Staphylococcus aureus
- 1. STAPHYLOCOCCUS AUREUS Prepared by A.TAJNISHA II M.Sc., Microbiology Under Guidence of MRS. SELVAJEYANTHI Asst.Professor Department of Microbiology Tiruppur Kumaran College For Women. Tirupur.
- 2. Staphylococcus aureus : overview of bacteriology, clinical diseases, epidemiology ,antibiotic resistance and therapeutic apporach. ABSTRACT: staphylococcus aureus is an important human pathogen that causes wide range of infectious both in nosocomial and community settings. The gram positive pathogen is armed with battery of virulence factors that facilitates to establish infections in the hosts. Class- Baccilli. Order- Bacillales. family- Staphylococcaeae. Genus – Staphylococcus. species : Staphylococcus aureus, Staphylococcus albus, Taxonomy
- 3. Morphology Gram positive cocci 0.5-to1.5µ in size A few strains are capsulated. Arranged in grape like cluster or groups. non motile ,non sporing
- 4. Cultural charateristics Grows an ordinary media. Optimum temperature 37◦c. Optimum ph -7.4. Aerobes and facultative anaerobe. GROWTH ON ORDINARY MEDIA: Nutrient agar : colonies are circular with entire edge, convex, smooth and opaque and emulsify easily. Colonies appears golden yellow in colour confluent growth resembles on oil plant.
- 5. MEDIAS BLOOD AGAR: colonies are bigger than these on nutrient agar . A clear zone of beta heamolysis is produced around the colonies.
- 6. Media in growth Macconkey agar : small, opaque ,pink colonies.
- 7. Media in growth Mannitol salt agar: nutrient agar containing mannitol, sodium choloride, and phenol red, Staphyloccocus aureus ferments mannitol and produces yellow c.oloured colonies.
- 8. Biochemical properties Ferments glucose,lactose,sucrose,maltose&mannitol with acid production. No gas is produced. Catalase positive & oxidase negative. Hydrolysis urea. Reduces nitrates to nitrites. Liquifies gelatin. MR,VP positive and negative.
- 9. Antigenic structure Capsular antigen A few strains are encapsulated and are more virulent than non capsulated formed The capsular polysaccharide inhibits phagocytosis and facilitates the adherence of their organisms to host cells
- 10. CELL WALL ANTIGEN Peptidoglycon- activates complement and induces release of the inflammatory cytokines Teichoic acid- specific antigenic determinant favours adhesion of the cocci to the host cell surface .products them from complement mediated opsonisation Protein A- of the cell posses chemotactic,an tiphagocytic,an ticomplementa ry properties
- 12. Enzymes and toxins Staphylococcus aureus -produces a number of enzymes and toxins which play an important role in the pathogenicity of the organisms. ENZYMES: Cogulase- its an enzyme that cause clotting of human or rabbit plasma .coagulase exit two forms – free and bound. Phosphate-its produced by coagulase positive strains of Staphylococcus.
- 13. Enzymes and toxins Hyaluronidase-it hydrolyses the hyaluronic acid present in the connective tissue and facilitates the speed of infection. Staphylokinase-it break down fibrin clots and allows the spread of organisms to adjacent tissues. Lipases- these lipids hydrolyses helps the organisms in infecting the skin and subcutaneous tissue. Deoxyribonuclease-hydrolyses the DNA TOXINS Hemolyisns- four antigenically distinct types of exotoxins called alpha, beta, gamma,and delta haemolyisns are produces
- 14. Kkkkkkkkk also known as panto valentine toxin toxin its consists of two components components both the components components damage polymorph onuclear leucocytes and macropahges . This toxin secreated by Staphylococus Aureus is responsible food poisoining, nausea, Vomiting and diarrhoea. leucocidins exterotoxin
- 15. TOXINS TOXIC STOCK SYNDROME TOXIN: It produced by strains belonging to group 1.these strains colonize vagina more frequently. The toxic shock syndrome is characterized by fever, hypotension, vomiting, diarrhoae, erythamatous rash which desquamates subsequently. EXOFOLITATE TOXIN: Staphylococcus aureus belonging to bacteriophage group is produce this toxin. Its is responsible for “Staphylococcal scalded skin syndrome”(SSSS) in which outer layer of epidermis gets separated from the under lying tissues. In newborn its sense form known as Riffer’s diseaes and in older patients as toxic epidermal necrolysis.
- 16. GENERAL PATHOGENESIS &CLINICAL DISEASES • PATHOGENESIS: The process of S.aureus infections involves five stages: colonizati on local infection Systemic dissemination sepsis Metastat ic infection Toxinosi s
- 17. Infections • The organisms in carrier state in the anterior nares and can remain without causing infections for weeks or month. • The colonization proceeds to infection under certain predisposing factors such as prolonged hospitalization, immune suppression, surgeries, use of invasive medical devices and chronic metabolic diseases . • Localized skin abcess develop when the organisms is inoculated into the skin from a site of carriage. • The organisms can enter into blood and spread systematically to different organs causing sepsis. • This haematogenous spread may result in endocarditis, osteomyelitis, renal carbuncle, septic arthritis and epidural abcess. Without blood stream infection, and pleuropulmonary infections.other Clinical infections are epidural abcess,meningitis,toxic shock syndromeand urinary tract infections.
