Staphylococcus aureus is a gram-positive, non-motile, non-sporing bacterium that forms clusters resembling bunches of grapes under the microscope due to multiplying in two planes. It grows on nutrient agar and blood agar to form creamy, circular colonies. It produces hemolysins and enterotoxins that can cause food poisoning when the toxins are ingested. S. aureus commonly resides in the nostrils and can cause infections when contaminated hands or objects touch wounds, leading to issues like cellulitis, pneumonia, or urinary tract infections.

1. STAPHYLOCOCCUS
AUREUS

2. MORPHOLOGICAL
CHARACTERISTICS

3. IT IS A GRAM POSITIVE ORGANISMS
AND NON- MOTILE, NON-SPORING
ORGANISMS.
IT IS PRESENT IN THE FORM OF BUNCH
OF GRAPES BECAUSE THEY MULTIPLY IN
TWO PLANES AND FORM BUNCH.

4. CULTURAL
CHARACTERISTI
CS

5. IT CAN BE GROWN ON SIMPLE
NUTRIENT MEDIUM WITH SOME ADDITION
OF SALT OR ON BLOOD AGAR AND IT
FORMS CONVEX, ROUND, CIRCULAR
COLONIES WHICH IS CREAMY IN
COLOUR. THEY REQUIRE A
TEMPERATURE OF 27-37*c.
THEY REQUIRE A SELECTIVE MEDIUM
FOR THEIR GROWTH, “ PHENOPHTHALIN
DIPHOSPHATE”.

6. BIO- CHEMICAL
RAECTIONS

7.  THEY FERMENT SUGARS LIKE
FRUCTOSE, MANNITOL.
 THEY CATLYSE POSITIVE REACTION IN
WHICH IT CLOTS THE BLOOD BY
CONVERTING FIBRINOGEN TO FIBRIN.

8. RESISTANCE

9.  IT IS A DELICATE ORGANISMS WHICH
CAN BE KILLED BY PHYSICAL
STERILISATION LIKE AUTOCLAVE AND
CHEMICAL STERILISATION LIKE
FUMIGATUION, HALOGEN AND OTHER
ALDEHYDES.

10. ANTIGEN

11.  IT HAS SURFACE ANTIGEN THAT IS
PRESENT ON PEPTIDOGLYCAN CELL
WALL.

12. TOXINS

13.  IT PRODUCES VARIOUS TOXINS,
IMPORATANT ARE:
3. HEMOLYSIN:
THIS IS THE TOXINS
PRODUCED WHICH CAUSES
DESTRUCTION OF RED BLOOD CELLS.
2. ENTEROTOXIN:
IT CAUSES FOOD POISONING IN A
PERSON .

14. IT CAUSES FOOD POISONING WHEN
THE PERSON INTAKES FOOD WHICH IS
ALREADY INFECTED WITH A ORGANISM
AND THIS ORGANISMS RELEASES TOXINS
INTO THE MEDIUM. IT CAUSES
DIARRHOEA AND VOMITTING.

15. PATHOGENICITY

16. IT CAUSES CUTANEOUS DISEASE LIKE
CELLULITIS, CARBUNCLE, BOIL, FRUNCLE .
IT ALSO CAUSE DEEPER INFECTIONS
LIKE PHARYNGITIS , TONSILITIS,
BRONCHITIS AND ULTIMATELY
PNEUMONIA, URINARY TRACT
INFECTIONS.

17. LAB DIAGNOSIS

18.  BY GROWING THE ORGANISM ON
CULTURE MEDIUM (BLOOD AGAR,
SELECTIVE MEDIUM).
 BY TAKING SAMPLE AND EXAMINING ITS
COLONIC CHARACTERISTICS.

19. EPIDEMEOLOGY

20.  STAPH. AUREUS NORMALLY RESIDES IN
NOSTRILS AND INFECTION OCCURS BT
TOUCHING THE CONTAMINATED FINGERS
OR HANDKERCHIEF TO THE WOUND
SURFACE.