AMOEBIC DYSENTRY / MedUrgent
AMOEBIC DYSENTRY
Dysentery
is defined as passage of small frequent motions of 3-20/day, containing blood
and mucus. Its incubation period is unknown, and could range from a few days to
several years. It may be divided into 3 main varieties depending on the
severity of the infection, and the nutritional status of the host.
These categories are:
1. Mild; it is of insidious onset and the patient is well nourished, and there is usually constipation rather than diarrhea. A few dysenteric motions may occur. Ulcers are few, and the trophozoites are scanty.
2. Moderate: The patient feels unwell, but is not forced to stay in bed, hence, the name (walking dysentery). Motions are 5-10 times a day, and contain mucus and blood. In the mild and moderate forms, tenderness over the transverse colon may be elicited; as well as tenderness over the right iliac fossa. Fever, abdominal pain and tenesmus are not features of the above two categories.
3. Severe: This has a rapid onset and the patient
looks ill, toxic and probably malnourished. Severe dehydration may occur and
the patient is febrile, and may have vomiting, abdominal colic and tenesmus.
Motions are 15 times/day containing mucus and blood. In exceptional cases acute
watery diarrhea and dysuria may occur. Extensive ulcers are found all over the
colon, and serious complications are quite common such as peritonitis and
ileitis and the disease can be fatal. Proctoscopy is contraindicated.
Chronic amoebic dysentery
The patient presents with bouts of abdominal
discomfort, gaseous distension of the colon and gaseous dyspepsia. Constipation
and diarrhea may alternate.
on examination the caecum and sigmoid may be
felt and the liver may Palpable. The patient may show signs of remissions and
relapses.
Examination of the stools is usually negative.
An Amoeboma may complicate the condition, causing the patient to present with a
mass in the right iliac fossa or intestinal obstruction. An important
differential diagnosis of this condition in adults is carcinoma of the large
bowel
Complications of Amoebic Dysentery
Death from exhaustion, hemorrhage ,perforation or liver abscess. The
commonest fatal complication is perforation of the bowel leading to
peritonitis. Perforation may occur during sigmoidoscopy. Apart from this the
bowel contents may leak through the bowel wall resulting in localized inflammatory
masses, abscesses or generalized peritonitis.
Generalized peritonitis may present in two
ways:
i) Perforation occurs in the course of
moderately severe dysentery, which is a rare form; or it may occur in the
patient who appears well-controlled with abrupt onset of severe abdominal pain
and rigidity of the abdominal muscles. Laparotomy is indicated in such cases
for repair of perforation of the bowel wall.
ii) The other type is a complication of severe
amoebic ulceration of the colon. In such patients there is usually a slow onset
of abdominal distension. Pain and rigidity are slight. Hiccough is a bad sign
and vomiting is even more significant
* Hemorrhage from the erosion of a blood vessel by an amoebic ulcer may be serious and require urgent blood transfusion.
Intussusceptions are possible, especially in children. It occurs mainly in the caeco-colic region and the pain caused is severe. Radiological examination shows an empty right iliac fossa. Surgical treatment may be required.
Ulcerative colitis is rare and occurs only
after treatment or when the dysentery is especially severe.
Stricture of the colon and specially the
rectum may occur and may remain for years.
Skin ulceration may be extensive around the
anal region or around the stoma of a colostomy. Its treatment by anti-amoebic
drugs shows dramatic response but its sequelae may remain.
In Papua, New Guinea, ano-genital amoebiasis
is the commonest form of infection seen and it may resemble squamous cell
carcinoma. Rarely complications may include balanitis with granuloma or
involvement of the prostate.
An abscess may be found in the spleen, psoas
muscle, buttocks or thighs. They may also be found in the brain where they
produce pressure symptoms that resemble cerebral tumor. They may occur in the
presence or absence of liver abscess and should be suspected in any patient
having mental deterioration. No signs of meningitis are present but such
abscesses are invariably fatal.
Amoebic meningitis has been reported but it is
rare.
