بسم الله الرحمن الرحيم. clinical approach to evaluate infectious diarrhea by...
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الرحمن الله بسمالرحيم
Clinical Approach to evaluate Infectious
DiarrheaBy
Raghda El-Sayed FaragAssist. Professor of Tropical Medicine
Intestinal Physiology A healthy adult takes about 2 liters of fluid
each day. Gastrointestinal secretions add about 7 liters making a total of 9 liters that enter the small intestine every day.
Water and electrolytes are simultaneously absorbed by the villi and secreted by the crypt cells of the bowel mucosa.
More than 90% of the fluid entering the small intestine is absorbed so that only one liter reaches the large intestine. There, most of them is absorbed leaving only 100-200 ml that pass daily in formed stool.
The normal stool output is 5-10 gm/kg/d.
Definitionof Diarrhea
Diarrhea is defined by the World Health Organization as: having three or more loose or liquid stools per day, or having more stools than normal for that person.
Mechanisms of Diarrhea
Examples Stool exam Defect Primary mechanism
Viruses, Cholera, toxigenic
E.coli, carcinoids
Watery, voluminous, osmolarity=2(Na+K)
Increased active secretion, decreased absorption
1-Secretory
Lactase deficiency,Laxatives,
malabsorption syndrome
Watery, lesser volume, acidic, high osmolarity >2 (Na+
K), stop with fasting
Maldigestion or absorption of non
absorbable solutes→influx of
water & electrolytes into
lumen
2-Osmotic
DM, Thyrotoxicosis, Irritable bowel, Post-vagatomy ,
Loose to normal stool stimulated by gastrocolic
reflex
Decreased transit time
3-Increased motility
Pseudo-obstruction, blind
loop
Loose to normal stool
Stasis, bacterial overgrowth
4-Decreased motility
Short bowel syndrome, celiac disease, rotavirus
Watery Decreased functional capacity
5-Decreased surface area
Salmonella, Shigella, Yersinia, Campylobacter,
amoebiasis, IBD, TB enteritis
Blood, mucus and WBCs in
stool
Inflammation, mucosal invasion
&damage of brush border →
decreased absorption, increased
motility
6-Inflammatory (exudative)
Clinical Manifestations
It is possible to subdivide clinical presentation of diarrheal diseases into two major categories:
Inflammatory Non-inflammatory.
Inflammatory diarrhea
Non-Inflammatory diarrhea
Mucosal invasion and inflammation
Osmotic or secretory Mechanism
Fever, abdominal pain, tenesmus
-Nausea, vomiting, abdominal pain
-Fever are not major feature
Symptoms
Frequent small volume, blood stained, pus and
mucus present
Voluminous, watery Stool
Distal ileum, colon Proximal small intestinel Site
Enteroinvasive E. coli, Shigella, Salmonella,
Yersinia, Campylobacter, E. histolytica.
Viruses, toxigenic E. coli, Cholera, Cryptosporidium ,
G. lamblia
Common Pathogens
Dysentery Generally, if there is blood visible in
the stools, it is called dysentery. The blood is trace of an invasion of bowel tissue. Dysentery is a symptom of, Shigella, Entamoeba histolytica, blantidium coli and Salmonella.
There are over 40 different enteropthogens able to cause diarrhea
To arrive at an etiologic diagnosis in all cases is neither possible nor necessary except for epidemiologic purposes e.g during vaccine trials or in epidemics or outbreaks.
Etiology (causative agents)
Infectious 1-Viruses: - Norovirus - Rota - Adenovirus 40/41 - Astrovirus - Calcivirus 2-Bacteria: -E. coli -Salmonella -Shigella
-Campylobacter -Yersinia enterocolitica -Cholera -Clostridium (difficile, perferingens) -Staph aureus 3-Protozoa: - E. histolytica -G. lamblia -Cryptosporidium -Isospora belli Non infectious causes: -Malabsorption (congenital or acquired). -IBD. - IBS. - laxative abuse
Rotavirus
Rotavirus is the most common cause of severe diarrhoea among infants and young children
The virus is transmitted by the faecal-oral route. It infects and damages the cells that line the small intestine and causes gastroenteritis
disease characterised by vomiting, watery diarrhoea, and low-grade fever.
