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Cocci 2011
- 1. Laboratory Diagnosis • ColonialMorphology (BAP) • S. aureus Golden yellow colonies, smooth, entirely raised, - hemolytic (>24 hrs of incubation) • S. epidermidis translucent, gray-white colonies, non- hemolytic • S. saprophyticus (same as S. epidermidis)
- 2. Laboratory Diagnosis Gram stain: Gram-positive cocci Differentiates Staphylococc us and Catalase test Streptococcu s Staphylococcus Streptococcus sp. sp.
- 3. Catalase test (Slide) Negative Positive
- 4. Medically important Staphylococci •Staphylococcus aureus • Staphylococcus epidermidis • Staphylococcus saprophyticus
- 5. Laboratory Diagnosis Catalasetest Coagulase test/ MSA Staphylococcus sp. S. aureus S. saprophyticus S. epidermidis
- 6. Coagulase Test • 2types 1.) Bound/Clumping factor Slide test (+) Result: agglutination of organism when mixed w/ plasma not all strains of S. aureus produced clumping factor 2.) Free Tube test (+) Clot formation Anticoagulant: EDTA
- 7. Coagulase test (Tube) Positive Negative
- 8. Mannitol Salt Agar •pH indicator: phenol red • Sugar: Mannitol • Salt conc.: 10% • (+) Result: Yellow Halo
- 9. Laboratory Diagnosis Coagulase test/ Novobiocin test MSA (S) (R) S. saprophyticus S. epidermidis S. epidermidis S. saprophyticus
- 10. Novobiocin disc test S.epidermidis S. saprophyticus
- 11. GENUS: Staphylococcus • Gram-positive •(0.5 – 1 m) • Non-motile, non-sporeforming • Catalase (+) • Facultative anaerobes
- 12. Medically important Staphylococci •Staphylococcus aureus • Staphylococcus epidermidis • Staphylococcus saprophyticus
- 13. Staphylococcus aureus • Catalase-positive,Coagulase-positive • Salt tolerant (7.5% NaCl) • Ferments mannitol on Mannitol salt agar
- 14. Reservoir • Normal floraon nasal mucosa and skin
- 15. Transmission • Spread viathe hands and sneezing • Fomites • Surgical wounds • Lungs of cystic fibrosis patients • Foods associated with food poisoning (Ham/Canned meats, Custard pastries and potato salad)
- 16. Predisposing Factors forInfections • Any break in skin (sx) • Any foreign body (sx packing, sutures, tampons) • Ventilators • WBC <500/ L • Dse: CF, CGD • IV drug abuse
- 17. Virulence factors: A. Cellassociated factors B. Extracellular factors
- 18. A) CELL ASSOCIATEDFACTORS: a) CELL ASSOCIATED POLYMERS 1. Cell wall polysaccharide (Peptidoglycan) 2. Teichoic acid 3. Capsular polysaccharide (some strains) b) CELL SURFACE PROTEINS: 1. Protein A (S. aureus) 2. Clumping factor (bound coagulase)- S. aureus
- 19.
- 20. B) EXTRACELLULAR FACTORS a)Enzymes: 1. Catalase – all Staph. 2. Free coagulase (S. aureus) 3. Lipase 4. Hyaluronidase (Spreading factor) 5. β-lactamases 6. Staphylokinase (Fibrinolysin) 7. Proteinases
- 21. B) EXTRACELLULAR FACTORS b)Toxins: 1. Cytolytic toxins i) Hemolysins (α,β,γ,δ) ii) Leucocidin (Panton-Valentine toxin) 2. Enterotoxin A-F (heat stable 60°C, 10 mins) 3. Toxic shock syndrome toxin-1 (TSST-1) 4. Exfoliative (epidermolytic toxin) .
- 22. Staphylococcal Diseases Infections Intoxications
- 23. 1) Skin andsoft tissue infections: • Folliculitis, furuncle (boil), carbuncle, styes, abscess, wound infections, impetigo, paronychia and less often cellulitis. • Coagulase
- 24. 2) Musculoskeletal • Osteomyelitis,arthritis, bursitis, pyomyositis.
