Other Gram Negative Bacilli

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Other Gram Negative Bacilli

  1. 1. <ul><li>Vibrios, Pseudomonas, Campylobacter, Helicobacter </li></ul>Other gram-negative bacilli
  2. 2. VIBRIOS <ul><li>Among the most common bacteria in surface waters worldwide </li></ul><ul><li>Curved, aerobic rods; motile with polar flagella </li></ul><ul><li>oxidase (+) </li></ul><ul><li>grow best on alkaline media </li></ul><ul><li>Often found in brackish water </li></ul>
  3. 3. Vibrio cholerae <ul><li>Classified based on somatic O antigen: </li></ul><ul><ul><li>V. cholerae O1 – most common cause of epidemic & pandemic cholera </li></ul></ul><ul><ul><li>V. cholerae O139 (Bengal strain) – epidemic </li></ul></ul><ul><ul><li>Non-O1 group </li></ul></ul><ul><li>Two biotypes (based on differences in biochemical reactions): </li></ul><ul><ul><li>El Tor – most common cause of epidemics and cause of 7 th pandemic </li></ul></ul><ul><ul><li>Cholerae or classical </li></ul></ul><ul><li>Three serotypes (based on antigenic differences): </li></ul><ul><ul><li>Ogawa, Inaba, Hikojima </li></ul></ul>
  4. 4. Vibrio cholerae <ul><li>MOT: fecal-oral </li></ul><ul><li>Sources of infection: humans, marine shellfish (shrimp and oysters) </li></ul><ul><li>Sensitive to gastric acid  high infective dose </li></ul><ul><li>Virulence factors: </li></ul><ul><ul><li>Mucinase – cause adherence to cells of the brush border of the gut </li></ul></ul><ul><ul><li>Choleragen – stimulate adenylyl cyclase </li></ul></ul>
  5. 5. Vibrio cholerae
  6. 6. Vibrio cholerae Cholera Toxin B subunit A subunit Binds GM1 ganglioside (surface of epithelial cells) Carried to ER (retrograde transport) Endocytosis Reduced by protein disulfide isomerase in ER Cytosol Unfolding Refolding Interact with cytosolic ADP ribosylation factors Activate G protein Stimulate adenylate cyclase Inc. cAMP Open CFTR Cl released in lumen; secretion of HCO 3 , Na + & water
  7. 7. Vibrio cholerae <ul><li>Clinical findings: </li></ul><ul><ul><li>Voluminous watery diarrhea – hallmark; “rice water” stool </li></ul></ul><ul><ul><li>Loss of fluid and electrolytes – marked dehydration </li></ul></ul><ul><ul><ul><li>“ washerwoman” hands </li></ul></ul></ul><ul><ul><ul><li>Cardiac and renal failure </li></ul></ul></ul><ul><ul><ul><li>Hypovolemic shock </li></ul></ul></ul>
  8. 8. Vibrio cholerae <ul><li>Diagnosis: </li></ul><ul><ul><li>Culture on MacConkey’s agar (slow lactose fermenter) or TCBS (Thiosulfate citrate bile salt sucrose) agar plate for selective isolation </li></ul></ul><ul><ul><li>Oxidase (+) – distinguished from the family Enterobacteriaceae </li></ul></ul><ul><ul><li>Serology </li></ul></ul><ul><li>Treatment: </li></ul><ul><ul><li>Prompt and rapid fluid and electrolyte replacement </li></ul></ul><ul><ul><li>Tetracycline – shorten duration </li></ul></ul>
  9. 9. Growth on TCBS agar plate
  10. 10. Vibrio parahaemolyticus <ul><li>Halophilic – grows on 8% NaCl solution </li></ul><ul><li>MOT: ingestion of raw or undercooked seafood, especially shellfish such as oysters </li></ul><ul><li>Mild to severe watery diarrhea, nausea and vomiting, abdominal cramps, fever  self-limited </li></ul><ul><li>No specific treatment indicated </li></ul>
  11. 12. Vibrio vulnificus <ul><li>Found in warm salt waters </li></ul><ul><li>Causes severe skin and soft tissue infections (cellulitis), especially in shellfish handlers </li></ul><ul><li>Rapid, fatal septicemia in immunocompromised people who have eaten raw shellfish </li></ul><ul><li>Treatment: doxycycline </li></ul>
