COCCI Flashcards
GENERA AND SPECIES
S. Aureus
COAGULASE-NEGATIVE
STAPHYLOCOCCI
S. Epidermidis
S. Haemolyticus
S. Saprophyticus
S. Lugdunensis
S. Schleiferi
COAGULASE-NEGATIVE
STAPHYLOCOCCI
S. Capitis
S. Caprae
S. Warneri
S. Hominis
S. Auricularis
S. Cohnii
S. Xylosus
S. Simulans
Micrococcus spp. and related genera
Alloiococcus
GENERAL CHARACTERISTICS: Staphylococcus
- catalase-producing gram (+) cocci
- aerobic or facultative anaerobic
- nonmotile, non spore forming
- spherical cells (0.5 to 1.5 micrometer)
- normal inhabitants pf skin, mucous membranes and intestines
Catalase producing gram positive cocci belongs to what family?
Staphylococcaceae
What are the species of staphylococcus that are not aerobic or facultative anaerobic?
- S. Aureus
- S. Sacchrolyticus
(Obligate anaerobes)
Spherical cells appear what?
Singly, in pairs, and in clusters
What are the colony characteristics of Staphylococcus aureus on blood agar plates (BAP)?
- Colonies are medium-sized (4 to 8 mm),
- cream-colored, white, or rarely light gold, with a “buttery” appearance
- Some colonies may be β-hemolytic
- Other Staphylococcus species may have gray colonies.
Difference of staphylococci and micrococci based on the test Bacitracin (0.04 U)
Staphylo: Resistant
Micro: Susceptible (greater than or equal to 10 mm)
Difference of staphylo and micrococci based on the test Furazolidone susceptibility test (100ug)
Staphylo: Susceptible (greater than or equal to 15 mm)
Micrococci: Resistant
Difference of staphylo and micrococci based on the test Lysostaphin Sensitivity test
Staphylo: Susceptible (10 to 16 mm)
Micro: Resistant
Difference of staphylo and microccoci based on the test Modified Oxidase Test or Microdase Test?
Staphylo: negative
Micro: positive
Difference of staphylo and micrococci based on the test Growth on Furoxone-Tween 80-oil Red O Agar?
Staphylo: negative
Micro: positive
difference of staphylo and micrococci based on the test Aid production from Glycerol (with erythromycin)
Staphylo: positive
Micro: negative
Difference of staphylo and micrococci based on the test OF reaction
Staphylo: Fermenter
Micro: Oxidizer
What are the test used between staphylococci and micrococci?
- Bacitracin (0.04 U)
- Furazolidone susceptibility test (100 ug)
- Lysostaphin sensitivity test
- Modified oxidase test / Microdase test
- Growth on Furoxone- Tween 80-oil Red O Agar
- Aid Production from glycerol (with erythromycin)
- OF reaction
Staphylococci that is true coagulase positive and the most virulent species?
S. Aureus
What media does S. Aureus grow?
- Nutrient agar (NA)
- Tryptic Soy Broth (TSB)
On solid media, what are the distinct colony characteristics displayed by S. Aureus?
- round
- smooth
- opaque
- butyrous
On Blood Agar Plate, what colony features does S. Aureus display?
Golden yellow color colonies and Beta hemolytic
What is added to cultivate S. Aureus?
7.5 to 10% NaCl
Is S. Aureus halophilic?
True
S. Aureus is responsible to different spectrum of infections such as?
Skin, wound, and deep tissue infections
What teichoice acid is found in the cell wall of S. Aureus?
Ribitol teichoic acid
________ and _______ protects the bacteria from lysis and aids in adherence
Peptidoglycan and teichoic acid
group of antigen unique to S. Aureus
Protein A
How does Protein A in S. Aureus prevents antibody mediated phagocytosis?
Protein A competes for the Fc portion of antibodies thereby preventing antibody-mediated phagocytosis by polymorphonuclear leukocytes
Protein A prevents what phagocytosis?
Antibody mediated phagocytosis
Protein A prevents phagocytosis by?
polymorphonuclear leukocytes
component on cell wall responsible for
clumping of the whole staphylococci in the
presence of plasma
Clumping factor
Clumping factor is responsible for the clumping in the presence of ____?