- 25.
- 26. 1. Respiratory: Tonsillitis,pharyngitis, sinusitis, otitis, bronchopneumonia, lung abscess, empyema, rarely pneumonia. 2. Central nervous system: Abscess, meningitis, intracranial thrombophlebitis. 3. Endovascular: Bacteremia, septicemia, pyemia, endocarditis. 4. Urinary: Urinary tract infection.
- 27. Infective endocarditis (Acute) •Fever, malaise, leukocytosis, heart murmur (may be absent initially) • # 1 cause S. aureus • Fibrin platelet mesh, cytolytic toxins
- 28. B) INTOXICATIOINS: The diseaseis caused by the bacterial exotoxins, which are produced either in the infected host or preformed in vitro. There are 3 types- 1. Food poisoning 2. Toxic shock syndrome 3. Staphylococcal scalded skin syndrome
- 29. Gastroenteritis (food poisoning) •1-8 hours after ingesting toxin • Nausea • abdominal pain • Vomiting • followed by diarrhea • No fever • Enterotoxins A-F preformed in food (heat-stable)
- 30. Toxic Shock Syndrome(TSS) • High fever (abrupt) • Vomiting • Diarrhea • Myalgias • Scarlatiniform rash • Hypotension • Cardiac/Renal failure (severe cases) • TSST-1
- 31. Staphylococcal Scalded SkinSyndrome (SSSS) • Exfoliative toxin
- 32. Laboratory Diagnosis: Specimens collected:Depends on the type of infection. • Suppurative lesion- Pus, • Respiratory infection- Sputum, • Bacteremia & septicemia- Blood, • Food poisoning- Feces, vomit & the remains of suspected food, • For the detection of carriers- Nasal swab.
- 33. Treatment • Methicillin/ Nafcillin/Oxacillin/ Cloxacillin • Methicillin-resistant S. aureus (MRSA) (due to changes in major penicillin-binding proteins) is commonly resistant to all antibiotics EXCEPT Vancomycin and Fusidic acid. • Topical mupirocin reduces nasal colonization.
- 34. Prevention • Basic hospitalinfection control
- 35. Staphylococcus epidermidis • Reservoir:skin and mucous membrane • Neonatal Sepsis • Peritonitis in patients with renal failure who are undergoing peritoneal dialysis through an indwelling catheter • Most common CSF shunt infection • Infxn related to intravenous catheters and prosthetic implants (e.g., heart valves, vascular grafts, and joints) • Coagulase (-); Novobiocin (S)
- 36. Staphylococcus saprophyticus • CausesU.T.I., particularly in sexually active young women. • 2nd cause community acquired U.T.I. young women (Most common cause E. coli) Coagulase (-); Novobiocin (R)
- 37. Characteristics S.aureus S.epidermidis S.saprophyticus Coagulase + - - Novobiocin Sensitive Sensitive Resistant sensitivity Acid from + - - mannitol fermentation anaerobically Hemolysis beta - (most) -
- 38. Laboratory Diagnosis Gram stain: Gram-positive cocci Differentiates Staphylococc us and Catalase test Streptococcu s Staphylococcus Streptococcus sp. sp.
