Staphylococci are gram-positive cocci that appear predominantly in grape-like clusters. They are catalase positive, non-motile, and non-spore forming. Staphylococcus aureus is a pathogenic species known to cause a variety of infections and diseases in humans through various virulence factors including enzymes, toxins, and surface proteins. Some of the infections it can cause include skin and soft tissue infections, osteomyelitis, pneumonia, sepsis, toxic shock syndrome, and food poisoning through enterotoxins. S. aureus produces a variety of toxins including hemolysins, leukocidins, enterotoxins, and exfoliative toxins which can lead to

1. STAPHYLOCOCCI
Arfina Aljaseer
121-i2b
Department of Microbiology

2. STAPHYLOCOCCI
– Gram positive cocci
– Arrangement: in single cells, pairs,
tetrads, short
chains but appear predominantly in
grape like
clusters
– Catalase positive
– Non-motile
– Non-spore forming
– Ubiquitous

3. Classification
Based on coagulase production

5. S.albus
S.aureus

6. Staphylococcus
Aureus

7. Morpho-biological characteristics
Spherical, 1 µm dia.
• Arrangement : Grape like
clusters.
• Non-motile, Non-sporing
• Non-capsulated {Few strains
possess microscopically visible
capsule (young cultures)}.
• Stain readily with aniline
dye & are uniformly Gram
Positive.

8. Cultural Characteristics
On Nutrient agar
golden yellow and
opaque colonies with
smooth glistening
surface, 2-4 mm in
diameter,circular,convex,
smooth, shiny & easily
emusifiable (max.
pigment production at 22
°C & only in aerobic
cultures).
On Blood agar
– golden yellow
colonies, surrounded by
a clear zone of
hemolysis (beta-
hemolysis),esp.
when incubated in
sheep or rabbit blood
agar in atmosphere of
20% CO2
On MacConkey
agar
– Smaller colonies
than those on
Nutrient agar and
are pink coloured
due to lactose
fermentation.
On Mannitol salt agar
– S.aureus ferments
mannitol and appear
as yellow colonies
– MSA is a useful
selective medium for
recovering S.aureus
from faecal specimens,
when investigating food
poisoning.

9. PATHOGENICITY
Source of infection:
A) Exogenous: patients or carriers
B) Endogenous: From colonized site
Mode of transmission:
A) Contact: direct or indirect( through fomites)
B) Inhalation of infected air borne droplets

10. Virulence factors
Two types:
Cell Associated Factors
1.Cell associated polymers
2.Cell surface proteins
Extracellular factors
1.Enzymes
2.Toxins

11. Cell Associated Polymers
1.Capsular polysaccharide
• Some strains produce exopolysaccharide (helps in adherence to host cell & prosthetic
devices).
• Clinical isolates of SA – classified into 11 types based on capsular polysaccharide
immunotyping.
• 70-80% of significant clinical isolate belong to capsular serotype 5 or 8.
2. Peptidoglycan & teichoic acid
• Cell wall contain peptidoglycan (NAG & NAM) & teichoic acid.
Functions:
• Specific adherence of bacteria to mucosal surfaces.
• Provides rigidity & resilience to cell wall.
• Adhesins, fibronectin-binding proteins, collagen-binding proteins & clumping factors
are covalently incorporated into peptidoglycan.

12. Cell Surface Proteins
Protein a
• MW: 42 kDa
• Found on cell surface & in growth medium.
• Ability to bind the Fc region of all human IgG (except IgG3).
• Interfere with opsonization & ingestion of the organism by PMN cells, activating
complement & eliciting immediate & delayed type
• hypersensitivity reactions.
• It is immunogenic; abs are found in patient with serious S.aureus infections.
• Presence of protein A provides basis for Co-agglutination reaction (used to identify
gonococci, streptococcal grouping) and detection of bacterial Ags in body fluids.
Clumping factors
• Cell bound material able to bind fibrinogen, responsible for binding of S.aureus to both
fibrin & fibrinogen.

