Infective diarrhoea Flashcards
Definition of diarrhoea
Three or more loose or liquid stools within a 24-hour period
Definition of Gastroenteritis
Inflammation of the stomach and intestinal epithelium
Definition of food poisoning
Development of vomiting and diarrhoea caused by eating food contaminated with microorganisms and/or toxins
Definitions of dysentery
Bloody diarrhoea with mucus, pain, fever usually caused by bacterial parasitic or protozoan infection
Incubation times for infective diarrhoea
• Less than 6 hours: preformed toxin of S. aureus or B. Cereus
• 6 to 24 hours: preformed toxin of C. perfringens and B. Cereus
• 16 to 72 hours: Noroviruses, Enterotoxigenic E coli, Vibrio, Salmonella, Shigella, Campylobacter, Cryptosporidium
Features of a medical emergency
• Severe dehydration
• Sepsis
• Acute bloody diarrhoea in a child
• Severe colitis with complications
• Neurological symptoms
• Febrile traveller from a malarial area –consider malaria
Features of a history to consider
•Age
•Immunocompromise or pregnancy (Listeria)
•Acute on chronic symptoms
•Recent food exposures –take aways, restaurant, BBQs
•Animal exposure, farms
•Recent antibiotic treatment
•Family or social contacts
•Travel history: Typhoid, parasites
•Consider non infective aetiology if there are chronic features i.e: Chron’s disease, ulcerative colitis, etc
•Consider diarrhoea associated with infection outwith the GI tract: sepsis, pyelonephritis, Legionellosis
Investigations of stool samples
-Microscopy (parasites)
-Culture and antimicrobial susceptibility testing
-Molecular: PCR/ sequencing
-Serology: latex agglutination (0157, salmonella)
Patterns of illness
•Acute vomiting
•Acute watery diarrhoea
•Diarrhoea with fever
•Enteric fever
•Persistent diarrhoea
Bacterial toxins in acute vomiting
-Bacillus cereus
-Staph aureus
Describe norovirus in acute vomiting
• Most common causative agent of viral gastroenteritis
• Seasonal predominance during winter in children and adults
• Person to person spread is common
• Outbreaks in hospitals, care homes, nurseries, cruise ships, refugee camps and military combat areas
• Viral identification by PCR in vomit and/or stool
• Supportive treatment, isolation, contact precautions
• Self-limiting disease lasts approx 3 days
• Can be severe in the immunocompromised
Describe acute watery diarrhoea
•Loose stools with mucus, no blood
•Occasional vomiting and anorexia, malaise, low grade fever
•Viruses: Norovirus, rotavirus (young children) and adenovirus
Bacteria in acute watery diarrhoea
-S.aureus
-Bacillus cereus
-Clostridium perfringens
-Enterotoxigenic E coli
-Vibrio cholerae
-Cryptosporidium
S. aureus in acute watery diarrhoea
• Heat stable enterotoxin
• contaminated ready to eat food
Bacillus cereus in acute watery diarrhoea
• Produces two toxins: emetic and diarrhoeal toxin
• Presents with sudden vomiting followed by diarrhoea later
• Present in food multiplies quickly if left at room temperature: i.e. rice left over, sauce
• Self-limiting – supportive measures
-Complications= ruptured oesophagus
Clostridium perfringens in acute watery diarrhoea
• Shot incubation 6-24 hours
• Toxin generated in the gut after ingestion
• Contaminated meat, sauce in poor storage conditions
• Abdominal cramps and diarrhoea, no vomiting
• Supportive measures
Enterotoxigenic E coli in acute watery diarrhoea
• Leading cause of bacterial diarrhoea in the tropics and returning traveller
• Watery diarrhoea, abdominal cramps
• Self resolving in 2 – 4 days
• Supportive measures
Vibrio cholerae in acute watery diarrhoea
• Toxin mediated disease: increase in cyclic AMP blocks absorption of Na and chloride in the small intestine
=Two serogroups O1 and O139
• Related to contaminated water / undercooked shelfish, natural disasters, social conflict areas
• Endemic in tropical areas: India, central America and Africa
• Severe watery diarrhoea “rice water stool” in a patient residing in an endemic area or returning traveller
• Fulminant disease due to hypovolaemic shock and death
• Treatment: rehydration
=Antibiotics shorten the duration of the illness
=Isolation
• Notifiable to public health
Cryptosporidium in acute watery diarrhoea
• Protozoan parasite: C. homini and C. parvum
• Occurs through direct exposure to infected people or animals
• Resistant to chlorine – swimming pools
=Contaminated water
=Contact with lambs and calves
• Usually asymptomatic
• Children or student vets
• Can cause watery diarrhoea
• Self resolving 1-2 weeks
• Can be severe in immunocompromised: HIV / infants
• Treatment:
=Oral rehydration
=Nitazoxanide
• Advice patients to avoid swimming pools for 14 days after symptoms stopped
Most common organisms in traveller’s diarrhoea
• Enterotoxigenic E coli (ETEC)
• Campylobacter
• Salmonella
• Shigella
• Vibrio cholerae
• Chronic diarrhoea:
=Giardia
=Cryptosporidium
=Cyclospora belli
Describe acute dysentery syndromes
Diarrhoea associated with fever suggests an acute inflammatory
enteritis.
