Gram Nega Flashcards
What is neisseria?
Gram negative cocci has many species but only two species is pathogenic
What are pathogenic species of neisseria?
1- N. gonorrhoeae (the gonococcus) is the causative agent of gonorrhoea and is transmitted via sexual contact (STD).
2- Neisseria meningitidis (the meningococcus) causes significant morbidity and mortality in children and young adults worldwide
How do neisserice appear in gram staining
Encapsulates or unencaupsulater, aerobic diplocaccus wish Kidney shape.
N. meningitidis is a fastidious bacterium, dying within hours on inanimate surfaces.
Talk about Blood culture of neisserie?
Grow better on chocolate agar than blood ‘also grow on
Tryptecase soy and muller-Hinton age.
Colonies of Neisseria meningitidis are unpigmented and appear round, smooth, glistening, and convex, with a clearly defined edge
Cultivation 24 hours in anaerobic atmosphere enriched with 5% CO2, 37°C.
Which naisserra species is most fastidious?
Neisseria gonorrhoeae
Thus require complex growth media and are highly susceptible to toxic substances
Gonococci are not able to grow on common blood agar.
How to differentiate between gonorrhoeae and meningitis?
N. Gonorrhoeae are positive by the oxidase test and the result is confirmed with carbohydrate reactions (meningococci oxidize glucose and usually maltose, but not sucrose and lactose).
Gonorrhoene is glucose positive
Meningitis is maltose and glucose positive
Glutamylaminopeptidase GGT:meningitis positive,, gonotrhocae negative
How to prepare culture media for neisserice gonorrhea?
Media for N. gonorrhoeae contain antimicrobials that inhibit the growth of organisms other than N. gonorrhoeae; typically vancomycin (inhibits Gram-positive bacteria), colistin (inhibits gram-negative bacteria including the commensal Neisseria spp.), trimethoprim (inhibits swarming of Proteus spp.) and nystatin or amphotericin B (antifungal agents). Often are used media resembling chocolate agar in appearance (e.g., modified Thayer-Martin agar (MTM) or Martin-Lewis agar (ML).
True or false
N. Gonorhoene culfre are incubated in a CO2-enriched, humid atmosphere (some gonococci require CO2 for growth, the growth of all species is enhanced by carbon dioxide).
True
What are virulence factors of n.gonorrheece?
1 _ Capsule:
2- fimbrice/pilli
3- Lipopolysaccharize
4 - cell wall proteins
What is pathogenicity of n.Gonorrhopae?
acquired by sexual contact,
Mostly effects columnar epithelial cells, including cervix and urethra (dysuria), but also rectum, pharynx, burning and itching.
GC LPS stimulates the production of tumor necrosis factor, which causes cell damage.
Whet are early symptoms of n. Meningitisdis?
fever, malaise, headache & vomiting, progressing with seizures, altered mental status and coma.
How to treat neisseria?
Ceftriaxone, a third generation cephalosporin, is recommended for therapy by CDC. Penicillin is still the drug of choice for treatment of infections caused by N. meningitidis Most M. catarrhalis strains produce beta lactamase, and are therefore penresistant.