  12. 14. Pseudomonas aeruginosa <ul><li>Gram-negative rods that resemble the Enterobacteriaceae but are strict aerobes </li></ul><ul><li>Derive energy by oxidation of sugars rather than fermentation </li></ul><ul><li>Oxidase (+) </li></ul><ul><li>Able to grow in water containing only traces of nutrients </li></ul>
  13. 15. Pseudomonas aeruginosa <ul><li>Produce two pigments: </li></ul><ul><ul><li>Pyocyanin (blue) </li></ul></ul><ul><ul><li>Pyoverdin (fluorescein) – yellow green pigments that fluoresce under UVL </li></ul></ul><ul><li>Found chiefly in soil and water </li></ul><ul><li>Found on the skin in moist areas </li></ul><ul><li>Primarily opportunistic </li></ul>
  14. 16. Pseudomonas aeruginosa <ul><li>Virulence factors: </li></ul><ul><ul><li>Endotoxins – cause sepsis and shock </li></ul></ul><ul><ul><li>Exotoxin A – cause tissue necrosis; inhibits eukaryotic protein synthesis similar to diphtheria exotoxin </li></ul></ul><ul><ul><li>Enzymes </li></ul></ul><ul><ul><ul><li>Elastases and proteases </li></ul></ul></ul><ul><ul><li>Pyocyanin – damages the cilia and mucosal cells of respiratory tract </li></ul></ul>
  15. 17. Pseudomonas aeruginosa <ul><li>Clinical: </li></ul><ul><ul><li>Urinary tract infections </li></ul></ul><ul><ul><li>Pneumonia in cystic fibrosis patients </li></ul></ul><ul><ul><li>Burn wound infection </li></ul></ul><ul><ul><li>Sepsis </li></ul></ul><ul><ul><li>Ecthyma gangrenosum – black necrotic lesions on skin </li></ul></ul><ul><ul><li>Malignant external otitis </li></ul></ul><ul><ul><li>Folliculitis </li></ul></ul><ul><ul><li>Osteochondritis of the foot due to punctured wounds through the soles of gym shoes - most common cause </li></ul></ul>
  16. 19. Ecthyma gangrenosum
  17. 21. Osteochondritis of foot
  18. 23. Pseudomonas aeruginosa <ul><li>Diagnosis: </li></ul><ul><ul><li>Culture – non-lactose fermenting </li></ul></ul><ul><ul><li>Oxidase production </li></ul></ul><ul><ul><li>Biochemical reactions – confirmatory </li></ul></ul><ul><li>Treatment: </li></ul><ul><ul><li>Resistant to many antibiotics </li></ul></ul><ul><ul><li>Ticarcillin or piperacillin + aminoglycoside (gentamicin or amikacin) </li></ul></ul>
  19. 24. Production of pyocyanin, water-soluble green pigment of Pseudomonas aeruginosa. (left tube)
  20. 25. Campylobacter jejuni <ul><li>Comma- or S-shaped rods </li></ul><ul><li>Microaerophilic (5% oxygen) </li></ul><ul><li>Grows well at 42 0 C </li></ul><ul><li>Sources of infection: domestic animals </li></ul><ul><li>MOT: fecal-oral (poultry, meat, unpasteurized milk common sources) </li></ul>
  21. 27. Campylobacter jejuni <ul><li>Clinical: </li></ul><ul><ul><li>Enterocolitis – begins as watery, foul-smelling diarrhea  bloody stools </li></ul></ul><ul><ul><li>Associated with </li></ul></ul><ul><ul><ul><li>Guillain-Barre syndrome </li></ul></ul></ul><ul><ul><ul><ul><li>Most common cause of acute neuro-muscular paralysis </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Autoimmune disease </li></ul></ul></ul></ul><ul><ul><ul><li>Reactive arthritis </li></ul></ul></ul><ul><ul><ul><li>Reiter’s syndrome </li></ul></ul></ul>
  22. 28. Campylobacter jejuni <ul><li>Diagnosis: </li></ul><ul><ul><li>Culture </li></ul></ul><ul><ul><li>Oxidase (+); sensitive to nalidixic acid </li></ul></ul><ul><li>Treatment: erythromycin or ciprofloxacin </li></ul>
  23. 29. Helicobacter pylori <ul><li>Curved; gram-negative; similar in appearance to Campylobacter </li></ul><ul><li>Strongly urease positive  convert urea to ammonia  neutralize gastric acid </li></ul><ul><li>Rapidly motile – allow organism to penetrate protective mucus layer </li></ul>
  24. 34. Helicobacter pylori <ul><li>Most common cause of chronic gastritis </li></ul><ul><li>Most common cause of duodenal ulcers </li></ul><ul><li>Second most common cause of gastric ulcer </li></ul><ul><li>Associated with development of gastric CA and gastric lymphoma </li></ul>
