STAPHYLOCOCCI SPECIES

 

INTRODUCTION

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Staphylococci is the gram +ve cocci having size 1 µm
in diameter and mostly arranged in irregular grape like structure. Greek word: styphale
= bunches of grapes      kokkos
= berry                                                          they are Opportunistic
bacteria. In 1871-Von Recklinghausen first observed staphylococci in human
pyogenic bacteria. In 1880-Sir
Alexander Ogston named staphylococci. It comprises about 40 species and
subspecies today.

CHARACTERISTICS                                                                                                                        
Staphylococci are facultative anaerobes, catalase positive,
non-motile, oxidase negative and do not forms spore (except S.saccharolyticus).
Peptidoglycan and protein A is the major component of the cell wall and
teichoic acid also present. Unique property of the protein A is to bind to Fc
part of the IgG3.On the basis of enzyme coagulase there are 2 groups:                                                       
         1.coagulase  positive e.g. S.aureus,
S.intermedialis, S.hyicus                     
                                                 2.coagulase negative:  e.g. S.haemolyticus                                                                                                                         

CULTURE CHARECTERISTICS

It can be grow readily on ordinary media. It requires optimum
tempereture: 37°C, pH-(7.4-7.6) & aerobe and facultative anaerobe. Colony
morphology is large 2-4 mm, circular, convex, smooth & opaque.The colonies produce
by staphylococci is golden yellow colony on nutrient agar (oil paint appearance). On the blood agar
it produces hemolytic or non-hemolytic colonies.It also grows on Mannitol salt
agar.

 

BIOCHEMICAL TEST

Indole test

 negative

Urease test

Positive

Methyl red test

Positive

Catalase test

Positive

Modified oxidase test

Negative

 

 

 

 

 

 

·        
Coagulase test: Suspension of
staphylococci is mixed with rabbit plasma. The coagulase enzyme secreted by
bacteria covert the fibrinogen of the rabbit plasma to fibrin and clotting
occurs.           

 A. slide test: Detect bound coagulase or
clumping factor on bacterial surface. Then clumping occurs in 1-2 min                                                                                                                       
                                    B.Tube
test: Detect coagulase which is secreted by bacteria in plasma. Then clotting
occurs after incubation at 37 °C for 24 hrs.                                                                                                                              

·        
HABITAT                                                                      
                                                                               Staphylococci are commensales
on skin of animals and man. Isolated commonly from mucus membrane of upper
respiratory tract and lower urogenital tract & transient digestive tract. Selective
affinity to species of animal.

                                                                                                                                                                               
PATHOGENESIS AND PATHOGENECITY

Staphylococci are the pyogenic bacteria mainly in suppurative
lesions.Minor trauma or immunosuppresion may predispose the development of infection.
Structural features like capsular polysaccharides, teichoic acid and protein A
interfere with opsonization and subsequent phagocytosis. Coagulase – major
indicator of pathogeneity.

hosts

Clinical condition

S.aureus

cattle

Mastitis, udder impetigo

sheep

Tick pyaemia
Dermatitis
Benign folliculitis

goats

Mastitis
Dermatitis

Pig

Botryomycosis of mammary
gland

horses

Scirrhous cord, mastitis

dogs

Suppurative conditions

poultry

Bumble foot , omphalitis

S.Intermedius

dogs

Pyoderma,endometritis,cystitis

cats

Various pyogenic conditions

cattle

mastitis

 

 

 

 

 

 

 

 

DIAGNOSTIC
PROCEDURE                                                                                                                         Infectious
material from exudates &mastitis milk. Gram stained smear from pus. Culture
on blood agar, selective blood agar and Mc Conkey’s agar and incubated
aerobically at 37°C for 24 -48 hrs.

 

IDENTIFICATION
CRITERIA

ü  Colonial characteristics

ü  Haemolysis

ü  Growth on Mc Conkey´s agar

ü  Catalase

ü  Biochemical procedure

 

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