shigella and salmonella Flashcards
vaccine for shigella
no
difference between shigella and salmonella
shigella is more likely to cause bloody diarrhoea, sheigella does not have a capsule, shigella is non motile unlike salmonella, shigella only needs a few organism 10-100 to cause disease as not destroyed by stomach acid like salmonella is, so salmonella you need many microbrew to be I infected also we get shiegalla by contact with human faces whereas salmonella is via animal faces(but can be human faces as well)
tx shigella
macrolide or fluroquinolones (ciprofloxacin)
shiegalla symptoms
abdominal cramps
bloody diarrhoea
tenesmus
fever
how do we catch shigella
fecal oral route
how to we catch salmonella
via contamination of animal droppings inf food as salmonella lives in the gIT of animals such as birds or by the faces of humans as the bacteria lives in the GI of humans too, contaminated vegetables etc contaminated surfaces
culture of shigella
macokeys agar both salmonella snd sheigella are lactose non fermenting so grow as colourless colonies
types of shiegella
s. boudin
s. flexnerri
s.sonnei
s.dystenery
virulence factors of shigella
endotoxin
exotoxin - some strains have the shigag toxin which is very similar to the EHEC , binds to the 60 s subunit of ribosomes and damages glomeruli and hence why can lead to HUS
complications of shigella
HUS
toxic megacoln
Reuters
seziures!!!! NB in young children
rectal prolaps due to the tensusmus
prevention of shigella
eating packaged food and water
chlorinated water
personal hygiene
diagnosis of shiegella
stools- will see polymorpho luekpcyets (neutrophils) and rbc
culture on maconkeys agar
target of shiegella
the colon, M cells of Peters patchers they invade cause inflammation and necrosis and ulcers
what group do salmonella and shigella fall under
family enterobactericae - they are primary organisms as they always cause disease unlike secondary where they are commensals
types of diarrhoea
No cell invasion: The bacteria bind to the in- testinal epithelial cells but do not enter the cell. Diar- rhea is caused by the release of exotoxins (called enterotoxins in the GI tract), which causes electrolyte
and fluid loss from intestinal epithelial cells or epithelial cell death. Watery diarrhea without systemic symp- toms (such as fever) is the usual picture. Enterotoxi- genic Escherichia coli and Vibrio cholera are examples.
2) Invasion of the intestinal epithelial cells: The bacteria have virulence factors that allow binding and invasion into cells. Toxins are then released that de- stroy the cells. The cell penetration results in a systemic immune response with local white blood cell infiltration (leukocytes in the stool) as well as fever. The cell death results in red blood cell leakage into the stool. Exam- ples: Enteroinvasive Escherichia coli, Shigella, and Sal- monella enteritidis.
taining white and red cells, this deeper invasion results in systemic symptoms of fever, headache, and white
blood cell count elevation. The deeper invasion can also result in mesenteric lymph node enlargement, bactere- mia, and sepsis. Examples: Salmonella typhi, Yersinia enterocolitica, and Campylobacter jejuni.
salmonella virulence factors
has h antigens meaning its motile and it constantly changes its antigens evading the immune system
has a polysaccharide capsule
what is shigella similar to
IEC) in that they both invade intestinal epithelial cells and release Shiga toxin, which causes cell de- struction. White cells arrive in an inflammatory reac- tion. The colon, when viewed via colonoscopy, has shallow ulcers where cells have sloughed off. The illness begins with fever (unlike ETEC and cholera, which do not invade epithelial cells and therefore do not induce a fever), abdominal pain, and diarrhea. The diarrhea may contains flecks of bright-red blood and pus (white cells). Patients develop diarrhea because the inflamed colon, damaged by the Shiga toxin, is unable to reabsorb fluids and electrolytes.
shiga toxin
This is the same toxin as in EHEC and EIEC, and its mechanism is the same. has an A subunit and b subunit (binding) to allow the a toxin to enter and inactivate the 60 s ribosome stopping protein synthesis
what type of disease is salmonella
its a zooinos but salmonella type is only humans harbour the disease!
pathogenesis of s. thphi
Salm onella typhi movesonestepbeyond EIECand Shigella. After invading the intestinal ep- ithelial cells, it invades the regional lymph nodes, fi- nally seeding multiple organ systems. During this invasion the bacteria are phagocytosed by monocytes andcansurviveintracellularly.
symptoms of thyphoid
rose spots - some poeple
abdominal pain that often mimics appendicitis
splenomegaly possible
white coating on the tongue
diarrhoea can be a feature but is actually uncommon !!!!!