- 39. Important Streptococci • Streptococcuspyogenes • Streptococcus agalactiae • Enterococcus faecalis • Streptococcus bovis • Streptococcus pneumoniae • Viridans group
- 40. Streptococcus • Hemolysis variesby species: • • •
- 41. Laboratory Diagnosis OPTOCHIN BACITRACIN 6.5% NaCl (S)S. pyogenes (R)S. agalactiae (S)S.pneumoniae (+)Enterococcus (R)Viridans group ( - )S. bovis
- 42. Laboratory Diagnosis • Optochin“Taxo P” Disc test
- 43. Laboratory Diagnosis • Bacitracin“Taxo A” Disc test (S)
- 44. GENUS: Streptococcus • Gram-positive • Non-motile, non-sporeforming • Catalase (-) • Facultative anaerobes
- 45. Streptococci • Are serogroupedusing known antibodies to the cell wall carbohydrates (Lancefield’s Group A-H, K-U) • Group A- Rhamnose-N-acetylglucosamine • Group B-Rhamnose-glucosamine polysaccharide • Group C-Rhamnose-N-acetylgalactosamine • Group D- Glycerol teichoic acid • Group F- Glucopyranosyl-N-acetylgalactosamine
- 46. Laboratory Diagnosis • SpecimenCollection & Processing: • No special consideration; site • Antigen Detection • S. pyogenes (throat) latex agglutination, Coagglutination, ELISA • Gram Stain
- 47. Laboratory Diagnosis • Cultivation • MOC: 5% Sheep’s Blood Agar (BAP)
- 48. Laboratory Diagnosis • Colonialappearance - Grayish white - Hemolysis
- 49. Streptococcus pyogenes (GABS) DistinguishingCharacteristics Beta-hemolytic Group A Colonies inhibited by Bacitracin on BA Gram-positive cocci in chains Catalase-negative PYR (+)
- 50.
- 51. Transmission • Spread byrespiratory droplets • Direct contact
- 52. Group A Streptococcalcell wall
- 53. Cell wall components •Hyaluronic acid capsule (a polysaccharide) is non- immunogenic; inhibits phagocytic uptake • M-protein: major virulence factor, hair-like projections; antiphagocytic, used to type group A Strep
- 54. Toxins • Hemolysins • Streptolysin O: immunogenic, hemolysin/cytolysin • Streptolysin S: non-immunogenic, hemolysin/cytolysin
- 55. Exotoxins A-C (pyrogenic/erythrogenic) • Phage-coded(e.g., the cells are lysogenized by a phage) • Cause fever and the rash of Scarlet fever • Inhibit liver clearance of endotoxin (from normal flora), creating shock-like conditions • Superantigens: activate many helper T cells by bridging T cell receptors and MHC class II markers without processed antigen
- 56. Spreading factors: • Streptokinase(fibrinolysin): breaks down fibrin clot • Streptococcal Dnase (Streptodornase): liquefies pus, extension of lesion • Hyaluronidase: hydrolyzes the ground substances of the connective tissues; important to spread in cellulitis
- 57. Diseases • Streptococcus pyogenescauses a wide variety of acute infections; some have immunologic sequelae
- 58. Acute (Suppurative) S.pyogenesInfxn • Pharyngitis (most common) • Scarlet fever • Pyoderma/ Impetigo (Also, cellulitis,necrotizing fasciitis (flesh-eating bacteria!), puerperal fever, lymphangitis, pneumonia, a toxic shock- like syndrome, etc.
- 59. Pharyngitis • Abrupt onsetof sore throat • Fever • Malaise • Headache • Tonsillar abscesses • Tender anterior cervical lymph nodes • Lab: For Strep throat: Rapid antigen test (misses 25% of the strep throat); culture all “negatives”
- 60. Pyoderma/ Impetigo • Pus-producingskin infection (honey-crusted lesions)
- 61. Erysipelas • Brawny edema,advancing margin of infection
- 62. Necrotizing fasciitis • S.pyogenes “flesh-eating bacteria”
- 63. Scarlet fever • Initial:S/Sx’s of pharyngitis • Followed by blanching, “sandpaper” rash
- 64.
- 65.
