Neisseria - Prac. Microbiology

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Neisseria - Prac. Microbiology

  1. 1. General Characters of the Genus 1. Gram-negative diplococci
  2. 2. 2. Aerobic 3. Oxidase positive (the key test of the genus)
  3. 3. The genus includes:  Many commensals  Two important human pathogens: 1. Neisseria gonorrhoeae (gonococci) 2. Neisseria meningitidis ( meningococci)
  4. 4. . Morphology . Culture characters: - Enriched media: Chocolate agar - Selective media: Modified Thayer Martin (Chocolate agar + antibiotics) . 5-10% CO2
  5. 5. Virulence Factors: • • • • Pili Outer membrane proteins LOS IgA protease
  6. 6. Diseases caused by N. gonorrehoeae 1. Gonorrhoeae : sexually transmitted disease (STD) Men: acute urethritis Women: cervicitis prostate, bladder & epididymis endometritis & salpingitis(PID) 2. Neonatal conjunctivitis 3. Vulvo-vaginitis 4. Oral infection
  7. 7. Gonorrhoeae Urethral discharge Cervical Discharge
  8. 8. Neonatal Conjunctivitis
  9. 9. Laboratory Diagnosis of Gonococcal Infections
  10. 10. A. Specimen: Urethral /Cervical Discharge / pharyngeal swabs
  11. 11. B. Gram-stained smear In men: Intracellular Gram-negative diplococci (diagnostic) In women: Less sensitive
  12. 12. C. Cultivation:
  13. 13. D. Identification:  Identification at the genus level Gram –ve diplococci Oxidase +ve
  14. 14.  Identification at the species level • Glucose utilization Glucose • Nucleic acid probe Maltose
  15. 15. N. meningitidis • Morphology: same + capsule • Culture characters: 1. It grows on chocolate & MTM 2. It can also grow on blood agar • Biochemical reactions: . Oxidase positive. . Utilization of glucose and maltose (acid only) Glucose Maltose
  16. 16. Virulence factors: 1. Polysaccharide Capsule is the most important at least 13 serogroups , the most common A, B, C, Y, and W135. All highly immunogenic EXCEPT B. 2. LOS 3. Pili 4. IgA protease.
  17. 17. Diseases caused by N. meningitidis N. meningitidis in the nasopharynx in 5- 30% 1. Meningitis 2. Meningococcemia Skin rash
  18. 18. Laboratory diagnosis of Meningococcal Meningitis Medical emergency
  19. 19. 1. Specimen: • CSF • Blood • Nasopharyngeal swab
  20. 20. 2. Direct Detection: A. Gram-stained smear
  21. 21. B. Direct Meningococcal Antigen Detection in CSF by:  Latex Agglutination  Report: within one hour to direct the antimicrobial therapy.  Definitive diagnosis by culture is essential to apply the infection control measures
  22. 22. 3. Cultivation: (CSF/ Nasopharyngeal swab)
  23. 23. Blood culture technique (1) (2) (3)
  24. 24. 4. Identification:  Identification to the genus level
  25. 25.  Identification to the species level • Sugar utilization Glucose Maltose • Antigen detection: by latex agglutination or immunofluorescence • Nucleic acid probe
  26. 26. Meningococcal Vaccine • Capsular polysaccharide vaccine (A,C,W135,Y) • Protein conjugate vaccine: Capsular polysaccharide vaccine + protein for young children • Given to groups at risk
  27. 27. Chemoprophylaxis • Close contacts • Doctors 2 days oral Rifampin Or One injection Ceftriaxone
  28. 28. 1. All of the following are characters of the genus Neisseria EXCEPT: a. Gram negative cocci b. Arranged in pairs c. Aerobic d. Oxidase negative e. Sugar fermentation identifies the species
  29. 29. 2. All of the following are true about N. gonorrhea EXCEPT: a. Can live intracellular b. Oxidase positive c. Produces acid only from glucose d. Can grow on nutrient agar e. Causes sexually transmitted diseases
  30. 30. 3. The following selective medium is used to isolate N. gonorrhea: a. Chocolate agar b. Blood agar c. MacConkey’s medium d. Mannitol salt agar e. Modified Thayer-Martin medium
  31. 31. 4. Culture of pathogenic Neisseria should be incubated : a. In humid atmosphere at 22 °C b. In 5-10 % CO2 c. Anaerobically d. Microaerophilically e. 2-4 weeks
  32. 32. 5. N. meningitidis may be detected in all of the following specimens EXCEPT: a. CSF b. Blood c. Stools d. Nasopharyngeal swab
  33. 33. Thank you

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