C10 - Catalase - Positive, Gram-Positive Cocci Flashcards
Coagulase-Positive Staphylococci
Staphylococcus aureus
Coagulase-Negative Staphylococci
Staphylococcus epidermidis
Staphylococcus haemolyticus
Staphylococcus saprophyticus
Staphylococcus lugdunensis
Staphylococcus schleiferi
Staphylococcus capitis
Staphylococcus caprae
Staphylococcus warneri
Staphylococcus hominis
Staphylococcus auricularis
Staphylococcus cohnii
Staphylococcus xylosus
Staphylococcus simulans
Micrococcus spp. and related
genera
Alloiococcus
Staphylococcus is a catalase-producing gram (+) cocci that belong to the family
Staphylococcaceae
Staphylococcus is aerobic or facultative anaerobic except what species?
S. aureus subsp. anaerobius and S. sacchrolyticus which are obligate anaerobes
nonmotile, non–spore-forming
spherical cells (0.5 to 1.5 μm) that appear singly, in pairs, and in clusters
normal inhabitants of skin, mucous membranes and intestines
Staphylococcus
In Blood Agar Plate, what are the colonies size and characteristics?
medium sized (4 to 8 mm) and appear cream-colored, white or rarely light gold, and “buttery looking”, other spp. may have gray colonies; some may be β-hemolytic (S. aureus
(Staphylococci/Micrococci)
Bacitracin Test Resistant
Staphylococci
(Staphylococci/Micrococci)
Bacitracin Test Susceptible
Micrococci (>10mm)
(Staphylococci/Micrococci)
Furazolidone Susceptibility Test (100ug) - SUSCEPTIBLE
Staphylococci (>15mm)
(Staphylococci/Micrococci)
Furazolidone Susceptibility Test (100ug) - RESISTANT
Micrococci (6-9 mm)
(Staphylococci/Micrococci)
Lysostaphin Sensitivity Test - Susceptible
Staphylococci (10-16 mm)
(Staphylococci/Micrococci)
Lysostaphin Sensitivity Test - Resistant
Micrococci
(Staphylococci/Micrococci)
Modified Oxidase Test/Microdase Test - NEGATIVE
Staphylococci
(Staphylococci/Micrococci)
Modified Oxidase Test/Microdase Test - POSITIVE
Micrococci
(Staphylococci/Micrococci)
Growth on Furoxone-Tween 80-oil Red O Agar - NEGATIVE
Staphylococci
(Staphylococci/Micrococci)
Growth on Furoxone-Tween 80-oil Red O Agar - POSITIVE
Micrococci
(Staphylococci/Micrococci)
Aid production from Glycerol (with erythromycin) - POSITIVE
Staphylococci
(Staphylococci/Micrococci)
Aid production from Glycerol (with erythromycin) - NEGATIVE
Micrococci
(Staphylococci/Micrococci)
OF reaction - Fermenter
Staphylococci
(Staphylococci/Micrococci)
OF reaction - Oxidizer
Micrococci
true coagulase positive and most virulent species of staphylococci
grow well on most routine media like NA and TSB
on solid media, round, smooth, opaque and butyrous
Staphylococcus aureus
on BAP, colonies have golden yellow color and β-haemolytic
responsible for various skin, wound and deep tissue infection
Staphylococcus aureus
Staphylococcus aurreus is cultivated by adding
7.5 to 10% NaCl—HALOPHILIC
VIRULENCE FACTORS of Staphylococcus Aureus
A. Antigenic Structure
B. Enzymes
C. Toxins
contain ribitol teichoic acid in cell wall
Teichoic Acid
together with teichoic acid, it protects the
bacteria from lysis and probably aids in
adherence
Peptidoglycan
group specific antigen unique to S. aureus
prevents antibody-mediated phagocytosis by
PMN—competes for the Fc portion
Protein A
component on cell wall responsible for clumping of the whole staphylococci in the presence of plasma
Clumping Factor
protects fro phagocytosis
Capsular Polysaccharide
coagulates fibrinogen in the plasma
promotes fibrin layer formation around the staphylococcal abscess protecting the bacteria from phagocytosis
Coagulase (Staphylocoagulase)
2 types of Coagulase (Staphylocoagulase)
Cell-bound Coagulase or Clumping Factor
Unbound or Free Coagulase
bound to the cell wall and clots human, rabbit or pig plasma
Cell-bound Coagulase or Clumping Factor
extracellular enzymes not bound to the cell wall and cause clot formation when bacterial cells are incubated with plasma
Unbound or Free Coagulase
hydrolyzes hyaluronic acid present in the intracellular ground substance, permitting the spread of infection
Hyaluronidase (Spreading Factor)
fibrinolytic activities by dissolving fibrin clot
Staphylokinase (Fibrinolysin)
produced by both coagulase (+) and coagulase (-) staphylococci
act on lipids present on the surface of the skin, particularly fats and oil secreted by the sebaceous glands
Lipase (Fat-splitting Enzyme)
important in the formation of furuncles, carbuncles and boils
Lipase (Fat-splitting Enzyme)
lowers viscosity of exudates giving the pathogen more mobility
destroys DNA
Deoxyribonuclease (DNAse) and Phosphatase