  25. 35. Helicobacter pylori <ul><li>Diagnosis: </li></ul><ul><ul><li>Culture </li></ul></ul><ul><ul><li>Urease production  urea breath test </li></ul></ul>
  26. 38. Helicobacter pylori <ul><li>Treatment: </li></ul><ul><ul><li>Proton pump inhibitors (Omeprazole) </li></ul></ul><ul><ul><li>Antibiotics – amoxicillin, metronidazole, tetracycline </li></ul></ul><ul><ul><li>Bismuth salts </li></ul></ul>
  27. 39. HAEMOPHILUS <ul><li>Family Pasteurellaceae </li></ul><ul><li>Small, gram negative, pleomorphic </li></ul><ul><li>Require enriched media containing blood or its derivatives </li></ul><ul><li>Facultative anaerobes </li></ul><ul><li>Obligate parasites </li></ul>
  28. 40. Haemophilus influenzae (Pfeiffer’s Bacilli) <ul><li>Found on mucus membrane of URT in humans (non-capsular form)  encapsulated species uncommon members of normal flora </li></ul><ul><li>Short, coccoid bacilli in pairs or chains </li></ul>
  29. 41. Haemophilus influenzae <ul><li>Classification: </li></ul><ul><li>Serotype – based on capsular antigen </li></ul><ul><li>Biotype – based on biochemical properties </li></ul><ul><li>a. indole production </li></ul><ul><li>b. urease activity </li></ul><ul><li>c. ornithine decarboxylase activity </li></ul><ul><li>Biogroup – useful for clinical purposes </li></ul>
  30. 42. Haemophilus influenzae: Culture <ul><li>Chocolate agar – flat, grayish brown colonies after 24 hrs incubation </li></ul><ul><li>Does not grow on sheep blood agar except around colonies of Staphylococci  “satellite phenomenon” </li></ul>
  31. 43. Haemophilus influenzae Growth Characteristics: <ul><li>Requires X factor (hemin) and V factor (NAD) </li></ul><ul><li>Ferments carbohydrates poorly and irregularly </li></ul>
  32. 44. Haemophilus influenzae Characteristics & Growth Requirements: Species X Factor V Factor Hemolysis H. influenzae H. parainfluenzae H. ducreyi H. haemolyticus H. parahaemolyticus H. aprophilus + - + + - - + + - + + - - - - + + -
  33. 45. Haemophilus influenzae: Virulence Factors <ul><li>Capsule </li></ul><ul><ul><li>Antiphagocytic; impair ciliary function </li></ul></ul><ul><ul><li>Main virulence factor </li></ul></ul><ul><ul><li>With capsular polysaccharides (a to f) </li></ul></ul><ul><ul><ul><li>Type b – polyribose-ribitol phosphate (PRP) </li></ul></ul></ul>
  34. 46. <ul><li>Somatic antigen </li></ul><ul><ul><li>Outer membrane proteins  lipooligo-saccharides (endotoxin) </li></ul></ul><ul><li>IgA1 proteases </li></ul>Haemophilus influenzae: Virulence Factors
  35. 47. Haemophilus influenzae: Clinical Features <ul><li>H. influenzae type b </li></ul><ul><ul><li>Most common serotype causing systemic disease </li></ul></ul><ul><ul><li>Meningitis </li></ul></ul><ul><ul><li>Pneumonia & empyema </li></ul></ul><ul><ul><li>Epiglottitis </li></ul></ul><ul><ul><li>Cellulitis </li></ul></ul><ul><ul><li>Septic arthritis </li></ul></ul>
  36. 48. <ul><li>Non-typable (non-encapsulated) H. influenzae </li></ul><ul><ul><ul><li>opportunistic </li></ul></ul></ul><ul><ul><ul><li>Chronic bronchitis </li></ul></ul></ul><ul><ul><ul><li>Otitis media </li></ul></ul></ul><ul><ul><ul><li>Sinusitis </li></ul></ul></ul><ul><ul><ul><li>Conjunctivitis </li></ul></ul></ul>Haemophilus influenzae: Clinical Features
  37. 49. <ul><li>Meningitis </li></ul><ul><ul><li>2 0 to bacteremic spread from nasopharynx </li></ul></ul><ul><ul><li>Peak incidence: 3 – 18 mos. old </li></ul></ul><ul><li>Epiglottitis </li></ul><ul><ul><li>Cellulitis & swelling of supraglottic tissues </li></ul></ul><ul><ul><li>Pharyngitis, fever & dyspnea  complete airway obstruction  death </li></ul></ul>
