Staphylococcus

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Staphylococcus

  1. 1. STAPHYLOCOCCUS GRAM + COCCI “BUNCH OF GRAPES”
  2. 2. Staph.aurues
  3. 4. <ul><li>Ubiquitous-,most common cause of localised supperative lesions in the human beingsHas ability to devlp resistance against penicilline </li></ul><ul><li>First observed in human pyogenic lesions-Von Recklinghousen </li></ul><ul><li>Pasteur-obtained liquid cultures of the cocci from pus& inoculated them into rabbits </li></ul><ul><li>Sir Alexander Ogston-causitve role of coccus in abcess.,named staphylococccus,found nonvirulent strains in skin </li></ul><ul><li>Mostly frm,pyogenic-golden yellow colonies </li></ul>
  4. 5. <ul><li>Nl skin-white colonies </li></ul><ul><li>Rosenbach-Staph.aureus & albus </li></ul><ul><li>Passet-citreus-lemon yellow colonies </li></ul><ul><li>Indicators of virulence-hemolysis,gelatin liquifaction,lipolytic activity,production of urease,phosphatase,etc-not reliable </li></ul><ul><li>Most constant asso.-virulence---coagulase enz. Production </li></ul><ul><li>Lesser eztend to fermentaion of mannitol </li></ul>
  5. 6. <ul><li>Staph.aureus/s.albicans-C+,Mf+,pathogenic </li></ul><ul><li>Staph.epidermidis/s.albus-C-,Mf-,non patho </li></ul><ul><li>Staph-haemolyticus-patho,C- </li></ul><ul><li>Staph.saprphyticus-patho,C- </li></ul><ul><li>Staph.hominis,S.capitus-commensal flora of human skin </li></ul>
  6. 7. Staphylococcus aureus <ul><li>MOPHOLOGY </li></ul><ul><li>spherical cocci—1micron d—grape like clusters—found singly—long chains never occur—NONMOTILE--NONSPORING—NONCAPSULATED </li></ul><ul><li>Some small am.capsular mat. </li></ul><ul><li>Stains-aniline dyes,G+ </li></ul><ul><li>Under penicillin,may change to L forms </li></ul>
  7. 8. <ul><li>CULTURAL CH. </li></ul><ul><li>Grows in ordinary media—optimum temt-37C—PH 7.4-7.6—aerobes &facultative anaerobes </li></ul><ul><li>On nutrient agar-colonies large,circular,covex,smooth,shiny,opaque& easily emulsfiable.pigment prodcn.22C,only on aerobic cultures </li></ul><ul><li>Pigment=Lipoprotein+carotene </li></ul><ul><li>-slope-Oil paint appearance-llr 2 in blood agar </li></ul><ul><li>--most strains r haemolytic </li></ul>
  8. 14. <ul><li>Esp.20-25%Co2 </li></ul><ul><li>MacConkys agar-smaller colonies-pink-lactoseF </li></ul><ul><li>Liquid media-uniform turbidity- </li></ul><ul><li>Selective media 4 isolation-4m specimens-feces-----8-10% NaCl(salt-milk ag.,salt broth)—LiCl,Tellurite(Ludlam’s media),& Polymyxin) </li></ul><ul><li>Prim isolation-Sheep blood ag. </li></ul><ul><li>Human blood not used-antibodies and othr inhibitors </li></ul>
  9. 15. <ul><li>BIOCHEMICAL REACTIONS </li></ul><ul><li>F-sugars,----acid,no gas </li></ul><ul><li>MannitolF-Staph.aureus,C+, </li></ul><ul><li>Urea hydrolysis </li></ul><ul><li>Reduce nitrates 2 nitites </li></ul><ul><li>Liquify gelatin </li></ul><ul><li>MR+,VP+,Indole- </li></ul><ul><li>Most—lipolytic,in egg yolk—dense opacity </li></ul><ul><li>Phophatse prdcn-aureus+,epidemidis- </li></ul><ul><li>K.tellurite---black colonies </li></ul><ul><li>Thermostable nucleases </li></ul>
