and B
11) toxic shock syndrome 1 enterotoxin F/Pyogenic exotoxin
12) protein A
1) it coagulates the fibrinogen in plasma
2) promotes the formation of a fibrin layer around staphylococcal abscess thereby protecting the bacteria from phagocytosis
3) forms coagulase-CFR complex
Coagulase
What is the (+) result of the coagulase
Clumping/coagulates
A thermostable thrombin-like molecule that forms coagulase-CFR complex
Coagulase-reducing factor
2 type of coagulase
1) cell-bound/clumping factor
2) unbound coagulase/free coagulase
1) is bound to the cell wall
2) causes bacterial cells to agglutinate in plasma
3) it clots human, rabbit or pig plasma
Cell bound coagulase/clumping factor
1) an extracellular enzyme not bound to the cell wall
2) cause clot formation when bacterial cells are incubated with plasma
3) free from cell wall
Unbound coagulase/free coagulase
1) it enhances invasion and survival in tissue
2) breaks down hyaluronic acid
3) bonds cells together and renders the intercellular spaces passable to pathogens
Hyaluronidase (spreading-factor enzyme)
1) opposite of coagulase
2) fibrinolytic activity; dissolves fibrin clot
Staphylokinase (fibrinolysin)
1) produced by both coagulate + and coagulase - staphylococci
2) essential for survival in sebaceous areas of the body
3) important in the formation of furuncles, carbuncles and boils
Lipase (fat-splitting enzyme)
1) it lowers viscosity of exudates, giving the pathogen more mobility
2) destroys DNA
DNAse and Phosphatase
1) breaks down penicillin and other beta-lactam drugs
2) 90% or more of clinical staphylococci isolates are resistant to penicillin as a result of enzyme production
3) cause resistance
Beta-lactamase
It inhibits cell wall synthesis
Beta-lactam
1) acts as neurotoxins that stimulates vomiting through the vagus nerve
2) produced by 30% to 50% of S. aureus isolates
3) superagents (TSST-1) that have the ability to interact with many T cells, activating an aggressive immune response
Enterotoxins (heat-stable)
1) stable to heating at 100 degrees Celsius for 30 minutes
2) resistant to hydrolysis by gastric and jejune like enzymes
3) do not cause odor, change in appearance or taste
4) found in milk products (enterotoxin B)
Enterotoxin
T or F: reheating contaminated food will not prevent disease
True
A Greek word meaning “bunches of grapes”
Staphle
