Staphylococcus Aureus

Question 1

Staphylococcus Family, Genus and Species

Answer 1

Micrococcae
Genus Micrococcus and Staphylococcus
Species S.aureus, S.saprophyticus, S.epidermidis, M.luteus about 33 species

Question 2

Staphylococcus xtics

Answer 2

Desiccation resistant
Gram positive
non motile
non spore formation 
they have 33 species
salt tolerant.

Question 3

Staphylococcus aureus

Answer 3

Habitat: skin and anterior nares
Primary pathogen of the genus
they produce superficial, deep and systemic infections.
Mode of transmission: traumatic introduction
Source of organism: self, infected human host carrier, fomite or environment.

Question 4

predisposing factors to staph infections

Answer 4

diabetes mellitus
injury
immune response defects
presence of foreign bodies

Question 5

pathogenicity of S.Aureus

Answer 5

production of enzymes
production of toxins
ability to evade immune system

Question 6

enzymes of staphylococcus

Answer 6

hyaluronidase 
staphylokinase
lipases
coagulase
lactamase which breaks down penicillin

Question 7

Toxins of S.Aureus

Answer 7

Enterotoxins
Cytolytic toxins
Exfoliating toxins
Toxic Shock Syndrome

Question 8

Classification of Staph infections

Answer 8

Non Invasive like food poisoning
Localized/Cutaneous impetigo, scalded skin syndrome
Systemic endocarditis, bacteremia.

Question 9

Diagnostic template

Answer 9

specimen
smear 
biochemical reaction
culture
antibiogram
typing

Question 10

S.Aureus produces hemolysis on blood agar T/F

Answer 10

True

Question 11

S.Aureus tests negative for catalase test,if ttrue why? If false why not?

Answer 11

False, because O2 is generated

Question 12

S. Aureus test negative for catalase test

Answer 12

False, generally Staphylococcus test negative except S.Aureus

Question 13

In novobicin test, S.saprophyticus is resistant

Answer 13

True

Question 14

Strepcoccae test negative for catalase T/F

Answer 14

True

Question 15

Treatment for staph infections

Answer 15

Drain infected area
if it deep use erythromycin, semi-synthetic penicillin
Endocarditis semi synthetic pencillin
Methicillin is used for staphylococcus infections

Question 16

in the presence of Methicillin resistant Staphylococcus what would you use?

Answer 16

Vancomycin

Question 17

Staphylococcus epiderdimis

Answer 17

Habitat: Skin and mucous membrane
Mode of transmission: Insertion of medical devices
Responsible for UTIs, serious infections in immunocompromised patients.
Treatment aided with ABST

Question 18

Staphylococcus saprophyticus coagulase -ve

Answer 18

Habitat: Skin commensal
Responsible for most UTIs in young women
Treated with wide range antibiotics

Question 19

Other Staphylococcus

Answer 19

S. hemolyticus in bacteremia, endocarditis and wound infections.
S.lugdunesis and S.schleifiri also opportunists

Question 20

Pathogenic Attributes of S.Aureus

strcutural factors

Answer 20

Presence of protein A coats that aid in blocking humoral response.
Clumping factor, aids in helping the staph aureus in converting soluble fibrinogen into insoluble fibrin. Fibrin hides the bacteria from the immune system.
Synthesize loosely organized polysaccharides slime layers called capsules.