microbiology Flashcards
how does strongyloides cause hyperinfection with gram negatives
when strongyloides pentrates through tissue walls –> go into circulation (can bring gram negative organisms with it into the blood) = sepsis
what is the proper name for worms
helminths
what is a paratenic host
host in which the parasite enters the body and does not undergo development, but remains infective (does not change into different parts of its life cycle)
what are the two main ways of catching toxoplasma gondii
- from cats faeces - undercooked meat
Who does Giardia classically infect
children - poor hand hygiene
symptoms of enterobius ermicularis
many asymptomatic perianal/vaginal itch
what are the 2 types of taeniasis
taenia saginate taenia doium
What is pathotyping mainly used for?
determining which virulence type it is - for E coli
what does echinococcus granulosus cause
hydatid cysts
why are type 3 secretion systems special
because it is used by pathogens to make a protein go directly from the cytoplasm of the bacteria to the cytoplasm of the host cell
What type of diarrhoea does EHEC cause? Which population is mostly affected?
- bloody diarrhoea - any age, developed coutries
life cycle of enterobius ermicularis
eggs ingested by humans –> hatch –> at night, females will crawl out and lay eggs around the anus and then go back in during the day –> itch –> hand in mouth
what are the aetiological agents of travellers’ diarrhoea
ETEC other bacteria viruses protozoa
2 types of parasites
ectoparasites protozoal parasites
treatment of scabies
- ivermentin - oral - topical scabicides (need to be over long time period) - hot wash clothes and bed linen
what kind of helminth is strongyloides stercoralis
roundworm
Main food source of Salmenella
raw eggs
what is the difference between a definitive host and an intermediate host
definitive - parasite reaches sexual maturity in the host intermediate - development occurs but the parasite does not reach sexual maturity
proper name for ticks
Ixodes holocyclus
two main forms of protozoa
trophozoite - active cysts - inactive
definition of haemorrhagic colitis
inflammation of the colon –> blood in the faeces (but no pus)
life cycle of scabies
burrow into the epidermis –> come out to lay their eggs on the surface –> eggs hatch –> burrow into epidermis
infection by lice is known as
pediculosis
how long is taeniasis
up to 10m long
how much fluid goes into the GIT in 24 hours and how much is excreted
10 Litres goes in 100ml comes out
how does staph cause food poisoning
eat the pre formed toxin in food
what are the aetiological agents of food bourne gastro
Staph Salmenella Clostridium Bacillus Vibrio Listeria viruses ciguatoxin
Which E coli use the Type 3 secretion system
EPEC and EHEC
what is the helminth that is able to complete its life cycle in the human
strogyloides
3 major types of helminths
roundworms (nematodes) tapeworms flukes
where does Schiestosoma mansonii live when in humans
in the intestinal veins
what is taeniasis
cestode parasite cuaing cysticercosis in their intermediate host –> causes neurocystercercosis most regognisedc
Which E coli produces Shiga toxin
All EHEC and the occasional EAEC (from acquired bacteriophage)
What was the aim of the WHO diarrhoeal disease control program
- reduce diarrhoea-associated mortality - reduce incidence of diarrhoea through education and immunisation
what are the aetiological agents of dysentery
Shigella EIEC protozoa (Shigella or amoboe)
what is the aetiological agent of haemorrhagic colitis
EHEC
symptoms of ascaris lumbricoides
- can be asymptomatic - asthma - pneumonitis intestinal obstruction (pancreatitis, cholangitis etc)
treatments of taenia solium
antihelmintics (cautiously –> dont wan the cyst to burst)
life cycle of ascaris lumricoides
eggs mature in soil –> ingested –> penetrate intestinal wall –> hepatic circulation –> lungs –> alveolar space –> trachea –> reswallowed
How do Shiga toxins affect humans
affect protein synthesis
diagnosis of taenia solium
serology imaging techniques
what are the anti-diarrhoeals
- anti-motility agents - anti-secretory agents - binding agents
what is Schistosoma mansonii
fluke (trematode)
What are the methods use to try and diagnose what is causing diarrhoea?
- macroscopic appearance - microscopy - culture (bacteria) - antigen detection (viruses, parasites, toxins) - nucleic acid detection (viruses, bacteria, protozoa)
How do you know if Entamoeba histolytica has changed to pathogenic (as opposed to a commensal)
has Red cells inside it
treatment of enterobius ermicularis
antihelminthic (can be bought over the counter) - people tend to self treat
where abouts in Australia are ticks a problem
eastern australia
what does entamoeba histolytica do
- invades tissues in the colon –> large volume diarrhoea - can spread by blood and lodge in other areas causing abscess
what is dysentry
presence of blood, pus and mucus in the faeces
associations between diarrhoea and malnutrition
- increased energy loss (diarrhoea and vomiting and increased metabolic needs) - reduced energy intake (malabsorption and with-holding of food)
difference in stools between diarrhoea of small and large intestinal origin
small –> infrequent or frequent stools of large volume and watery large –> frequent stools of lowish volume
What is Tir?