- 66. Non-suppurative Sequelae toGroup A Streptococcal Infections • Rheumatic fever • Acute glomerulonephritis (M12 serotype)
- 67. Rheumatic fever • Sequelaeto : Pharyngitis with group A Strep (not group C) • Mechanism: in genetically susceptible individuals, the infection results in production of antibodies that cross- react with cardiac antigens
- 68. Rheumatic fever • Symptomsoccurs 2-3 weeks after a pharyngeal infection • Lab: elevated ASO titers (>200) • Jones Criteria
- 69. Major Jones Criteria •“J NES” • J- Joints (Migratory arthritis) • -Carditis • N- Subcutaneous Nodules • E- Erythema marginatum • S- Sydenham chorea
- 70. Minor Jones Criteria •Fever • Arthralgias • Elevated acute phase reactants
- 71. Rheumatic fever • DIAGNOSIS: • 2 major or • 1 major & 2 minor
- 72. Acute Glomerulonephritis • Sequelaeto: Pharyngitis or Cutaneous strep infxn • Mechanism: Immune complexes bound to glomeruli
- 73. Laboratory Diagnosis • PYRtest • Principle:hydrolysis of L- pyrrolidonyl-- naphthylamide (PYR)
- 74. Treatment • Penicillin G DOC • Beta-lactam drugs • Erythromycin
- 75. Prevention • Penicillin inRF px to prevent recurrent S. pyogenes pharyngitis
- 76. Streptococcus agalactiae =Group B Streptococci (GBS) • Distinguishing Characteristics • Beta-hemolytic • Bacitracin-resistant on BAP • Gram-positive cocci in chains • Group B • Catalase-negative, hydrolyzes hippurate • CAMP test-positive: CAMP(Christie-Atkins-Munch-Peterson) factor is a polypeptide that “compliments” a Staph aureus sphingomyelinase to make an area of new complete beta- hemolysis
- 77. Reservoir • Colonizes humanvagina (15 – 20% of women)
- 78. Transmission • Newborn infectedduring birth • Increased risk with PROM
- 79.
- 80. Diseases • Neonatal septicemia •Neonatal meningitis (Neonate – 2 mths) • Most common causative agent ( GEL) # 1 – S. agalactiae (GBS) 2 – E. coli Rare: L. monocytogenes
- 81. Laboratory Diagnosis • 0.04U Bacitracin disk – Resistant • CAMP (Christie, Atkins, Munch- Peterson) Test detects production of a diffusible, extracellular protein that enhaces hemolysis of sheep erythrocytes by S. aureus • (+) Arrowhead shape at the juncture of S. agalactiae & S. aureus
- 82. Treatment • Ampicillin withCefotaxime or Gentamicin
- 83. Prevention • Treat motherprior to delivery if she had a previous baby with GBS, has documented GBS colonization, or prolonged rupture of membranes
- 84. Streptococcus pneumoniae (Pneumococcus) • DistinguishingCharacteristics - Alpha-hemolytic - Colonies inhibited by optochin on BAP - Gram-positive, lancet-shaped diplococci (or short chains) - Lyse by bile - Quellung (+)
- 85. Reservoir • Human UpperRespiratory Tract
- 86. Transmission • Respiratory droplets;not considered highly communicable • Often colonizes without causing disease
- 87. Pathogenesis • IgA protease:colonization
- 88. Pathogenesis • Teichoic acids:attachment • Polysaccharide capsule: major virulence factor • Pneumolysin O: hemolysin/cytolysin • Damages respiratory epithelium (hemolysin similar to streptolysin O, which damages eukaryotic cells) • (Inhibits leukocyte respiratory burst and inhibits classical complement fixation.)
- 89. Pathogenesis • Pneumococcus inalveoli stimulate release of fluid and red and white cells producing “rusty sputum” • Peptidoglycan/ teichoic acids highly inflammatory in CNS
- 90. Diseases • Bacterial Pneumonia •Adult Meningitis • Otitis Media and Sinusitis in children • Septicemia
- 91. Bacterial Pneumonia • Mostcommon bacterial cause, especially after 65 years but also in infants • Sx: • “big” shaking chills • Sharp pleural pain • High fever • Lobar with productive blood-tinged sputum (rusty-colored)
- 92. Predisposing Conditions for Pneumonia •Antecedent influenza or measles infection: damage to mucociliary elevator • Chronic obstructive pulmonary disorders • Congestive heart failure • Alcoholism • Asplenia predisposes to septicemia
- 93. Adult Meningitis • Mostcommon cause (> 40 y/o) • CSF: WBC (PMN) Glucose Protein Pressure
- 94. Otitis Media andSinusitis in Children • Most common cause
- 95. Septicemia • In splenectomizedpatients
- 96. Treatment • Penicillin G DOC • Resistance (both low level and high level) is chromosomal (altered penicillin-binding proteins); major concern in meningitis (Vancomycin Rifampin used)
- 97. Prevention • Vaccine 23serotypes of capsule
- 98. Viridans Streptococci (S.sanguis, S. mutans, etc.) • Distinguishing Characteristics • Alpha-hemolytic, resistant to optochin • Gram-positive cocci in chains • NOT bile soluble
- 99. Reservoir • Human oropharynx(normal flora)
- 100. Diseases • Dental carries •Infective Endocarditis (Subacute)
- 101. Dental carries • S.mutans dextran-mediated adherence glues oral flora onto teeth, forming plaque and causing caries
- 102. Infective Endocarditis • Sx: • Malaise • Fatigue • Anorexia • Night sweats • Weight loss • Predisposing factors: • Damage (or prosthetic) heart valve • Dental work w/o prophylactic antibiotics • Extremely poor oral hygiene
- 103. Pathogenesis • Dextran (biofilm)-mediatedadherence onto tooth enamel or damaged heart valve and to each other (vegetation). Growth in vegetation protects organism from immune system.
