Staphylococcus aureus is a spherical, gram-positive bacterium that can be found singly or in pairs. It is a facultative anaerobe that metabolizes glucose via the Embden-Meyerhof and hexose monophosphate pathways. S. aureus produces several toxins and exotoxins such as enterotoxins, coagulases, hemolysins, and nuclease. The bacterium is an important cause of food poisoning due to production of enterotoxins in contaminated foods.

1. STAPHYLOCOCCUS AUREUS

2. Classification
• Domain -Bacteria
• Kingdom -Eubacteria
• Phylum -Firmicutes
• Class -Bacilli
• Order -Bacillales
• Family -Staphylococccaceae
• Genus -Staphylococcus
• Species -S.aureus

3. • This is known as the golden cluster seed or the
seed gold
• Shape : spherical,cells occur singly and in pairs.
• Colonies are smooth,raised,glistening,circular,
entire and translucent.Appear grape like clusters
• Size: single colony may obtain a size of 6-8mmin
diameter on non-selective media for the
propagation of staphylococci.With increase in
age,Colonies become nearly transparent on the
above media.

4. • Properties: Non motile, These are facultative
anaerobes.Growth is best under aerobic
conditions.Growth in the anaerobic portion of a semisolid
thioglycolate medium is rapid and uniformly dense
• Gram staining: gram positive
• Metabolism: They are Chemoorganotrophs
Metabolism is respiratory and fermentive. Glucose is
metabolized to pyruvate via Embden Meyerhof Glycolytic
pathway and Hexose Monophosphate(HMP) pathway.
Anaerobically,Pyruvate is oxidized to acetate which
through acetyl co.a can be further oxidized through TCA
cycle

5. Toxin production
• Many strains produce enterotoxins,which if ingested may
produce symptoms of staphylococcal food poisoning.
• Coagulases are produced by nearly all strains,several
antigenically distinct and substrate specific coagulases are
produced.Detection of coagulases is very important in the routine
identification of S.aureus
• Many strains produce staphylokinase (Muller factor,SKA,or
fibrinolysin)-especially those of human orgin.
• Four different haemolysins(exotoxins) are produced including
alpha,beta ,gamma – hemolysins
• Some strains produce an epidermolytic toxins
(exfolitin,ET,exfoliative toxin)which has been implicated in the
staphylococcal scalded skin syndrome

6. • Heat –resistant staphylococcal
nuclease(thermonuclease,
TNase,DNase,phosphodiesterase) having endo and exo
nucleolytic properties, which can cleave either DNA or
RNA is produced by most strains.This nuclease maybe
used as an indicator for the detection of S.aureus in
foods
• Some strains produce antibiotic- like substances
describedc as staphylococcins (bacteriocins,Sta-cins)
and micrococcins which may be bacteriostatic or
bactericidal to other staphylococci and certain other
bacteria.
• Differentiation of strains of S.aureus by phage typing is
widely used
• Serological typing of S.aureus may have limited value in
epidemiological studies

7. Importance of S.aureus in sea food:
• S.aureus is a leading cause of gastroenteritis resulting
from the consumption of contaminated
food.Staphylococcal food poisoning is due to the
absorption of staphycoccal enterotoxins preformed in the
food.Some strains produce the exotoxin TSST-1 are the
causative agents of toxic shock syndrome.S.aureus
strains produce enterotoxins,including enterotoxin A
(4),D(1),AB(4) that affects fish and fish fillets,shrimp
tails,shell fish meat.It is able to grow in a wide range of
temperature from 7-48.5,pH-4.2-9.3 and sodium
chloride15% concentration.These characteristics enable
s.aureus to grow in a wide variety of food.The symptoms
of staphylococcal food poisoning r abdomonial
cramps,nausea,vomiting sometimes followed by diarrhea