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Neisseria

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Neisseria

  1. 1. CLASSIFICATION Kingdom: Bacteria Phylum: Proteobacteriacea Class: Betaproteobacteria Order: Neisseriales Family: Neisseriaceae Genus: Neisseria Species: gonorrhoeae meningitidis lactamica,etc
  2. 2. INTRODUCTION & HISTORY: Discovered Neisseria gonorrhoeae (1879) Albert stain Mycobacterium lepraeAlbert Ludwig Sigesmund Neisser
  3. 3. CHARACTERISTICS: characteristics Gram negative/ cocci Aerobes Oxidase positive diplo cocc i
  4. 4. CONTAINS TWO IMPORTANT PATHOGENS  Nesseria meningitidis  Nesseria gonorrhoeae
  5. 5. IMPORTANT DIFFERENCE BETWEEN N.gonorrhoeae & N. meningitidis N. gonrrhoeae N. meningitidis I have got an antibiotic resistant plasmid I have got a polysaccharide capsule
  6. 6. NEISSERIA MENINGITIDIS Gram negative oval/spherical cocci 0.6 to 0.8 µm in size Arranged in pairs (adjacent sides flattened) Bean shaped Encapsulated Shape of Neisseria meningitidis Described and isolated by weichselbaum from spinal fluid of patient,1887
  7. 7. CULTURAL CHARACTERISTICS Media used:  non selective media:  Blood agar  Chocolate agar  Mueller-Hinton starch casein hydrolysate agar  Selective media  Modified Thayer-Martin Agar  Colony characteristics  Color: Bluish grey  Shape: Round  Size: About 1mm  Surface: Smooth  Elevation: Convex  Opacity: Transluscent  Consistency: Butyrous
  8. 8. Neisseria meningitidis growing on chocolate agar Neisseria meningitidis growing on sheep blood agar
  9. 9. BIOCHEMICAL TESTS • Oxidase positive • Catalase positive • Ferments glucose and maltose with acid production • Nitrate negative • Colistin resistant • Doesn’t ferment lactose, sucrose and fructose • Gamma-glutamyl aminopeptidase positive • DNAase Positive
  10. 10. SEROGROUPS AND SEROTYPES on the basis of specificity of capsular polysaccharide antigens divided into 13 serogroups . These are A,B,C,D,X,Y,Z,W -135,29-E,H,I,K and L. Serogroups A,B,C,X,Y,W 135 : most commonly associated with meningococcal disease Group A: epidemics Group C: localised outbreaks Group B: both epidemics and outbreaks
  11. 11. CONTD…  Serotypes:  Based on the outermembrane protein serogroups further divided into serotypes  About 20 serotypes have been identified
  12. 12. VIRULENCE FACTORS  Fimbrae (common pili)-  Lipooligosaccharide:  Capsule  Cell membrane proteins  IgA protease-
  13. 13. EPIDEMIOLOGY Natural habitat and reservoir human nasopharynx urogenital tract anal canal Nasopharyngeal carriers 5-10% adults asymptomatic carriers Modes of infection Direct contact or respiratory droplets from the nose and throat of infected people Prevelence of meningitis is highest in meningitis belt of Africa (frequent epidemics occurred there) In 1996,largest 150000 cases 15000 deaths reported
  14. 14. Inhalation of contaminated droplets Adherence of organism to nasopharyngeal mucosa Local invasion and spread from nasopharynx to meninges through blood stream (directly along perineural sheath of olfactory nerve,cribriform plate to subarachnoid space) In meninges, organsims are internalised into phagocytic cells They replicate and migrate to subepithelial spaces Incubation period : 3-4 days PATHOGENESIS (STEPS)
  15. 15. CLINICAL FEATURES  Febrile illness : Mild and self limiting  Pyogenic meningitis : High fever, stiff neck, Kernig’s sign, severe headache, vomiting, photophobia, chills  Meningococcemia : acute fever with chills, malaise, prostation, Waterhouse- frederichsen syndrome, DIC  Other Syndrome : Pneumonia, arthritis, urethritis, respiratory tract infection
  16. 16. Hemorrhage in the adrenal glands in Waterhouse- Fridericksen syndrome Meningococcal disease is favoured by defieciency of the terminal complement components (C5-C9)
