N Meningitidis(Kim)


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N Meningitidis(Kim)

  1. 1. K05-08 Neisseria meningitidis SPC Daniel S Kim
  2. 2. N. meningitidis CASE A 3⅟₂-year-old male presented to an outside emergency room with fever and lethargy since the previous evening and a petechial rash first noted on the day of evaluation. On physical examination the patient was listless and had a temperature of 39°C, blood pressure of 104/52mmHg, and heart rate of 148 beats/min.
  3. 3. N. meningitidis CASE (Cont.) Examination of the skin revealed a petechial rash as well as two purpuric lesions. Blood cultures were obtained, and he was given intravenous antibiotics and transferred to this hospital. On arrival here, he underwent a lumbar puncture, which was notable for cerebrospinal fluid with 190 white blood cells/mm³, with 94% neutrophils, consistent
  4. 4. N. meningitidis CASE (Cont.) with bacterial meningitis. NO organisms were seen on Gram stain of the cerebrospinal fluid. Blood cultures from the outside hospital were subsequently positive for an oxidase-positive, gram- negative diplococcus.
  5. 5. N. meningitidis Background THE NEISSERIAE The neisseriae are a group of gram-negative diplococci 0.6-1.5 µm in diameter. Two species of Neisseria, N. gonorrhoeae and N. meningitidis, are considered as true human pathogens. Both of these organisms possess pili and adhesions for adherence to host cells, produce endotoxins, and resist destruction within phagocytes. N. meningitidis also produces a capsule to resist phagocytic engulfment.
  6. 6. N. meningitidis Background The gonococcus may also cause extragenital infections such as pharyngitis (from oral-genital sex), ophthalmia (from inoculation of the eyes with contaminated fingers), and proctitis (from anal sex). In 1% - 3% of infected women and a lower percentage of infected males, the organism invades the blood and disseminates, causing a rash, septic arthritis, endocarditis, and/or meningitis.
  7. 7. N. meningitidis Background Dissemination occurs more frequently in females. Congenital gonorrhea is known as ophthalmia neonatorum and occurs as a result of the eyes of newborns becoming infected as the baby passes through the birth canal. Neisseria meningitidis (the meningococcus) is the causative organism of meningococcal (epidemic) meningitis.
  8. 8. N. meningitidis Background There are between 2000 and 3000 cases of meningococcal meningitis per year in the U.S. Approximately 50% of the cases occur in children between 1 and 4 years old. N. meningitidis infects the nasopharynx of humans causing a usually mild or subclinical upper respiratory infection. Colonization of the nasopharynx may persist for months.
  9. 9. N. meningitidis Background However, in about 15% of these individuals, the organism invades the blood and disseminates, leading septicemia and from the there may cross the blood-brain barrier causing meningitis. A petechial skin rash, caused by endotoxin in the blood, appears in about 75 percent of the septic cases and fatality rates for meningococcal septicemia are as high as 30 percent as a result of the shock cascade.
  10. 10. N. meningitidis Background A fulminating form of the disease, called Waterhouse-Frederichsen syndrome, can be fatal within several hours due to massive intravascular coagulation and resulting shock, probably a result of massive endotoxin release. N. meningitidis is especially dangerous in young children.
  11. 11. N. meningitidis Isolation and Identification • Gram stain A presumptive diagnosis of meningococcal meningitisis often made by doing a gram stain of cerebrospinal fluid or petichial skin lesions and looking for gram-negative diplococci seen both inside and outside of polymorphonuclear leukocytes. This can be followed by serologic tests, nucleic acid probes, or culturing.
  12. 12. N. meningitidis Isolation and Identification • Serologic identification There are at least 12 different serological groups of N. meningitidis based on their capsular polysaccharides, but over 90 percent of meningococcal meningitis cases are caused by five serologic groups: A, B, C, Y, and W135. Serogroups A and C usually causes the epidemic form of meningitis. Serogroup C is is the most common serogroup in North America whereas B is the most common in Europe and Latin America.
  13. 13. N. meningitidis Isolation and Identification Serogroup Y has been increasing in the U.S., Israel, and Sweden. Direct serologic testing to detect meningococcal capsular polysaccharides can be performed on cerebrospinal fluid or on organisms from skin lesions for rapid identification.
  14. 14. N. meningitidis Isolation and Identification • Nucleic acid identification A polymerase chain reaction test to amplify meningococcal DNA can also be used to detect N. meningitidis in cerebrospinal fluid or blood.
