1.STAPHYLOCOCCUS INHOSPITAL PRACTICE Dr.T.V.Rao MDDR.T.V.RAO MD1

2. STAPHYLOCOCCUS Sir Alexander Ogston, a Scottish surgeon, first showed in 1880that a number of human pyogenic diseases were associatedwith a cluster-forming micro-organism. He introduced the name staphylococcus (Greek: staphyle = bunch of grapes; kokkos = grain or berry), now used as the genus name for a group of facultatively anaerobic, catalase-positive, Gram- positive cocci.DR.T.V.RAO MD2 3. DR.T.V.RAO MD 3 4. INTRODUCTION Staphylococci - derived from Greekstapyle (bunch of grapes) Gram positive cocci arranged inclusters Hardy organisms surviving many nonphysiologic conditions Include a major human pathogen andskin commensalsDR.T.V.RAO MD4 5. Staphylococci: Gram positive Cocci( from Greek staphyle, means bunch of grapes ) that occur singly and in pairs,short chains and irregular grape-likeclusters.DR.T.V.RAO MD 5 6. STAPHYLOCOCCUS= nonmotile, grapelike clusters, nonsporeformers= nonencapsulated but few strains form capsules= aerobic or facultative anaerobes= catalase positive 2H 202 2H20 + 02= most strains --- heat stable (60oC x 30 mins.)SPECIES:Staphylococcus aureuscoagulase ( + ) (clots citrated plasma)Staphylococcus epidermidiscoagulase ( - )TOXINS:hemolysins6 enterotoxinsLeukocidinexfoliatinDR.T.V.RAO MD6 7. ALEXANDER FLEMINGPenicillin: is the antibioticagent that AlexanderFleming a Scottishphysician discovered in1929. In 1950 only15% of S.aureus wassusceptible to penicillin. Approximately only 5% of S. aureus today are sensitive to penicillin.DR.T.V.RAO MD 7 8. FamilyCLASSIFICATIONGenus MicrococcaceaeSpecies Micrococcus and Staphylococcus S. aureus S. saprophyticus S. epidermidismore M. luteus than 20 speciesDR.T.V.RAO MD 8 9. STRUCTURE AND PHYSIOLOGY Gram-positive cocci, nontitle,facultative anaerobes Cells occur in grapelike clustersbecause cells division occursalong different planes and thedaughter cells remain attached toone another Salt-tolerant: allows them totolerate the salt present onhuman skin Tolerant of desiccation: allowssurvival on environmentalsurfaces (fomites)DR.T.V.RAO MD 9 10. S. AUREUS A UNIQUE ORGANISMPVLAdapted from: Lowy. N Engl J Med. 1998;339:520-532. DR.T.V.RAO MD10 11. STRUCTURE AND PHYSIOLOGYTwo species are commonly associated with staphylococcal diseases in humans Staphylococcus aureus-Themore virulent strain that canproduce a variety of conditionsdepending on the site ofinfection Staphylococcus epidermidis-Normal micro biota of humanskin that can causeopportunistic infections inimmunocompromised patientsor when introduced into thebodyDR.T.V.RAO MD 11 12. GENERAL CULTURAL CHARACTERISTICS Staphylococcusspecies, mostnotably S. aureus,produce a hemolysisthat completely lysesred blood cells ofhumans and someother mammals(sheep blood). Thisis referred to asbeta hemolysis.DR.T.V.RAO MD12 13. Staphylococcus aureus: is thestaphylococcus which has the ability to clot plasma, which is coagulase positive. Morethan 80% of Staphylococcus aureus strainsproduce beta-lactamases.DR.T.V.RAO MD 13 14. OTHER S. AUREUS CHARACTERISTICSMannitol fermentation is another useful characteristic it isunique to, and consistent among S. aureus strains. Virtuallyall strains of S. aureus ferment mannitol.Bright yellow colonies on a yellow background indicates mannitol fermentation on mannitol salt agar.DR.T.V.RAO MD14 15. PATHOGENICITYStaph infections result when staphylococci breach the bodys physical barriers Entry of only a few hundred bacteria can result indisease Pathogenicity results from 3 features Structures that enable it to evade phagocytosis Production of enzymes Production of toxinsDR.T.V.RAO MD 15 16. CELL-ASSOCIATED VIRULENCE FACTORS Capsule or slime layer (glycocalyx) Peptidoglycan (PG) Teichoic acid is covalently linked to PG and is speciesspecific: S. aureusribitol teichoic acid(polysaccharide A) S. epidermidis glycerol