Empyema due solely to E. histolytica has also
been report.
DIAGNOSIS
• Microscopic examination: the diagnosis is
not confirmed until active trophozoites containing RBCs are demonstrated in the
stools, or from the ulcers. Fresh stools should be examined, especially on the
mucus containing portion. Also specimens may be taken from ulcer scrapings. The
trophozoite may remain alive for a few hours. The differential diagnosis of
moving cells under a microscope includes:
• Macrophages seen in bacillary dysentery
(movement is less and no trophozoites within RBCs)
• Trophozoites of Entamoeba Coli.
• Sigmoidscopy should be used when the stools
are found to be negative. The presence of ulcers is not diagnostic, until the
trophozoites are isolated from a scraping. This applies even if the ulcer has the
characteristic shape. Also the absence of ulcers does not rule out the
diagnosis.
• Radiological methods, by the use of a plain
X-ray of the abdomen, may show evidence of perforation, or features of
intestinal obstruction
• Serological methods may be used to detect
the presence of antibodies. These in turn are not produced unless invasion of
tissue takes place. Infection alone does not confer immunity.
The most important serological test used is
Haemagglutination, which is positive in 98% of the invasive cases and 100% of
cases with amoebic abscess. Serological tests are mainly of value
epidemiologically, especially when positive. When they are negative then
infection may be excluded.
• Other tests that may be used are the Gel diffusion, precipitation, or fluorescent antibody test.
• Leukocytosis may be
present and is usually high.
Differential diagnosis include
1- Bacillary dysentery
2- Bilharziasis
3- Tuberculous
4- Ulcerative colitis 5- Region 5- Regional
ileitis colitis
6- Irritable Bowel syndrome 7- Cancer of the
colon
8- Gall bladder disease
9- Diverticular disease of the colon
TREATMENT
Drugs used are divided into 2 types:
a) Drugs that act on the lumen of the gut.
b) Drugs that act on the tissues (large bowel, liver and other organs). The most useful will be a drug that can eradicate the trophozoites and also act on the tissue. Therefore treatment with tissue amoebicidal should be followed by a luminal amoebicidal to eradicate the source of infection
A) Drugs that act on the lumen of the gut:
1. Di-iodohydroxy quinoline (diodoquine) -
500mg tds for two weeks Ite side-effects are diarrhea and drug rash
2. Diloxanide furoate (Furamide) - 500mg
t.d.s. for 10 days
3. Tetracycline - 250mg /6 hours for 10 days.
It does not act effectively against amoeba, but changes the body flora. It has
mild amoebicidal action and it is indicated with Metronidazole or emetine in
severe amoebic dysentery with extensive ulceration.
4. Paromomycin (Mumatin): 500mg tds for 5
days. It is not toxic and has a direct amoebicidal action.
B) Drugs that act on amoeba in the tissues:
1. Emetine Group: (alkaloids of ipecacuanha).
Emetine acts on both the tissue and luminal parasites. This group is rather
toxic and may cause cardiac arrest. However as yet they are the most effective
treatment for amoebiasis and should be given in hospital. They are
contra-indicated in patients suspected of heart disease, pregnant women and
children. Close monitoring of the cardiovascular system must be done as they
can cause tachycardia, hypotension, chest pain, dyspnoea, and palpitations. The
ECG will show a prolonged PR interval, a wide QRS and a flat or inverted T
wave. Fatal arrhythmias can occur. Ô Emetine hydrochloride – Img/kg body wt/day
for 5 days. The dose should not exceed 60mg/day and it is administered either
deep IM or subcutaneously.
Ô Dihydroemetine- Given IM in the same dose.
It is less toxic.
Ô Emetine Bismuth iodide (oral), or
Dihydroemetine Bismuth jodide: 200mg/day for 10 days.
2. Chloroquine can act on the parasites, especially that of liver abscess. When used for the treatment it should be combined with a drug that acts on the luminal parasites.