It is the receptor for Intimin bacteria brings Tir with it –> pumps it from the cytoplasm from the bacteria –> cytoplasm of the cell
Which bacteria destroy the microvilli of the mucosa but do not invade it?
EPEC
what is in oral rehydration sachets
NaCl, KCl, bicarb, glucose/sucrose
T/F humans are part of the normal life cycle of ticks
false
what kind of worm is enterobius ermicularis
roundworm
what are the aetiological agents of antibiotic associated colitis
Clostridium difficile
what part of the life cycle are we for echinococcus granulosus
accidental
treatments of Schistosoma mansoni
antihelminitic - short courses effective
Pathotypes of diarrhoeagenic E coli
ETEC (toxigenic) EPEC (pathogenic) EHEC (haemorrhagic) EIEC (invasive) EAEC (aggregative)
Which bacteria systemically invade the body from the gut? How?
Salmenella (survive inside macrophages)
disease control for strongyloides
sewage disposal shoes
Diagnosis of strongyloides
eggs in the feaces serolgy
Adhesins of ETEC
CFA (colinising factor antigens)
what type of diarrhoea does EAEC cause? Which population is mostly affected?
- watery diarrhoea - children in LDCs
how do you diagnose echinococcus granulosus
imaging techniques seroogy
how are ticks normally transferred to humans
ticks climb up to the ends of long grass. As your leg brushes by –> jumps on
length of ascaris lumricoides
30-40cm
what are the functional areas of a LEE pathogenicity island
- Type 3 secretion system - effectors (toxins - that need the Type 3 SS to get out of the bacteria)
main reason for travellers diarrhoea
people from developed countries visit developing countries, where they have not encountered specific organisms before –> diarrhoea
main population that gets infected with enterobius ermicularis
young children
proper name for lice
pediculus…. humanis/capitis/pubis
Tx of ticks
removal of the tick
what are the aetiological agents of cholera-like gastro
vibrio cholerae ETEC
Which E coli can acquire the ability to produce Shiga toxin
EAEC - from bacteriophages
Which E coli produces Shiga toxins
EHEC
In which situations do you prescribe antibiotics for diarrhoea
- cholera - systemic infections (eg typhoid fever) - immunocompromised patients - severe infections with Shigella - protozoal infections - pseudomembranous colitis
What does intimin do?
a large outer membrane protein required for the intimate adherence between bacteria and cell.
Sx of ticks
paralysis (local or generalised ascending)
life cycle of lice
egg –> hatches –> several stages of malting –> adult –> lays eggs –> adult dies
Where does most of the fluid that goes into the GIT come from?
secretions of the GIT system
Tx of entamoeba histolytica
metnodizaole and paromomycin, drainage of abscess
diagnosis of Schistosoma mansoni
characteristic eggs in the faeces serolgy
what is a reservoir host
an animal which can be normally infected with a parasite that also infects people
what does toxoplasma gondii infect
all mammals, many birds
How do you go about culturing faeces
- enrichment for Salmonella and others - direct plating on selective/indicator media - confirm suspicious colonies using biochemical tests, serotyping and pathotyping
Which bacteria are the least invasive of the mucosa?
cholera ETEC –> adhere to intact intestinal mucosa
main animals that echinococcus granulosus nfects
dogs and cattle
what is ascaris lumricoides
a roundworm
what is the difference between the main infective causes of diarrhoea between developing and developed coutries
- developed countries - agent more likely to be viral - developing countries - agent more likely to be bacterial
how is diagnosis made of ascaris lumbricoides
- eggs in the faeces - imaging of obstructions
Which E coli have the LEE pathogenicity islands?
EHEC and EPEC
treatment of lice
topical insecticides
presentation of toxoplasma gondii
usually asymptomatic unless immunocompromised
when is toxoplasma gondii most infectious
from undercooked meat
what are the 2 primary sites for entamoeba histolytica abscesses
brain and liver
symptoms of Toxoplasma in immunocompromised patients
CNS lesions ocular disease in HIV
major problem of taeniasis
neurocystercercosis
what are two examples of tapeworms
echinococcus granulosus taeniasis
where abouts are scabies infection most seen on the body
fingerwebs elbows axillae genitals
treatment of echinococcus granulosus
surgery, PAIR, anthelmintics
what are the 2 scary things about stronglyoides
- can complete whole life cycle inside humans - can cause gram negative hyperinfection in immunocompromised hosts
main way we get taeniasis
eating the egg in the muscle of meat we eat
what is a pathogenicity island
a block of genes that are found on the chromosome in pathogens that are missing from non pathogens of the same species. Split into functional areas that work cooperatively.
diagnosis of giardia
cysts in the faeces
what are the important fimbriae and non fibriate adhesins in E coli
Fimbriae - CFAs of ETEC, BFP of EPEC non-fimbriate - Intimin of EPEC and EHEC
What type of diarrhoea does EPEC cause? Which population is mostly affected?