The incubation period is about two days.
Diagnosis &Treatment
Specific diagnosis of infection with rotavirus A is made by viral isolation in the stool by enzyme immunoassay.
Electron microscopy and PCR, are used in research laboratories.
The hallmark of ttt is maintenance of hydration. If untreated, children can die from severe dehydration
Prevention
Two vaccines against Rotavirus A infection are safe and effective in children. Both are taken orally and contain attenuated live virus.
Cholera
The main symptoms of cholera are profuse, painless diarrhea and vomiting of clear fluid.
Symptoms usually start suddenly, one to five days after ingestion of the bacteria (IP).
The diarrhea is frequently described as "rice water" in nature and may have a fishy odor.
An untreated person with cholera may produce 10 to 20 litres of diarrhea daily with fatal results.
Cholera has been nicknamed the "blue death" due to a patient's skin turning a bluish-gray from extreme loss of fluids.
The typical symptoms of dehydration include low blood pressure, poor skin turgor (wrinkled hands), sunken eyes, and a rapid pulse.
For every symptomatic person, 3 to 100 people get the infection but remain asymptomatic.
Diagnosis Clinical presentation A rapid dip-stick test is available. In those samples that test positive,
further testing should be done to determine antibiotic resistance.
Stool and swab samples collected and cultivated using:
Enrichment media - Alkaline peptone water at pH 8.6 - Monsur's taurocholate tellurite
peptone water at pH 9.2
Treatment
In epidemic situations, treatment is usually started by clinical diagnosis without or before confirmation by laboratory analysis.
Fluids: In most cases, cholera can be
successfully treated with oral rehydration therapy (ORT), which is highly effective, safe, and simple to administer
Antibiotic treatments for 1-3 days shorten the course of the disease and reduce the severity of the symptoms.
Use of antibiotics also reduces fluid requirements.
Doxycycline is first line antibiotic. Other antibiotics proven to be
effective include cotrimoxazole, erythromycin, tetracycline, chloramphenicol, and furazolidone.
Fluoroquinolones, such as norfloxacin, also may be used, but resistance has been reported.
Prevention
Surveillance Surveillance and reporting allow for controlling
cholera epidemics rapidly Vaccine (Cholera vaccine)- safe and effective oral vaccines for cholera are
available (inactivated whole cell vaccine), has an overall efficacy of about 52%.
- injectable vaccine was found to be effective for two to three years. The protective efficacy was 28%.
- The World Health Organization (WHO) recommends immunization of high risk groups, such as children and people with HIV, in countries where this disease is endemic
Scanning electron microscope image of Vibrio cholerae
Amoebiasis.
A disease occur due to infection by Entamoeba histolytica
Is estimated to infect about 50 million people worldwide.
The active (trophozoite) stage exists only in the host and in fresh loose feces; cysts survive outside the host in water, in soils, and on foods, especially under moist conditions for months.
Clinical Presentation infection may be asymptomatic or
symptoms may be so svere up to fulminating colitis
amoebic dysentery with bloody diarrhea, weight loss, fatigue, abdominal pain.
amoebic liver abscess : the amoeba can actually 'bore' into the intestinal wall, causing ulcers → intestinal symptoms, and it may reach the blood stream → vital organs ; the liver (most comon), the lungs, brain, spleen, etc.
A common outcome of this invasion of tissues is amoebic liver abscess, which can be fatal if untreated.
Diagnosis & Treatment
It can be diagnosed by stool samples.
ELISA or RIA can also be used. Metronidazole for the invasive
trophozoites PLUS a lumenal amoebicide for those still in the intestine. Paromomycin or Diloxanide furoate (Furamide).
Giardiasis
Giardiasis
Giardia infection can occur through ingestion of dormant microbial cysts of flagellated protozoan parasite called Giardia lamblia in contaminated water, food, or by the faecal-oral route.
It colonizes and reproduces in the small intestine. The parasite attaches to the epithelium by a ventral adhesive disc.
Colonization → inflammation and villous atrophy → reduce the gut's absorptive capability → diarrhea.
