Infections Flashcards
What ae 5 important things to ask about in a history of a suspected GI infection?
Travel, pets, contacts, functions and food history
What is gastroenteritis?
Inflammation of the lining of the stomach, small intestine and large intestine
Most cases of gastroenteritis are infectious, but what are two other less common causes?
Drugs and chemical toxins
What are the 8 scenarios in which you WOULD give antibiotics?
Shigellosis, enterotoxic E. coli, C. diff, Amoebiasis, giardiasis, enteric fever, cholera, invasive salmonellosis
What do all stool samples get tested for?
Shigella, campylobacter, salmonella, E.coli 0157, cryptosporidium
What do all stool samples in patients over 15 years get tested for? Why is this the case?
C. diff- this is a normal finding in young people
How long does it take for a stool sample result?
48 hours
Patients with what infections should get a side room and transfer to infectious diseases?
C. diff and norovirus
What are other infection control procedures which are important to remember?
Cohort nursing, PPE, hand hygiene, maybe closing wards
What bacteria can survive against alcohol hand gel?
C. diff
What are short term infecting organisms? What is the incubation period of these?
Staph aureus and bacillus cereus- 1 to 6 hours
Where is staph aureus found?
Preformed toxin in food, meat, potato salads, cream and eggs
What are common and less common symptoms of staph aureus?
Common- abdominal pain and vomiting
May be present- non-bloody diarrhoea and fever
Where is bacillus cereus mainly found?
Rice and other starchy foods
What does bacillus cereus cause?
Profuse vomiting and maybe non-bloody diarrhoea
What is a medium term infecting organism and what is the incubation time?
Salmonella- 12-48 hours
What is there a risk of with salmonella?
Bacteraemia
Where does salmonella come from?
Poultry, meat and raw egg. Also common in reptiles
What does salmonella cause?
Diarrhoea which can sometimes be bloody, vomiting and fever
What is used for testing salmonella?
O antigen found on the organism surface
What is the commonest cause of food poisoning?
Campylobacter (jejuni)
What is the incubation time of campylobacter?
2-5 days
Where is campylobacter usually found?
Poultry and raw milk
How is campylobacter treated?
No treatment really/ Only give clarithromycin in very sick or immunocompromised patients
What is a rare but important complication of campylobacter?
Guillain-Barre syndrome
What may been seen on an AXR of campylobacter?
Indentations of the bowel-thumbprint colitis
What does E.coli 0157 produce?
Shiga-like/verotoxins
What does giving antibiotics in E.coli 0157 do?
Increases shiga-like toxins
What agar is used to make a diagnosis of E.coli 0157 and what colour would this show up?
McConkey agar which will show up pink
What other studies can be used to identify toxins in E.coli 0157?
DNA studies or ELISA
What causes E.coli 0157?
Beef, raw milk, animal contact, person to person
Who are many cases of E.coli in?
< 16
What is the incubation period of E.coli 0157?
1-14 days
Does E.coli 0157 cause bloody diarrhoea?
Yes
What is the major complication of E. coli 0157 and how does this happen?
Haemolytic ureamic syndrome- toxins bind to receptors on renal cells and inhibit protein synthesis
What will be some test results of HUS?
Increased WCC, low platelets, low Hb, red cell fragments and increased lactate dehydrogenase (LDH)
What should not be given in E. coli 0157?
Antibiotics, anti-motility agents or NSAIDs
What should you always do in a case of E.coli 0157?
Report to public health
What is a common healthcare acquired infection causing diarrhoea which can be transmitted person to person?
C. difficile
What 2 toxins does C. diff contain?
Toxin A- enterotoxin
Toxin B- cytotoxin
What brings about infection of C. diff?
Antibiotics are prescribed which kill off the normal competitive gut flora which allows C. diff to overgrow
What type of organism is C. diff?
Gram + spore bearing bacillus
What is important about the spores of C. diff?
Commonly antibiotic resistant
What is C. diff colitis commonly?
Pseudomembranous
What antibiotic is given in less severe C. diff?
Oral metronidazole
What antibiotic is given in more severe C. diff?
Oral vancomycin
How can C, diff infection be prevented?
Good hand hygiene, avoid broad spectrum antibiotics- especially 4 C’s, isolate patients
1 or more of what markers suggests C. diff infection?
Pseudomembranous colitis
WCC > 15
Creatinine 1.5 x baseline
Persistent symptoms of C. diff despite 2 treatments
What virus is most common in children under 3?
Rotavirus
How is rotavirus spread?
Faecal-oral
What does rotavirus cause in the body?
Affects absorption and secretion in the bowel
How does rotavirus present?
Moderate fever, vomiting and then non-bloody diarrhoea
How long does rotavirus last?
About a week- self-limiting
What commonly occurs in children following rotavirus infection?
Post infection malabsorption which leads to further diarrhoea
How is rotavirus and norovirus diagnosed?
PCR of faeces
What is the key to rotavirus and norovirus treatment?
Hydration
Does a vaccine for rotavirus exist?
