Chapter 14-15 Neisseria and Bacteroides Flashcards
describe neisseria spp
-gram negative diplococci
- lipooligosaccharide: lacks O antigen extensions
where is neisseria spp found
common oral flora and other mucous membranes
what pathogens are neisseria spp
n. gonorrhoeae and n meningitis
what is the only host for neisseria
humans
what are the virulence factors of N. gonorrhoeae
-pili
-antigenic variation
-OPA
-IgA protease
-endotoxin/LOS
is there a vaccine for n gonorrhoaea
no
is there a capsule around N gonorrhoeae
no
why do gonococci at different infection sites express different pilin genes
because they adhere to different cell surface receptors on distinct mucosal epithelial cells
describe the antigenic variation of bacterial surface proteins in neisseria
- PilE single chromosomal copy of pilin
- strains contain 10-15 copies of PilE variants lacking promoter and 5’end of gene called PilS genes
-PilS genes recombine with PilE creating unlimited antigenic variants of PilE
what is phase variaition of gonorrhea
on/off switch for surface protein expression
- slipped strand mispairing resulting from presence of multiple identical repeated sequences at 5’ end of gene. replication errors due to strans misalignment creates reading frame errors
- results in on/off switch
what do pili do
mediate bacterial attachment to non-ciliated epithelial bacteria proliferate and shed into secretions
what does IgA protease do
cleaves IgA
what do serum resistance virulent strains cause
disseminated gonococcal infections
how do serum resistant virulent strains cause disseminated gonococcal infections
- strains lack Opa proteins so neutrophils cant engulf bacteria lacking Opa proteins
- sialic acid on LOS binds complement regualtory proteins, prevents complement based phagocytosis
what are the virulence factors for N gonorrhoeae
- pili
- IgA protease
- serum resistant virulent strains
- shedding on endotoxin
- secretion of pro inflammatory cytokines
what are the symptoms of gonorrheal disease
asymptomatic generally
- urethritis in men, urethral pus secretion
- cervicitis in women, urination sensitivity
what is opthalmis neonatorum and how is it treated
- destructive eye infection acquired during birth from gonorrheal disease
- application of erythromycin ointment into both eyes
what is pelvic inflammatory disease and cause
-cause: infection of ccervix, fallopian tubes, and vaginal wall glands
- gonococci enter abdominal cavity causes liver disease
- tissue scarring causes fallopian tube abnormalities which lead to ectopic pregnancies and sterility
what is uretheral and testicular tube scarring caused by and what does it lead to
caused by epididymitis
- leads to sterility and increased urethral infections by other microbes
what does disseminated gonococcal infection cause
skin lesions, suppurative arthritis of a major joint, heart valve destruction
is there any protective immuity after recovery from N gonorrhoeae
no
what percentage of healthy people are carriers for neisseria meningitis
10%
how is neisseria meningitis transferred
sputum
what are the factors affecting the survivial of neisseria meningitidis
-capsule
- acquisition of iron from transferrin
what does capsule prevent
complement mediated bacteriolysis and phagocytosis
what does neisseria meningitidis cross
blood brain barrier
what are the initial symptoms of neisseria meningitidis
mild cold, throbbin headache, fever, stiffness in neck and back, nausea and vomitting, deafness and coma
how long does it take for shock and death to occur with neisseria meningitidis
within 24 hours
what does obstruction of release of increased fluid pressure in neisseria meningitidis cause
impairs brain, causes paralysis of motor nerves and come, loss of blood supply to brain
what causes shock in neisseria meningitidis
LOS/endotoxin release from blood circulating meningococci
what causes small local skin hemorrhages and localized loss of vascualr integrity in neisseria meningitidis
inflammatory cytokines release induced by endotoxin activation of macrophages
what are purpura fulminans
blood spots, bruising, and discoloration of skin from coagulation in small blood vessels
what is disseminated intravascular coagulation
blood clots throughout the circulatory system resulting in blockages and excessive bleeding
what leads to disseminated intravascular coagulation
large capsule with sialic acid
what are the virulence factors of neisseria meningitidis
- large capsule
- IgA protease
- Pili
-shedding of endotoxin
what aare the vaccines for neisseria meningitidis against capsular polysaccharides
-MenACWY vaccine
- Men B vaccine
what is the epidemiology for neisseria meningitidis
-asymptomatic carrier
-aerosol transmission
- children and young adults
what is the epidemiology for N gonorrhoeae
-sexual transmission
-asymptomatic carrier
what are the clinical features of gonorrhoeae
-gonorrhea
-pelvic inflammatory disease
-arthritis
what are the clinical features of neisseria meningitidis
-meningitis
- meningococcoemia
describe bacteroidales and where its found
-gram negative bacteria
-strict anaerobes
-commensals
- opportunistic pathogens
- found in colon and oral cavity
what is the most oxygen resistant bacteroides
bacteroides fragilis
what are the virulence factors of bacteroidales and each function
- superoxide dismutase- detoxifies O2 radials
- catalse - breaks down hydrogen peroxide
- polysaccharide capsule
what are the diseases of bacteroidales and describe each
- peritonitis- rupture of infected appendix/ diverticulum
- pulmonary abscess- aspiration of oropharyngeal bacteria
bacteroides fragilis is one component in these 2 polymicrobial diseases:
-biphasic- starts with acute inflammation progress to formation of localized abscesses
-bacterial composition changes as disease progresses
what is the course of disease in bacteroidea
- perforation of intestine
- neutrophils mobilized
-surviving bacteria resistant to phagocytosis
-oxygen sensitive bacteria are killed - facultative anaerobes growth first
- some strict anaerobes survive
- site becomes anaerobic
-surviving strict anaerobes become predominant
what do you treat bacteroidales with
surgery and antibiotic combinations targeting aerobes and anaerobes
