STAPHYLOCOCCI SPECIES INTRODUCTIONStaphylococci is the gram +ve cocci having size 1 µmin diameter and mostly arranged in irregular grape like structure.
Greek word: styphale= bunches of grapes kokkos= berry they are Opportunisticbacteria. In 1871-Von Recklinghausen first observed staphylococci in humanpyogenic bacteria. In 1880-SirAlexander Ogston named staphylococci. It comprises about 40 species andsubspecies 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 andteichoic acid also present. Unique property of the protein A is to bind to Fcpart 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 CHARECTERISTICSIt can be grow readily on ordinary media. It requires optimumtempereture: 37°C, pH-(7.4-7.6) & aerobe and facultative anaerobe.
Colonymorphology is large 2-4 mm, circular, convex, smooth & opaque.The colonies produceby staphylococci is golden yellow colony on nutrient agar (oil paint appearance). On the blood agarit produces hemolytic or non-hemolytic colonies.It also grows on Mannitol saltagar.
BIOCHEMICAL TEST Indole test negative Urease test Positive Methyl red test Positive Catalase test Positive Modified oxidase test Negative · Coagulase test: Suspension ofstaphylococci is mixed with rabbit plasma. The coagulase enzyme secreted bybacteria covert the fibrinogen of the rabbit plasma to fibrin and clottingoccurs. A. slide test: Detect bound coagulase orclumping factor on bacterial surface. Then clumping occurs in 1-2 min B.Tubetest: Detect coagulase which is secreted by bacteria in plasma. Then clottingoccurs after incubation at 37 °C for 24 hrs.
· HABITAT Staphylococci are commensaleson skin of animals and man. Isolated commonly from mucus membrane of upperrespiratory tract and lower urogenital tract & transient digestive tract. Selectiveaffinity to species of animal. PATHOGENESIS AND PATHOGENECITYStaphylococci are the pyogenic bacteria mainly in suppurativelesions.Minor trauma or immunosuppresion may predispose the development of infection.
Structural features like capsular polysaccharides, teichoic acid and protein Ainterfere with opsonization and subsequent phagocytosis. Coagulase – majorindicator 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 DIAGNOSTICPROCEDURE Infectiousmaterial from exudates &mastitis milk.
Gram stained smear from pus. Cultureon blood agar, selective blood agar and Mc Conkey’s agar and incubatedaerobically at 37°C for 24 -48 hrs. IDENTIFICATIONCRITERIAü Colonial characteristicsü Haemolysisü Growth on Mc Conkey´s agarü Catalaseü Biochemical procedure