 Staphyloccocci
- derived from Greek
“stapyle” (bunch of grapes)
 Gram positive cocci arranged in clusters
 Hardy organisms surviving many non
physiologic conditions
 Include a major human pathogen and skin
commensals
 Spherical
cells arranged in irregular
clusters
 Gram-positive
 Lack spores and flagella
 May have capsules
 31 species
3
 Staphylococcus
species are generally
nonfastidious
 They grow well on media without blood or
other special supplements
 Micrococcus species and R. mucilaginosa
are mildly fastidious and grow more slowly
than Staphylococcus sp.
 Staphylococcus
and Micrococcus tolerate a
high salt concentrations; they grow on media
containing 5%-7.5% NaCl (e.g. Mannitol Salt
Agar)
 Staphylococcus species are facultatively
anaerobic, as is Rothia. Micrococcus is an
obligate aerobe.
 Staphylococcus species produce a variety of
hemolysins and other toxins
 Staphylococcus
species can be differentiated
from Micrococcus species based upon oxygen
requirements: Staph is facultative and
Micrococcus species are obligate aerobes
 Rothia can be differentiated from
Staphylococcus and Micrococcus by its lack of
growth on a high-salt medium, its negative
catalase reaction, and its tendency to adhere
firmly to an agar surface
 All
Staph group organisms that grow in air are
catalase positive
 Rothia
is catalase negative (or weakly
positive).
Catalase POS
Staphylococcus
Catalase NEG
Gram Positive Coccus
Catalase
+
Salt Tolerant
Yes
Facultative
Yes
Staphylococcus
No
Rothia
No
Micrococcus
_
Streptococcus
Group
Coagulase negative
Coagulase positive

S. aureus
S. epidermidis
 S. saprophyticus
 S. haemolyticus

 Gram-positive
spherical
cells (0.5-1.5 mm) in
singles, pairs, and
clusters
 Appear as “bunches of
grapes”
Gram-stained smear of
staphylococci from
colony
Scanning electron
micrograph of staphylococci

Nonmotile

Non–spore-forming

Nonencapsulated

Catalase-producing

Oxidase: negative

Glucose fermenters

Primarily aerobic, some facultatively anaerobic
 Bacitracin
resistant
 Grow on agar that contains peptone
 Inhibited by media that has high bile salt
concentration
 Some are ß-hemolytic
 Colony morphology: buttery looking, cream or
white colored
 Staph.
Are gram positive cocci arranged in
grape like clusters.


The genus Staphylococcus includes 3 species of
medical importance; staph. aureus,
staph.epidermidis and staph. Saprophyticus.
Of the three, staph. aureus is the most
important.
 Staph.aureus
is distinguished from the others
by being coagulase positive, manitol positive
and by causing haemolysis of RBCs in vitro.
Staph epidermidis and staph. Saprophyticus
are coagulase negative and are usually
commensals.
 However, they are considered to be
potentially pathogenic.
Staph. aureus causes pyogenic infections which
can be hospital acquired, food poisoning and
toxic shock syndrome. (catalase
positive)Coagulase-positive Staphylococcus
aureus
Coag.-neg. Staphylococcus epidermidis, S.
saprophyticus
Impetigo is a contagious superficial pyoderma,
caused by Staphylococcus aureus and/or group A
 Capsule
or slime layer (glycocalyx)
 Peptidoglycan (PG)
 Teichoic acid is covalently linked to PG and is
species specific:

S. aureus

S. epidermidis
 Protein
ribitol teichoic acid
(polysaccharide A)
glycerol teichoic acid
(polysaccharide B)
A is covalently linked to PG
 Clumping factor (bound coagulase)
 Coagulases

