Neisseria gonorrhoeae

Question 1

What are the general characteristics of Neisseria gonorrhoeae (gonococcus)?

Answer 1

Gram-negative cocci often arranged in pairs (diplococci) with adjacent sides flattened
Oxidase positive
Most catalase positive
Non-motile, non-spore forming
Sensitive to aerobic conditions but grow better with low CO2
Susceptible to cool temperatures, drying, and fatty acids

Question 2

What structures are present in Neisseria gonorrhoeae?

Answer 2

Pili (N-methylphenylalanine)
Outer membrane with phospholipids, proteins (OMP I, OMP II, Opa), and lipooligosaccharide (LOS)
Antigenic variation in Pili, OMPs, and LOS
Capsule
Cytoplasmic membrane
Cytoplasm

Question 3

How is Neisseria gonorrhoeae transmitted

Answer 3

Primarily by sexual contact
Can be transmitted from an infected mother during birth
Asymptomatic carriage is a major reservoir

Question 4

What is the pathogenesis of Neisseria gonorrhoeae?

Answer 4

Attachment and invasion using pili and outer membrane proteins
Survival and multiplication in the submucosa
Spread and dissemination, leading to local cell injury and inflammation
Common sites of inoculation: cervix or vagina in females, urethra or penis in males

Question 5

What are some virulence factors of Neisseria gonorrhoeae?

Answer 5

Secretion of IgA protease that inhibits IgA antibodies
Outer membrane proteins that prevent phagolysosome, mediate attachment, and protect surface antigens
Lipooligosaccharide (LOS) with endotoxin activity
Acquisition of antibiotic resistance through plasmid-encoded beta-lactamase and changes in cellular permeability

Question 6

What are the clinical presentations of Neisseria gonorrhoeae in men and women?

Answer 6

In Men: Urethritis with purulent discharge and dysuria
In Women: Cervicitis with mild symptoms, pelvic inflammatory disease, and disseminated gonococcal infection leading to bacteremia

Question 7

How is Neisseria gonorrhoeae diagnosed in the laboratory?

Answer 7

Gram Stain: Grame-negative diplococci inside polymorphonuclear leukocytes, 95% specific and sensitive in men, 50%-70% in women
Culture: Using specialized media and incubation conditions
Biochemical Tests: Oxidase positive, glucose fermentation positive, nitrite reduction negative
Immunological Tests: Particle agglutination tests using specific monoclonal antibodies
Antimicrobial Susceptibility Tests: Resistance to penicillin is common, ceftriaxone is effective for treatment
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