teichoic acid (polysaccharide B) Protein A is covalently linked to PG Clumping factor (bound coagulase) DR.T.V.RAO MD16 17. VIRULENCE FACTORSEXTRACELLULAR ENZYMES Coagulases (bound or free) Antigenic Hyaluronidase spreading factor of S. aureus Nuclease Cleaves DNA and RNA in S. aureus Protease Staphylokinase (fibrinolysin) Lipases EsterasesDR.T.V.RAO MD 17 18. BIOCHEMICAL CHARACTERISTIC Staphylococcusspecies can bedifferentiated fromMicrococcus speciesbased upon oxygenrequirements: Staphis facultative andMicrococcus speciesare obligate aerobesDR.T.V.RAO MD 18 19. STRUCTURAL DEFENSES AGAINST PHAGOCYTOSIS1.Protein A coats the cell surface Interferes with humoral immune responses by binding toclass G antibodies Inhibits the complement cascade2.Clumping Factor (Bound coagulase) Converts the soluble blood protein fibrinogen in insolublefibrin molecules that form blood clots Fibrin clots hide the bacteria from phagocytic cellsDR.T.V.RAO MD19 20. VIRULENCE FACTORS: EXOTOXINS Cytolytic (cytotoxins; cytolysins) Alpha toxin - hemolysin Reacts with RBCs Beta toxin Sphingomyelinase Gamma toxin Hemolytic activity Delta toxin Cytopathic for: RBCs Macrophages Lymphocytes DR.T.V.RAO MD20 21. Virulence Factors: Exotoxin Enterotoxin Exfoliative toxin(epidermolytictoxin) PyrogenicexotoxinsDR.T.V.RAO MD21 22. STAPHYLOCOCCAL TOXINSENTEROTOXINS Enterotoxins, types A-E,G, H, I and J, arecommonly produced byup to 65% of strains ofStaph. aureus,sometimes singly andsometimes incombination. Thesetoxic proteins withstandexposure to 100C forseveral minutes.DR.T.V.RAO MD 22 23. DISEASE MANIFESTATIONS Boils, carbuncles Scalded skin syndromeWound infection Pemphigus neonatroumAbscessesToxic shock syndrome ImpetigoFood poisoningMastitis Bacteraemia OsteomyelitisPneumonia Endocarditis DR.T.V.RAO MD23 24. CLINICAL MANIFESTATIONS/DISEASE SKIN folliculitis boils (furuncles) carbuncles impetigo (bullous & pustular) scalded skin syndrome Neonates and children under 4 yearsDR.T.V.RAO MD 24 25. A painful cluster ofboils with a centralwell of pus, oftenfound on the neck.take a long time toheal and often leavea scar. caused byinfections of theskinStaphylococcusDR.T.V.RAO MDaureus 25 26. Bedsores or pressure sores,local loss of skin and softDECUBITUS tissue as a result of pressureULCER ORfrom prolonged bed rest. Also known as decubitus ulcers, BEDSOREbedsores common on the buttocks, and onbony points such as the heels,elbows, shoulders, and the backof the head.affect elderly or infirm people whoare confined to bed for longperiods, including comatosepatients, whose conditionprevents them from moving freely.DR.T.V.RAO MD 26 27. MASTITIS Inflammation of the breast especially during nursing. also a frequent site of both benign and malignant tumors.DR.T.V.RAO MD27 28. MENINGITIS Involving thecovering ofthe brain & thespinal cord(meninges).DR.T.V.RAO MD28 29. CYSTITISinflammation of theurinary bladder,usually frombacterial infectionoriginating in theurethra, vagina, or,in the kidneys.DR.T.V.RAO MD 29 30. most common form usually associated withadolescence but may alsooccur in adults. primarily from hormonalchanges taking place in thebody Other factors include stress,drugs, bacteria, and certainfoodstuffs. DR.T.V.RAO MD30 31. SKIN LESIONS Boils Styes Furuncles(infection of hair follicle) Carbuncles (infection of several hair follicles) Wound infections(progressive appearance of swelling andpain in a surgical wound after about 2 days from thesurgery) Impetigo(skin lesion with blisters that break and becomecovered with crusting exudate)DR.T.V.RAO MD31 32. SCALDED SKIN SYNDROME (TOXIC EPIDERMAL NECROLYSISDR.T.V.RAO MD32 33. DEEP ABSCESSSES Can be single or multiple Breast abscess can occurin 1-3% of nursingmothers in puerperiem Can produce mild tosevere disease Other sites - kidney, brainfrom septic foci in blood Needs specialinvestigationsDR.T.V.RAO MD 