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بسم الله الرحمن الرحيم

بسم الله الرحمن الرحيم. Aerobic Gram-Negative Cocci. Dr. Manal El Said. Head of Microbiology Department. Neisseria. Dr. Manal El Said. Head of Microbiology Department. Neisseria meningitidis (Meningococcus). Diseases.

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بسم الله الرحمن الرحيم

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  1. بسم الله الرحمن الرحيم

  2. Aerobic Gram-Negative Cocci Dr. Manal El Said Head of Microbiology Department

  3. Neisseria Dr. Manal El Said Head of Microbiology Department

  4. Neisseria meningitidis (Meningococcus) Diseases - Meningitis(inflammation the meninges of the brain or spinal cord) - Meningococcemia. Characteristics • Gram-negative "kidney-bean" diplococci. • Oxidase-positive. • Large polysaccharide capsule. One of the three classic encapsulated pyogenic bacteria (Streptococcus pneumoniae and Haemophilus influenzae are the other two). Habitat and Transmission • Habitat is the human upper respiratory tract • Transmission is via respiratory droplets.

  5. Neisseria meningitidis (Meningococcus) Pathogenesis • The organism reaches the meninges via the bloodstream. • Endotoxin in cell wall causes symptoms of septic shock. • IgA protease produced. • Capsule is antiphagocytic. • Deficiency in late complement componentsrecurrent meningococcal infections. The characteristic skin rash (purpura) of meningococcal septicemia, caused by Neisseria meningitidis

  6. Neisseria meningitidis (Meningococcus) Laboratory Diagnosis • Gram-stained smear and culture. • Oxidase-positive colonies on chocolate agar. • Ferments maltose in contrast to gonococci, which do not.

  7. Neisseria meningitidis (Meningococcus) Laboratory Diagnosis Round, moist, glistening & convex colonies N. meningitidis - proper streaking and growth on blood agar plate.

  8. Neisseria meningitidis (Meningococcus) - - + + Mal Glu Lac Suc Laboratory Diagnosis

  9. Neisseria meningitidis (Meningococcus) Treatment Penicillin G (no significant resistance). Prevention • Vaccine contains capsular polysaccharide of strains A, C, Y & W-135. • One form of the vaccine contains the polysaccharides coupled to a carrier protein (diphtheria toxoid) and one contains only the polysaccharides. • Rifampin or ciprofloxacin given to close contacts to decrease oropharyngeal carriage.

  10. Neisseria gonorrhoeae (Gonococcus) Diseases • Gonorrhea. • Neonatal conjunctivitis • Pelvic inflammatory disease. Characteristics • Gram-negative "kidney-bean" diplococci. • Oxidase-positive. • Insignificant capsule.

  11. Neisseria gonorrhoeae (Gonococcus) Habitat and Transmission • Habitat is the human genital tract. • Transmission in adults is by sexual contact. • Transmission to neonates is during birth. Pathogenesis • Organism invades mucous membranes inflammation. • Endotoxin weaker than that of meningococcus less severe disease when bacteremiaoccurs. • IgA protease & pili are virulence factors

  12. Neisseria gonorrhoeae (Gonococcus) Laboratory Diagnosis • Gram-stained smear and culture. • Organism visible intracellularly within neutrophils in urethral exudate. • Oxidase-positive colonies. • Gonococci do not ferment maltose (meningococci do). Left: Neisseria gonorrhoeae Gram stain of pure culture; Right: Neisseria gonorrhoeae Gram stain of a pustular exudate.

  13. Neisseria gonorrhoeae (Gonococcus) Laboratory Diagnosis

  14. Neisseria gonorrhoeae (Gonococcus) Treatment • Ceftriaxone for uncomplicated cases. • Tetracycline added for urethritis caused by Chlamydia trachomatis. • High-level resistance to penicillin is caused by plasmid-encoded penicillinase. • Low-level resistance to penicillin is caused by reduced permeability and altered binding proteins.

  15. Neisseria gonorrhoeae (Gonococcus) Prevention • No drug or vaccine. • Trace contacts and treat to interrupt transmission. • Treat eyes of newborns with erythromycin ointment or silver nitrate to prevent conjunctivitis.

  16. Moraxellacatarrhalis • Small coccobacillary gram-negative rod • It causes : • -Otitis media & sinusitis in children. • -Bronchitis & pneumonia in older people with chronic obstructive pulmonary disease • It is found only in humans • It transmitted by respiratory aerosol.

  17. Anaerobic Gram-Negative Cocci Dr. Manal El Said Head of Microbiology Department

  18. Veillonella • Veillonella parvulais an anaerobic gram-negative diplococcus • It is a normal flora of the mouth, colon & vagina. • It is a rare opportunistic pathogen that causes abscesses of the sinuses, tonsils & brain • It is usually in mixed anaerobic infections.

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