Gastrointestinal infections
Among the most common infections in
the world
Diarrhoea, vomiting, abdominal pain,
malaise, possible pyrexia
Faecal - oral
Environmental factors
Sanitation
Water supplies
Ambient temperatures and frost
Levels of education
Personal and community hygiene
Transmission
Water - food - secondary spread
Natural defences
Gastric acid - infections common in
achlorhydria
Bile salts - disrupt the membranes of
some bacteria
Normal bowel flora - competition between
micro-organisms, e.g. salmonella infection more likely after antibiotics
Immune responses - lymphocytes in
mucosa, cell mediated and humoral immunity (Ig A), lymphoid tissue, enjoyed
when OPV is given, colostrum
Motility - blind loops become infected
may lead to abscess formation, faeces weight 50% bacteria, stasis ferments gut
contents, diarrhoea flushes
Protection against toxins - some
normally produced, the hepatic portal circulation
Principles of management
Specimens - stool, mucosal, intestinal fluid, vomit,
blood cultures
Oral rehydration - Sodium 150 - 155
mmol/l, Glucose, 200 - 220 mmol/l, Potassium 4 - 5 mmol/l
Intravenous rehydration - half
strength saline, monitor electrolyte balance
Feed children with diarrhoea
Lactose intolerance may temporally
occur after GI infection in children
Drug treatment
Antiemetics
Antidiarrhoeal drugs
Prevention of food poisoning
Clean water supplies
Safe food production and manufacture
Prevent cross contamination e.g.
uncooked to cooked meat
Kill salmonella
Cooking
Notifiable
Viral infections
May be caused by a variety of viruses,
e.g. adenoviruses, small round structured viruses, small round viruses,
astroviruses
Rotavirus
Common in young children, adults are
often immune
Epidemiology -
most infections occur in winter
Clinical picture -
abrupt onset of diarrhoea and vomiting, possible mild pyrexia
Incubation
-
24 hours
Duration - usually 1
- 2 days
Management - keep hydrated,
avoid dairy products - low lactose milk
Diagnosis
-
useful for outbreaks is by electron microscopy
Bacterial infections
Escherichia coli
Commensal and pathogenic types
Epidemiology
Very transmissible, from animals
Clinical picture
Abrupt onset of diarrhoea and
vomiting, possible moderate fever, followed by watery diarrhoea
Incubation
1 - 2 days up to 5 days
Duration
Usually 1 - a few days
Management
Keep hydrated, early recognition of
complications, possible ciprofloxacin
Diagnosis
Epidemiology, clinical picture,
culture
Complications
From some forms of E. coli -
Haemorrhagic colitis, Haemolytic uraemic syndrome
Prevention
Close down source, prevent cross
infection, cook hamburgers, avoid infection while travelling
Salmonella
2 200 different serotypes which are
found in people and animals, eg. poultry pigs and cows
Infection
From infected animal material, e.g.
poultry (60% infected) egg shells, egg white, raw meat
Faecal-oral
Pathophysiology
An infection of the gut epithelium
Excess fluid secretion from small
bowel
Clinical features
Incubation 18 - 36 hours
Malaise, nausea, vomiting, often fever
followed by diarrhoea
Diarrhoea is watery and brown and may
later become greenish
Not a lot of abdominal pain except on
call to stool
Normally resolves in 2 days but may go
on for several weeks leading to debility
Complications
Elderly at risk from low fluid volumes
which may lead to MI and CVA
Salmonella colitis - up to 10% of patients
may develop colic and bloody stools
Salmonella bacteraemia - uncommon,
possible metastatic infection, may occur in the absence of clinical bowel
infection
Continued excretion after recovery,
usually stoops within 4 weeks
Management of salmonellosis
Rehydrate and await spontaneous
recovery
IV fluids for dehydration or
exhaustion