13. Enzymes
Catalase
• All staphylococci produce catalase, which catalyzes the conversion of toxic hydrogen peroxide
to water and oxygen.
• Hydrogen peroxide can accumulate during bacterial metabolism or after phagocytosis.
Coagulase
• S. aureus strains possess two forms of coagulase:
- bound,
- Free.
• Coagulase bound to the staphylococcal cell wall can directly convert fibrinogen to insoluble
fibrin and cause the staphylococci to clump.
• The cell-free coagulase accomplishes the same result by reacting with a globulin plasma
factor.
Hyaluronidase
• Hyaluronidase hydrolyzes hyaluronic acid, the acidic mucopolysaccharides present in the
acellular matrix of connective tissue. This enzyme facilitates the spread of S. aureus in tissues.
• More than 90% of S. aureus strains produce this enzyme.

14. Lipases
• Seen in chronic furunculosis
patient.
• Spread organism in
cutaneous & sub-cutaneous
tissues.
. Others
• DNAse
• Thermonuclease
• Staphylokinase(fibrinolysin)
• Phosphatase

15. TOXINS
Cytolytic Toxins: membrane active
substances, consisting of four hemolysins & a
leucocidin
1. Alpha hemolysin
2. Beta hemolysin
3. Gamma hemolysin
4. Delta hemolysin
5. Leucocidin

16. Alpha Hemolysin
– inactivated at 70°C but reactivated at 100°C
– Lyse rabbit erythrocyte but less active against sheep and human red cells.
– Toxic to macrophages, lysosome, muscle tissue, renal cortex & circulatory system.
Beta Hemolysin
– It is a sphingomyelinase, hemolytic for sheep cell but not for human & rabbit cell.
– Exhibit hot-cold phenomenon(hemolysis being initiated at 37°C but become evident only
after chilling)
Gamma Hemolysin
– Composed of 2 separate proteins ( necessary for hemolytic activity)
Delta Hemolysin
– Detergent like effect on cell membrane of erythrocyte, leucocyte, macrophage & platelet
Leucocidin (Panton-valentine Toxin/Pvl)
– Composed of S & F components.
– Damages PMN cells & macro-phages.
– Grouped as synergo-hymenotropic toxins.

17. ENTEROTOXINS
– Staphylococcal Food poisoning: contaminated
food.
– Nine antigenic types currently known
(A,B,C1,C2,C3,D,E,H,I).
– Toxin A – most cases.
– Resistance
• Gut enzymes
• Boiling for 30 minutes
– Common food items: carbohydrate, protein
food, meat & fish, milk & milk product cooked &
left at room temperature.
Source of infection: food handler(carrier).
- Recovery: 24-48 hours.
- Toxin act directly on ANS.
- Enterotoxin : superantigen
- Toxin is antigenic-neutralized by specific
antitoxin.
- Toxin detection: ELISA, latex agglutination.

18. TOXIC SHOCK SYNDROME TOXIN (TSST)
Toxic shock syndrome toxin-1 (TSST-1), a prototype
superantigen secreted by a Staphylococcus aureus bacterium
strain in susceptible hosts, acts on the vascular system by
causing inflammation, fever, and shock. The bacterium strain
that produces the TSST-1 can be found in any area of the body,
but lives mostly in the vagina of infected women. TSST-1 is a
bacterial exotoxin found in patients who have developed toxic
shock syndrome (TSS), which can be found in menstruating
women or any man or child for that matter.
One-third of all TSS cases have been found in men.This
statistic could possibly be due to surgical wounds or any skin
wound.TSST-1 is the cause of 50% of non-menstrual and 100%
of all menstrual TSS cases.