•Dysentery: frequent small stools accompanied by blood, mucus with
pain and tenesmus
•High risk of person-to-person transmission:
=Day-care centres, institutions, poor hygiene
Organisms causing acute dysentery syndromes
• Campylobacter
• Invasive E coli (0157)
• Salmonella / Typhoid fever
• Entamoeba histolytica
Campylobacter in acute dysentery syndromes
•Campylobacter jejuni
=Undercooked poultry
=Incubation: 1 to 3 days
=Bloody stool, abdominal cramps, fever
•Complications:
=Bacteraemia (immunocompromised)
=Guillain-barre syndrome (1200 cases per annum in the UK)
•Self-limiting
•Rarely requires antimicrobial treatment
Salmonella in acute dysentery syndromes
•Non typhoidal Salmonella
• Eggs – imported / poultry/ meat/ pets
• Incubation: 6 - 72 hours
• Diarrhoea and vomiting, high fever
• Complications:
=Bacteraemia
=Aortitis
=Osteomyelitis
=Meningitis
=Splenic cyst
• Requires blood cultures and stool sample
• Intravenous antimicrobials when invasive: ceftriaxone
•Typhoid is travel related and presents usually with fever and constipation
Shiga toxin producing E coli diagnosis
-Serious clinical and Public Health problem- E coli O157:H7 and non- O157
STEC
-Haemolytic uraemic syndrome (HUS)in 10-15%, usually aged <16 years or
>60 years
-Diagnosis: Culture or molecular tests (PCR) stool/ Serology on clotted blood (antibody detection)
Clinical presentation and management of STEC
-Clinical presentation:
• Acute abdominal pain, fever, pallor, petechiae
• If there is oliguria: maker of severe disease
-Management:
• Seek urgent advice
• Blood tests: FBC, blood film, U&Es, CRP, LDH
• Submission of stool sample is essential
• Do not give antimicrobials / NSAIDs or anti-motility drugs (interfere with clearance)
• Encourage oral fluids prior referral
• Inform microbiology and public health
Shigella in acute dysentery syndromes
•Shigella sonnei/ Flexneri/ dysenteriae/ boydii
•Low infectious dose: 10 to 100 organisms
•Risk group: children / MSM
•Causes dysentery and bloody diarrhoea
•Fever, vomiting and abdominal pain
•Travellers returning from India / Pakistan
•Important public health problem especially in developing countries
•Treatment: ceftriaxone or ciprofloxacin
Examples of parasites
-Amoebiasis
-Giardiasis
Describe entamoeba hystolitica (amoebiasis)
• Orofaecal infection
• Tropical areas – poor sanitation
• Human reservoir
• Returning travellers in the UK and MSM (men that have sex with men)
• Clinical presentation
=Asymptomatic 80%
=Loose stool and abdominal cramps
= +++ Bloody stools and abdominal cramps: colitis with ulcer formation (potential perforation)
Diagnosis and treatment of amoebiasis
•Stool samples for ova cysts and parasites
• Pus samples and stool for trophozoites require urgent examination
• PCR
•Serology for liver disease
•Liver aspirate: No evidence of parasites
-Treatment:
• Metronidazole
• Paronomycin – clears intraluminal parasites
Extraintestinal infections of amoebiasis
Liver abscess:
◦ More common in men
◦ Fever, abdominal pain and pleuritic pain
◦ Single large abscess
◦ 80% right lobe, can cause pleural effusion
◦ Treatment:
=Drainage
=High dose metronidazole
Describe Giardiasis
•Asymptomatic
•Abdominal pain, diarrhoea – subacute – chronic
•Malabsorption (lactose)
•Examination of stools for ova, cysts as parasites
=PCR
•Management: Albendazole
Infection control measures
•Single room accommodation with En- suite toilet
•Wash hands with soap and water
=alcohol gel not sufficient in many cases
•PPE/ linen and waste disposal
•Dedicated equipment
•Bristol stool charts
•Drugs/ interventions that worsen diarrhoea (anti-motility drugs, stop laxatives)
Public health actions
•Contact tracing
•Exclusion of infected individuals from
=pre-school nurseries
=Healthcare settings
=Workplace – food handlers
• Clearance samples may be required prior to returning to work
