Diarrheal Syndrome Flashcards
What does diarrheal syndrome include?
- 3 or more bowel movements
- fecal masses with changed consistency, color, smell, +/- pathologic admixtures of mucus and/or blood
What are the criteria for infectious diarrhea?
- the presence of acute diarrheal syndrome (upto 14 days)
- one or more of the following symptoms:
abdominal pain
nausea
vomiting
tenesmus in combination with toxiinfectious syndrome
and/or epidemiological findings
What are the different causative agents?
Bacterial: E. Coli, Campylobacter, Shigella species, Vibrio cholera, Salmonella
Viral: Rotavirus, Human calicivirus, adenovirus
Parasitic: Cryptosporidium parvum, Giardia intestinalis, entamoeba histolytica, cyclospora cayetanensis
Which are the main E.Coli species that produce diarrheal syndrome?
- Enterotoxigenic E. coli (ETEC)
- Enteropathogenic E. coli (EPEC)
- Enteroinvasive E. coli (EIEC)
- Enterohemorrhagic E. coli (EHEC)
- Enteroaggregative E. coli (EAggEC)
Which strain of E.Coli causes traveler’s diarrhea?
- Enterotoxigenic E. coli (ETEC)
Which strain of E.coli rarely causes disease in adults?
Enteropathogenic E. coli (EPEC)
Which strain of E.coli causes bloody mucoid (dysentery) diarrhea?
Enteroinvasive E. coli (EIEC)
Which strain of E.coli causes bloody diarrhea, severe hemorrhagic colitis, and hemolytic uremic syndrome in 6–8% of cases?
Enterohemorrhagic E. coli (EHEC)
Which strain of E.coli causes watery diarrhea in young children and persistent diarrhea in children with human immunodeficiency virus (HIV)?
Enteroaggregative E. coli (EAggEC)
Which are the main sources of Campylobacter infections in developed countries?
Poultry
Which are the main sources of Campylobacter infections in developing countries?
Asymptomatic infection is very common in developing countries and is associated with the presence of cattle close to dwellings
What clinical signs can be seen in campylobacter infection?
- watery diarrhea
- dysentery
- Guillan Barre syndrome (1/1000 cases of campylobacter infections in developed countries)
Is campylobacter infection common in children in developing countries?
yes
Campylobacter is one of the most frequently isolated bacteria from the feces of infants and children in developing countries, with peak isolation rates in children 2 years of age and younger
What are the common disease-causing species of shigella?
- S. sonnei (developed countries)
- S. flexneri (developing countries)
- S. dysenteriae type 1 (Sd1) (only serotype that produces Shiga toxin)
Which age group is mainly affected by Shigella infections (in developing countries)?
An estimated 160 million episodes occur in developing countries, primarily in children
It is more common in toddlers and older children than in infants
Which serotypes of the vibrio cholerae species are pathogenic for humans?
All serotypes
Which serotypes cause severe cholera?
V. cholerae serogroups O1 and O139 are the only two serotypes that cause severe cholera, and large outbreaks and epidemics
What can happen if proper rehydration is not given in a vibrio cholera infection?
In the absence of prompt and adequate rehydration, severe dehydration leading to hypovolemic shock and death can occur within 12–18 h after the onset of the first symptom
What is the profile of the stools in a vibrio cholerae infection?
Stools are watery, colorless, and flecked with mucus; often referred to as “rice water” stools
Which serotypes of salmonella cause enteric fever?
Enteric fever — Salmonella enterica serovar Typhi and Paratyphi A, B, or C (typhoid fever);
fever lasts for 3 weeks or longer; patients may have normal bowel habits, constipation or diarrhea
What are the main reservoirs for Salmonella?
Animals are the major reservoir for salmonellae
Humans are the only carriers of typhoidal Salmonella
What are the clinical symptoms of nontyphoidal salmonellosis?
(Salmonella gastroenteritis), there is an acute onset of nausea, vomiting, and diarrhea that may be watery or dysenteric in a small fraction of cases
Fever develops in 70% of affected children
Bacteremia occurs in 1–5%, mostly in infants
Who are at the greatest risk for salmonellosis?
The elderly and people with immune-compromised status for any reason (e.g., hepatic and lymphoproliferative disorders, hemolytic anemia),
Infants and children with immune-compromised status for any reason (e.g., severe malnourishment) appear to be at the greatest risk
Who is affected mostly by rotavirus diarrheal infections?
Leading cause of severe, dehydrating gastroenteritis among children
Nearly all children in both industrialized and developing countries get infected by the time they are 3–5 years of age
Neonatal infections are common, but often asymptomatic
The incidence of clinical illness peaks in children between 4 and 23 months of age
Accounts for one-third of diarrhea hospitalizations and 500,000 deaths worldwide each year
What are human caliciviruses?
Belong to the family Caliciviridae—the noroviruses and sapoviruses (previously called “Norwalk-like viruses” and “Sapporo-like viruses”
Which calicivirus mainly affects all groups?
Noroviruses are the most common cause of outbreaks of gastroenteritis, affecting all age groups
Which calicivirus mainly affects children?
Sapoviruses primarily affect children. This may be the second most common viral agent after rotavirus, accounting for 4–19% of episodes of severe gastroenteritis in young children
Do adenoviruses cause gastroenteritis symptoms?
Most commonly cause illnesses of the respiratory system
Depending on the infecting serotype, this virus may cause gastroenteritis especially in children
Which parasites can also cause gastroenteritis symptoms?
