Neisseriae

Question 1

General Morphology

Answer 1

Gram Negative diplococci (bean-shaped)

Question 2

Where are non-pathogenic Neisseria found?

Answer 2

Commensals in Nasopharynx

Question 3

Neisseria gonorrhea- General characteristics (4)

Answer 3

Fastidious Gram-negative diplococci (bean-shaped)

Grow at 37 degrees on layer blood and chocolate agar in atmosphere of 5-10% CO2

Oxidase positive

Identification: Glucose utilization —> acid

Question 4

Neisseria gonorrhea- Pathogenicity (3)

Answer 4

1- FIMBRIAE or TYPE IV PILI —> attachment to mucosal surface

2- CATALASE —> Resistance to Intracellular killing by Phagocytic cells (protects organism from toxic effects or O2 radicals)

3- ANTIGENIC VARIATION —> FIMBRIAE and OUTER MEMBRANE PROTEIN II

Question 5

Neisseria gonorrhea- Habitat

Answer 5

NEVER NORMAL FLORA

Question 6

Neisseria gonorrhea- Local Infections (4)

Answer 6

Acute urethritis in males

95% symptomatic (male)

Dysuria, urethral discharge

Local spread: epidiymitis, prostatitis, urethral stricture

Question 7

Neisseria gonorrhea- Clinical Features (3)

Answer 7

1- Acute vaginitis and Endocervicitis

- 50% of females symptomatic
- Local spread: PID, Salpingitis, Infertility 
- Ophthalmia neonatorum 

2- Disseminated Gonococcal Infection

- Common in female
- Fever, arthritis, septic skin lesions on extremities 
- Rarely: meningitis, infective endocarditis 

3- Vulvovaginitis in prepubertal girl
- Child abuse

Question 8

Neisseria meningitidis- General Characteristics (4)

Answer 8

Fastidious, aerobic Gram-negative diplococci (bean-shaped)

Grow at 37 degrees on blood and chocolate

Oxidase positive

Identification: Glucose and Maltose positive

Question 9

Neisseria meningitidis- Viability

Answer 9

Organism die quickly at room temp outside human host

Question 10

Neisseria meningitidis- Serogroup Typing (3)

Answer 10

1- Produces POLYSACCHARIDE CAPSULE

2- 13 serogroup: A, B, C, X, Y, Z, W-135 (commonest = A, B, C)

3- Typing: slide agglutination with specific antisera

Question 11

Neisseria meningitidis- Major serogroups (5)

Answer 11

A —> Epidemic meningitis (Africa) —> Vaccine

B —> Epidemic strains (outbreaks) —> Vaccine

C —> Local outbreaks —> Vaccine

W-135 —> Pilgrims returning from Haj —> Vaccine

X, Y, Z —> Rare

Question 12

Neisseria meningitidis- Reservoir

Answer 12

Human Nasopharynx

Question 13

Neisseria meningitidis- Pathogenesis (2)

Answer 13

1- TYPE IV PILUS —> mucosal colonization of Nasopharynx

2- POLYSACCHARIDE CAPSULE —> resist host immune defense

Question 14

Neisseria meningitidis- Clinical Features (4)

Answer 14

Meningitis

Conjunctivitis

Arthritis

Infective endocarditis

Question 15

Neisseria meningitidis- Age Risk Factor

Answer 15

3months - 3years

18-23years

Question 16

Neisseria meningitidis- Virulence Factors (3)

Answer 16

1- POLYSACCHARIDE CAPSULE —> prevent phagocytosis

2- LOS ENDOTOXIN —> present in OUTER MEMBRANE, damage to BLOOD VESSELS associated with meningococcal infection

3- LIPOOLIGOSACCHRIDE —> stimulates TNF-a which results in HOST CELL DAMAGE

Question 17

Neisseria meningitidis- Immunoprophylaxis

Answer 17

A, B, C, Y, W-135