NEISSERIA!!! MICROM 442 Deck 15 Flashcards
2 pathogenic species?
- N. gonorrhoeae
- N. meningitidis
what GM and shapre are these? -> c’mon literally loops like a pair of balls
GM- diplococci, kidney bean shaped
these are non-motile and??
non-sporeforming
Fastidious, requires enriched
medium like
chocolate agar
primary selective media used to culture
Modified Thayer Martin Agar
fast or slow growth?
fast -> 24 to 48 hours
oxidase???
positive
gonococus uses which sugar?
glucose
meningococcus uses what sugar?
theres two, maltose and glucose
what type of spectrometer is used to identify it?
MALDI-TOF
host range of pathogenic neisseria?
-obligate for human
-mouse for n. gonorrheae
what about commensal nessieria species?
usually just stay in the pharynx
what are the major antigens?
-pili
-outer membrane proteins
-lipoogliosaccharides (LOS)
outer membrane proteins
Por, Opa
LOS
in place of
lipopolysaccharides for other Gram-
negative bacteria
these are masters of???
disguise -> immune evasion
pili
- Function in initial attachment to host cells
- Variable in sequence
- Host receptors:
-CD46 on male urogenital epithelial cells
-CR3 on female cervical epithelium
pili phase variation
transcriptional regulation
pili antigenic variation = different sequences
Contains conserved regions and 6
immunodominant variable regions
Por (OMP I) -> most abundant structural surface proteins
- Mediates attachment to mucosal cell surface
- Invasion of host cells by binding to
complement receptor 3 (CR3) on cervical
epithelial cells in women
por (OMP I) can be used for serological classification because it has two distinct
structural classes -> PorA & PorB
Opa (OMP II) expression determines?
colony phenotype:
opaque or transparent
OMP II also functions in??
close attachment to host cells
LOS
- Major role in production of inflammatory
mediators - Plays a role in attachment to some host cells
- Sialylated LOS – confers serum resistance and
attenuates the inflammatory response
male infx often causes
urethritis
female infx is often
asymptomatic
male genitalia pathogenesis
-Initial attachment via pili to urethral epithelium
-Cell receptor is CD46
-Not sufficient to trigger internalization
-Opa expression results in closer adhesion between
gonococci and host cells
-Opa receptors are varied: tissue tropism?
-Internalization occurs
pathogenesis male urthrea
- Gonococcus enters and multiply within
epithelial cells, reach the submucosa - Triggers inflammatory response
- Hematogenous spread can occur
➢ Symptomatic infection
Pathogenesis—Female genitalia
- Pili and Por bind to CR3 on cervical
epithelial cells - iC3b deposits on LOS, binds to CR3
- Internalization via CR3 does not trigger
an inflammatory response
➢ Asymptomatic infection
Clinical Spectrum and Manifestations
- Urethritis
- Rectal
- Pharyngeal
- Cervicitis
- Salpingitis
- Disseminated Infection
- Conjunctivitis (infants)
Urogenital infection in Females
- Asymptomatic in many
- Symptoms range from minimal to severe
- Increased vaginal discharge due to
endocervical infection - Dysuria – urethral colonization
Salpingitis
- Symptoms: lower abdominal pain, abnormal
menses - Can result in inflammation of fallopian tube, with
scarring - Important cause of infertility, ectopic pregnancy
Disseminated Gonococcal Infection (DGI)
causes minor lesions on the skin
Predominant test for GC diagnosis
NAAT
abx-R is an issue so what drug is reccomended?
ceftriaxone
Neisseria meningitidis
- Semi-typical Gram-
negative cell wall - Same as N.
gonorrhoeae except
that N. meningitidis
has a polysaccharide
capsule
Neisseria meningitidis Antigens
- Major antigens are capsular polysaccharide
(CPS), LOS, pili, OMP’s - N. meningitidis has fewer Opa genes, but has
another similar family Opc - Antigenic diversity is due partly to
interspecies genetic exchange with closely
related Neisseria species
NM capsule expression is
down-regulated during
carriage; up-regulated during invasion into
bloodstream
Asymptomatic carriage
- More common in adolescents, young adults
- Usually transient: 75% clear within a few months
- Is primary reservoir of infection
- Transmission via respiratory droplets and throat
secretions (saliva or spit) - Carriage is immunizing
NM pathogenesis
- Attachment to oropharynx – via pili
- Most organisms remain as extracellular
adherent pathogens - Dissemination from pharynx is via blood
stream; invasion through blood-brain barrier
Meningitis
- Seen primarily in children 6 months – 10 years
- Fever, vomiting, headache, confusion
Meningococcemia
Abrupt onset of illness: spiking fever, chills,
arthralgias, myalgias
Dx NM
- Real-time PCR for N. meningitidis most sensitive
- Gram stain of CSF (85% sensitivity)
- Culture from blood (50-60% sensitivity) for CSF;
less commonly from skin lesions, joints
Treatment & Vaccination
- Penicillin G has been drug of choice, but some
resistance has been identified - IDSA now recommends ceftriaxone or cefotaxime
- Adjunct steroid therapy is beneficial in children
“New” Meningococcal Vaccines
- Protein-based
- Bivalent vaccine (Trumenba, Pfizer)
- fHbp variants
- 4 Component MenB vaccine (GSK)
- 3 conserved proteins mixed with OMV
- Approved for use in Europe and US
- GET THIS IMMUNIZATION!!!!
- Some protection against gonorrhea
