Clostridia Chlamydia, Rickettsia, Ehrlichia, Mycoplasma Flashcards
clostridium traits
anaerobic gram + rods pro endospores found in env. prod proteinaceous toxins resp for disease sympt.
clostridium species and their assoc diseases
c. difficile - pseudomembranous colitis
c. perfringens - cellulitis, gas gangrene, food poisoning
c. botulinum - botulism
c. tetani - tetanus
traits of pseudomembranous colitis
spread thru c. dificile endospore leading cause of nosocomial diarrhea disease state assoc w/ antimicrobial drugs b/c it induces spore state spore releases toxin toxin causes diarrhea doesn't invade bowel wall
C. difficile toxin A vs. B
A - enterotoxin - damages mucosa, used to diagnose
B - cytotoxin
both act in cytoplasm of host
C perfringens traits
in soil and intestinal tracts of animals
path of wound infection esp war wounds
local and systemic effects
conditions of wounds that cause c. perfringens spores to germinate
anaerobic
compromised blood supply
calcium ions
available peptides and AA’s
toxins of c. perfringens
prod. 12 toxins
alpha toxin damages cell membranes and causes gas gangrene
toxins cause necrosis of muscle tissue
if untreated leads to shock renal failure and death
treatment/ prevention of c perfringens
amputation
high oxygen concentrations
prompt care and restoration of arterial blood supply
how does c. perfringens cause food poisoning? and what results from it?
sporulating c. perfringens prod. enterotoxin in intestines
results in self-limiting diarrhea
clostridium botulinum traits
found in soil and marine sediments
spores are heat resistant (not toxin) and germinate in canned food
botulinum toxin traits
produces 8 neurotoxins among most deadly poisons spore doesn't need to be present to get toxin formed from 1 prot w/ a heavy non toxic chain and light toxic chain botulism, just the toxin used in bioterrorism
3 types of botulism
food-bourne
wound botulism
infant botulism (has a slow onset, and causes babies to be floppy - favorable outcome)
mechanism of c. botulinum toxin
prevents release of Achol. neurotransmitter by using zinc metalloprotease to cleave the receptor proteins
people get flaccid paralysis w/in 12-36 hrs.
c. botulinum treatment
trivalent antitoxin isolated from horses
c. tetani traits
ubiquitous in GI tracts of humans and animals and soil
infect wounds
toxin of c. tetani
tetanospsmin = toxin
has heavy and light chain connected by disulfide bridge, individual chains are non-toxic
mechanism of tetanus
toxin attaches to n near wound and moves up to its body where it inhibits neurotrans release and inhibitory input
typically starts as lockjaw, then moves down to trunk area
results in reflex spasms and spastic paralysis
treatment/ prevention
DPT vaccine
antitoxin s/b administered w/ penicillin G
wound region should be surgically cleared to elliminate spores
small gram negtive pathogens
chlamydiae rickettsiae and ehrlichia
chlamydiae traits
gram - no peptidoglycan in cell wall obligate intracellular path energy parasites (dep on host for ATP) comp dev. cycle
4 species of chlamydia
human paths: c. trachomatis c. pneumoniae animal paths: c. psittaci c. pecorum
traits of chlamydial infections in general
causes preventable blindness
thought every human has had it
droplet or direct contact infection of mucosal ep. cells
localized
spread by fingers, flies, fomites and fornication
c. trachomatis infection traits
usually asymptomatic in females
infants can get it during birth causing conjunctivitis and pneumonia
infections can be acute or chronic
mechanism of c. trachomatis infection
elementary bodies as as nutrients/ hormones to bind to specific receptors and get into cells via receptor mediated endocytosis
EB’s modify endocytic vesicle by keeping it at 6.2 pH and preventing it from fusing w/ lysosome, it also uses host glycolipids as camouflage
EB changes into active RB which uses host resources and divides by binary fission
how do RB’s take up nutrients?
use tube like structures to feed off cytoplasm so they don’t have to leave the vacuole
traits of trachoma
caused by chlamydia trachomitis
effects eyes inflaming conjunctiva
causes blindness and cornea scarring
traits of lymphogranuloma venerum
chlamydial STD
systemic b/c it attacks lymph and genital tract
mainly in dev. countries
traits of chlamydophila pneumoniae
most common chlamydial infection
asymptomatic or acute respiratory response
esp seen in people w/ atherosclerotic heart lesions
treatment of chlamydia pneumoniae
target RB forms of antimicrobials
has to penetrate 4 membranes: host plasma membrane, inclusion membrane, chlamydial outer membrane, chlamydial cytoplasmic membrane
traits of rickettsiae
sm. gram - rods
obligate intracellular bact
zoonoses
capable of ind. metabolism
no flagella or endospores
rickettsiae transmission
only hard mountain tick is naturally infected
spread thru tick bites via bloodstream
cause endothelial cells to endocytose then lyse phagosome w/ phospholipase
exit cell thru cell lysis, projections or budding
injury /treatment to host from rickettsiae
lysis of cells results in hemorrhagic blood rash
treated by immune syst. or antibiotics
typhus group fevers of rickettsiae
r. prowazekii - typhus fever, transmitted by lice
r. typhi - murine typhus, trans by rats and fleas
orientia tsutsugamushi - scrub typhus , NO RASH
traits of ehrlichia
obligate intracellular bact
transmitted by lone star tick
infects monocytes and macrophages
dev. w/in host cell vacuoles first as reticulate cells (RC) then as dense core cells (DC)
echrlichiosis diagnosis
patients dont have symptoms at first or know of tick bite
handling is harzardous
req. cell culture or animal inoculation and diagnostic tests (titer, assay, complement fixation, or agglutination)
traits of mycoplasma
v. small req sterol (for cell membranes) colony looks like a fried egg no cell wall found in other mammals and birds
4 species of mycoplasma
m. pneumoniae
m. genitalium
m. hominis
ureaplasma urealyticum
m. pneumoniae encounter/entry
humans = only reservoir
walking pneumonia - not cured by penicillin
mild and contagious infections
adhere to resp. ep
spread of m. pneumoniae
cause bronchopneumonia
cell resp thru lymphocytes
impair ciliary fcn by releasing tissue toxic substances
causes hemolytic anemia (cold clumping of IgM), encephalitis and erythema multiforme (rash)
types genital mycoplasmas
m genitalium - sim. to pneumoniae
affect newborns:
m. hominis
u. urealyticum