  10. 16. <ul><li>RESISTANCE </li></ul><ul><li>Well resistant non sporing—dried threads-3-6 months </li></ul><ul><li>Thermal death point-62c for 30 min-----some 80C,sm grow at 45C </li></ul><ul><li>Most grow-10-15% NaCl---imp in food preservation </li></ul><ul><li>Resist 1% phenol for 15 min </li></ul><ul><li>HgCl(1%)-10 min,aniline dyes bactericidal,crystal violet </li></ul><ul><li>FA inhibits growth-highly unsaturated—more on C+ than C- </li></ul>
  11. 17. <ul><li>Uniformly resistant 2 lysozymes----ex.sm micrococci </li></ul><ul><li>Sensitive 2 LYSOSTAPHIN-mix of enz produced by particular strains of Staph.epidermidis </li></ul><ul><li>* PENICILLIN Resistance </li></ul><ul><li>3 types </li></ul><ul><li>1.Prodcn of beta –lactamase(penicillinase)-4types-A(hospital strains),B,C,D-inducible,controlld by plasmids,transmitted-transduction/conjugation </li></ul>
  12. 18. <ul><li>2.Chromosomal chng---chng in receptors,ruduce binding---covers beta lactamase resistnt penicilline-METHICILLINS,CLOXACILLINS </li></ul><ul><li>EMRSA-epidemic Methicilline resist.staph.aureus-----hospital inf. </li></ul><ul><li>3.Devlpmnt of tolerence-only inhibited not killed </li></ul><ul><li>* Pathogenecity & virulence </li></ul><ul><li>Staph-2 typs of infections-infections& intoxications </li></ul>
  13. 19. <ul><li>Infections-damaged skin—adhere 2 cells---evade host’s defence mech.—multiply—tissue damage </li></ul><ul><li>Intoxications-d/s-bac.toxins---exotoxins </li></ul><ul><li>Virulence factors </li></ul><ul><li>1.Cell associatd polymers </li></ul><ul><li>2.Cell surface proteins </li></ul><ul><li>3.Extracellular enzymes </li></ul><ul><li>4.Toxins </li></ul>
  14. 20. <ul><li>Cell associated polymers </li></ul><ul><li>1.Cell wall polysach,peptidoglycan----+ts complements-release of inflammatory cytokines </li></ul><ul><li>2.Teichoic acid-complement mediated opsonisation </li></ul><ul><li>3.Capsular poly sach. Surrounding cellwall----inhibits opsonisation </li></ul>
  15. 21. <ul><li>Cell surface proteins </li></ul><ul><li>*Protein A-chemotactic,antiphagocytic,anticomplementaryplt damage hypersensitivity </li></ul><ul><li>*binds 2 Fc (Ig),except IgG3,Fab free---proteinA +IgG---mixd with corresponding antgen—agglutination----used fr grouping </li></ul><ul><li>P-A is a B cell mitogen </li></ul><ul><li>Also used as ligand fr isolation of IgG </li></ul><ul><li>Clumping Factor(bound coagulase),heat stable,no need of CRF 2 coagulate-anothr surf.pro.---recp. fr Slide coagulase test. </li></ul>
  16. 22. <ul><li>Slide Coagulase Test </li></ul><ul><li>Saline staph.aureus+human plasma---cocci clumped---for identification of aures </li></ul><ul><li>Capsulated—negas clumping f,envelopd by capsular polysach </li></ul><ul><li>*Extra cellular Enzymes </li></ul><ul><li>Coagulase-binds CRF(reacting factor)—bins 2 prothrombin-fibrinogen tom fibrin---clots human plasma </li></ul><ul><li>Coagulase 8 types-,eg,C-A in human strains </li></ul><ul><li>Coagulase is secretd into medium-clotting </li></ul>
  17. 23. <ul><li>Lipases </li></ul><ul><li>To infect skin& subcutaneous tissue----Hyaluronidase breaks down connective tissue,Staphylokinase(fibrinolysin),fatty acid modifying enzymes& proteases---initiation &spresd of infestion </li></ul><ul><li>*Nuclease </li></ul><ul><li>*Protein receptor </li></ul><ul><li>Posses rec. for many human proteins-fibronectin,fibrinogen,IgG,C1q----facilitate adhesion </li></ul>