  17. 17. PROPHYLAXIS a. Chemoprophylaxis :  Rifampicin  Minocycline  Ciprofloxacin b. Vaccination:  A vaccine containing capsular polysaccharide of serotypes A and C : for infants below 2 years  A quadrivalent vaacine constituted by polysaccharides of serotypes A,C,Y and W-135 : for children and adults  conjugate vaccine: polysaccharide antigen is conjugated to diptheria toxoid
  18. 18. LABORATORY DIAGNOSIS 1. Specimen:  CSF  Blood 2. Examination of CSF:  Increased Pressure  Turbid  The collected CSF is divided into 3 portions (for microscopy, for biochemical tests and for culture)
  19. 19.  Microscopy:  Gram stained smear of CSF deposit commonly shows Gram negative intracellular diplococci.  White cell count increases to several thousand per cubic mm with 90-99% PMNs.  Biochemical tests:  Glucose is markedly diminished  CSF protein is markedly raised CSF:  Culture:  Inoculated into chocloate agar  Incubated at 37c in 5-10% Carbondioxide and high humidity  After 24 hours bacterial colonies appear  The organism is tested for biochemical and agglutination reaction
  20. 20. Normal CSF: Clear , colorless 0-5 lymphocytes Sterile 150-450 mg /l protein 2.8-3.9mmol/l glucose CSF in viral meningitis Clear or slightly turbid 10-500 cells mainly lymphocytes Stool culture, or serology +ve Normal or slightly raised protein Normal glucose CSF in TB meningitis: Clear or slightly turbid 10-500 cells,mainly lymphocytes( polys early) AFB in Z-N stain Grow in LJ medium Moderately raised protein Sugar reduced CSF in bacterial meningitis: Turbid 500-20,000 cells,few lymphocytes Bacteria in Gram stain Markedly raised protein Reduced or absent glucose CSF IN DIFFERENT MENINGITIS
  21. 21. 3.Blood culture:  Blood culture is positive in over 40% cases of meningiococcal meningitis 4.Other Cultures:  Nasopharyngeal swab  Skin lesions  Joint fluid  Tracheal aspirate  Urethral discharge  Serology  Petechial lesions
  22. 22. d) Detection of antigen:  For Detection of Meningiococcal DNA  Polymerase Chain Reaction (PCR)  For detection of soluble polysaccharide antigen  Counter current immunoelectrophoresis (CIEP)  Latex agglutination test
  23. 23. Neisseria gonorrhoeae (Gonococcus)  N. gonorrhoeae causes the sexually transmitted disease gonorrhoea.  first described by Neisser in 1879 in gonorrheal pus.  resembles meningococci very closely in many properties.
  24. 24. MORPHOLOGY: Gram negative oval/spherical cocci usually found with in the polymorphs Arranged in pairs (adjacent sides concave) Kidney shaped possess pili on their surface
  25. 25. CULTURE & CULTURAL CHARACTERISTICS:  fastidious organisms do not grow on ordinary culture media.  aerobic but may grow anaerobically also  The optimum temperature for growth is 35-36°C & optimum pH is 7.2-7.6.  It is essential to provide 5-10% CO2.
  26. 26. Media used: a) Non selective media: Chocolate agar, Mueller-Hinton agar Modified New York City medium b) Selective media: Thayer Martin medium with antibiotics (Vancomycin, Colistin & Nystatin)
  27. 27. Colony morphology: Colonies are small round translucent convex or slightly umbonate finely granular surface lobate margins.
  28. 28. Biochemical reactions: 1) Oxidase test: Positive 2) Ferments only glucose but not maltose.
  29. 29. PATHOGENICITY: Source of infection: 1. Asymptomatic carriers 2. Patients Mode of infection: 1. Venereal infection (sexual contact) 2. Nonvenereal infection
  30. 30. Antigenic structure & virulence factors: 1. Pili 2. Lipooligosaccharide: Endotoxic. 3. Outer membrane proteins: 3 types a) Protein I (por)- it is a porin & helps in adherence. b) Protein II (opa)- helps in adherence. c) Protein III (rmp)- it is associated with protein I. 4. IgA1 protease: Splits & inactivates IgA.