19. EXFOLIATIVE (EPIDERMOLYTIC) TOXIN
2 types:
• ET-A and ET-B
– ET-A – heat stable (chromosomal)
– ET-B – heat labile (plasmid mediated)
• Produced by some strains of Staph. aureus (phage group II)
• Proteolytic, dissolve mucopolysaccharide matrix of epidermis.
• Epidermal splitting  blistering disease.
• Staphylococcal Scalded Skin Syndrome (SSSS).
• Severe form : Ritter’s disease (newborn) & toxic epidermal necrolysis (older patients)

20. STAPHYLOCOCCAL
DISEASES

22. INFECTIONS
Skin and soft tissue infection
– Folliculitis
– Furuncle (boil)
– Carbuncle
– Impetigo
– abscess
– Wound infection

23. Folliculitis: It is inflammation of the
hair follicles.
•A small red bump or pimple develops at
infection sites of hair follicle.
Sty: A sty is folliculitis affecting one or
more hair follicles on the edge of the upper
or lower eyelid.

24. Furuncle/boils: Furuncle is deep seated
infection, originating from folliculitis,( if
infection extends from follicle to
neighbour tissue)
• Causes redness, swelling, severe pain
• Commonly found on the neck, armpit
and groin regions
Carbuncle: Carbuncle is an
aggregation of infected furuncles.
Carbuncles may form large abscesses.
• It is a large area of redness, swelling and pain,
punctuated by several sites of drainage pus.
Impetigo: a very superficial skin infection, usually
produces blisters or sores on the face, neck,
hands, and diaper area.
• It is characterized by watery bristles, which
become pustules and then honey coloured crust

25. Musculoskeletal infection
•Septic arthritis – knee, shoulder, hip, phalanges
•Osteomyelitis – children: long bones, adults:vertebrae
•Pyomyositis – skeletal muscle infection
•Bursitis

26. Osteomyelitis: inflammation of bone
• Bacteria can get to the bone
– Via bloodstream
– Following an injury
Clinical features: pain, swelling,deformity,
defective healing,in some case pus flow,
Diagnosis: X-ray, MRI, bone aspirates
Periostitis: inflammation of periosteum
• Clinical features: fever, localised pain,leucocytosis
• Diagnosis: needle aspiration of subperiosteal
Fluid.

27. Respiratory
•Tonsilitis
•Pharyngitis
•Sinusitis
•Otitis
•Bronchopneumonia
•Lung abscess
•empyema
Central nervous system
•Abscess
•Meningitis
•Intracranial thrombophlebitis
Endovascular
•Bacteremia
•Septicemia
•Pyemia
•Endocarditis - Endocarditis:
It is an inflammation of the
inner layer of the heart, the
endocardium.
• Endocarditis occurs
when bacteria enter
bloodstream, travel
to heart, and lodge on
abnormal heart
valves or damaged
heart tissue.

28. The diseases are caused by bacterial
toxins.
1. Food poisoning
2. Toxic sock syndrome (TSS)
3. Staphylococcal scalded skin syndrome
(SSSS)
INTOXICATION

29. Food poisoning: (Enterotoxin)
•Enterotoxin is responsible for manifestations of staphylococcal food poisoning.
•Nine types of enterotoxin are currently known, named A, B, C1-3, D, E, H & I.
•It usually occurs when preformed toxin is ingested with contaminated food.
•The toxin acts directly on the autonomic nervous system tocause the illness, rather than gut mucosa.
The common food items responsible are - milk and milk products, meat, fish and ice cream.
•Source of infection- food handler who is a carrier.
•Incubation period- 2 to 6 hours.
•Clinical symptoms- nausea, vomiting and diarrhea.
•The illness is usually self limited, with recovery in a day or so.
Staphylococcal Toxic shock syndrome (STSS): STSS is associated with infection of mucosal or
sequestered sites by TSST( formerly known as
enterotoxin type F) producing S.aureus. It is fatal multisystem disease presenting with fever,
hypotension, myalgia, vomiting, diarrhea, mucosal hyperemia and erythematous rash which
desquamates subsequently.
Staphylococcal scalded skin syndrome (SSSS): Exfoliative toxin produced by S.aureus is
responsible for this.
•It is a skin disease in which outer layer of epidermis gets separated from the underlying tissues.

30. TYPES OF SSSS

32. THANK YOU!