neissriae.pptx
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This document discusses Streptococcus pneumoniae (pneumococcus), a gram-positive coccus that is part of the normal respiratory flora but can cause pneumonia. It has a polysaccharide capsule that is a main virulence factor. It requires enriched media to grow and shows alpha hemolysis on blood agar. Identification methods include bile solubility, optochin sensitivity, Quellung reaction, and inulin fermentation tests. The document also discusses Neisseria gonorrhoeae and N. meningitidis, which are gram-negative cocci that appear in pairs and are detected in pathological specimens by gram stain. They require enriched media to grow and are identified by oxidase and sugar fermentation tests
neissriae.pptx
- 1. By Dr /Eman A. Abd Alrahman
- 2. Pneumococci are members of upper respiratory tract normal flora. They can cause lobar pneumonia and its complications. Gram positive cocci slightly elongated and arranged in pairs, not motile and capsulated. Capsules appear as unstained hallow around the organism in Gram stained film. Strept pneumoniae in tissue
- 3. The polysaccharide capsule is the main virulence factor of the organism. Cultural Characters: Require enriched medium e.g. blood agar. On blood agar, gives alpha haemolysis or greenish discolouration due to partial haemolysis of RBCs, (similar to S.viridans) Alpha hemolysis by S. pneumoniae on blood agar
- 4. Strept.viridans Pneumococci - + Bile solubility Difference between Pneumococci & Strept.viridans
- 8. ENTEROCOCCI • Gram positive cocci, arranged in short chains or in pairs. • Non motile, non-capsulated. • No haemolysis on blood agar. • Ferment lactose, give rose pink colonies on MacConkey’s medium. • Normal flora of intestine. • It may cause urinary tract infection, endocarditis and abdominal infection. Strept faecalis in culture
- 9. The genus Neisseria includes: 1-Pathogenic: two species: •N. gonorrhoeae Gonorrhea. •N. meningitidis Epidemic cerebrospinal meningitis. 2- Commensals: include N.Sicca, N.subflava,…etc, are found in mouth, throat, pharynx and vagina. GRAM NEGATIVE COCCI Neisseria
- 10. GRAM NEGATIVE COCCI Neisseria Morphology: Gram negative cocci arranged in pairs with flattened adjacent sides, (kidney shaped appearance). Detected intracellularly in the pathological specimens Gram stained film of pathogenic Neisseria
- 11. Cultural Characters: - N.gonorrhoeae and meningitidis are fastidious organisms; grow only on enriched media e.g. chocolate, Thayer- Martin and modified Thayer- Martin media at 37°C, in the presence of 5-10% Co2, Its colony is smooth, translucent and non-pigmented. Neisseria culture on chocolate agar
- 12. Biochemical reactions: •Oxidase test: All Neisseria give a positive oxidase reaction. •Sugar fermentation: •N. gonorrhoeae ferments glucose only. •N. meningitidis ferments glucose and maltose Oxidase test
- 13. Laboratory diagnosis of N. meningitidis infections: Cerebrospinal meningitis cases: •Specimen: CSF is obtained by lumber puncture, centrifuged and the deposit is used. Spinal needle
- 14. •Direct detection: •Gram-stained smears: showing Gram-negative diplococci intracellular, in some pus cells. •Direct detection of meningococcal antigen in body fluids by latex agglutination or fluorescent antibody test. ve ve
- 15. •Cultivation: Culture on chocolate, Thayer- Martin and modified Thayer- Martin media, incubated at 37°C in 10 -20%CO2.
- 16. Diagnosis of meningococcal carriers:- •Nasopharyngeal swab is obtained and cultured on chocolate agar and the isolated Gram negative diplococcic should be differentiated from commensal Neisseria by using meningococcal antisera. •Diagnosis of N.gonorrhoeae infection: i.Specimen: urethral discharge in males and cervical swab in females. ii.Gram stained film showing gram negative diplococcic intracellularly in pus cells is diagnostic in acute cases. iii.Culture on chocolate agar, the growth is identified by oxidase test and sugar fermentation.