Lecture 4 - Gram Negative Cocci

Question 1

Neisseria meningitidis

Answer 1

Gram negative diplococci

Question 2

Neisseria meningitidis:

Isolation

Answer 2

• Laboratory isolation using chocolate agar, 5-10% CO2, 37 C

- use selective media (i.e., Thayer-Martin) when isolating from nasopharynx

Question 3

Neisseria meningitidis:

Found Where?

Answer 3

Frequently found in the naso-pharynx of healthy individuals

Question 4

Neisseria meningitidis:

Answer 4

• Antiphagocytic polysaccharide capsule
  • 13 different serogroups
  • A, B, C, X, Y and W135 most prevalent

Question 5

Neisseria meningitidis:

Carriers

Answer 5

• Carriers can occasionally develop infection or pass organism to non- immune individuals who develop infection

Question 6

Neisseria meningitidis:

Infections

Answer 6

• Meningitis
• Septicaemia (starts as skin rash)
• Waterhouse-Friderichsen Syndrome (complication of septicaemia…most severe form of septicaemia by N. meningitidis)

Question 7

Neisseria meningitidis:

Prevention

Answer 7

• Penicillin is primary antibiotic used

- Vaccination is recommended for children (11-12 years), teenagers and college/university students living in dormitories

Question 8

Neisseria meningitidis:

Vaccination

Answer 8

• Conjugated vaccine for serogroups A, C, Y and W135

- Now have meningococcus vaccine for infants at 2-5 months (serogroup C)

Question 9

Neisseria gonorrhoeae:

general

Answer 9

• Gram negative diplococci, 0.6-1μm in diameter

Question 10

Neisseria gonorrhoeae:

Lab

Answer 10

• In a clinical lab, grow on Thayer-Martin plates, in damp environment
  with CO2
• VERY sensitive to drying and changes in temperature

Question 11

Neisseria gonorrhoeae:

Causes

Answer 11

• Causative agent of STD gonorrhea
• In US, it is the second highest reported STD, after chlamydia
  • >350,000 cases/year reported in the US (2001) • Number of cases is now decreasing every year

Question 12

Neisseria gonorrhoeae:

Clinical

Answer 12

• MEN: causes acute infection of urethra (90-95%)
• WOMEN: 50% are ASYMPTOMATIC!!!
  • Cervicitis
  • If untreated can cause PID, sterility

Question 13

Neisseria gonorrhoeae:

Disseminated Gonococcal Infection (DGI)

Answer 13

• 1-3% cases, usually women

- Fever, skin infection, arthritis

Question 14

Neisseria gonorrhoeae:

Neonatal infections

Answer 14

• Rare, but newborns can acquire infection from
  mother during birth
• Causes gonococcal ophthalmia neonatorum (acute purulent conjunctivitis)

Question 15

Neisseria gonorrhoeae:

Diagnosis Men

Answer 15

MEN: use microscopy to directly observe swabs of urethral

discharge

Question 16

Neisseria gonorrhoeae:

Diagnosis Women

Answer 16

WOMEN: culture is necessary from endocervical, urethral

and anal swabs

Question 17

Neisseria gonorrhoeae:

Prevention

Answer 17

• Penicillin resistance is emerging (South-East Asia, West
  Africa, Canada and US)
• Treat using ceftriaxone, cefixime, ciprofloxacin or ofloxacin combined with doxycycline/azithromycin
• Resistance to ciproflaoxacin (quinolones) emerging
• SIMULTANEOUS treatment of partners is ESSENTIAL
• No vaccine available