  38. 50. <ul><li>Cellulitis </li></ul><ul><ul><li>Reddish blue patches on cheeks or periorbital areas </li></ul></ul>
  39. 51. <ul><li>Arthritis </li></ul><ul><ul><li>Infection of a single large joint </li></ul></ul><ul><ul><li>Children < 2 y/o or immunocompromised patients or those with previously damaged joints </li></ul></ul><ul><li>Conjunctivitis </li></ul><ul><ul><li>Epidemic and endemic </li></ul></ul><ul><ul><li>H. influenzae biogroup aegypticus </li></ul></ul>
  40. 52. Haemophilus influenzae Clinical Features: Sepsis with gangrene
  41. 53. Haemophilus influenzae: Prevention <ul><li>Chemoprophylaxis with Rifampicin for non-immune children < 4 y/o who are close contacts </li></ul><ul><li>Hib conjugate vaccine </li></ul><ul><ul><li>> 2 mos. old  Hib conjugated with C. diphtheriae toxin protein or N. meningitidis outer membrane complex </li></ul></ul><ul><ul><li>> 15 mos. old  Hib conjugated with diphtheria toxoid </li></ul></ul>
  42. 54. Haemophilus aegypticus <ul><li>H. influenzae biotype III </li></ul><ul><li>Koch-Weeks bacillus </li></ul><ul><li>Resembles H. influenzae closely </li></ul><ul><li>Diseases: </li></ul><ul><ul><li>Conjunctivitis – highly communicable </li></ul></ul><ul><ul><li>Brazilian purpuric fever – fever, purpura, shock and death </li></ul></ul>
  43. 55. Haemophilus ducreyi <ul><li>Causes chancroid (soft chancre) </li></ul><ul><li>Ragged ulcer on genitalia with marked swelling and tenderness </li></ul><ul><li>Lymph nodes enlarged and painful </li></ul><ul><li>Organism grows best on chocolate agar incubated in 10% CO 2 </li></ul><ul><li>No permanent immunity </li></ul>
  44. 56. Haemophilus ducreyi
  45. 57. Bordetella pertussis <ul><li>Small, coccobacillary, encapsulated, gram (-) </li></ul><ul><li>With bipolar metachromatic granules (toluidine blue stain) </li></ul><ul><li>Non-motile; strict aerobe </li></ul><ul><li>Forms acid from glucose and lactose </li></ul>
  46. 58. Bordetella pertussis <ul><li>Requires enriched media </li></ul><ul><ul><li>Bordet-Gengou medium (potato-blood-glycerol agar) </li></ul></ul><ul><ul><li>Contains Pen G 0.5 ug/mL </li></ul></ul><ul><li>Virulence genes – bvgA and bvgS </li></ul>
  47. 59. Bordetella pertussis Gram stain Culture on chocolate agar
  48. 60. Bordetella pertussis: Virulence Factors <ul><li>Filamentous hemagglutinin </li></ul><ul><ul><li>Protein on pili; adhesion to ciliated epithelial cells </li></ul></ul><ul><li>Pertussis toxin </li></ul><ul><ul><li>promote lymphocytosis via inhibition of signal transduction by chemokine receptors  lymphocytes do not enter lymphoid tissues </li></ul></ul><ul><ul><li>promote sensitization to histamine </li></ul></ul><ul><ul><li>enhance insulin secretion </li></ul></ul><ul><ul><li>stimulate adenylate cyclase via ADP-ribosylation </li></ul></ul>
  49. 61. <ul><li>Adenylyl cyclase toxin – inhibit phagocytosis </li></ul><ul><li>Tracheal cytotoxin </li></ul><ul><ul><li>Fragment of bacterial peptidoglycan </li></ul></ul><ul><ul><li>Induce nitric oxide  destroy ciliated epithelium </li></ul></ul><ul><li>Dermonecrotic toxin </li></ul><ul><li>Hemolysin </li></ul>Bordetella pertussis: Virulence Factors
  50. 62. <ul><li>Adheres to and multiplies rapidly on epithelial surface of trachea and bronchi  interfere with ciliary action </li></ul><ul><li>No invasion of blood </li></ul>Bordetella pertussis: Pathogenesis
  51. 63. <ul><li>MOT: airborne droplets </li></ul><ul><li>Source of infection: patients in early catarrhal stage </li></ul><ul><li>Disease: Pertussis or Whooping Cough  acute tracheobronchitis </li></ul><ul><li>Incubation period: approx. 2 weeks </li></ul>Bordetella pertussis: Pathogenesis
