bacteria Flashcards
what host factors are risk factors for gastrointestinal infections?
Age (very young & elderly) ↓ gastric acid secretion ↓ gut motility Influence of colonic microflora Intestinal immunity
what are the common bacteria seen in the UK? 5
- campylobacter coli/jejuni
- salmonella enterica
- E.Coli 0157
- shigella sonnei
- Staph aureus/ clostridium perfringens/ bacillus cereus
what are the common viruses seen in the UK? 2
- norovirus
- rotavirus
rota virus is seen in _____ ____
small children
what are the bacteria that are usually imported from abroad? 4
- vibrio cholerae/ parahaemolyticus
- salmonella typhi/ paratyphi
- aeromonas
- shigella dysenteriae/ flexneri/boydii
name 2 parasites found in the UK?
cryptosporidum sp and giardia lamblia
what does campylobacter look like?
a curved gram negative bacillus - seagull
______ is the commonest cause of bacterial GI infection in the UK – >6,500 cases per year in Scotland
campylobacter
what is the incubation period for campylobacter?
3-10 days
campylobacter leads to inflammation of the ___ and ___
colon and rectum
camplylobacter can become systemic, true/false?
true
what is the source/vehicle for campylobacter?
Farm animals, esp. undercooked poultry, water & unpasteurised milk
what are the symptoms of campylobacter?
Abdominal pain, diarrhoea +/- blood
the treatment for campylobacter is ___ ___ however, if it becomes systemic give ___ or ____ for 5 days
self limiting
erythromycin, ciprofloxacin
person to person spread of campylobacter , true/false?
false
non typhoidal salmonella is called ____
enterica
what is the incubation period for salmonella enterica?
12-48 hours
salmonella enterica causes inflammation of the ____ and ____. They multiply in the gut and cause ___ ___ , decreased ___ ___ and increased ___
ileum and colon, multiply in gut and cause mucosal damage, ↓fluid absorption and ↑fluid excretion
salmonella can become systemic, true/false?
true
what is the source/vehicle for salmonella ?
Farm animals, esp. undercooked poultry. Much less common since immunisation of poultry against Salmonella spp.
what are the symptoms of salmonella?
Abdominal pain, diarrhoea, occasionally bloody, vomiting
salmonella is ____ ___ ___ , -___ for 5 days if patient at risk of or develops systemic illness (fever, rigors, flu-like symptoms etc)
Usually self-limiting, ciprofloxacin for 5 days if patient at risk of or develops systemic illness (fever, rigors, flu-like symptoms etc)
Shigella sonnei, the most )_____ species of Shigella, is the only species seen in UK. ____ occur every few years amongst cohorts of vulnerable ____
Shigella sonnei, the most benign species of Shigella, is the only species seen in UK. Outbreaks occur every few years amongst cohorts of vulnerable children
what is the incubation period for shigella sonnei?
1-9 days
shigella sonnei invades ___ ___ causing severe inflammation, but does not invade further (never seen in ___ ____ ). ___ cells and ____ seen in stools
Invades intestinal mucosa causing severe inflammation, but does not invade further (never seen in blood cultures). Pus cells and blood seen in stools
what is the source/vehicle for shigella sonnei ?
Human only infection. Often spread person-person esp. amongst young children in schools, nurseries or via fomites (towels, toilet door handles etc)
what are the symptoms of shigella sonnei?
Abdominal pain, diarrhoea, occasionally bloody
what is the management for shigella?
symptomatic treatment only
Other species of Shigella (dysenteriae, flexneri, boydii), acquired ___ from food or water contaminated with human ____ cause more ____ infection (bacillary dysentery) that usually requires treatment with _____
Other species of Shigella (dysenteriae, flexneri, boydii), acquired abroad from food or water contaminated with human sewage cause more severe infection (bacillary dysentery) that usually requires treatment with ciprofloxacin
what does the O in e.coli 0157 refer to ?
the “O” (somatic) antigen on the surface of the organism i.e. it is a specific serotype of the usually benign E. coli. “H” is the flagellar antigen
the ____:___ strain of e.coli produces verotoxin
The O157:H7 strain
what does the verotoxin do?
