Gram Negative cocci

Question 1

How could you identify a sample of Neisseria meningitidis (Meningococcus)?

gram stain?

growth requirement?

Oxidase test?

Carbohydrate utilization test?

outer surface antigens?

colonization location?

Transmission?

Answer 1

• gram stain?
  
  • gram (-) capsulated diplococci (in PMN)
• growth requirement?
  
  • fastidious
  • optimum growth 35-37 degrees C
  • obligate aerobe
  • culture on chocolate agar
• Oxidase test?
  
  • oxidase positive
• Carbohydrate utilization test
  
  • can use glucose and maltose
  • NOT sucrose
• outer surface antigens?
  
  • capsule, pili, LOS (lacks ‘O’ antigen)
• colonization location?
  
  • nasopharynx
  • school children
• Transmission
  
  • respiratory droplets & prolonged close contact

Question 2

What is the major virulence factor of N. meningitidis

Answer 2

Outer membrane components

• Capsule
  
  • Antiphagocytic (increased survival in blood and CSF)
• PorA/B (OMP)
  
  • Nutrient & waste product exchange
• LOS (lipooligosaccharide):
  
  • antigenic variability, intense immune response
  • related to LPS, but lack adn O-antigen
• Pili
  
  • antigenic variability, assist in mucosal adherence

Question 3

N. meningitidis pathogenisis progression.

Which group of people is most susceptible to infection?

Answer 3

URT, internalized by non-ciliated epithelial mucosal cells

enter submucosa, and enter the blood stream

circulating bacteria release blebs of outermembrane (increase concentration LOS and OMP in blood)

people with compliment (C5-C9) deficiency

Question 4

What disease is characterized by the following symptoms?

Rapid sepsis, blood leakes into skin and organs, hemorrhagic skin lesions, purpura fulminans (skin lesions coalesce) and ischemia, confusion

Whaterhouse-Friderichsen Syndrome (what is this)

Answer 4

Meningococcemia

N. meningitidis

• Whaterhouse-Friderichsen Syndrome
  
  • mass hemorrhage into one or both adrenal glands, disseminated intravascular coagulation

Question 5

What disease is characterized by the following symptoms?

headache, fever, children may vomit, photophobia

Answer 5

meningitis

N. meningitidis

100% fatal if untreated

Question 6

How can you identify a sample of Neisseria gonorrhoeae?

gram stain?

Oxidase?

Carbohydrate utilization test?

Growth requirment?

Transmission?

Infection sites?

Genetic testing?

Answer 6

• gram negative diplococci
• oxidase (+)
• Carbohydrate utilization
  
  • produce acid from glucose
  • NOT maltose
• Growth requirement
  
  • fastidious
  • Thayer Martin Agar (chocolate agar w/ antibiotics)
  • require CO2 and humid conditions
  • grows better 35-37 degees C
  • susceptible to dehydration
  • require iron
• Transmisison
  
  • sexual contact
• Infection sites
  
  • urethra (men)
  • uterine cervix (women)
  • females frequently asymptomatic
• Nucleic acid amplification test (NAAT)

Question 7

What disease is characterized by the following symptoms?

2-5 days after exposure

dysuria, itching, purulent discharge, testicular pain; mostly acute

epididymitis, prostatitis, and periurethral abscess

Answer 7

Gonoccol urethritis

N. gonorrhoeae

Question 8

What are the major virulence factors of N. gonorrhoeae?

Answer 8

glycoproteins in outermembrane

they can switch off and switch on– change its antigenicity, and can fool our immune system

Can only acquire iron from human iron binding proteins– only infects humans

Question 9

What disease is characterized by the following symptoms?

In people with vaginas

painful urniation, vaginal bleeding, pain during sex

Pelvic Inflammatory Disease (PID): proximity of endometrium, FT, ovaries to cervical bacteria

Answer 9

Cervicitis

N. gonorrhoeae

menstruation conducive for bacterial growth in cervical canal

Question 10

What disease is characterized by the following symptoms?

neonates (2-5 days old)

eye lid edema, redness, purulent discharge, swelling, pain

polymorphonuclear cells

Answer 10

Ophthalmia neonatorum (Neonatal conjunctivitis)

N. gonorrhoeae

transmission from mother during delivery

Question 11

What disease is characterized by the following symptoms

fever, migratory arthralgia, supputative arthritis, pustular rash

more common in females

Answer 11

Septic arthritis

N. gonorrhoeae

(#1 cause 16-45 yr age group)

Question 12

How would you identify a sample of Moraxella catarrhalis?

gram stain?

Growth requirements?

Oxidase test?

location of infection?

carbohydrate utilization?

Answer 12

• gram negaitve diplococcus
• Growth requirement
  
  • grows on blood agar
  • aerobic
• Oxidase positive
• Infection
  
  • URT; more common in children
• Cannot utilize any carbohydrates

Question 13

What disease are caused by Moraxella catarrhalis?

Answer 13

sinusitis and otitis media of young children

Question 14

How could you identify a sample of Acinetobacterm (Acinetobacter baumanii)?

gram stain?

Oxidase?

Growth requiement?

Motility?

Natural colony location?

Where do most infectiosn occur?

Important virulence?

Answer 14

• gram negative bacillus
• Oxidase negative
• growth requirement
  
  • aerobic
  • non-fastidious
• lack pigment, motility, & ability to ferment
• widely distributed in nature
• Emerging nosocomial pathogen
  
  • produces biofilms and resistant ot most antibiotics
• Outer membrane proteins and LPS critical for virulence

Question 15

What diseases are commonly cuased by A. baumanii?

Answer 15

• Pneumonia: w/ ventilator use
• Bacteremia
• Battlefield infections
• Meningitis after neuor-surgeries & catheter associated UTIs