33 34. PATHOLOGY - PREDISPOSING FACTORS This list is virtually true for all pathogens Immune system suppressed or otherwisecompromised. Specifically Skin injuries (e.g. burns, surgicalincisions, cuts, etc) Presence of foreign bodies (e.gintravenous lines, prosthetic devices,sutures, tampons-)DR.T.V.RAO MD 34 35. Pre-existing infections Chronic underlying conditions (e.g. auto-immune conditions, malignancies,alcoholism, heart disease, etc.) Compromised micro biota viaantimicrobial therapy Infants susceptible: oral, skin: impetigo,scalded skin, respiratory, otherDR.T.V.RAO MD35 36. PRE-EXISTING INFECTIONS With obvious focus Osteomyelitis, septic arthritis 2. No obvious focus heart (infective endocarditis) Brain(brain abscesses) 3. Associated With predisposing factors multiple abscesses, septicemia(IV drug users) Staphylococcal pneumonia (Post viral)DR.T.V.RAO MD 36 37. FACTORS THAT FACILITATETRANSMISSION Frequent ContactCrowdingAntimicrobial Use Contaminated SurfacesCompromised Skin and Shared ItemsCleanlinessDR.T.V.RAO MD37 38. TOXIN MEDIATED DISEASES1 . Staphylococcal food poisoning Due to production of entero toxins heat stable entero toxin acts on gut produces severe vomiting following a very short incubation period Resolves on its own within about 24 hoursDR.T.V.RAO MD 38 39. TOXIC SHOCK SYNDROME TOXIN (TSST-1)This was discovered in the early 1980s as a result ofepidemiological and microbiological investigations inthe USA of toxic shock syndrome, a multi-systemdisease caused by staphylococcal TSST-1 orenterotoxin, or both. A link was established with theuse of highly absorbent tampons in menstruatingwomen, although non-menstrual cases are now ascommon. The absence of circulating antibodies toTSST-1 is a factor in the pathogenesis of thissyndrome.DR.T.V.RAO MD 39 40. TOXIC SHOCK SYNDROME TOXIN (TSST-1) TSST-1 and the enterotoxins are nowrecognized as super antigens, that is, they arepotent activators of T lymphocytes resulting inthe liberation of cytokines such as tumournecrosis factor, and they bind with high affinity tomononuclear cells. These characteristics partlyexplain the florid and multi-system nature of theclinical conditions associated with these toxins.DR.T.V.RAO MD40 41. TOXIC SHOCK SYNDROME High fever, diarrhea, shock and erythematousskin rash which desquamate Mediated via toxic shock syndrome toxin 10% mortality rate Described in two groups of patients ass. With young women using tampons duringmenstruation Described in young children and menDR.T.V.RAO MD41 42. ENZYMES1. Coagulase Triggers blood clotting2. Hyaluronidase Breaks down hyaluronic acid, enabling the bacteria to spread between cells3. Staphylokinase Dissolves fibrin threads in blood clots, allowing Staphylococcus aureus to free itself from clotsDR.T.V.RAO MD42 43. ENZYMES (CONT.). Lipases Digest lipids, allowing staphylococcus to grow onthe skins surface and in cutaneous oil glands5.-lactamase Breaks down penicillin Allows the bacteria to survive treatment with -lactam antimicrobial drugsDR.T.V.RAO MD 43 44. TOXINS Staphylococcus aureus produces toxins more frequentlythan S.epidermidis1. Cytolytic toxins Disrupts the cytoplasmic membrane of a variety of cells Leukocidin can lyse leukocytes specifically2. Exfoliative toxins Causes the patients skin cells to separate from eachother and slough off the bodyDR.T.V.RAO MD44 45. FOOD POISONING S. aureus is the #1 most common cause of foodpoisoning although it is comparatively mild inmost cases. Symptoms include nausea, vomiting, diarrhea,abdominal cramping and mild fever. Symptom onset can be within minutes or hours ofingestion, with similar duration Foods: handled foods: wet, sugary or salty,handled after some preparation cooked, mixed,then served cold, at least initially DR.T.V.RAO MD45 46. COAGULASE Coagulase (staphylocoagulase) is a fibrinogen activatingenzyme produced by some staph