Plasma
This protects the S. Aureus from phagocytosis?
Capsular polysaccharide
What are the antigenic structure of S. Aureus?
- teichoic acid
- peptidoglycan
- protien A
- clumping factor
- capsular polysaccharide
Coagulates fibrinogen in the plasma and promotes fibrin layer formation around the staphylococcal abscess protecting the bacteria from phagocytosis
Coagulase (staphylocoagulase)
Staphylocoagulase promotes _____ around the staphylococcal abscess protecting the bacteria from _____
Fibrin layer formation ; phagocytosis
Types of coagulase
- cell-bound coagulase or clumping factor
- unbound or free coagulase
A coagulase that is bound to the cell wall and clots plasma of _____, _____, or _____?
Cell-bound coagulase or clumping factor ; human, rabbit, or pig plasma
Extracellular enzymes not bound to the cell wall and cause clot formation when bacterial cells are incubated with plasma
Unbound or free coagulase
Free coagulase cause clot when bacterial cells are _____?
Bacterial cells areIncubated with plasma
This hydrolyzes hyaluronic acid present in the intracellular ground substance, permitting the spread of infection
Hyaluronidase (spreading factor)
Permits the spread of infection
Hyaluronidase
Have fibrinolytic activities by dissolving fibrin clot
Staphylokinase (fibrinolysin)
Coagulase in staphylococcus is also know as?
Staphylocoagulase
Hyaluronidase is also known as
Spreading factor
Staphylokinase is also known as
Fibrinolysin
This is produced by both coagulas - and + staphylococci
Lipase (fat splitting enzyme)
This acts on lipids present on the surface of the skin (particularly fats and oil) that is secreted by the sebaceous glands
Lipase
____ is important in the formation of furuncles, carbuncles, and boils
Lipase
Lipase allows staphylococci to penetrate deeper into the skin tissues, promoting localized infections such as _______, ______, and________
Furuncles, carbuncles, and boils
What skin substance does lipase act on? And where they are produced?
Acts on fats and oils ; secreted by the sebaceous glands on the skin
Function of deoxyribonuclease and phosphatase in S. Aureus infections?
DNAse lowers the viscosity of exudates by breaking down DNA which enhances the pathogen’s mobility in infected tissues.
This destroys DNA
Deoxyribonuclease (DNAse) and phosphatase
What does Beta lactamase breaks down
Penicillin and beta lactam drugs
What are the enzymes of S. Aureus
- coagulase (staphylocoagulase)
- hyaluronidase (spreading factor)
- staphylokinase (fibrinolysin)
- lipase (fat splitting enzyme)
-DNAse and phosphatase - protease
- gelatinase
- beta lactamase
What are the cytolytic toxins
Hemolysins and Leokocidins
This damage RBC, platelets and macrophages and cause sever tissue damage
Alpha hemolysin
Alpha hemolysins damage _____, _____, _____ and cause severe ______
Rbc, platelets, macrophage; severe tissue damage
Predominant hemolysin
Alpha hemolysin
Acts on the sphingomyelin in the plasma memrane of rbc
Beta hemolysin (Sphingomyelinase C)
Where does beta hemolysin acts on?
Sphingomyelin in the plasma membrane of RBC
Enhance hemolytic activity on ________ and subsequent exposure to ________
Incubation at 37 celsius (heat labile) ; cold a 4 celsius
Beta hemolysin is exhibited in what test?
CAMP test
effect of beta hemolysin
Lethal and dermonecrotic
Beta hemolysin aka _____
Hot-cold lysine
Less toxic to cells than alpha or beta
δ-Hemolysin (delta hemolysin)
This toxin is produced by all S. Aureus strain
Delta hemolysin
Associated with Panton-Valentine Leukocidin (PVL)
Gamma hemolysin (y-hemolysin)
Gamma hemolysin is associated with
Panton-Valentine Leukocidin (PVL)
An exotoxin that is lethalto Polymorphonuclear leukocytes
Staphylococcal Leukocidin (Panton- Valentine Leukocidin)
PVL is lethal to?