  31. 31. Antigenic structure & virulence factors
  32. 32. Mechanism of pathogenesis: Gonococci adhere to epithelial cells of urethra or other mucosal surface through pili penetrate through the intercellular space reach the sub epithelial connective tissue & causes inflammation Leads to clinical manifestations Incubation period: 2-8 days.
  33. 33. Disease: A) In men: The disease starts as an acute urethritis with a mucopurulent discharge extends to the prostate, seminal vesicles & epididymis In some it may become chronic urethritis leading to stricture formation The infection may spread to the periurethral tissues, causing abscesses & multiple discharging sinuses (Watercan perineum)
  34. 34. B) In women: The initial infection is urethritis & cervicitis but vaginitis does not occur in adult female (vulvovaginitis can occur in prepubertal girls) The infection may extend to Bartholin’s glands, endometrium & fallopian tubes causing Pelvic Inflammatory Disease (PID) Rarely peritonitis may develop with perihepatic inflammation (Fitz-Hugh-Curtis syndrome)
  35. 35. C) In both the sexes: Proctitis, pharyngitis, conjunctivitis, bacteraemia which may lead to metastatic infection such as arthritis, endocarditis, meningitis, pyemia & skin rashes. D) In neonates: Opthalmia neonatorum (a nonvenereal gonococcal conjunctivitis in the newborn) results from direct infection during passage through birth canal.
  36. 36. LABORATORY DIAGNOSIS: Specimens collected: A) In men: a) Acute infection- Urethral discharge b) Chronic infection- i) Morning drop ii) Discharge collected after prostatic massage iii) Centrifuged deposit of urine B) In women: i) Urethral discharge ii) Cervical swabs
  37. 37. C) In both the sexes: Blood, CSF, synovial fluid, throat swab, rectal swab & material from skin rashes. Transport: If there is delay in processing than the specimens should be sent in “ Stuart’s medium”.
  38. 38. Methods of examination: A) Direct microscopy: 1. Gram staining: Smear provides a presumptive evidence of gonorrhea in men. Gram negative diplococci are found. But it is unreliable in women.
  39. 39. 2. Immunofluorescence:
  40. 40. B) Culture: Media used: Colony morphology: Gram’s smear: Reveals Gram negative cocci in pairs with adjacent sides concave. Biochemical reactions:
  41. 41. C) Serology:  Complement fixation test,  Precipitation,  Passive agglutination,  Immunofluorescence,  Radioimmunoassay.(uses whole-cell lysate,pilus protein and lipopolysaccharide antigen)
  42. 42. TREATMENT:  Previously Penicillin was drug of choice but resistance developed rapidly.  Penicillin resistant is due to production of penicillinase enzyme & the strains are called as penicillinase producing Neisseria gonorrhoeae (PPNG).  Now Ceftriaxone or Ciprofloxacin plus Doxycycline or Erythromycin is useful.
  43. 43. EPIDEMIOLOGY:  Gonorrhoea is an exclusively human disease.  The only source of infection is a human carrier or less often a patient.  Asymptomatic carriage in women makes them a reservoir to spread infection among their male contact.  Gonorrhoea is an venereal disease (STD).
  44. 44. PROPHYLAXIS:  Early detection of cases,  Tracing of contacts,  Health education,  General measures,  Vaccination has no role in prophylaxis.
  45. 45. NONGONOCOCCAL (NONSPECIFIC) URETHRITIS  Urethritis due to causative agents other than gonococcus.  Etiology: a) Bacteria- Chlamydia trachomatis Mycoplasma urealyticum Ureaplasma urealyticum b) Parasites- Trichomonas vaginalis c) Viruses- Herpes simplex Cytomegalovirus d) Fungi- Candida  NGU can be a part of Reiter’s syndrome- a clinical condition characterized by urethritis, arthritis & conjunctivitis.
  46. 46. COMMENSAL NEISSERIAE N. lactamica N.pharyngis N. polysaccreae N. cinerea N. flavescens N. mucosa Commensal neisseriae

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