L4 - Neisseria, Haemophilus and Anaerobes Flashcards
Neisseria
Gram-negative cocci
_2 important specie_s - gonorrhea, meningitis
- Important in humans
- Found around and inside of neutrophils
- Share 80% DNA, LPS, colonize mucous membranes, purulent infections
Systemic, life-threatening disease
Meningococci
Upper respiratory tract
Gonococci
Genital tract
N. gonorrhea causes:
Genitourinary infection gonorrhea – sexually transmitted
- Urethritis;
- Cervicitis;
- Salpingitis;
- Pelvic inflammatory disease (PID)
In addition:
Disseminated gonococcemia, septic arthritis, gonococcal ophthalmia neonatorum, septicemia, pharyngitis, proctitis
True or False
Gonorrhea is a superbug
True
- Hides from the immune response
- IR, inflammation, uterine scarring, sterility, blindness in babies
- Has become antibiotic-resistant
Lab cultures-
Fastidious Growth
Requires special media
- Thayer-Martin agar
- Chocolate agar (heated blood agar)
Enhanced with nutrients and antimicrobials
Neisseria Tests
Oxidase +
- oxidized = putple
- reduced (not oxidized) = colorless
Catalase +
- H2O2 added
- positive = oxygen bubbles
- negatove = nothing
Neisseria
Virulence Factors
Pilus
- aids attachment to human mucosal epithelium
- contains constant and hypervariable regions
- analogous to Igs that contribute to antigenic diversity in gonococci
Por Proteins
- forms pores through outer membrane
- antigenic
- specific serotypes associated with virulence
Opa Proteins
- assist binding to epithelial cells
LOS
- lipooligosaccharide (endotoxin activity)
Rmp Protein
- inhibit “cidal” activity of serum
Capsule
- resist phagocytosis unless Ab present (N. Meningitis has this)
IgA Protease
- core contains enzyme, released by cell to destroy igA
Neisseria
Cell surface Functions
Opa (Opacity) Proteins
- cell to cell contact
Rmp (Reduction-modifiable) Proteins
- Stimulate abs that block serum bactericidal activity
Lipooligosaccharide (LOS)
Composed of lipid A and a core oligosaccharide (similar to LPS);
Lipid A – endotoxin activity
Porins
- Interfere with degranulation of neutrophils
- Facilitates bacterial invasion into epithelial cells
- Increases bacterial resistance to complement-mediated killing
Pilli
True or False
Pili never changes and has immunologic memory
False
- Pili is constantly changing
- Has No immunologic memory
- No vaccine has been developed
Pili
Hair-like appendages found in many bacteria
- From cytoplasmic membrane through outer membrane
Some types of pili allow transfer of genetic material
Some facilitate motility; limits phagocytosis
Some types (Type IV) attach to host cells
- Recombined genes result in new pilin variants
- No immunologic memory is generated
- No vaccine has been developed
N. Gonorrhoeae
Pili Function & Structure
Neisseria gonorrhoeae –> there are 100 serotypes
Pilin proteins have:
Proteins - conserved region at amino-terminal end
(N terminal –> begins = no change)
Highly variable region at exposed carboxyl terminus
( C terminal –> end = change)
The antigenic variation:
- Prevents immunologic memory
- Limits development of vaccines
N. Gonorrhoeae
Clinical Disease
Men
- May or may not be symptomatic
- about 80% are symptomatic
If symptomatic
- Urethritis characterized by dysuria and purulent penile discharge
- If not treated, may spread - Epididymitis and prostatitis
Women
- Usually asymptomatic
- about 20% of women are symptomatic
If symptomatic
- Dysuria, vaginal discharge
If not treated, may spread - (leads to infertility) Pelvic inflammatory disease
Babies and adults
- Eye infections
Immune Response
Even when IR stimulated:
- Very low levels of IgG and IgA
- Immune response tends to be local rather than systemic
- Little memory is generated
IgA protease
- Cleaves IgA in the hinge region
IR can be harmful
- Inflammation
Treatment
Penicillin resistance now common
- Mutated penicillin binding protein (PBP)
- plasmid encoded beta-lactamase
3rd generation cephalosporin (ceftriaxone) with azithromycin or doxycycline
Sexual contacts should be treated to prevent “ping pong” infections
Prevention through education and safe sex
N. Gonorrhoea Review