- 18. Hospital and community infections • S.aureus causes wide range of infections in human. • The clinical infections S.aureus are classified into two community and nosocomial categories based on origin infection. • These two types are distinct in clinical manifestation of infections, antibiotic susceptibility and the genetic background of the infecting S.aureus strains. • for decades ,S.aureus has been predominately a nosocomial pathogen and is a leading cause of mortality and morbidity in hospitals. • However, the community S.aureus infections are in rise.
- 20. VIRULENCE FACTORS • S.aureus posses battery of virulence factors. • these factors enable the organisms to be successful as pathogen that causes wide range of human and animal infections. • Virulence factors help in attachment to host cells, breaking down host immune shield tissue invasion, causing sepsis,and elicit toxin mediated syndromes. • This is basis for persistant Staphylococcal infections without strong host immune response . • Based on their mechanism of action and role in pathogenesis, Staphylococcal virulence factors are classified.
- 21. EPIDEMIOLOGY OF INFECTION • Nasal carriage • Emergence and evolution of MRSA • Health care associated and community MRSA • Community associated MRSA MRSA (methicilin resistance S.aureus) Methicilin resistance S.aureus (MRSA ) infection is caused by a type of bacteria that become resistant to many antibiotic used to treat ordinary staph infections.
- 23. TRANSMISSION OF Staphylococcus aureus • risk factors in athletes SA infecti on Outbreak.
- 25. Infections caused during the S.aureus in affected Cutaneous infection • Carbuncles. • Pustules. • Boils. • Abscesses. • Styes. • Impetigo. • Wound. • Burn infections.
- 26. • DEEP INFECTION • osteomycelitis • Sinustis • Tonsillitis • Pharyngists • Pneumonits • Empyema • Endocardititis meningitis • Septiciemia
- 27. LABORATORY DIAGNOSIS Sample collection Direct smear microscopy Culture Biochemicals Typing of S.aureus Antibiotic sensitivity testing (AST)
- 28. • SAMPLE COLLECTION. • TYPE OF SAMPLE DEPENDS ON THE SITE OF INFECTION. INFECTION SPECIMEN SUPPURATIVE LESIons Pus, wound swap RESPIRATORY INFECTION sputum UTI Mid stream urine PUO,BACTEREMIA blood FOOD POISIONING Feces, vomitus,food CARRIERS Nasal and perinal swab.
- 29. DIRECT SMEAR MICROSCOPY • Staphylococcus aureus appear as GPC measuring 0.5-1.5 microns • Occur singly ,in pairs, short chains or clusters. • present within outside PMNs. • Reporting of direct smears • Quantifation of cell types and microorganisms. • Eg. Many pus cells along with moderate number GPC seen. CULTURE: Specimen are inoculated onto the suitable media. Plates incubated for 18-24 hour at 37◦c On nutrient agar Colonies are golden yellow and opaque with smooth glistening surface, 2-4 mm in diameter,circular,convex,shiny
- 30. • Nutrient agar Confluent growth, oil paint appearance. Blood agar: colonies similar to those on nutrient agar. Colonies are beta –hemolytic Liquid media –uniform turbitity
- 31. • LIQUID MEDIUM • Uniform turbity Mac conkey agar : Small pink colonies due to lactose.
- 32. SELECTIVE MEDIA MSA -1% mannitol + 7.5% Nacl+phenol red SALT MILK AGAR :-6.5%Nacl + phenol +10% skimmed milk LUDLAMS MEDIUM- lithium chloride and tellurite.
- 33. BIOCHEMICALS REACTIONS Catalase : positive Cogulase test : positive Oxidase : negative Ferment glucose, lactose, maltose, sucrose, and mannitol, with production of acid but no gas. Indole : negative MR : positive Vp : positive Gelatin liquefaction :positive Phosphatase : positive
- 34. TREATMENT • Benzyl pencillin – is the most antibiotic but almost all the strains of Staphylococcus aureus have developed resistance towards this drug due to the production beta lactamase.
- 35. TREATMENT • PENCILLINS like methicilin and cloxacillins . Are effective against such strains . However,since 1980 methicillin – resistant staphylococcus. have been isolated world wide.
- 36. CLOXACILLIN
- 37. VANCOMYCIN AND TEICHOPLANIN • Vancomycin and teichoplanin are the drugs of choice for treatment of MRS
- 38. PREVENTION • Keep your hand clean by washing them throughly with soap and water • Keep cut and scarps clean and covered with bandages untill they heal • Avoid contact with other people’s wounds or bandages
- 39. REFERENCES 1)FRONTIERS IN STAPHYLOCOCCUS AUREUS EDITED BY SHYMAA ENANY AND LAURA E.CROTTY ALEXANTER PAGE NO 1-67.... 2)LABORATORY DIAGONIS OF STAPHYLOCOCCUS MADE BY SHSLINI BISHT... 3) STAPHYLOCCOCI –MAHESH YADEV MEDICAL MICROBIOLOGY .......