- 104. Treatment • Penicillin Gwith Aminoglycoside for endocarditis
- 105. Prevention • For individualswith damage heart valve • Prophylactic penicillin prior to dental work
- 106. GENUS: Enterococcus • Catalasenegative • PYR + • Hydrolyzes Esculin in 40% bile • (+) growth 6.5% NaCl
- 107. Enterococcus faecalis = Streptococcusfaecalis • Distinguishing Characteristics • Group D Gram-positive cocci in chains • PYR test + • Catalase-negative, varied hemolysis • Hydrolyzes esculin in 40% bile (bile esculin agar turns black) • (+) growth 6.5% NaCl
- 108. Reservoir • Human colon •Urethra • Female genital tract
- 109. Pathogenesis/ Predisposing Conditions • Bile/ Salt tolerance allows survival in bowel and gall bladder • During medical procedures on GI or GU tract: E. faecalis bloodstream previously damaged valves ENDOCARDITIS (SBE)
- 110. Diseases • Urinary, biliarytract Infections • Infective endocarditis (SBE)
- 111. Treatment • All strainscarry some drug resistance • Some vancomycin-resistant strains of Enterococcus faecium or E. faecalis: no reliably effective treatment
- 112. Prevention • Prophylactic useof penicillin and gentamicin in patients with damaged heart valves prior to intestinal or urinary tract manipulation
- 113.
- 114. GENUS: Neisseria • Gram-negative •Diplococci with flattened sides • Oxidase positive
- 115. Important Genera • Neisseriameningitidis • Neisseria gonorrhoeae
- 116. Neisseria Species N. meningitidis N. gonorrhoeae Capsule Pili Vaccine Portal of entry Respiratory Genital Glucose Utilization Maltose Fermentation Oxidase test Beta-lactamase prdxn Rare
- 117. Neisseria meningitidis (meningococcus) • DistinguishingCharacteristics • Gram-negative kidney bean-shaped diplococci • Large capsule • Grows on chocolate (not blood) agar in 5-10% CO2 • Ferments maltose • Oxidase positive • 13 Serogroups: A, B, C, D,29E, H, I, K,L,X,Y,Z & W-135
- 118. Reservoir • Human nasopharyngealarea • ≥ 5% carriers (asymptomatic)
- 119. Transmission • Respiratory droplets •Oropharyngeal colonization • Spread to the meninges via the bloodstream • Disease occurs in only small percent of colonized
- 120. Pathogenesis • Important VirulenceFactors • Polysaccharide capsule (most impt) • IgA protease allows oropharynx colonization • Endotoxin (LPS): fever, septic shock in meningococcemia, overproduction of outer membrane • Pili and outer membrane proteins important in ability to colonize and invade • Deficiency in late complement components (C5-8) predisposes to bacteremia
- 121.
- 122. Waterhouse-Friderichsen Syndrome • Mostsevere form of meningococcemia • High fever • Shock • DIC • Ecchymoses • Adrenal insufficiency • Coma • Death
- 123. Laboratory Diagnosis • Specimen: • Blood culture only • CSF smear, culture (tube #2), chemical determination • Petechial aspirate smear/culture (?)
