Neisseria- Brockman Flashcards
neisseria is the only genus of _____ that frequently cause disease
Gm negative cocci
species of neisseria
N. gonorrhoeae (gonorrhea)
N. menigitidis (bacterial meningitis and septicemia)
characteristics of Neisseria
- gram negative cocci, usually diplococci
- non-motile
- aerobes (but can grow anaerobically)
- obligate human pathogens
meningococci ferment ____ and ____, but not ____
glucose; maltose; sucrose or lactose
gonococci ferment ____, but not ____
glucose; maltose or sucrose
virulence factors of N. meningitidis
large capsule, LPS endotoxin, outer membrane blebs, hemolysin
VFs of N. gonorrhoeae
no capsule, pili and strong adhesions, LPS endotoxin, IgA1 protease, phase/antigenic variation
gonococci adhesions controlled by:
presence/absence of phase variation
composition of antigenic variation
do NOT have flagella and are NOT motile
gonococci
in spread and multiplication of gonococci, extracellular protease cleaves IgA1 which may enable _____
escape from phagocytosis
gonococci attach to ____ cells which have microvilli
non-ciliated
non-ciliated microvilli engulf bacteria, internalized by _____
parasite directed endocytosis
gonococci may multiply within vacuoles
intracellular replication (protection)
vacuoles fuse with basement membrane
intracellular trafiic
in ____, vacuoles discharge bacteria into subepithelial connective tissue
exocytosis
3 general disease of meningococci
- uncomplicated bacteremic process
- metastatic infection of the meninges
- overwhelming systemic infection- circulatory collapse and disseminated intravascular coagulation (DIC)
virulence factor differences
meningococci are heavily encapsulated by polysaccharide and produce hemolysin
gonococcal infection of upper female/male reproductive tracts
pelvic inflammatory disease (PID)
called epididymitis in males
disseminated gonococcal infections (DGI)
- can result from PID due to endotoxin
- pustular lesions of skin
- inflammation of joints and tendons
- suppurative arthritis
- more common in women
survival of gonococci
- serum antibodies recognition
- evasion
PID can cause ____ in women
-ectopic pregnancy
-chronic pelvic pain
-infertility
(all due to scarring of upper reproductive tract and adjacent organs)
most Neisseria species are ____ resistant
penicillin
_____ of close contacts is the primary means of preventing secondary cases of sporadic meningococcal disease
antimicrobial chemoprophylaxis
vaccines for ____ are difficult to produce due to _____
gonococci; antigenic and phase variation and protective intracellular components
expression of gene product is turned on or off at high frequency
phase variation in E. coli
slipped strand mispairing is an example of ____ in N. gonorrhea
phase variation
changes in composition or structure of surface molecules (i.e. pili– host cell attachment)
antigenic variation in N. gonorrhea
Haemophilus species
small gram negative coccobacilli; aerobic (some anaerobic)
H. influenzae requires _____ and ____ for growth
hemin (X factor); NAD+ (V factor)
typeable H. influenzae strains are seven antigenically distinct ____
capsular polysaccharides
non-typeable H. influenzae strains are ____
unencapsulated
H. influenzae _____ is the most virulent
type B (Hib)
virulence factors of Haemophilus
- polyribosyl Ribitol phosphate (RPR) capsule
- endotoxin, causing pathogen-directed endocytosis
- IgA1 protease
- pili and OM proteins
many H. influenzae and non-typeable isolates produce ____, making them resistant to ____
beta-lactamase; penicillin or ampicillin
____ is drug of choice to treat; ____ penetrate meninges well
chloramphenicol; 3rd generation cephalosporins
