Gram Negative Cocci Flashcards
Neisseria characteristics
-Aerobic
-Nonmotile
-Cat+
-GNDC
-Capnophilic
-Ox+
Neisseria carbohydrate for ID
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 +
GC characteristics
-Humans only natural host
-Infects columnar and transitional epis
Gram stain morphology of Neisseria
Gram neg; kidney-shaped; diplococci
Growth requirements for Neisseria gonorrhoeae
1) Must have cysteine
2) Must have energy source (glucose, pyruvate, or lactate)
3) 35-37C
4) Needs CO2 (3-7%)
Spread of GC
1) Male from female: 20% per exposure; 80% after 4 exposures
2) Female from male: 50-70% per exposure
3) Male from oral: 26%
N. meningitis - serogroups
1) 13 serogroups total
2) Most infections: A, B, C, Y, W125
3) 90% of meningitis : A, B, C
Meningococcal meningitis
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
GC specimen collection
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
GC Smears
1) Direct smear diagnostic sensitivity: 95% (men) / 50-70% (women)
2) Only good for genitals b/c GNC normal flora in throat
Diagnostics of GC
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
Culture characteristics of GC
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
N. meningitidis biosafety
BSL 2
Culture characteristics of N. meningitidis
1) Larger than GC
2) Low, convex, smooth, and moist - may be mucoid due to capsule
3) Glu + ; Mal + ; other sugars =
Diagnostics of N. meningitidis
1) Slide agglutination based on serogroup
2) Serotype / Subtype based on OMP/PorB and LPS antigens
Treatment of Neisseria
1) GC: Cephalosporins; Fluoroquinolones
2) N. men.: PenG, Cepholosporins
Test with Cefinase for B-lac resistance
GC characteristics
-Humans only natural host
-Infects columnar and transitional epis
GC Virulence factors
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
GC Pili
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
GC Membrane Proteins
-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
GC LOS
-Mediates damage to body tissue and elicits inflammatory response
-Destroys cilia on neighboring epi cells
-Blebs released from GC containing LOS
GC Disease
-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
GC virulence transmission
1) Plasmids for penicillinase and tetR
2) Chromosome
–PenR
–TetR
–SpectinomycinR
–FluoroquinoloneR
N meningitidis virulence
Same as GC but also
–IgA protease