  15. 15. N. meningitidis Isolation and Identification •Isolation of N.meningitidis To isolate N. meningitidis, cultures are taken from the nasopharynx, blood, cerebrospinal fluid, and skin lesions. Typically cultures are done on an enriched, non-selective medium such as blood agar or chocolate agar grown in 3-7% carbon dioxide. MTM Chocolate agar is also sometimes used for isolation. Medium to large, blue-gray, mucoid, convex, colonies form in 48 hours at 35-37°C.
  16. 16. N. meningitidis Isolation and Identification • Identification of N.meningitidis Once isolated, N. meningitidis is identified by the oxidase test, gram staining, and carbohydrate utilization reactions. N. meningitidis, like all neisseriae, is oxidase- positive and appears in a gram stain as gram- negative diplococci.
  17. 17. N. meningitidis Isolation and Identification In carbohydrate utilization tubes, N. meningitidis produces acid from both glucose and maltose, but not from lactose and sucrose . The acid end products turn the phenol red pH indicator from red to yellow. N. meningitidis also produces gamma- glutamylaminopeptidase, an enzyme that can be detected by biochemical testing.
  18. 18. N. meningitidis CASE STUDY Q1. Which bacterium was causing this patient’s illness? Is the finding of meningitis a positive or negative prognostic sign?
  19. 19. N. meningitidis CASE STUDY A1. The clinical presentation, the finding of meningitis (190 white blood cells/mm³, primarily neutrophils, in the CSF), and the finding of oxidase-positive, gram-negative diplococci growing in the blood strongly indicated that the etiologic agent of this infection was Neisseria meningitidis.
  20. 20. N. meningitidis CASE STUDY Q2. Is this organism ever part of the normal oropharyngeal flora?
  21. 21. N. meningitidis CASE STUDY A2. N. meningitidis is usually considered to be part of the oropharyngeal flora and can be found in 20 to 40% of healthy young adults. During epidemics of meningococcal disease in institutionalized populations such as the military, colonization rate may approach 90%.
  22. 22. N. meningitidis CASE STUDY Q3. which immunologic abnormalities predispose individuals to infection with this organism?
  23. 23. N. meningitidis CASE STUDY A3. Most people who are colonized with this organism mount a humoral response to it. These individuals produce bactericidal antibodies, which appear to be protective. The very small percentage of patients who do not make bactericidal antibodies in response to colonization by this organism are high risk for development of invasive disease.
  24. 24. N. meningitidis CASE STUDY Q4. Which serogroup(s) causes illness? The serogroup is based on antigen from which part of the bacterium?
  25. 25. N. meningitidis CASE STUDY A4. The serogruops most commonly associated with meningitis in the United States are types A,C,Y,W135, and B. The two most frequently isolated serogroups are B(50%) and C(20%). Typically groups A and C are thought of as epidemic strains because of their association with epidemics, whereas group B isolates are most likely to cause sporadic cases.
  26. 26. N. meningitidis CASE STUDY Cases due to group B are most frequent because of the rarity of epidemics of N.meningiditis disease in the United States. The serogroups are based on the biochemical structure of the capsular polysaccharide that surrounds the organism. Nonencapsulated isolates rarely cause invasive disease, indicating that encapsulation is critical to the pathogenicity of the organism.
  27. 27. N. meningitidis CASE STUDY Q5. Which prophylactic strategies are useful for large populations?
  28. 28. N. meningitidis CASE STUDY A5. Vaccination is the mainstay of prophylactic strategies for large populations. Vaccines derived from capsular polysaccharide are highly protective against groups A and C in adults and children over 2 years of age.
  29. 29. N. meningitidis CASE STUDY Q6. Which prophylactic strategies can be used for exposed individuals?
  30. 30. N. meningitidis CASE STUDY A6. Both vaccination and chemoprophylaxis may be in order for exposed individuals, especially health care workers who come in close contact with respiratory secretions of infected individuals. Rifampin is the drug of choice for antimicrobial prophylaxis. It penetrates well into respiratory secretions and is well tolerated.
  31. 31. N. meningitidis CASE STUDY Q7. What are purpuric lesions and a petechial rash, and which virulence factor plays a central role responsible for their appearance?
  32. 32. N. meningitidis CASE STUDY A7. Petechial rash and purpuric lesions can be manifestation of disseminated intravascular coagulation (DIC). Petechial lesions are pinpoint, purplish red lesions that are caused by hemorrhage in the intradermal vascular bed. Purpuric lesions are similar to petechial lesions but are largerm probably representing coalescence of number of petechial lesions.
  33. 33. N. meningitidis
  34. 34. N. meningitidis
  35. 35. Petechial rash
  36. 36. Lumbar puncture
  37. 37. Purpura
  38. 38. Diplococcus
  39. 39. N. meningitidis
  40. 40. WF syndrome
  41. 41. symptom
  42. 42. symptom
  43. 43. nasopharynx
  44. 44. PCR
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