3. Metronidazole which
acts on both luminal and tissue parasites. It is given in a dose of 400 mg
t.d.s for 7 days. It is a relatively safe drug and may be used in all forms of
amoebiasis except for the chronic intestinal form. It may cause nausea,
vomiting, anorexia, a metallic taste of the tongue and confusion. The metallic
taste may be lessened by taking the drug with food. The other side-effects may
be combated by taking the dry in divided doses and not as a single dose. The
patient should not drive a it causes dizziness.
4. Tinidazole is given as 2 grams / day (4 tablets as each 500mg). It is continued for 3-5 consecutive days. Its side-effects are the that of Metronidazole and are even worse. There might be forget the recent events.
5. Diloxanide furoate is usually used after
using the above mentioned drugs to clean up the cyst form. It is given 5 days
after the treatment, and continued for 10 days. It is of particular importance
in heavy infections. For those who pass cysts in the stool, treatment may or
may not be given. Treatments used are drugs that act on the luminal parasites.
These are taken in the same dose and duration as for treatment of acute cases
i.e. Furomide, Metronidazole or Di-jodohydroxy quinoline.
Treatment of Amoebiasis in Children
Drugs of choice in treatment of Amoebiasis in
children are:
1- For asymptomatic carriers: Luminal amoebicidal
• lodoquinol: 30-40mg/kg/day oral in 3 divided
doses for 20 days.
• Paromomycin: 25 - 30mg/kg/day oral in 3
divided doses for 7 days
• Diloxanide furoate: 20-25mg/kg/day oral in 3 divided doses for 10 days
2-For mild intestinal infections:
• Metronidazole: 40 -50mg/kg/day oral in 3
divided doses for 10 days,
• Tinidazole: 50mg/kg/day for 3 days, followed by a luminal amoebicidal.
3-For Dysentery or extra-intestinal disease (liver abscess):
• Metronidazole or Tinidazole followed by a
luminal amoebicidal • Dehydroemetine: 1.5/kg/day i.m. for 5-8 days, followed by
a luminal amoebicidal
• Dehydroemetine+ chloroquine phosphate:
(10mg/kg/day twice daily for 2 days and then once daily for 19 days), followed
by Metronidazole or Tinidazole.
AMOEBIC LIVER ABSCESS
Amoebic hepatitis with the
formation of multiple small liver aber may occur in some patients. The liver is
tender and enlarged and trophozoites are found in aspirates from the liver
abscess.
CLINICAL MANIFESTATIONS
• Fever is the most constant feature. It is
intermittent or remittent and is accompanied by profuse sweating especially at
night. It may be associated with rigors.
• Pain is usually localized to the right
hypochondrium. It is sharp and may be referred to the right shoulder. Coughing,
breathing, and movement tend to make it worse. • There may be a feeling of
fullness or a weight in the right hypochondrium. Some patients may present with
a mass.
• Upper G1T symptoms: Anorexia, nausea, and vomiting.
Clinical examination:
• The patient is usually febrile and anaemic.
The blood picture shows microcytc hypochromic anaemia which may be severe
enough to require blood transfusion • Jaundice, if present may range from
slight to severe, and may suggest obstruction due to the presence of an
abscess.
• The liver is enlarged and tender in most of
cases. There may also be right intercostal tenderness over the liver.
Occasionally, there may be edema in the intercostal spaces, which is
diagnostic.
• Signs of lung consolidation, cavitation, and
pleural effusion may be detected. These may be confused with signs of lobar
pneumonia. DIAGNOSIS
• The classic clinical picture.
• Chest X-ray: shows elevation of the right
dome of the diaphragm, pleural effusion and segmental lung collapse.
Radiological screening will show paradoxical movement of the diaphragm, and a
fluid level within the abscess. In rare occasions, the liver abscess may become
calcified.
• Blood picture shows leukocytosis of
15,000-30 000. The ESR is invariably raised. A normal WBC count is against the
diagnosis while a normal ESR excludes the presence of a liver abscess.
• Liver function test will show a raised serum
alkaline phosphates level. Others tests may be normal.
