 Staphyloccocci
- derived from Greek
“staphyl” (bunch of grapes)
 Gram positive cocci arranged in clusters
but some, especially when examined in
pathological specimens, may occur as
single cells or pairs of cells.
 Include a major human pathogen and skin
commensals
 Non
motile
 Non spore forming
 Usually non-capsulate
 32 species
 Catalase- positive distinguishing them from
the genus streptococcus wich are catalsenegative
 Oxidase- negative
4
 Staphylococcus
species are generally
nonfastidious
 They grow well on media without blood or
other special supplements
the genus Staphylococcus was separated from
Micrococcus .differentiated the two genera
depends mainly on the basis of their action on
gelatin and on relation to their hosts.
Staphylococci liquefied gelatin whereas
micrococci were variable in their action on
gelatin .
The genera Staphylococcus,
Micrococcus and Planococcus,
containing Gram-positive,
catalase-positive cocci,
were later placed in the
family Micrococcaceae
 Staphylococci
are tolerate a high salt
concentrations; they grow on media containing
5%-7.5% NaCl (e.g. Mannitol Salt Agar)
 pathogenic Staphylococci are commonly
identified by their ability to produce
coagulase, and thus clot.
 Staphylococcus aureus a major pathogen of
increasing importance due to the rise its
antibiotic resistance.
 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.
Catalase POS
Staphylococcus
Catalase NEG
Gram Positive Coccus
Catalase
+
Salt Tolerant
Yes
Facultative
Yes
Staphylococcus
No
Rothia
No
Micrococcus
_
Streptococcus
Group
 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
 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.

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
 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
Staph. aureus causes pyogenic infections which
can be hospital acquired, food poisoning and
toxic shock syndrome.
Impetigo is a contagious superficial pyoderma,
caused by Staphylococcus aureus and/or group A
Differential
Characteristics
S. aureus
Coagulase
Fibrinogen  Fibrin
1)
All Staph group organisms that grow in air
are catalase positive
Rothia is catalase negative (or weakly
positive).
2) Coagulase testi) Slide coagulase test- Positive.
ii) Tube coagulase test- Positive.
SLIDE COAGULASE TEST
TUBE COAGULASE TEST
Staphylococcus aureus
Coagulase POS
Coagulase NEG
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.
Some virulence factor of
Staphylococcus aureus
A) CELL ASSOCIATED FACTORS:
CELL WALL POLYMERS
1. Cell wall polysaccharide inhibits inflammatory
response; endotoxin-like activity
2. Teichoic acid: Phage adsorption; reservior of
bound divalent action
3. Capsular polysaccharide
b) CELL SURFACE PROTEINS:
1. Protein A: reacts with Fsregion of Ig G
2. Clumping factor: binds to fibrinogen
Structure of Staphylococcal cell wall
B) EXTRACELLULAR FACTORS
a) Enzymes
b) Toxins
a) Enzymes:
1. Free coagulase: converts fibrinogen to fibrin in
plasma
2. Catalase
3. Lipase: degrades lipid
4. Hyaluronidase
5. DNAase: degrades DNA
6. Thermonuclease
7. Staphylokinase: degrades fibrin (Fibrinolysin)
8. Phosphatase
b) Toxins:
1. Cytolytic toxins
i) Haemolysins
Alpha haemolysin
Beta haemolysin
Gamma haemolysin
ii) Leucocidin (PantonValentine toxin)
Impairment of
membrane
permeability;
cytotoxic effects on
phagocytic and tissue
cells
Staphylococcus toxins
1. Enterotoxin: commonly produced by up to 65%
of S.aureus, these toxic proteins withstand
Exposure to 100c for several minutes.
When ingested as performed toxins in
contaminated food microgam
amount of toxin can induce within a few hours
the symptoms of staphylococcal
food poisoning: nausea, vomiting and
diarrhoea. Resolves on its own
within about 24 hours
.
2. Toxic shock syndrome toxin (TSST):
discovered in the early of 1980s, a
multysystem disease caused by
staphylococcal TSST-1. the absence of
circulating antibodies to SST-1 is a
factor in the pathogenesis of this
syndrome

Toxic shock syndrome:
 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
 With young women using tampones
during menstruation
 Described in young children and men
3. Exfoliative (epidermolytic toxin): the
most dramati manifestation of
epidermolytic toxin is Scalded skin
syndrom where the toxin speeds
systematically in individuals who lack
neutrolizing antitoxin: extensive areas of
skin are affected, wich after the
development of painful rash, slough off;
the skin surface resembles scalding. Such
blistering lesions are seen mainly, but not
exlusively, in small children.
 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
PATHOGENICITY:
Source of infection:
A) Exogenous: patients or carriers
B) Endogenous: From colonized site
Staphylococci do not grow outside the body except
occationally in moist nutrient materials such as meat,
milk and dirty water, and it is important to remember
that the body surfaces of human beings and animals
are the main reservoir. Although not spore forming,
they may remain alive in a dormant state for several
months when dried in pus, sputum, bed clothes or
dust
Mode of transmission:
A) Contact: direct or indirect
( through fomites)
B) Inhalation of air borne
droplets
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.
1. In all pus forming lesions
 Gram stain and culture of pus
2. In all systemic infections
 Blood culture
3. In infections of other tissues
 Culture of relevant tissue or exudate
4. Faeces or vomit from patients with
suspected food poisoning or remains of
implicated food.
5. Blood from patients with suspected
cystitis or pyelonephritis
 Staphylococci
are inherntly sensitive to many
antimicrobial agents, but 90% of strains
found in hospitals are now resistant.
Resistance of pencillin depends on
production of the enzyme pencillinase.
Antibiotic resistance can arise by various
mechanisms. MRSA strains are an increasing
infection control problome and therapeutic
challenge. These strains, wich are resistant to all
β- lactam agents, commonly colonize broken
skin, but cause the full range of staphyolococcal
infections. MRSA not a hospital pathogens with
multiresistance , it also become more common in
the community.
Glycopeptides (Vancomycin or Teicoplanin) are
the agents of choice in the treatment of
systemmic infection.
 They
are commonly found on the surface
of healthy persons in whom they are rarely
the cause of infection.
 More than 30 species are recognized, but
few are commonly incriminated in human
infection.
 Staph. epidermidis accounts for about 75%
of all clinical isolates, probably reflecting
its preponderance in the normal skin flora.
Staph.
epidermidis
Staph. Haemolyticus
Staph. Saprophyticus
Staph.hominis
Staph. capitis
 Opportunistic
pathogens, often
colonize biomedical device such as
protheses, implants and intravascular
lines, they cause particular probloms
in Cardiac surgery
 Continuous ambolatory peritoneal
dialysis
 Immunocompromised patients
 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