  52. 64. <ul><li>Clinical: Stages of Disease </li></ul><ul><li>Catarrhal </li></ul><ul><ul><li>Mild coughing and sneezing </li></ul></ul><ul><ul><li>Highly infectious but not very ill </li></ul></ul><ul><li>Paroxysmal (1-4 weeks) </li></ul><ul><ul><li>Series of hacking coughs, accompanied by copious amts. of mucus, ending with inspiratory “whoop”  exhaustion, vomiting, cyanosis and convulsions </li></ul></ul><ul><ul><li>High wbc count (16,000-30,000/uL) with absolute lymphocytosis </li></ul></ul><ul><li>Convalescence - slow </li></ul>
  53. 65. <ul><li>Specimen: saline nasal wash (preferred) or nasopharyngeal swab </li></ul><ul><li>Direct fluorescence antibody test – 50% sensitivity </li></ul><ul><li>Culture of saline nasal wash fluid </li></ul><ul><li>PCR – most sensitive </li></ul><ul><li>Serology – (+) only on third week of illness  of little diagnostic value </li></ul>Bordetella pertussis: Diagnosis
  54. 66. <ul><li>First defense is antibody that prevents attachment </li></ul><ul><li>Recovery from disease or immunization is followed by immunity </li></ul><ul><li>Second infection may occur but is mild </li></ul><ul><li>Re-infection occurring years later in adults may be severe </li></ul><ul><li>Vaccine-induced immunity not completely protective </li></ul>
  55. 67. <ul><li>Chemoprophylaxis – Erythromycin  for exposed, unimmunized individuals OR exposed, immunized children < 4 years old </li></ul><ul><li>Vaccine – two vaccines available: </li></ul><ul><ul><li>acellular vaccine – contains 5 purified antigens  main immunogen is inactivated pertussis toxin; first vaccine to contain a genetically inactivated toxoid  ADP-ribosylating activity removed </li></ul></ul><ul><ul><li>DPT x 3 doses </li></ul></ul>
  56. 68. BRUCELLA <ul><li>Zoonotic  obligate parasite of animals & humans </li></ul><ul><li>Intracellular organism </li></ul><ul><li>Gram negative coccobacilli </li></ul><ul><li>Aerobic; non-motile; non-spore-forming </li></ul>
  57. 69. BRUCELLA <ul><li>Catalase (+); oxidase (+) </li></ul><ul><li>Produces H 2 S </li></ul><ul><li>Culture: trypticase soy agar OR blood culture media; B. abortus requires 5-10% CO 2 for growth </li></ul>
  58. 70. <ul><li>Route of infection in humans: </li></ul><ul><ul><li>Intestinal tract – ingestion of infected milk & contaminated dairy products (cheese from unpasteurized goat’s milk) </li></ul></ul><ul><ul><li>Mucous membranes – droplets </li></ul></ul><ul><ul><li>Skin – contact with infected tissues of animals </li></ul></ul><ul><li>Pathogenesis: endotoxin – O antigen polysaccharide </li></ul>
  59. 71. Species Animal Pathology B. melitensis Goats Acute and severe infection B. suis Swine Chronic with suppurative lesions; caseating granulomas B. abortus Cattle Mild disease without suppuration; Non-caseating granulomas of the RES (LN, liver, spleen, BM) B. canis Dogs Mild disease
  60. 72. <ul><li>Clinical: Brucellosis (Undulant or Malta Fever) </li></ul><ul><li>Acute </li></ul><ul><ul><li>Malaise, fever, weakness, aches & sweats </li></ul></ul><ul><ul><li>Fever rises in the afternoon  fall during the night with drenching sweats </li></ul></ul><ul><ul><li>(+) lymphadenopathy w/ palpable spleen; + hepatitis with jaundice </li></ul></ul><ul><li>Chronic </li></ul><ul><ul><li>With psychoneurotic symptoms </li></ul></ul><ul><ul><li>Weakness, aches & pains, low grade fever </li></ul></ul>
  61. 73. <ul><li>Diagnosis: </li></ul><ul><li>Culture </li></ul><ul><ul><li>BM & blood – commonly used specimen </li></ul></ul><ul><ul><li>Brucella agar, trypticase soy medium, brain heart infusion medium, chocolate agar </li></ul></ul><ul><li>Serology – inc. IgM during 1 st week of illness; peak at 3 months </li></ul>

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