Clinical Presentation Infection is symptomatic in about 50% . Symptoms include :
- diarrhea, malaise, excessive gas, steatorrhoea (pale, foul smelling, greasy stools), epigastric pain, bloating, nausea, loss of appetite, weight loss. Pus, mucus and blood are occasionally present in the stool.
In healthy individuals, the condition is usually self-limiting, although the infection can be prolonged in patients who are immunocompromised, or who have decreased gastric acid secretion.
Diagnosis
G. lamblia infection in humans is frequently misdiagnosed.
Multiple stool examinations are recommended since the cysts and trophozoites are not shed consistently.
Upper endoscopy and deudenal aspirate analysis or biopsy may be needed.
So many patients should be treated on the basis of empirical evidence based on symptoms.
Human infection is treated with: - Metronidazole (7day).
- Tinidazole (single dose ) - Nitazoxanide ( 3 day)
Cryptosporidium
Cryptosporidium is a genus of protozoans that can cause gastrointestinal illness with diarrhea.
In humans, it remains in the lower intestine and may remain for up to five weeks and result in an infection of intestinal epithelial tissue.
Cryptosporidiosis is typically an acute, short-term infection, but can become severe and nonresolving in children and immunocompromised individuals.
Most commonly isolated in HIV-positive patients presenting with diarrhea.
Treatment is symptomatic, with fluid rehydration, electrolyte correction and management of any pain
Nitazoxanid may be needed in immunecompromised person and children for 2 weeks.
Traveler's diarrhea
Traveler's diarrhea (TD) is the most common illness affecting travelers.
TD is defined as three or more unformed stools in 24 hours passed by a traveler, commonly accompanied by abdominal cramps, nausea, and bloating.
Enterotoxigenic Escherichia coli is the most commonly isolated pathogen.
Most cases are self-limited. The pathogen identifiction and treatment
are not a routine unless symptoms become severe or persistent.
Antibiotics are typically given for three to five days, but single doses of azithromycin or levofloxacin have been used.
If diarrhea persists despite therapy, travelers should be evaluated for possible viral or parasitic infections, bacterial or amoebic dysentery, Giardia, helminths.
Shigellosis bacillary dysentery Marlow Syndrome
Shigellosis is a foodborne illness caused by infection by bacteria of the genus Shigella.
The causative organism is frequently found in water polluted with human feces, and is transmitted via the fecal-oral route. The usual mode of transmission is directly person-to-person hand-to-mouth, in the setting of poor hygiene.
less than 100 bacterial cells can be enough to cause an infection
Clinical presentation
Symptoms may range from mild abdominal discomfort to severe dysentery characterized by cramps, diarrhea, fever, vomiting, blood, pus, or mucus in stools or tenesmus as infections are associated with mucosal ulceration, rectal bleeding,
Onset time is 12 to 96 hours, and recovery takes 5 to 7 days.
Treatment Oral replacement is satisfactory for most
people. In most cases, the disease resolves within
four to eight days without antibiotics. Severe prolonged infections, antibiotics,
such as trimethoprim-sulfamethoxazole (Co-Trimoxazole), norfloxacin, ciprofloxacin or furazolidone, may be given.
Additionally, ampicillin (but not amoxicillin) is effective in treating this disease.
Antidiarrheal drugs (loperamide) may prolong the infection and should not be used.
Enteritis salmonellosis or food poisoning Salmonella
is an infection with Salmonella bacteria. In most cases, the illness lasts 4-7days, and most people recover without treatment.
In some cases, the diarrhea may be so severe, the patient becomes dangerously dehydrated and must be hospitalized.
The type of Salmonella usually associated with infections in humans, nontyphoidal Salmonella, is usually contracted from sources such as:
Poultry, pork, and beef, if the meat is prepared incorrectly or is infected with the bacteria after preparation.
Infected eggs, egg products, and milk.
Clinical Presentation
Symptoms are usually gastrointestinal, including nausea, vomiting, abdominal cramps, and bloody diarrhea with mucus. Headache, fatigue, and rose spots are also possible.
These symptoms can be severe, especially in young children and the elderly.
Symptoms last generally up to a week, and can appear 12 to 72 hours after bacterial ingestion.
Diagnosis & Treatment
Stool smear revealed red and white blood cells.
Culture ( from stool or vomitus) is positive in 10-15%.