species - it has thrombin-like activity. In situ, coagulase combines with coagulasereacting factor (CRF) to catalyze the formation of fibrin clotsaround cells as a barrier to host immune components it isa virulence factor. Clinically significant staphylococci are usually divided intotwo groups: those that produce coagulase and those that donot Coagulase positive species include S. aureus, S.intermedius and S. hyicus S. intermedius and S. hyicus mostly inhabit animals and areonly rarely found as a cause of human infectionsDR.T.V.RAO MD 46 47. COAGULASE TESTING The tube is observed hourly during the four hourincubation period The formation of a fibrin clot or gel indicates apositive test DR.T.V.RAO MD47 48. EMERGING MULTI-DRUG RESISTANCE INUSA300? Clusters of USA300 isolates with multiple resistance to erythromycin, clindamycin, tetracycline, ciprofloxacin, and mupirocin 1 Resistance to one class of antibiotics other than beta-lactams is still the most common resistance pattern in MRSA USA300 TMP/SMX resistance rare in MRSA USA3001Diep et al Lancet 2006. Han et al J Clin Micro 2007.DR.T.V.RAO MD 48 49. BETA LACTAMS:Beta lactams: are the antibiotics that contain thebeta lactam ring. These are : penicillins, cephamycins, cephalosporins, carbapenemsmonobactams. The ring structure is common to all beta-lactams and must be intact forantibacterial action. They are cellwall synthesis inhibitors.DR.T.V.RAO MD49 50. COMMUNITY-ASSOCIATED MRSA:CDC POPULATION-BASED SURVEILLANCE DEFINITION MRSA culture in outpatient setting or 1 st 48 hours ofhospitalization AND patient lacks risk factors forhealthcare-associated MRSA: Hospitalization Surgery Long-term care Dialysis Indwelling devices DR.T.V.RAO MD 50 51. ANTIMICROBIAL SUSCEPTIBILITY Penicillin resistance (possession of penicillnase) iscoded on a plasmid the enzyme is also known asbeta-lactamase: inactivates the beta-lactam ring ofpenicillins and other beta-lactam antibiotics such asthe cephalosporins Semi-synthetic drugs (modified penicillins) such asmethicillin and oxacillin were developed for treatingbeta lactamase positive S. aureus infections Some strains are now resistant to these drugs MRSA, etc. A recent survey indicated that as manyas 34% of S. aureus isolates were MSRA.DR.T.V.RAO MD 51 52. ANTIMICROBIAL SUSCEPTIBILITY Penicillin resistance (possession ofpenicillnase) is coded on a plasmid theenzyme is also known as beta-lactamase:inactivates the beta-lactam ring of penicillinsand other beta-lactam antibiotics such as thecephalosporins Semi-synthetic drugs (modified penicillins) suchas methicillin and oxacillin were developed fortreating beta lactamase positive S. aureusinfections Some strains are now resistant to these drugs MRSA, etc.. DR.T.V.RAO MD 52 53. EPIDEMIOLOGY OF S AUREUS INFECTIONS Predominant reservoir of organisms = human beings Approximately 15% 35% of normal people harbor S aureus in nares or pharynx at a given point. Longitudinal view of carriage: 30% prolonged, 50% intermittent, 20% never Vaginal carriage in ~10% of premenopausalwomen Rectal and perineal carriage also occurSheagren. N Engl J Med. 1984;310:1368-1373.Rimland et al. J Clin Microbiol. 1986;24:137-138.Centers forMDDR.T.V.RAO Disease Control (CDC). MMWR Morb Mortal Wkly Rep. 1982;31:605-607. 53 54. HAND WASHING Cross-infection is animportant method of spreadof staphylococcal disease,particularly in hospitals,and scrupulous handwashing is essential inpreventing spread. Foodhandlers may similarlyintroduce enterotoxin-producing food poisoningstrains into food.DR.T.V.RAO MD54 55. PREVENTION Hand antisepsis is themost important measurein preventingNosocomial infections Also important is theproper cleansing ofwounds and surgicalopenings, aseptic use ofcatheters or indwellingneedles, an appropriateuse of antisepticsDR.T.V.RAO MD 55 56. PREVENTION Proper hygiene,segregation of carrier