Yes-live attenuated, only given to children of 2-3 months
How can norovirus be spread?
Faecal oral or droplet
How does norovirus occur?
Asymptomatic shedding for 48 hours followed by a sudden explosive onset of V and D
How long does norovirus last?
2-4 days
What should you ask for in a history of a returned traveller with an infection?
Where, when, accommodation, is anyone else ill, insect bites, what did they do, did they take precautions
What are pre-hepatic causes of jaundice in a returned traveller?
Malaria, HUS, sickle cell crisis
What are hepatic causes of jaundice in a returned traveller?
Hepatitis A and E, malaria, enteric fever, rickett’s,
What are post-hepatic cause of jaundice in a returned traveller?
Helminths
What is acute traveller’s diarrhoea defined as?
3 loose stools in 24 hours
What is the most common cause of acute traveller’s diarrhoea?
E.coli
If diarrhoea in a returned traveller is profuse and watery what is this likely to be?
Cholera
What investigations should be done on acute traveller’s diarrhoea?
Stool culture and wet stool prep for amoebiasis
What is the treatment for acute traveller’s diarrhoea?
Supportive, hydration and ciprofloxacin in severe cases
Where is enteric fever most common?
Indian subcontinent and SE asia
What is the typical incubation period of enteric fever?
7-18 days
What are symptoms of enteric fever?
Fever, dry cough, headache, constipation/diarrhoea
What are complications of enteric fever?
GI bleed, perforation, encephalopathy and bone/joint infection
What causes enteric fever?
Salmonella Typhi/Paratyphi
If a patient with enteric fever is unstable, what should you give them?
IV ceftriaxone (azithromycin can also be useful orally)
What tests should be taken for enteric fever?
Blood cultures first followed by urine and stool samples
How is amoeba spread?
Faecal-oral (associated with poor hygiene)
How is a diagnosis of Amoebiasis made?
Hot stool sample for ova and cysts
How is Amoebiasis treated?
Metronidazole
What investigations would be done for Amoebiasis?
Stool microscopy, AXR and endoscopy
What can severe or untreated Amoebiasis lead to?
Amoebic liver abscess
Who are amoebic liver abscessed more common in?
Men
How will an amoebic liver abscess present?
Subacutely over 2-4 weeks, fever, sweats, upper abdominal pain, GI upset, hepatomegaly
What will you see on an X-ray of Amoebic liver abscess?
Raised right hemi-diaphragm
What investigations should you do for Amoebic liver abscess?
US, CT, serology for IgG and stool microscopy
How do you treat amoebic liver abscess?
Metronidazole or tinidazole
How is giardia spread and what is its incubation period?
Faecal-oral, around 7 days
What is a feature of a giardia protozoa?
Flagellated
What are some symptoms of giardiasis?
Watery, malodourous diarrhoea, bloating, flatulence, abdominal cramps and weight loss
How do you investigate for giardia?
Stool microscopy
How do you treat giardia?
Metronidazole or tinidazole
What is cryptosporidiosis transmitted from?
Water, food, animal contact
How is cryptosporidium diagnosed?
Duodenal aspirate or stool samples
What is the treatment for cryptosporidium?
Supportive
What are helminths often associated with?
Eosinophilia
What are nematodes and trematodes?
Nematodes- roundworms
Trematodes- flukes
What is an example of a fluke which is associated with fresh water exposure which can cause a rash and portal hypertension?
Schistosomiasis
Where do tapeworms commonly come from and what can they cause?
Undercooked meat and seizures
What is colonisation?
Bug present but no inflammatory response
What is infection?
Inflammatory response as a result of a bug
What is bacteraemia?
Bacteria growing in blood culture
What is sepsis?
Infection resulting in a systemic infection. Life threatening organ dysfunction- dysregulated host response
What is septic shock?
Subset of sepsis with circulatory and cellular dysfunction
What causes difficult infections?
An abnormal host response e.g. immunocompromised, co-morbidity drugs, genetics or an abnormal microbe response
What is SIRS?
Systemic inflammatory response syndrome. 2 or more of the following suggests SIRS: Temp <36 or >38 Heart rate > 90 Resp rare > 20/PaCO2 < 32 Abnormal white cell count
Can a patient have sepsis without an infection?
No
What must a patient have to be defined as being in septic shock?
Infection, 2 SIRS criteria and at least one organ in failure
What is an important sign of septic shock?
Hypotension
What are common bacteroides?
Coliforms and anaerobes from perforated large bowel
What antibiotics should be given for an intra-abdominal infection?
Amoxicillin/Vancomycin, gentamycin, metronidazole
What do amoxicillin/vancomycin target?
Streptococci and enterococci
What does gentamycin target?
Aerobic coliforms
What does metronidazole target?
Anaerobes
What is the sepsis 6?
Give high flow oxygen (target 94-98%), start IV fluids (500mls IV saline), take blood cultures, IV antibiotics, measure lactate and FBC, monitor hourly urine output
What does a creatinine > 150 suggest?
Kidney damage