In most cases, the disease resolves within few days.
Immunocompromised and patients with evedence of bacteremia, antibiotics, such as norfloxacin, ciprofloxacin or third generation cephalosporin (in children) may be given.
Clostridium difficile
is a species of Gram-positive bacteria of the genus Clostridium.
C. difficile is a commensal bacterium of the human intestine in 2–5% of the population.
It causes severe diarrhea and other intestinal disease when competing bacteria in the gut flora have been wiped out by antibiotics(clindamycin) and chemotherapeutic antineoplastic drugs.
bacteria release toxins that can cause bloating and diarrhea, with abdominal pain, which may become severe.
It is the most common cause of pseudomembranous colitis, and in rare cases this can progress to toxic megacolon, which can be life-threatening.
Mild cases of C. difficile infection can often be cured by discontinuing the antibiotics responsible.
In more serious cases, oral administration of: oral metronidazole and — if that fails give — vancomycin and if unsuccessful again, intravenous metronidazole can be used.
Relapses of C. difficile have been reported in up to 20% of cases
Pathogenic Escherichia coli
Most E. coli strains are harmless, but some serotypes are pathogenic and can cause serious food poisoning in humans.
Transmission of pathogenic E. coli often occurs via faecal–oral transmission.
Common routes of transmission include: unhygienic food preparation, farm contamination due to manure fertilization, irrigation of crops with contaminated greywater or raw sewage, or direct consumption of sewage-contaminated water
It induce its effect through production of enterotoxin or diffuse mucosal adherence
Typically, diagnosis has been done by culturing on sorbitol-MacConkey medium and then using typing antiserum.
Staphylococcus aureus
Staphylococcus food poisoning is caused by ingesion of performed stephylococcus toxins.
It is the third most common cause of food borne illnesses.
Symptoms accur 1-6 hours after ingesion of contaminated food (cream-filled cake, salad, ham) with heat stable toxins
Nausea, vometing, abdominal pain followed by diarrhea.
Fever is rare.
Diagnosis &Treatment
Definite diagnosis is by culturing the organism from contaminated food, stool or vomitus.
Treatment is supportive. No role for antibiotics as the whole
pathology is due to bacterial toxins.
Recommendations for the diagnosis and management of diarrheal illnesses.
Guerrant R L et al. Clin Infect Dis. 2001;32:331-351
© 2001 by the Infectious Diseases Society of America
Summary
diarrhea may function as an evolved expulsion defense mechanism. As a result, if it is stopped, there might be a delay in recovery.
Diarrhea may represent a defense mechanism.
infants Moderate or severe diarrhea in young children Associated with blood Continues for more than two days Associated non-cramping abdominal pain, fever,
weight loss. In travelers In food handlers, because of the potential to infect others In institutions such as hospitals, child care centers, or
geriatric and convalescent homes.
The following types of diarrhea may indicate further
investigation
Rehydration
The primary treatment of infective diarrhea in both children and adults.
This is preferably achieved by oral rehydration therapy, although intravenous delivery may be required if a there is a decreased level of consciousness or if dehydration is severe.
Role of Antibiotics
Antibiotics are not usually used for gastroenteritis, although they are sometimes recommended if:
- symptoms are particularly severe or- if a susceptible bacterial cause is isolated or
suspected. - Certain bacteria and protozoans
that are amenable to treatment include Shigella, Salmonella typhi, and Giardia species.
Role of Antibiotics- In infection with Giardia species or
Entamoeba histolytica, tinidazole treatment is recommended and superior to metronidazole.
- The Pseudomembranous colitis, usually caused by prolonged antibiotic use, is managed by discontinuing the causative agent and treating it with either metronidazole or vancomycin.
There are concerns that antibiotics may increase the risk of hemolytic uremic syndrome in people infected with Escherichia coli O157:H7
Antimotility drugs shoud be avoided (children) . Physical adsorbants:
Compounds as kaolin, charcoal are postulated to act by adsorbing toxins. They have had little effects.
Role of micronutients:Trials of zinc supplementation demonstrated clinically important decrease in severity and duration of diarrhea.
Role of probiotics:Adminstration of Lactobacillus casei GG may resulted in decrease of duration and frequency of watery diarrhea.