(bound or free)
Antigenic
 Hyaluronidase

“spreading factor” of S. aureus
 Nuclease

Cleaves DNA and RNA in S. aureus
 Protease

Staphylokinase (fibrinolysin)
 Lipases
 Esterases
Differential
Characteristics
S. aureus
Coagulase
Fibrinogen  Fibrin
Staphylococcus aureus
Coagulase POS
Coagulase NEG
Biochemical reactions:
1) Catalase test- Positive.
2) Coagulase testi) Slide coagulase test- Positive.
ii) Tube coagulase test- Positive.
SLIDE COAGULASE TEST
TUBE COAGULASE TEST
3) Reduces nitrate to nitrite.
4) Ferments mannitol anaerobically with acid only.
5) Urea hydrolysis test- Positive.
6) Gelatin liquefaction test- Positive.
7) Produces Lipase.
8) Produces Phosphatase.
9) Produces Thermostable nuclease.
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 air borne droplets
Virulence factors:
These include
A) Cell associated factors
B) Extracellular factors
A) CELL ASSOCIATED FACTORS:
a) Cell associated polymers
b) Cell surface proteins
a) CELL ASSOCIATED POLYMERS
1. Cell wall polysaccharide
2. Teichoic acid
3. Capsular polysaccharide
b) CELL SURFACE PROTEINS:
1. Protein A
2. Clumping factor (bound coagulase)
Structure of Staphylococcal cell wall
B) EXTRACELLULAR FACTORS
a) Enzymes
b) Toxins
a) Enzymes:
1. Free coagulase
2. Catalase
3. Lipase
4. Hyaluronidase
5. DNAase
6. Thermonuclease
7. Staphylokinase (Fibrinolysin)
8. Phosphatase
b) Toxins:
1. Cytolytic toxins
i) Haemolysins
Alpha haemolysin
Beta haemolysin
Gamma haemolysin
Delta haemolysin
ii) Leucocidin (Panton-Valentine toxin)
2. Enterotoxin
3. Toxic shock syndrome toxin (TSST)
4. Exfoliative (epidermolytic toxin)
.
Disease:
Diseases produced by Staphylococcus aureus
is studied under 2 groups:
A) Infections
B) Intoxications
A) INFECTIONS:
Mechanism of pathogenesis:
Cocci gain access to damaged skin, mucosal or
tissue site
Colonize by adhering to cells or extracellular
matrix
Evade the host defense mechanisms and multiply
Cause tissue damage
Common Staphylococcal infections are:
1) Skin and soft tissue: Folliculitis, furuncle (boil),
carbuncle, styes, abscess, wound infections,
impetigo, paronychia and less often cellulitis.
Folliculitis
Folliculitis
Furuncle (boil)
Carbuncle
Styes
Abscess
Impetigo
Wound infection
Paronychia
Cellulitis
2) Musculoskeletal: Osteomyelitis, arthritis, bursitis,
pyomyositis.
osteomyelitis
3) Respiratory: Tonsillitis, pharyngitis, sinusitis, otitis,
bronchopneumonia, lung abscess, empyema, rarely
pneumonia.
4) Central nervous system: Abscess, meningitis,
intracranial thrombophlebitis.
5) Endovascular: Bacteremia, septicemia, pyemia,
endocarditis.
Endocarditis
6) Urinary: Urinary tract infection.
B) INTOXICATIOINS:
The disease is caused by the bacterial exotoxins,
which are produced either in the infected host
or preformed in vitro.
There are 3 typesFood poisoning
Toxic shock syndrome
Staphylococcal scalded skin syndrome
.1
.2
.3
1) Food poisoning:
Enterotoxin is responsible for manifestations of
staphylococcal food poisoning.

Eight types of enterotoxin are currently known,
named A, B, C1-3, D, E, and H.

It usually occurs when preformed toxin is ingested
with contaminated food.

The toxin acts directly on the autonomic nervous
system to cause the illness, rather than gut
mucosa.

Cytolytic (cytotoxins; cytolysins)

Alpha toxin - hemolysin


Beta toxin


Hemolytic activity
Delta toxin



Sphingomyelinase
Gamma toxin


Reacts with RBCs
Cytopathic for:
 RBCs‫ش‬
 Macrophages
 Lymphocytes
 Neutrophils
 Platelets
Enterotoxic activity
Leukocidin
Virulence Factors: Exotoxins
Enterotoxin 
Exfoliative toxin (epidermolytic toxin) 
Pyrogenic exotoxins 
Pass skin – first line of defense 
Benign infection
Phagocytosis
Antibody
Inflammatory response



Chronic infections
Delayed hypersensitivity



 1.

Staphylococcus aureus
 2.


Coagulase positive Staphylococci
Coagulase negative Staphylococci
Staphylococcus epidermidis
Staphylococcus saprophyticus
 Major
human pathogen
 Habitat
- part of normal flora in some
humans and animals
 Source
of organism - can be infected
human host, carrier, fomite or
environment
 Many
neonates, children, adults intermittently colonised by S. aureus
 Usual sites - skin, nasopharynx, perineum
 Breach in mucosal barriers - can enter
underlying tissue
 Characteristic abscesses
 Disease due to toxin production
Due to direct 
effect of organism
Local lesions of 
skin
Deep abscesses 
Systemic 
infections
Toxin mediated 
Food poisoning 
toxic shock 
syndrome
Scalded skin 
syndrome
 Boils
 Styes
 Furuncles(infection
of hair follicle)
 Carbancles (infection of several hair follicles)
 Wound infections(progressive appearance of
swelling and pain in a surgical wound after
about 2 days from the surgery)
 Impetigo(skin lesion with blisters that break
and become covered with crusting exudate)
 Can
be single or multiple
 Breast abscess can occur in 1-3% of nursing
mothers in puerperiem
 Can produce mild to severe disease
 Other sites - kidney, brain from septic foci
in blood
 1.

With obvious focus
Osteomyelitis, septic arthritis
 2.


 3.


No obvious focus
heart (infective endocarditis)
Brain(brain abscesses)
Ass. With predisposing factors
multiple abscesses, septicaemia(IV drug users)
Staphylococcal pneumonia (Post viral)
 1.




Staphylococcal food poisoning
Due to production of entero toxins
heat stable entero toxin acts on gut
produces severe vomiting following a very
short incubation period
Resolves on its own within about 24 hours
 High
fever, diarrhoea, shock and
erythematous skin rash which
desquamate
 Mediated via ‘toxic shock syndrome
toxin’
 10% mortality rate
 Described in two groups of patients


ass. With young women using tampones
during menstruation
Described in young children and men
 Disease
of young children
 Mediated through minor Staphylococcal
infection by ‘epidermolytic toxin’
producing strains
 Mild erythema and blistering of skin
followed by shedding of sheets of
epidermis
 Children are otherwise healthy and most
eventually recover
 1.

Gram stain and culture of pus
 2.

In all systemic infections
Blood culture
 3.

In all pus forming lesions
In infections of other tissues
Culture of relevant tissue or exudate
 Skin
commensal
 heart valves,
 Causes urinary tract infection in
cathetarised patients
 Skin
commensal
 Imp. Cause of UTI in sexually active young
women
 Usually sensitive to wide range of
antibiotics