- Binds to receptors found on renal cells, RBC & others
- Inhibit protein synthesis
- Causes cell death
who is most at risk at getting HUS?
children under 5 and the elderly
____ is the commonest cause of renal failure in children
e.coli O157
what is the source/vehicle for e.coli?
- Source - Carried as part of the normal gut flora in cattle.
- Beef becomes contaminated on the outside at slaughter – so ↑risk from minced meat & hamburgers than from a steak.
- Nursery/school visits to farms
- Private (untreated) water supplies – run off water from fields
- Low infecting dose, so person-person spread causes 2y cases
what are the symptoms of e.coli ?
Abdominal pain, bloody diarrhoea is common
what is the management for what is the management for e.coli? 3
- Symptomatic and supportive treatment only
- Antibiotics contraindicated as may ↑ release of toxin
- Check bloods for HUS 1 week after onset of symptoms
what does the O157 strain do?
produces a verotoxin that damages red cells and the kidney, causing haemolytic-uraemic syndrome (HUS)
what is HUS? 3
↑blood urea, red cell haemolysis & thrombocytopenia
what is the clinical presentation of HUS?
- Abdo pain, fever, pallor, petechiae (haemorrhages in skin), oliguria (↓urine production)
- bloody diarrhoea
Peak presentation of HUS is __-___ days after onset of diarrhoea
7-10
what would be found of blood tests?5 for HUS
- High white cells
- Low platelets
- Low HB
- Red cell fragments
- Lactate dehydrogenase ↑>1.5 x normal
salmonella, shigella and e.coli O157 appears as ___ ___ ___
gram negative bacilli
what? causes typhoid/paratyphoid fever
salmonella typhi/ salmonella paratyphi A and B
____/____ ___ These are febrile illnesses initially (bacteria circulating in bloodstream) causing headache, flu-like symptoms followed by diarrhoea 3 weeks later
Typhoid/paratyphoid fever
what is the intubation period for Typhoid/paratyphoid fever
14-21 days
Organism invades from ___ ____ →_____ system→ bloodstream→______system & gall bladder→gut lumen and invades Peyer’s patches.
Organism invades from gut lumen→lymphatic system→ bloodstream→reticuloendothelial system & gall bladder→gut lumen and invades Peyer’s patches.
what is the source/ vehicle of infection for salmonella typhi/ paratyphi ?
Human only infection. Spread person-person or from drinking contaminated water/eating contaminated food/poor sanitation
what are the symptoms of salmonella typhi/paratyphi?
- Fever, rash on abdomen (“Rose spots”) and diarrhoea
what is the management of salmonella typhi/paratyphi?
Antibiotics are required, choice depends on sensitivities. Resistance to ciprofloxacin becoming common in developing countries
what organism causes cholera?
vibrio cholerae - a small curved gram negative bacillus
where are outbreaks of cholera common?
Outbreaks common in “disaster” or war situations
what is the intubation period for cholera?
1-9 days
in cholera
Organism produces an _____ that causes active outpouring of __ from cells of small intestine, resulting in severe ___ diarrhoea
Organism produces an exotoxin that causes active outpouring of fluid from cells of small intestine, resulting in severe watery diarrhoea
cholera is the exception to the rule that ____ are produces by gram positive
exception to the rule that exotoxins are produces by gram positiv
what is the source/ vehicle of infection for cholera?
Human only infection. Spread person-person or from drinking contaminated water/poor sanitation
what are the symptoms of salmonella cholera?
Watery diarrhoea – “rice water stools” causing rapid dehydration
what is the management of cholera? 2
- Fluid and electrolyte replacement is essential
- Antibiotics NOT indicated