• A liver scan is of great help. It shows the presence and the site of the abscess as a filling defect within the liver parenchyma.
• Ultrasound is useful for diagnosis and location of the abscess.
• Aspirations is used to
confirm the diagnosis. A long wide bore needle Is Carefully used, by means of
an aseptic technique and preferably under ultrasound guidance. Analgesics such
as Pethidine with a local anesthetic are applied. The needle is projected into
the site of maximum tenderness, or definite oedema. If US facility is not
available, then the needle may be introduced between the 8th and 9th
intercostal spaces, on the right mid-axillary line. The needle should not be
introduced more than 9cm, for fear of reaching the inferior vena cava.
The diagnosis is confirmed by:
a) Pus aspirated has an offensive smell.
b) Presence of the trophozoites in the last
portion of pus aspirated.
c) Trypsin is added to digest the debris, and
the fluid is then centrifuged. The deposit is examined for the trophozoites.
Differential diagnosis
1. Pyogenic abscess, but then the patient is
more ill, toxic and has high fever. The pus is creamy, yellow and offensive
2. Hepatitis, but then there is severe
jaundice and the whole liver is enlarged and tender
3. Hydatid cyst, but this is not associated
with fever or toxicity but it may become infected by Salmonella.
4. Primary hepatocellularcancerwhich may be
associated with hepatomegaly. A mass may be felt.
5. An abscess of the Porta Hepatica will show
empyema of the gall bladder and deep jaundice.
COMPLICATIONS
• Rupture of the abscess into the pleural space causing empyema and pleural effusion.
• Hepatic-bronchial
fistula when the abscess ruptures into the lung. Most of the pus is coughed up,
causing hemoptysis, hemorrhage and abscess formation.
• Rupture into the peritoneum resulting in
peritonitis and shock.
• Rupture into the pericardium leading to
pericardial effusion and Constrictive pericarditis.
• Rupture into the stomach and large bowel.
TREATMENT
a) Admit the patient and advise absolute bed
rest. b) if abscess is large, then aspiration done once or repeated as
necessary
c) If abscess is small, aspiration is not done
as it will subside on medical treatment alone.
Chemotherapeutic agents
a) Emetine hydrochloride in a dose of 1mg/kg
body wt /day. This is not to exceed 60mg per day.
b) Dihydroemetine at a dose of not more than
80mg/day for 10 days given as injections, in combination with Chloroquine. This
is taken 600mg initially, to be followed by
300mg after 6 hours and then 300mg daily for 3
- 4 weeks
Both of these have now been replaced by:
1. Metronidazole at a dose of 400–800mg t.d.s; depending on the severity of the condition. This is continued for 5 days. An injection form is available which is given as an infusion in a dose of 2 - 2.5 grams over 6 hours for 5 days. Treatment with Metronidazole is then followed by diloxanide furoate at a dose of 500mg tds for 10 days to eradicate intraluminal infestation. If the patient improves, a shift to oral treatment is done. The tablets are spaced to avoid development of side effects.
2. Tinidazole may be given as a single dose of 2 grams per day for 3-5 days. Some resistance to Metronidazole and Tinidazole has occurred, and therefore Chloroquine is advised to be given in conjugation at the dose mentioned above (600mg initially, followed 6 hours later byT300mg, and then 300mg daily for 3-4 weeks).
Treatment of complications
. Abscess should be drained .
. Full course of anti-amoebic treatment is
given to any patient developing complications.
. If there is empyema then aspiration under
aseptic technique becomes necessary.
. Rupture into the peritoneum is treated by
surgical drainage.
. Antibiotics such as tetracycline should be
given. Treatment of children with amoebic abscess:
1. lodoquinol dose: 30-40mg/kg/day in divided
doses for 20 days
2. Diloxanide furoate: 20mg/kg/day in divided
doses for 10 days
3. Metronidazole: 35-50mg/kg/day in divided
doses for 10 days
4. Tinidazole: 50mg/kg/day single dose for 3days.
5. Chloroquin phosphate: 10mg base/kg/day for 2-3 weeks.
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