  18. 24. <ul><li>Toxins </li></ul><ul><li>1.Cytotoxin </li></ul><ul><li>2.Enterotoxin </li></ul><ul><li>3.Exfoliative toxin </li></ul><ul><li>Cytotoxins </li></ul><ul><li>Membrane active substances-4haemolysins+1lecocidin </li></ul><ul><li>*Alpha,Beta,Gamma,Delta </li></ul><ul><li>Alpha </li></ul><ul><li>Inactivatd at 70C,reactivatd at 100C-at 60C it combines with a heat labile inhibitor which is denatured at 100C </li></ul>
  19. 25. <ul><li>Less active against human cells,leucocidal,cytotoxic,dermonecrotic,neurotoxic,lethal,toxic to macrophages,lysosomes,muscle tissues,renal cortex,circulatory sys. </li></ul><ul><li>Beta </li></ul><ul><li>Sphingomyelinase,hemolytic for sheep cells,not for human cells, </li></ul><ul><li>Exhibits a HOT-COLD phenomenon,hemolysis being initiatd at 37C,but become evident only after chilling </li></ul>
  20. 26. <ul><li>Gamma-twp separate pro. </li></ul><ul><li>Delta detergnt like action on macro,rbc,wbc,plts </li></ul><ul><li>Leucocidin/Panton Valentine Toxin-two compont toxin(s&f),---Synergohymenotropic hormones </li></ul><ul><li>* Enterotoxin </li></ul><ul><li>Cause food poi.NVD—2-6hrs after intake of preformd toxin </li></ul><ul><li>Heat stable,100C—10-40min,mostly-meat,fish,milk and milk products---at room temp </li></ul><ul><li>Illness self limited,recovery in a day,eight antigenic types—A,B,C(1-3),D,E,H </li></ul><ul><li>Directly act on ANS-fever,thn on GI mucosa,toxin is antigenic-neutralisd by specific antitoxin, </li></ul>
  21. 27. <ul><li>Serological test-latex agglutination,ELISA </li></ul><ul><li>Potent toxin,microgrms-illness,sm cause post antibiotic diarrhoea,-----also exhibits miogenic,pyogenic,hypotensive,thrombocytopenic,and cytotoxic </li></ul><ul><li>TSST(Toxic Shock SyndromeToxin) </li></ul><ul><li>Multisystem ds.fever,hypotn,myalgia,v,d,mucosal hyperemia,erythromatous rash,-desquamate latr </li></ul><ul><li>Inf-by staph.aureus producing TSST,(bacteriophage group 1) </li></ul>
  22. 28. <ul><li>TSST type 1,/enterotoxin type F/pyogenic exotoxin C, </li></ul><ul><li>*TSST 1-superantigens---potent activators of Tlymphocytes </li></ul><ul><li>Being Vbeta restrictd T cell mitogens-+ts laege no. of T cells—without relation to their epitope specificity---dys regulatd immune response.---with release of cytokines,IL1,2,TNF,TNgamma--- explains multisystem inv. </li></ul>
  23. 29. <ul><li>Exfoliative Toxin/ET/Exfoliatin </li></ul><ul><li>Resp.4 SSSS-Staph.scalded skin syndrome </li></ul><ul><li>Outr layr of epidermis gets seperatd from the underlying tissue </li></ul><ul><li>Sevr form—Ritter’s Ds.(newborn).& Toxic epidermal necrolysis(older) </li></ul><ul><li>Milder forms r pemphigus neonatorum&bullous empetigo </li></ul>
