Neisseria, haemophilus, pseudomonas and Listeria Flashcards
Neisseria traits
only gram - cocci that frequently cause disease non-motile aerobes OBLIGATE human path FASTIDIOUS
diagnosis of neisseria
cultured on chocolate agar
catalase and oxidase +
sugar fermentations
modified Thayer-Martin agar
main neisseria sp.
meningitidis and gonorrhoeae
virulence factors of neisseria sp.
meningitidis : large CAPSULE
gonorrhoeae : strong adhesins and PHASE/ANTIGENIC variation
how do meningococci invade/cause damage?
enter thru nasopharnx and attach to COLUMNAR ep cells
only cause bacterimia in folks w/ C5-8 complement deficiency
type IV pili attach bact to meninges in CNS
lipooligosaccharide causes inflammatory resp damaging host tiss
how do gonococci enter/attach
apread thru body fluid
attach to columnar ep of cervix/urethra
has adhisins which are controlled by phase variation (!!) and antigenic variation
how does gonorrhoeae phase variation work?!?
Opa genes encode membrane prot. and have slipped strand mispairing so they’re always making diff prot.
Opa genes result in neutrophil uptake but gonococci don’t have them and avoid phagocytosis
makes it hard to vaccinate
how do gonococci spread and multiply?!?
multiply rapidly and are shed in genital secretions
enter ep. cells
avoid phagocytosis by removing Fc- receptor end of IgA antibody (!!)
how do gonococci invade tissue?
attach to non-ciliated so they slow and kill ciliated cells
then cause non-ciliated cells to endocytose them so they can multiply w/in the vacules
vacuoles discharge bact into subep. connective tiss
how do gonococci cause damage?
LPS (endotoxin)
induce TNF-alpha
how do gonococci evade antibody recognition?
antibodies target the LPS but gonococci can alter it to look more like a red blood cell
3 diseases of menigococci
1 uncomplicated becteremic
- metastatic infection of meninges
- systemic infection causing cirulatory collapse and disseminated intravascular coagulation
what is pelvic inflammatory disease?
gonococcal infection of upper female reproductive tract (b/c ciliated cells) and epididymis in men
symptoms of disseminated gonococcal infections
pelvic inflammatory disease pustular lesions of skin inflammation of tendons/joints suppurative arthritis risk factor= women
treatment for neisseria
penicillin/tetracycline resistant
antimicrobial chemoprophalaxis
why is it hard to vaccinate for gonococci?
phase and antigenic variation and protective intracellular components
traits of haemophilus
sm gram - coccobacilli
aerobic
colonize upper respiratory tract
what does H. influenzae require for growth?!?
HEMIN (X factor) and NAD+ (V factor)
haemophilus diseases
influenzae - bacteremia and meningitis
parainfluenzae - pneumonia and endocarditis
ducreyi - chancroid
aphrophilus - normal flora
aegyptius - conjunctivitis and brazilian purpuic fever
haemophilus VIRULENCE FACTORS ?!?
POLYRIBOSYL RIBITOL PHOSPHATE (PRP) - basis for vaccine, causes resistance to phagocytosis (makes HiB most virulent
endotoxin
IgA protease, pili and OM proteins (like nisseria)
how/why are children immunized for haemophilus?
get PRP conjugated diptheria toxoid b/c they’re most succeptible
best treatments for haemophilus?
3rd gen cephalosporins b/c they penetrate menines
and chloramphenicol
traits of pseudomonas
gram - bacillo ubiquitous (in soil and water esp hot tubs) motile aerobic need compromised skin large innoculation size
traits of pseudomonas aeruginosa
colonies produce water-soluble antibacterial pigments
colonies smell like grapes
v. robust
minimal nutritional req. (don’t ferment)
survive in soaps/handcreams and antiseptics
pseudomonas virulence factors
capsule siderophores (help bind iron) elastase exotoxin phospholipase (hydrolyzes phospholipids in eukaryotic membranes for C source)
pseudomonas entry/ability to spread depends on…?!?
avoiding phagocytosis (capsule and exotoxins) successful adherence to surface (flagella and type 4 pili (creates its own attachment site by cleaving sialic acid to create asialo GM))
how does pseudomonas cause damage?
endotoxin - inflammatory resp
exotoxin - kill host cells
elastase - cleaves elastin, collagen, proteinase inhibitors and immune syst components
lasA-serine protease that helps elastase degrade elastin
type III EsoS,T,U, and Y secretion system (transfers virulence factors directly from bacterial to host cytosol)
how is cystic fibrosis a risk factor for p. aeruginosa?!?
CYSTIC FIBROSIS TRANSMEMBRANE CONDUCTANCE REGULATOR is dysfunctional in CF patients and causes decreased sialylation of surface glycolipids making them asialo-glycolipids which aeruginosa easily adhere to.
also makes mucus thicker impairing mucociliary system and shielding bact from immune syst
diagnosis and treatment for pseudomonas?!?
easily cultured
a lot of hospital strains are resistant
frequently req antibiotic synergism
Listeria traits
gram + rod
grows in fridge
motility thru peritrichous flagella and actin polymeriation
what is listeriosis
infection of fetus, and immunocompromised
causes bacteremia and meningitis
some people are asymptomatic carriers
where do listeria replicate?
w/in cytoplasm
listeria virulence factors
internalins - mediate adherence and invasion of cells
listerolsin O - lets them escape from vacuoles
phospholipases - also helps escape from vacuoles and lets it pass thru placenta
listeria prevention
avoid unpasturized food
immunocomp people avoid deli meat and soft cheese
antibiotics are effective