Cryptosporidium parvum (children in developing countries)
Giardia intestinalis (low prevalence among children in developed countries, high in developing countries)
Entamoeba histolytica
Cyclospora cayetanensis (children in developing countries)
These are uncommon in the developed world and are usually restricted to travelers
Is there a definitive etiological diagnosis for diarrheal syndrome?
not possible clinically
What are the three possible classifications for diarrheal episodes?
Acute diarrhea: Presence of three or more abnormally loose or watery stools in the preceding 24 h
Dysentery: Presence of visible blood in stools
Persistent diarrhea: Acutely starting episode of diarrhea lasting more than 14 days
What key clinical features should be noted in diarrheal syndrome related to the associated pathogens?
- abdominal pain
- fever
- fecal evidence of inflammation
- vomiting
- nausea
- heme-positive stool
- bloody stool
What should the initial clinical evaluation of the patient focus on (diarrheal syndrome)?
- Assessing the severity of the illness and the magnitude (degree) of dehydration
- Determining likely causes on the basis of the history and clinical findings, including stool characteristics
What features should you look out for in the patient history?
- onset, stool frequency, type, and volume
- presence of blood
- vomiting
- headaches
- medicines received
- past medical history
- underlying conditions
- epidemiological clues
What should you look for in the physical examination? (diarrheal syndrome)
- body weight
- temperature
- pulse/heart and respiratory rate
Which laboratory evaluations should you perform?
- Maintaining adequate intravascular volume and correcting fluid and electrolyte disturbances take priority over identifying the causative agent
- stool cultures (in immuno-compromised patients)
- blood in stool
- epidemiological clues
What is the main goal in dealing with diarrheal syndrome?
Maintaining adequate intravascular volume and correcting fluid and electrolyte disturbances take priority over identifying the causative agent
How can epidemiological clues help in treating infectious diarrhea?
Epidemiologic clues to infectious diarrhea can be found by evaluating the incubation period, history of recent travel in relation to regional prevalence of different pathogens, unusual food or eating circumstances, professional risks, recent use of antimicrobials, institutionalization, and HIV infection risks
What does the presence of visible blood in the stools suggest?
Presence of visible blood in febrile patients generally indicates infection due to invasive pathogens, such as Shigella, Campylobacter jejuni, Salmonella, or Entamoeba histolytica
When do you need a stool culture?
Stool cultures are usually unnecessary for immune-competent patients who present with watery diarrhea, but may be necessary to identify Vibrio cholerae and the pathogen causing dysentery
What are some differential diagnostics for acute diarrhea in children?
- Pneumonia—may occur together with diarrhea in developing countries
- Otitis media
- Urinary tract infection
- Bacterial sepsis
- Meningitis
What are some prognostic factors for diarrhea in children?
- malnutrition
- zinc deficiency
- immunosuppression
How does malnutrition cause diarrhea in children?
- Approximately 10% of children in developing countries are severely underweight
- Macronutrient or micronutrient deficiencies in children are related to more severe and prolonged diarrhea, and hypokalemia and rectal prolapse are likely to develop in association with dysentery
- Poor nutritional status leads to a higher risk of death
How does zinc deficiency lead to diarrhea?
- Suppresses immune function and is associated with an increased prevalence of persistent diarrhea and a higher frequency of diarrhea
What are the complications of persistent diarrhea?
- Often results in malabsorption and significant weight loss, further promoting the cycle
How does immunosuppression cause diarrhea?
- Secondary to infection with HIV or other chronic conditions, may be associated with an increased risk for developing clinical illness, prolonged resolution of symptoms, or frequent recurrence of diarrheal episodes
What are some treatments for diarrhea?
Rehydration in adults and children
supplemental zinc therapy, multivitamins, and minerals in children
diet
probiotics
What are some treatments for diarrhea?
Rehydration in adults and children
supplemental zinc therapy, multivitamins, and minerals in children
diet
probiotics
What is oral rehydration therapy?
Oral rehydration therapy (ORT) is the administration of appropriate solutions by mouth to prevent or correct diarrheal dehydration
What is oral rehydration therapy?
Oral rehydration therapy (ORT) is the administration of appropriate solutions by mouth to prevent or correct diarrheal dehydration
ORT is a cost-effective method of managing acute gastroenteritis and it reduces hospitalization requirements in both developed and developing countries
How does ORT work? (oral rehydration therapy)
Oral rehydration salts (ORS), used in ORT, contain specific amounts of important salts that are lost in diarrhea stool
The new lower-osmolarity ORS (recommended by WHO and UNICEF) has reduced concentrations of sodium and glucose and is associated with less vomiting, less stool output, lesser chance of hypernatremia, and a reduced need for intravenous infusions in comparison with standard ORS
This formulation is recommended irrespective of age and the type of diarrhea including cholera
What does ORT consist of?
- Rehydration—water and electrolytes are administered to replace losses.
- Maintenance fluid therapy to take care of ongoing losses once rehydration is achieved (along with appropriate nutrition)
When is ORT contraindicated?
ORT is contraindicated in the initial management of severe dehydration, paralytic ileus, persistent vomiting (more than four episodes per hour), and painful oral conditions such as moderate to severe thrush (oral candidiasis)
What is the antimotility agent of choice for adults?
Loperamide (4-6mg/day)
Which antisecretory agent is used?
Racecadotril (enkephalinase inhibitor with antisecretory activity)
which adsorbents are used?
kaolin-pectin, activated charcoal, attapulgite
