Gram Negative Cocci

Question 1

Neisseria characteristics

Answer 1

-Aerobic
-Nonmotile
-Cat+
-GNDC
-Capnophilic
-Ox+

Question 2

Neisseria carbohydrate for ID

Answer 2

N. gon = glu+
N. men = glu+, mal+
N. lac = glu+, mal+, lac+
N. sicca = glu+, mal+, suc+
Morax = all - but only one that is DNAase +

Question 3

GC characteristics

Answer 3

-Humans only natural host
-Infects columnar and transitional epis

Question 4

Gram stain morphology of Neisseria

Answer 4

Gram neg; kidney-shaped; diplococci

Question 5

Growth requirements for Neisseria gonorrhoeae

Answer 5

1) Must have cysteine
2) Must have energy source (glucose, pyruvate, or lactate)
3) 35-37C
4) Needs CO2 (3-7%)

Question 6

Spread of GC

Answer 6

1) Male from female: 20% per exposure; 80% after 4 exposures
2) Female from male: 50-70% per exposure
3) Male from oral: 26%

Question 7

N. meningitis - serogroups

Answer 7

1) 13 serogroups total
2) Most infections: A, B, C, Y, W125
3) 90% of meningitis : A, B, C

Question 8

Meningococcal meningitis

Answer 8

1) Upper respiratory tract then into bloodstream
2) Classic symptoms: confusion, headache, fever, nuchal rigidity, vomiting (children)
3) Petechial hemorrhage = meningococcemia
4) Fulminant shock
5) Gangrenous changes to extremities due to peripheral vasoconstriction
6) DIC
7) Adrenal gland necrosis (Waterhouse-Friderichsen syndrome)

High-risk: Complement deficient indivitduals

Question 9

GC specimen collection

Answer 9

1) Dacron or rayon swab (no calcium alginate or cotton)
2) Charcoal can inactive swab toxins
3) Viability decreases after 24 hours; Amies can increase to 48 hrs
4) Decrease in viability after refrigeration of 6 hours

Question 10

GC Smears

Answer 10

1) Direct smear diagnostic sensitivity: 95% (men) / 50-70% (women)
2) Only good for genitals b/c GNC normal flora in throat

Question 11

Diagnostics of GC

Answer 11

1) Nucleic Acid (Direct Probe hybridization, NAATs, amplified signal probe tests)
2) Ag (Binax NOW - urine)
3) Culture (Enriched selective media w/ Vanc (gpc), colistin (gnr), trimethoprim (proteus), and/or antifungals

Question 12

Culture characteristics of GC

Answer 12

1) Oxidase +
2) Supoxol (30% H2O2) +++ (Other Neisseria +)
3) Catalase + (K. denitrificans =)
4) CTA (Cysteine-tryptic digest agar) w/ sugars or Rapid Carb Test: Glu +, other sugars =

ONLY CULTURE CAN BE USED TO ID GONORRHEA FOR LEGAL PURPOSES

Question 13

N. meningitidis biosafety

Answer 13

BSL 2

Question 14

Culture characteristics of N. meningitidis

Answer 14

1) Larger than GC
2) Low, convex, smooth, and moist - may be mucoid due to capsule
3) Glu + ; Mal + ; other sugars =

Question 15

Diagnostics of N. meningitidis

Answer 15

1) Slide agglutination based on serogroup
2) Serotype / Subtype based on OMP/PorB and LPS antigens

Question 16

Treatment of Neisseria

Answer 16

1) GC: Cephalosporins; Fluoroquinolones
2) N. men.: PenG, Cepholosporins

Test with Cefinase for B-lac resistance

Question 17

GC characteristics

Answer 17

-Humans only natural host
-Infects columnar and transitional epis

Question 18

GC Virulence factors

Answer 18

1) Human transferrin receptors
2) Capsule
3) Pili (fimbriae)
4) Cell membrane proteins (PorA / PorB) / (Opa)
5) Lipooligosaccharide (LOS) endotoxin (NOT LPS)
6) IgA protease

Question 19

GC Pili

Answer 19

1) Divided into 5 distinct colony types based on pili presence or absence
–Type I and II = Virulent
2) Pili are hypervariable due to recombination
3) Adhere to host cells
4) Prevent phagocytosis

Question 20

GC Membrane Proteins

Answer 20

-Promote invasion into epi
-Protein I = PorB forms channels for nutrients to go in and waste to go out
–also protects against complement
-Protein II = Opa (opacity) adheres to phagocytic and epi cells
-Protein II = Rmp blocks IgG

Question 21

GC LOS

Answer 21

-Mediates damage to body tissue and elicits inflammatory response
-Destroys cilia on neighboring epi cells
-Blebs released from GC containing LOS

Question 22

GC Disease

Answer 22

-2-7 day incubation period
1) Acute urethritis w/ purulent discharge
2) PID
3) Perihepatitis (Fitz-Hugh-Curtis syndrome)
4) Septicemia (but inhibited by SPS so may not be found in routine blood culture)
5) Arthritis
6) Ophthalmia neonatorum = neonatal eye infection

Question 23

GC virulence transmission

Answer 23

1) Plasmids for penicillinase and tetR
2) Chromosome
–PenR
–TetR
–SpectinomycinR
–FluoroquinoloneR

Question 24

N meningitidis virulence

Answer 24

Same as GC but also
–IgA protease

Question 25

Neisseria culture

Answer 25

MTM = Chocolate
–Nystatin (inhibit fungus) (Anisomycin / Ampho B used in other agar types)
–Vanc (inhibit GPC)
–Colistin (inhibit GNR)
–SXT (inhibit proteus)

Question 26

Moraxella catarrhalis

Answer 26

-Upper respiratory tract commensal
-Opportunistic cause of upper resp infections in children, elderly, COPD
-3rd most common cause of ear infection / sinusitis
-Can cause endocarditis, meningitis
-Wagon wheel colony on Choc; hockey puck
-DNAase+ is differential ID