- 124. Laboratory Diagnosis • G/S •Presumptive dx: (+) gram-negative cocci on CSF smear • Presumptive Dx: (+) Oxidase test (tetramethyl-para- phenylenediamine- dihydrochloride)
- 125. Laboratory Diagnosis • CultureCAP 5-10% CO2 (candle jar) Incubate at 36-37 C at least 5 days before discarding as negative • Confirmatory test: Carbohydrate Fermentation test • (+) Glucose • (+) Maltose
- 126. Treatment • Penicillin G– DOC • Ceftriaxone • β- lactamase production (rare)
- 127. Prevention • Vaccine: capsularpolysaccharide of strains Y, W-135, C, A
- 128.
- 129. Neisseria gonorrhoeae • DistinguishingCharacteristics • Gram-negative kidney bean-shaped diplococci • Intracellular Gram-negative diplococci in PMNs from urethral smear is suggestive of N.g. • Sensitive to drying and cold
- 130.
- 131.
- 132. Pathogenesis • Pili • Attachment to mucosal surfaces • Inhibit phagocytic uptake • Antigenic (immunogenic) variation • Most impt
- 133. Pathogenesis • Outer membraneProteins • OMP I: Structural, antigen used in serotyping • OPA proteins (opacity): antigenic variation, adherence • IgA protease: aids in colonization and cellular uptake
- 134.
- 135. Laboratory Diagnosis • Specimen • Discharge from the GUT • Discharge from the rectal mucosa • Discharge from the throat/ oropharynx • Skin lesions • Eye/ Conjuntival Discharge • Synovial Fluid
- 136. Laboratory Diagnosis • Collection: • Use Non-toxic cotton swabs (treated with charcoal to absorb toxic fatty acid present in the cotton fiber) • Swabs should be plated immediately (best method) or within 6 hours • Specimen from sterile sites requires no special method in transport like synovial fluids in the syringes, they should be transpotred immediately to the laboratory • Blood culture is an exception, N. gonorrheae and N. meningitidis are sensitive to SPS (Sodium Polyanetholsulfate) which is present in vacutainer tubes, if present should < 0.025% • Transport media: • Amie’s charcoal transport medium • Transgrow medium • New York City medium • JEMBEC
- 137. Laboratory Diagnosis • G/S& C/S of d/c • Presumptive test – (+) gram-negative intracellular diplococci • Presumptive test – Oxidase test
- 138. Laboratory Diagnosis • Culture • Gold-standard in diagnosis • Colonies: translucent, grayish, convex, shiny colonies with entire margin, non-hemolytic • TYPES: • T1 & T2 Small, bright reflective colonies, typical of fresh isolates from gonorrheae (+) fimbrae/pili • T3, T4 & T5 Larger, flatter, non-reflecting (-) fimbrae/pili
- 139. Media Used: • Chocolateagar plate (CAP) • Sterile sites • Thayer-Martin Chocolate (T M) medium • Modified medium of CAP • Non-sterile sites • Vancomycin, Colistin, Nystatin • Modified Thayer-Martin (MTM) • T-M + trimetroprim to (-) swarming Proteus • M-Lewis Agar • Same as T-M but instead of Nystatin, Anisomycin is use
- 140. Treatment • Ceftriaxone –DOC • Test for Chlamydia trachomatis or treat with tetracycline • Penicillin-binding protein mutations led to gradual increases in penicillin resistance from the 50s to the 70s • Plasmid mediated β lactamase produces high level penicillin resistance
- 141. Prevention Adult forms: AB C • Abstinence • Be faithful/careful • Condom
- 142. Prevention • Neonatal: • 0.5 % erythromycin ointment • 1.0 % Tetracycline ointment • 1.0 % Silver nitrate drops (Crede’s prophylaxis)
- 143. Moraxella catarrhalis • Gram-negativediplococcus (close relative of neisseriae) • Normal upper respiratory flora • Otitis media • Cause bronchitis and bronchopneumonia in elderly with COPD • Drug resistance a problem; most strains produce a β lactamase