Antibiotics if no recovery after 36 -
48 hours, e.g. ciprofloxacin
Shegellosis (bacillary dysentery)
Shigellosis is generally mild in the West
but severe in the tropics, especially in children
Infection
Faecal-oral - direct, water, food
Mostly in children under 5 years
Clinical features
Incubation 3 - 4 days
Starts with a high fever lasting 12 -
24 hours
Diarrhoea with colitis and colic
Brown watery diarrhoea often with
mucus, may be some blood
Recovery is usual in 3 - 5 days
Management
Maintain hydration
Antibiotics if persistent
Antispasmodics for colic
Campylobacter
Most common food poisoning in the UK,
40 000 reported cases per year
Very limited person to person spread
Very few metastatic of bacteraemic
complications
Infection
Mostly from poultry or wild birds
drinking human milk
Most cases in Summer
Infective dose may be as low as 500
organisms
Clinical features
Incubation 3 - 4 days
24 hour prodromal pyrexia, headache
and prostration
Diarrhoea - watery and possibly bloody
Vomiting at outset
Abdominal pain common with possible
rebound tenderness
Fluid accumulates in bowel loops from
action of the toxin
Management
Symptomatic treatment
Specific treatment of prolonged, oral
erythromycin
Prevention
Good hygiene
Get it out of poultry
Other bacterial causes
Vibrios - from shellfish
Yersinia
Helicobacter pylori - acute gastritis,
chronic gastritis, peptic ulceration, human to human infection
Food poisoning caused by toxins
Staphylococcal
Incubation 30 mins - 6 hours
Malaise, nausea, severe vomiting
Possible iv. emergency rehydration
required
Botulism
Clostridium from poorly canned or bottled food
Usual picture followed by
neuromuscular paralysis from the head down including swallowing and respiration
Incubation 24 - 48 hours, Consider
antitoxin or polyvalent antiserum
Parasitic infections
Protozoa
Giardia, other amoeba, amoebic
dysentery
Helminths
Among the commonest chronic conditions
in humans
Endemic in areas of poor sanitation
Faecal - oral usually
Produce eosinophilia
Threadworms
Mebendazole
Ascaris
Respiratory features due to larvae
migrating through the lungs, Mebendazole
Hookworms
Larvae get in through the skin,
migrate to the lungs, are swallowed and infect the gut, eggs are excreted with
faeces
Treat anaemia, Mebendazole
Strongyloides
Similar to hookworm treat with
albendazole for 3 days
Bannister BA. Begg NT. Gillespie SH. (1996) Infectious diseases, Blackwell Scientific, Oxford
Gastrointestinal infections
Among the most common infections in
the world
Diarrhoea, vomiting, abdominal pain,
malaise, possible pyrexia
Faecal - oral
Environmental factors
Sanitation
Water supplies
Ambient temperatures and frost
Levels of education
Personal and community hygiene
Transmission by water, food, secondary spread
Natural defences
Gastric acid - infections common in
achlorhydria
Bile salts - disrupt the membranes of some
bacteria
Normal bowel flora - competition
between micro-organisms, e.g. salmonella infection more likely after
antibiotics
Immune responses - lymphocytes in
mucosa, cell mediated and humoral immunity (Ig A), lymphoid tissue
Motility - stasis leads to infection,
may lead to abscess formation
Diarrhoea flushes
Faeces weight 50% bacteria,
Protection against toxins - the
hepatic portal circulation
Principles of management
Specimens - stool, mucosal, intestinal fluid, vomit,
blood cultures, vomit
Oral rehydration
Intravenous rehydration - half
strength saline, monitor electrolyte balance
Feed children with diarrhoea
Lactose intolerance may temporally
occur after GI infection in children
Drug treatment
Antiemetics
Antidiarrhoeal drugs
Prevention of food poisoning
Clean water supplies
Safe food production and manufacture
Prevent cross contamination e.g.