- non-specific gastroenteritis - children in LDCs
symptoms of taenia solium
cysts in subcutaneous and neural tissue
which E coli pathogen mostly affects people in developed countries
EHEC –> bloody diarrhoea
what causes the majority of symptoms of tapeworms
their excessive energy consumption
how do you get entamoeba histolytica
foecal-oral transmission (usually in the cystic stage)
What type of diarrhoea does EIEC cause? Which population is mostly affected?
- dysentery - any age, mainly in LDCs
main use for serotyping
to distinguish between different types of Salmonella
treatment of giardia
tinidazole
how does diarrhoea kill?
- fluid and electrolyte imbalance - delayed –> malnutrition
Which bacteria invade the mucosa but then dont go any further
Shigella
what are the virulence determinants
- adhesins - invasive activity - exotoxins - ability to resist killing
treatment of diarrhoea
- replace fluid and electrolytes (intravenous or oral) - reduce fluid loss
how do you get giardia intestinalis
faecal-oral transmission zoonotic transmission
mechanism behind diarrhoea of small intestinal origin
too much fluid enters a healthy colon - unable to absorb all the water –> diarrhoea
diagnosis of viral infections
antigen detection (mainly) - capture assay detection of nucleic acid - PCR electron microscopy
how does diarrhoea lead to malabsorption
gut villi are damaged by the organism –> malabsorption
what affects the pathogenicity of protozoa
host factors - eg. immunocompromise
what are the aetiological agents of enteric fever
Salmonella typhi Salmonella paratyphi
what happens with the cysts
proliferation internally in crypts producing infective protoscoeces
why did the modified shiga Toxin Receptor drug not work
because by the time you diagnose the patient, enough Shiga toxin has already been absorbed to make them really sick
how do you get schistosoma mansonii
trasmitted by fresh water snails –> larva penetrates the skin
how are lice and mites spread
direct contact
what type of cell cycle is taeniasis
humans can replace animal in the life cycle (but dont need to be involved)= - can be both definitive and intermediate hosts)
What does oral rehydraton not do?
reduce fluid loss
why do we test for toxoplasma in pregnancy
can go haematogenously –> to baby. Can cause miscarriage or birth defects
what is the proper name of pinworm
enterobius vermicularis
which E coli species have intimin as an adhesin
EPEC and EHEC
in the past, lice were vectors of
rickettsia and spirochetes
life cycle of stronglyoides
2 cycles: 1. eggs mature –> hatch and then penetrate skin 2. adults lay eggs in GI system –> eggs in faeces –> mouth (reinfection)
life cycle of schistosoma mansonii
gut –> liver –> portal venous system –> maturation in portal vein –> lay eggs in the BVs and lumen of the gut –> into the faeces –> hatch in water –> into fresh water snails
where do lice undergo their life cycle
the whole time they have to be in direct contact with the scalp
What type of diarrhoea does ETEC cause? Which population is mostly affected?
- watery diarrhoea - infants in LDCs, travellers
Sx of Schistosoma mansoni
cercarial dermatitis
What is bundle forming pili? and where are they found?
They are like CFAs of ETEC - allow the bacteria to stick to microvilli, stopping them from being washed away by peristaltic activity ONLY FOUND ON EPEC
what are the aetiological agents of non-specific gastro
viruses bacteria protozoa
how long is enterobius vermicularis
1cm
how do you diagnose toxoplasma gondii
serolgy
what percentage of death in children under 5 is caused by diarrhoea
11%
major importance of ticks
they can be vectors of other viral agents
How do anti-motility agents work
inhibit perstalisis
what is toxoplasma gondii
obligate intracellular parasite
symptoms of scabies
itch
what are some types of protozoal parasites
entamoeba histolyica giardia intestinalis toxoplasma gondii
treatment of strongyloides
antihelminthic
what is giardia intestinalis
a flagellate, primitive eukaroyte
aetiological agents (broadly) of diarrhoea
bacteria viruses protozoa
Why is the sand particle used for the drug of the modified Shiga Toxin Receptor
because without it, the receptor would insert into our gut membrane –> susceptible gut tissue
How do the different E coli cause different types of diarrhoea
they have different virulence factors
length of echinococcus granulosus
5mm
Which bacteria invade the submucosa and they drain to regional lymph nodes
Salmenlla Campylobacter
what are some types of ectoparasites
lice - insects mites - arachnid ticks arachnid
what stops head lice from infecting pubic hair
cant infect hair with oval hair follicles
what is special about lice and scabies in terms with their life cycle
they can fulfill their whole life cycle on a single host
where are hyatid cysts mostly seen
liver and lungs
proper name for mites/scabies
sarcoptes scabiei
why are anti-motility agents classed as “bad”?
- because the body is then unable to flush the toxin out of the body - doesnt stop the fluid coming out of the tissues
diagnosis of enterobius ermicularis
detection of eggs
Sx of acute 1st infection of Schistosoma mansoni
nonspecific fibrile illness with high cytokines
how does oral rehydration work
acts on the secondary absorption system in the villi (low MW compound is taken up over the villi, taking up Na and water with it passively)
how long can giardia cysts last for outside of thehost
2 months