breaks down Penicillin and β-lactam drugs
β-LACTAMASE
Cytolytic Toxins
Hemolysins and Leukocidins
4 types of Hemolysins
a. α-Hemolysin
b. β-Hemolysin (Sphingomyelinase C)
c. δ-Hemolysin
d. γ-Hemolysin
damage RBC, platelets and macrophages and cause severe tissue damage
Predominant hemolysin
α-Hemolysin
acts on sphingomyelin in the plasma membrane of RBC
aka“hot-cold” lysine : enhanced hemolytic activity on incubation at 37° C (heat labile) and subsequent exposure to cold (4° C)
β-Hemolysin (Sphingomyelinase C)
exhibited in the CAMP test
lethal and dermonecrotic
β-Hemolysin (Sphingomyelinase C)
less toxic to cells than either α-hemolysin or β-hemolysin
produced by all S. aureus strain that cause RBC injury in culture an produce edematous lesions
δ-Hemolysin
associated with Panton-Valentine leukocidin (PVL)
γ-Hemolysin
exotoxin lethal to polymorphonuclear leukocytes
Pore forming exotoxin that suppress phagocytosis and associated with severe cutaneous infections and necrotizing pneumonia
associated with community-acquired staphylococcal infections
Staphylococcal Leukocidin/ Panton-Valentine leukocidin
heat-stable exotoxin: 100° C for 30 minutes
resistant to hydrolysis by gastric and jejunal enzymes
Enterotoxins
act as neurotoxins that stimulate vomiting through the vagus nerve
produced by 30% to 50% of S. aureus isolates
Enterotoxins
Staphylococcal food poisoning
Enterotoxins A, B, and D
TSS (Enterotoxins)
Enterotoxins B and C and sometimes G and I
Staphylococcal Pseudomembranous
Enterocolitis (contaminated milk products)
Enterotoxin B
aka ENTEROTOXIN F or PYROGENIC EXOTOXIN C
menstruating-associated TSS= TSS associated with tampon use
chromosomal-mediated toxin
TOXIC SHOCK SYNDROME TOXIN-1(TSST-1)
SUPERANTIGEN stimulating T-cell proliferation and production of a large amount of cytokines
low concentrations= leakage by endothelial cells; higher concentrations= cytotoxic
TOXIC SHOCK SYNDROME TOXIN-1(TSST-1)
aka EPIDERMOLYTIC TOXIN A and B or EXFOLIATIN serotypes A and B
Serine protease that divides the intercellular bridges of the epidermis and causes excessive sloughing of the epidermis (stratum granulosum)
Exfoliative Toxins
causes STAPHYLOCOCCAL SCALDED SKIN SYNDROME referred to as RITTER’S DISEASE
implicated in BULLOUS IMPETIGO
Exfoliative Toxins
mild inflammation of a hair follicle or oil gland; infected area is raised and red
Folliculitis
focal suppurative lesions which has resulted from an infection (folliculitis) that extend into subcutaneous tissue; large, raised, superficial abscesses
Furuncles (Boils)
larger, more invasive lesions develop from multiple furuncles, which can progress into deeper tissues; present with fever and chills, indicating systemic infection
Carbuncles
larger pustules surrounded by a small zone of erythema
highly contagious infection that spread by direct contact, fomites, or autoinoculation
Bullous Impetigo
superficial cutaneous infection commonly seen in newborns and young children characterized by the formation of encrusted pustules surrounded by red border
Impetigo
bullous exfoliative dermatitis that occurs primarily in newborns and previously healthy young children
localized skin lesion: few blisters, pemphigus neonatorum, Ritter disease; generalized form: cutaneous erythema, profuse peeling of the epidermis
Scalded Skin Syndrome
clinical manifestation with multiple causes; symptoms are due to hypersensitivity reaction
Toxic Epidermal Necrolysis (TEN)
rare but potentially fatal, multisystem disease characterized by sudden onset of fever, chills, vomiting, diarrhea, muscle aches, and rash, which can quickly progress to hypotension and shock
Toxic Shock Syndrome
intoxication resulting from ingestion of a toxin formed outside the body
symptoms appear rapidly (2 to 8 hours after ingestion) and resolve within 24 to 48 hours: nausea, vomiting, abdominal pain, and severe cramping, diarrhea
Food Poisoning
Percentage of Enterotoxins A, D, and B in Food Poisoning
Enterotoxins A (78%), D (38%), and B (10%)
perfuse and watery diarrhea due to water and electrolyte loss
Food Poisoning
Enterotoxin A and (leukocidins) LukE and LukP
Enterocolitis
leads to secondary pneumonia and endocarditis observed among IV drug users
Staphylococcal Bacteremia
secondary to bacteremia
Staphylococcal Osteomyelitis
secondary to influenza virus infection
multiple abscesses and focal lesions in the pulmonary parenchyma
Staphylococcal Pneumonia
frequent in children and occur in patients with a history of rheumatoid arthritis or IV drug abuse
Septic Arthritis