Without treatment, symptoms may last weeks or months
treatment of typhoid
fluoroquinolone ciprofloxacin or ceftriaxone
what is the issue with typhoid
people become chronic carriers and so harbour the disease in their gall bladders . These people are not actively infected and do not have any symptoms. A famous example occurred in 1868 when Typhoid Mary, a Swiss immigrant who worked as a cook, spread the disease to dozens in New York City. Some carriers actually require surgical
removal of their gallbladders to cure them.
people with splenectomy and salmonella
RememberthatSalmonella isencapsulatedwiththeVi capsule. Our immune system clears encapsulated bacte ria by opsonizing them with antibodies and then the macrophages and neutrophils in the spleen (the reticulo-endothelial system) phagocytose the opsonized bacteria. So, patients who have lost their spleens (asplenic), either from trauma or from sickle-cell disease, have difficulty clearing encapsulated bacteria and are more susceptible to Salmonella infections. Pa- tients with sickle-cell anemia are particularly prone to Salmonella osteomyelitis
types of salmonella
s. thyphi- number 1 cause of osteomyelitis with SCC
s. enteritis
is there a vaccine for salmonella
for thyphi yes-
for enteritis - no
diagnosis of salmonella
stool culture
culture on mackonkey agar
treatment of s. enteritis
Treatment usually involves only fluid and electrolyte replacement, as antibiotics do not shorten the course of the disease and do cause prolonged bacterial shedding in the stool. The diarrhea only lasts a week or less.
vaccine for typhoid
One is an inactivated (killed) vaccine (injection) and the other is a live,(mouth) attenuated (weakened) vaccine. its not a routine vaccination but is recommend if you are going to a country where thphoid is common or will be incotnact with a carrier of typhoid
how do we classify salmonella
based on serotype into typhoidal and non thyphoida
typhoidal: s.thypi +s. parathphi A B C
non thyroidal : causes enteritis
there are more than 2,500 species
how long does salmonella last in the git version
usually less than a week
is it possible to have asymptomatic carriers in any of the diseases
yes specially for shigellaa, and possible for salmonella too
incubation period for salmonella
up to 72 hours
definition of infectious diarrhoea
3 or more watery stools within a 24 h period
most common cause of infectious diarrhoea is
viruses
what does it mean by endotoxin
ist the lipid portion of the LPS that surrounds the organism and forms part of the cells all o of the organism. the endotoxins are liberated when the bacteria die and cell wall breaks
IP for shigella
3-7 ( up to a week) but can be as small as 12 hours after ingestion
IP for thyroid
7-14 days
epi of thyroid
africa, pakistan and banglesesh
what happens if you down treat thyroid
it can be fatal about 30% of people will die
how does thyroid cause disease
because it invades the Peters patchers and causes systemic symptoms as it spreads to other organs (heaptosplenomegaly) and spreads to the lN and can cause bacteria
complications of thyroid
intestinal perforation
diagnosis of thyphoid
blood culture is the choice
as a stool culture has no diagnostic values
what toxins does salmonella produce
BOTH EXO + ENDO
complications of typhoid
Sepsis
Intestinal perforation all due to necrosis of the peyer’s patcher
Intestinal haemorrhage- necorosi
Focal infections in other sites e.g., osteomyelitis(because bacteria seed through peyers patches and spread to the other sites like bones, leaving abscesses in places, pneumonia e.g
because bacteria excreted in bile — cholecysttisi