Polymorphonuclear leukocytes
Mechanism of action of PVL?
Pore forming exotoxin that suppress phagocytosis, associated with severe cutaneous inections and necrotizing pneumonia
Pvl is associated what infections and dxs?
Severe cutaneous infections and necrotizing pneumonia
4 types of hemolysins?
Alpha, beta, delta and gamma hemolysins
What are staphylococcal enterotoxins?
They are heat stable exotoxins produced by S. Aureus that can withstand boiling and resistant to hydrolysis by gastric and jejunal enzymes
Enterotoxins can withstand boiling for ____
100 celsius for 30 minutes
Enterotoxins are resistant to hydrolysis by _____ and _____
Gastric and jejunal enzymes
How do enterotoxins affect the body?
They act as neurotoxins that stimulate vomiting through the vagus nerve
Percentage of S. Aureus isolates produce enterotoxins?
Enterotoxins are produced by 30% to 50% of S. Aureus isolates.
Which enterotoxins are primarily associated with food poisoning?
A, B, AND D
Enterotoxins that are implicated in TSS
B AND C ; SOMETIMES G AND I
What condition can enterotoxin B cause?
B
Toxic shock syndrome toxin-1 is also known as
Enterotoxin F or Pyrogenic exotoxin C
What condition is TST 1 particuarly associated with?
Menstruation-related toxic shock syndrome (TSS)
Menstruating-related TSS is especially linked to?
Tampon use
How is TSST1 produced by S. Aureus?
Chromosomal mediated toxin
TSS act as ____ and trigger an extreme immune response. leading to t cell proliferation and release cytokines
Superantigen
Effects of diff. Concentrationsof TSST1 on cells?
At low concentration = TSST1 causes leakage -> low blood pressure
At higher concentration = cytotoxic
TSST1 causes leakage by _____
Endothelial cells
Exfoliative toxins also known as
Epidermolytic toxin A and B or Exfoliatin serotypes A and B
what kind of protease is he exfoliative toxin?
serine protease
divides the intracellular bridges of the epidermis and causes excessive sloughing of the epidermis (stratum granulosum)
exfoliative toxin
what skin condition is caused by exfoliative toxins?
Staphylococcal Scalded Skin Syndrome
what skin condition is caused by exfoliative toxins?
Staphylococcal Scalded Skin Syndrome
SSSS is also known as
Ritter’s disease
Which skin condition s exfoliatie oxin implicaed in
Bullous Impetigo
result to a widespread blistering and peeling of the skin (appearance of burns)
Ritter’s disease
Localized skin infection that also involves blister formation
Bullous impetigo
What are the toxins produced by S.aureus?
- Cytolytic toxins
- Enterotoxins
- TSST-1
- Exfoliative toxin
Mild inflammation of a hair follicle or oil gland; infected area is raised and red (INITIAL AND LESS SEVERE)
Folliculitis
Folliculitis is what?
Mild inflammation of hair follicle
Folliculatis forms ___ around hair follicles
domed pustules
Large, raised, superficial abscesses
Furuncles (boils)
Arises when a large abscess forms around the hair follicle
furuncles
Present with fever and chills, indicating systemic infection
Carbuncles
type of infection that affects the whole body and is caused by carbuncles
systemic
carbuncles consist of a ____ around several hair follicles
multilocular abscess
Larger pustules surrounded by a small zone of erythema
Bullous impetigo
Bullous impetigo is what?
Highly contagious infection that spread by direct contact, fomites or autoinoculation
Bullous impetigo spread through?
Direct contact, fomites, or autoinoculation
It is a superficial cutaneous infection commnly seen in newborns and young chidren
Impetigo
Impetigo is characterized by formation of ______ surrounded by red border
encrusted pustules
Clinical manifestation with multiple causes; symptoms are due to hypersensitivity reaction
Toxic epidermal necrolysis (TEN)
what are the cutaneous infections?
- folliculitis
- furuncles
- carbuncles
- bullous impetigo
- scalded skin syndrome
- toxic epidermal necrolysis