fromhighly susceptibleindividuals Good aseptic techniqueswhen handling surgicalinstruments Control of NosocomialinfectionsDR.T.V.RAO MD 56 57. OUR HABITS TOO SPREAD STAPHYLOCOCCAL INFECTIONSDR.T.V.RAO MD57 58. WHY ARE MRSA IMPORTANT?1. Hospital acquired infections. MRSA are common Nosocomial pathogens around the world.2. The treatment is very difficult. Vancomycin often is the only drug of choice for severe infections.DR.T.V.RAO MD 58 59. WHY ARE MRSA IMPORTANT?3. MRSA with reduced susceptibility to glycopeptides. Since 1996 has been identified in Europe, Asia and United States. That increases the possibility some strains became fully resistant to glycopeptides.4. MRSA are easily transmissible between patients.DR.T.V.RAO MD 59 60. CONTROL OF MRSA IN HOSPITALSGeneral Principles: Prevention of acquisition and spread ofinfection by patients and staff Priorities are high risk units, such asintensive care units and patients who aresusceptible to infection.DR.T.V.RAO MD 60 61. CONTROL OF MRSA IN HOSPITALS Hand washing. Health care workersshould wash their hands before andafter contact with all patients, evenwhen gloves are worn. A writtenprotocol detailing proper hand washtechnique should be available forreference.DR.T.V.RAO MD 61 62. CONTROL OF MRSA IN HOSPITALS Gloves should be worn when in contactwith any body substance. Glovesshould be changed and hands washedimmediately after contact with eachresident. Appropriate use of antimicrobials.Monitoring and auditing of drug use.DR.T.V.RAO MD62 63. CONTROL OF MRSA IN HOSPITALS Isolation is necessary for infectedpatients and possible carriers in asingle room or preferably in anisolation unit with designated staff.Isolation reduce staphylococcalcross-infection.DR.T.V.RAO MD 63 64. CONTROL OF MRSA IN HOSPITALS Carriage of MRSA by health care workers.During outbreaks staff should be remindedof the hand washing and transient carriageof MRSA. Staff with infected or colonizedlesions should not be at work especially incritical areas, as intensive care units,cardiothoracic words e.t.c.DR.T.V.RAO MD 64 65. CONTROL OF MRSA INHOSPITALS Treatment of carriers. Nasal carriageis treated topical with mupirocin. Systemic treatment of infections Theglycopeptide antibiotics are currentlythe agents of choice for treatment. Microbiological characterization ofMRSA.DR.T.V.RAO MD65 66. COAGULASE NEGATIVE STAPHYLOCOCCUS Coagulase negative staphylococci (Cons) are generally lessvirulent that S. aureus Cons are inherently difficult to speciate even using modernclinical products and methods Unless a Cons isolate is cultured repeatedly from a normallysterile body site (e.g. Blood, CSF), identification to species levelis usually not attempted Isolates that must be definitively identified to species level aresent to reference labsDR.T.V.RAO MD66 67. CONS S. EPIDERMIDIS The most common Cons species in clinical samples is S.epidermidis, comprising 50-80% of these isolates. S. epidermidis can be presumptively differentiated from otherStaph species on the basis of the following observationsIt does not ferment mannitol or trehalose Coagulase negative It is sensitive to novobiocin It is resistant to polymyxin B Pathology of S. epidermidis is almost exclusively associatedwith skin penetration in the hospital setting DR.T.V.RAO MD 67 68. CONS S. EPIDERMIDIS S. epidermidis produces a capsule that adheres to plastic devices such as intravenous catheters, prosthetic heart valves, and shunts S. epidermidis and otherCons are cause of nativevalve endocarditisDR.T.V.RAO MD 68 69. SOAP, WATER, AND COMMON SENSE ARE BEST ANTISEPTICS WILLIAM OSLERDR.T.V.RAO MD 69 70. DR.T.V.RAO MD 70 71. FOLLOW ME FOR MORE ARTICLES OF INTEREST ONISSUES ON INFECTIOUS DISEASESDr.T.V.Rao MD71 72. Programme created by Dr.T.V.Rao MD for Medical and Paramedical Professionals in theDeveloping World Email doctortvrao@gmail.comDR.T.V.RAO MD 72