uncooked to cooked meat
Kill salmonella
Cooking
Viral infections
Causes, e.g. adenoviruses, small round
structured viruses, small round viruses, astroviruses
Rotavirus
Common in young children, adults are
often immune
Epidemiology - most infections occur
in winter
Clinical picture - abrupt onset of
diarrhoea and vomiting, possible mild pyrexia
Incubation - 24 hours
Duration - usually 1 - 2 days
Management - keep hydrated, avoid dairy products
Diagnosis - useful for outbreaks is by
electron microscopy
xxxxxxxxxxxxxxxxxxxx
Bacterial infections
Escherichia coli
Commensal and pathogenic types
Epidemiology - very transmissible,
from animals
Clinical picture - abrupt onset of
diarrhoea and vomiting, possible moderate fever, followed by watery diarrhoea
Incubation - 1 - 2 days up to 5 days
Duration - Usually 1 - a few days
Management - keep hydrated, early
recognition of complications, possible ciprofloxacin
Diagnosis - epidemiology, clinical
picture, culture
Complications
From some forms of E. coli -
Haemorrhagic colitis, Haemolytic uraemic syndrome
Prevention
Close down source, prevent cross
infection, cook hamburgers, avoid infection while travelling
Salmonella
2 200 different serotypes which are
found in people and animals, eg. poultry pigs and cows
Infection
From infected animal material, e.g.
poultry (60% infected) egg shells, egg white, raw meat
Faecal-oral
Pathophysiology
An infection of the gut epithelium
Excess fluid secretion from small
bowel
Clinical features
Incubation 18 - 36 hours
Malaise, nausea, vomiting, often fever
followed by diarrhoea
Diarrhoea is watery and brown and may
later become greenish
Not a lot of abdominal pain except on
call to stool
Normally resolves in 2 days but may go
on for several weeks leading to debility
Complications
Elderly at risk from low fluid volumes
which may lead to MI and CVA
Salmonella colitis - up to 10% of
patients may develop colic and bloody stools
Salmonella bacteraemia - uncommon,
possible metastatic infection, may occur in the absence of clinical bowel
infection
Continued excretion after recovery,
usually stoops within 4 weeks
Management of salmonellosis
Rehydrate and await spontaneous
recovery
IV fluids for dehydration or
exhaustion
Antibiotics if no recovery after 36 -
48 hours, e.g. ciprofloxacin
Shegellosis (bacillary dysentery)
Shigellosis is generally mild in the
West but severe in the tropics, especially in children
Infection
Faecal-oral - direct, water, food
Mostly in children under 5 years
Clinical features
Incubation 3 - 4 days
Starts with a high fever lasting 12 -
24 hours
Diarrhoea with colitis and colic
Brown watery diarrhoea often with
mucus, may be some blood
Recovery is usual in 3 - 5 days
Management
Maintain hydration
Antibiotics if persistent
Antispasmodics for colic
Campylobacter
Most common food poisoning in the UK,
40 000 reported cases per year
Very limited person to person spread
Very few metastatic of bacteraemic
complications
Infection
Mostly from poultry or wild birds
drinking human milk
Most cases in Summer
Infective dose may be as low as 500
organisms
Clinical features
Incubation 3 - 4 days
24 hour prodromal pyrexia, headache
and prostration
Diarrhoea - watery and possibly bloody
Vomiting at outset
Abdominal pain common with possible rebound
tenderness
Fluid accumulates in bowel loops from
action of the toxin
Management
Symptomatic treatment
Specific treatment of prolonged, oral
erythromycin
Prevention
Good hygiene
Get it out of poultry
Other bacterial causes
Vibrios - from shellfish
Yersinia
Helicobacter pylori - acute gastritis,
chronic gastritis, peptic ulceration, human to human infection
Food poisoning caused by toxins
Staphylococcal
Incubation 30 mins - 6 hours
Malaise, nausea, severe vomiting
Possible iv. emergency rehydration
required
Botulism
Clostridium from poorly canned or bottled food
Usual picture followed by
neuromuscular paralysis from the head down including swallowing and respiration
Incubation 24 - 48 hours, Consider antitoxin
or polyvalent antiserum
Parasitic infections
Protozoa
Giardia, other amoeba, amoebic
dysentery
Helminths
Among the commonest chronic conditions
in humans
Endemic in areas of poor sanitation
Faecal - oral usually
Produce eosinophilia
Threadworms
Mebendazole
Ascaris
Respiratory features due to larvae
migrating through the lungs, Mebendazole
Hookworms
Larvae get in through the skin,
migrate to the lungs, are swallowed and infect the gut, eggs are excreted with
faeces
Treat anaemia, Mebendazole
Strongyloides
Similar to hookworm treat with
albendazole for 3 days
Bannister BA. Begg NT. Gillespie SH. (1996) Infectious diseases, Blackwell Scientific, Oxford