  24. 30. <ul><li>Staphylococcus diseases </li></ul><ul><li>Mostly localised pyogenic lesions </li></ul><ul><li>Skin and soft tissue-folliculitis-furuncle-abcess-carbuncle-wnd inf-impetigo-paronychia-cellulits </li></ul><ul><li>Muskuloskeltal-Osteoarthritis-arthritis-bursitis-pyomyositis </li></ul><ul><li>Respiratory-Tonsilitis-pharyngitis-sinusitis-otitis-bronchopnuemonia-lung abcess-empyems- </li></ul><ul><li>CNS-abcess-meningitis-intracranial thrombophlebitis </li></ul><ul><li>Endovascular-Bacteremia,septicemia,pyemia,endocarditis </li></ul><ul><li>Urinary-uncommon-bt with instrumnts,implants,diabets,urinary isolats-sigfic-related to bacteremia </li></ul>
  25. 31. <ul><li>Bacteriophage typing </li></ul><ul><li>Staphylococci typed basd on their susceptability to bacteriophage </li></ul><ul><li>Acceptd set of phages r thr </li></ul><ul><li>Staph stain-culturd in nutrint agar-dried—phage applied—if lysed by phage---typed </li></ul><ul><li>* Epedemiology </li></ul><ul><li>Primary parasites of humans-colonising skin-skin glands-mucus memb.carries in nose ,perinium, hairs,vagina(rises during mensus-TSS relatd 2 menstruation) </li></ul><ul><li>Shedders-large no. of coccal spread </li></ul><ul><li>MOT-fomites,dust,airborne droplts </li></ul><ul><li>Common cause of post operative wound inf.hosp.staff attackd—local application neomycin,chlorhexidine </li></ul>
  26. 32. <ul><li>Lab diagnosis </li></ul><ul><li>Specimen-pus,supperative lesions-sputum,feces </li></ul><ul><li>Carriers-nasal swab </li></ul><ul><li>diagnosis---by culturing—platd on blood agar appear aftr overnight incubation </li></ul><ul><li>Scanty no.-ludlam’s media/salt milk agar/Robertson’s cookd meat medium+10% NaCl </li></ul><ul><li>Coagulase test done-Tube & Slide </li></ul><ul><li>Tube-detects free coagulase </li></ul>
  27. 33. <ul><li>0.1 ml cultr+0.5ml human/rabbit plasma-----EDTA,oxalate/heparin----incubatd in water bath at 37C---3-6hrs </li></ul><ul><li>If poitive----plasma clots and does not flow when the tube is tilted </li></ul><ul><li>Citrates not used-utilised by conatminent bact </li></ul><ul><li>Continued incubation-not preferrd-clot lysed by fibrinogen of sm strains </li></ul><ul><li>Slide test-bound coagulase-in divergence tube test is the determinent.Slide coagulse test </li></ul><ul><li>Antibiotics sensitivity checkd </li></ul><ul><li>Bacteriuophage typing-epidemiological </li></ul><ul><li>Hidden deep inf—Antistaphylolysin titres of more than 2unitsper ml---deep seatd---bone abcess </li></ul>
  28. 34. <ul><li>Treatment </li></ul><ul><li>Benzyl penicilln-most effective </li></ul><ul><li>Methicilline </li></ul><ul><li>Cloxacilline </li></ul><ul><li>Vancomysin </li></ul><ul><li>Other C+ Staphylococci-intermedius,hyicus </li></ul><ul><li>C- staphs…nl flora---epidermidis,hemlyticus,saprophyticus </li></ul><ul><li>Epidermidis-human skin----stitch abcess—rows on implanted foreign bodies </li></ul>
  29. 35. Micrococci <ul><li>G+ </li></ul><ul><li>Pairs tetrads,irregular clusters </li></ul><ul><li>C+,O+ </li></ul><ul><li>Aerobic +strictly respiratory met,parasitic nl skin </li></ul><ul><li>Resmble staph—in staind smears generally larger & more gram variable—in cultures form small colonies </li></ul><ul><li>Differentiate---HUGH & LEIFSON’S oxidation fermentation tests---micrococci-oxidative </li></ul><ul><li>Staph--fermentation </li></ul>

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