Infections of the GI tract Flashcards
What is the difference between microbiome and microbiotia?
Microbiome: all the genome within the gut environment
Microbiota: all the organisms within the gut environment
What are the functions of the gut microbiota?
- pathogen inhibition
- immune protection
- nutrient metabolism - synthesis vit B + K
- Drug metabolsim
- Gut brain axis
What approach would you take on investigating the symtpoms of a patient with a suspected GI infection?
- Is there diarrhoea? - onset, duration, frequency, consistency
- Is there mucus/ blood in stools?
- Is there vomiting? - onset, frequency
- Is there pain? - site, radiation, intermittent, continuous
What Past medical history would be useful to know in a suspected GI infection?
- History of immunocompromise / immuodeficiency
- Any other GI conditions
What are some important social questions to ask if someone presents with a suscpected GI infection?
- Recent travel history? - where, when and how long, what they did whilst they were there
- Drug history - recent antibiotics? proton pump inhibitors? laxatives? immunsuppressants?
- Social History - occupation
What things can you look for on GI examination that can help establish if there is a GI infetion?
Volume status: Check mucous membranes, BP, pulse, JVP
Abdominal exam: ileus, peritontitis
What investigations can be done on a stool sample to help identify GI infection?
- Stool culture
- Enzyme immunoassay
- PCR
- Microscopy
Impossible to do all, need to know what sample you’re looking for
What infectious causes can cause watery diarrhoea?
- Norovirus
- Rotavirus
- C. difficile
- Enterotoxigenic E. Coli
- Giardia lamblia
- Cryptosporidium parvum
What infectious causes can cause inflammatory diarrhoea?
- Non- typhoidal salmonella
- Campylobater
- Clostridiodes difficile
- Shigella
- E. coli O157
- Entamoeba hysoltica
What are the 2 general subdivisions of salmonella infection?
Typhoidal salmonella which causes enteric fever (Salmonella typhi and Salmonella paratyphi)
Non-typhoidal salmonella whichc causes gastroenteriris (Salmonells enteritidis, Salmonella virchow)
What are some of the general features of non- typhoidal salmonella?
- Diarrhoea
- Nausea
- Vomiting
- Abdominal Cramps
How is non- typhoidal salmonella transmitted?
- In food
- Faeco- orally
- Animals
What are some of the complication sof non-typhoidal salmonella infection?
- Bacteraemia
- Endovascular infections
- Abscesses
- Osteomyeltitis
- Septic arthritis
How do you treat non-typhoidal salmonella?
usuall self limiting
If bateraemic: can use antibitoics, ciprofloxacin, azithromycin, ceftriaxone
What are the most 2 common organisms of infection with camylobacter?
Camplyobacter jejuni
Camplyobacter coli
Gram -ve corkscrew like bacterium
What are some of the general features of a campylobacter infection?
- abdominal cramping
- diarrhoea
- may have fever and malaise
What is the transmission route of camplyobacter?
Food, water or animal contact
How do you treat campylobacter?
Usually self limiting
Treat immunocompromised patients, elderly or severe infetion with macrolides or fluoroquinolones
What are some of the complications of a campylobacter infection?
- Reactive Arthritis
- Guillain-Barre Syndrome (GBS) - ascending paralysis
What kind of food/ drink can cause campylobacter?
- Uncooked poultry - peaks on BBQ over summer
- Milk- transmitted by birds pecking milk tops
- Uncooked defrosted turkey
Which types of shigella can cause dysentry? (blood diarrhoea)
Shigella dysenteria 1 / Shigella flexneri
What are some of the general features of an infection with Shigella?
- Fevers
- Frequent low volume, blood stools
- Tenesmus
- Nausea and vomiting usually asbent
How can shigella be trasmitted?
- Faeco - oral
- Food and water
- Person-to-person can occur due to low infective dose
What are some of the complications of shigella infections?
Intestinal (rare): proctisis, rectal prolapse, toxic megacolon, perforation, obstruction
Systemic: bacteraemia, seizures (children), reactive arthritis, haemolytic iraemic syndrome
What treatment can you give for shigella?
Usually self limiting
If not give ciprofloxacin, azithromycin, ceftriaxone
Which E.coli subtype prodcues shiga toxin?
E. coli O157
Describe the clinical features and aetiology of E.coli O157 infection
- Very contagious infection
- causes painful, bloody diarrhoea and haemolytic uraemic syndrome
- Children <10 year and elderly particularly vulnerable
- No fever
- Worsened by antibiotics → cause more toxin to be produced
What is haemolytic uraemic syndrome?
Diease characterised by: Non immune mediated haemolytic anaemia, thrombocytopenia and acute kidney injury
What kind of bacteria is clostridiodes difficile?
Anaerobic gram negative bacilli
How do c. dificile bacterium remain in the environment for so long?
Produce spores that are very resistant
Not killed by handgel - always use soap and water after a diaorrhoea infection
What are some risk factors for developing an infection from clostridiodes difficile?
- Age >65
- Antibiotic therapy
- PPI therapy
- prolonged hospitalisation
What complications can arise from infection with clostridiodes difficile?
- Toxic megacolon,
- colitis
- perforation
How do you treat a clostriodes difficile infection?
- Metrondiazole
- Oral Vancomycin
- Fidazomicin - superior for recurrent infection
- Faecal microbiota transplant - repooulates gut with healthy microbiota
Describe the clinical features and aetiology of a norovirus infection
- Causes profuse diarrhoea and vomiting
- Transmitted faceo-orally, direct contact or aerosols
- Highly infectious due to low infective dose
- Usually self limiting (1-2 days)
Describe the clinical features and aetiology of a rotavirus infection
- Cause of gastroenteriris in young children
- Transmitted faeco-rally
- highly infective
- General features of diarrhoea, vomiting and fever
- Usualy self limiting with supportive treatment
What rare complications can arise from a rotavirus infection?
- seizures
- encephalopathy
- acute encephalitis
Describe the clinical features and aetiology of a cryptosporidium infection
- Intracellular protozoan parasite
- Cryptosporidium parvum main species to cause infection
- Associated with sporadic, water associated outbreaks i.e. swimming pools
- Usually self limiting within 10-14 days
- Treat with nitazoxanide if immunocompromised
Describe the clinical features and aetiology of a giardia infection
- Caused by giardia duodenalis, a protozoa parasite
- can last in cold water for months
- Children, immunocompromised patients and cystic fibrosis are high risk
- Transmited in food, water, faeco-orally
- Features of malaise, steatorrhoea, abdominal cramps and bloating
- Chronic infection can cause malabsorption and weight loss
How do you treat a giardia infection?
NOT self limiting
If symptomatic give metronidazole or nitazoxanide
Describe the clinical features and aetiology of a entamoeba histolytica infection
- protozoan parasite
- most infections asymptomatic
- Can cause amoebic dysentry
- Transmitted in food, water, faeco-orally highly transmissable
- General features: diarrhoea, abdominal pain, fulminany colitis with necrosis and perforation
- Treat with high dose metronidazole followed by an intraluminal agent
