Gastroenteritis. Mohamed Ahmed Fouad Lecturer of pediatrics Jazan faculty of medicine

Transcription

1 Gastroenteritis Mohamed Ahmed Fouad Lecturer of pediatrics Jazan faculty of medicine

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3 Objectives Review the epidemiology and most common etiologies of diarrhea Discuss specific characteristics of most common viral and bacterial pathogens Recognize the most important aspects of the diagnosis a patient with diarrhea Discuss proper laboratory evaluation and treatment of GE

4 Defention Acute gastroenteritis (AGE) is a diarrheal disease of acute onset, with or without accompanying symptoms and signs, such as nausea, vomiting, fever, or abdominal pain Gastroenteritis: Acute inflammation of the lining of the stomach/intestines Anorexia, nausea, vomiting, diarrhea, abdpain (hallmark is diarrhea)

5 According to the World Health Organization (WHO), AD is the passage of loose(takes the shape of the container )* or watery stools, three times or more in a 24 hour period for upto14 days In the breastfed infant, the diagnosis is based on a change in usual stool frequency and consistency as reported by the mother

6 epidemiology Gastroenteritis ranks with respiratory tract infection as the most common infectious disease syndrome of humans. Approximately five billion episodes of diarrhea occur worldwide annually, accounting for 15 to 30 percent of all deaths in some countries. More than 20 viruses, bacteria and parasites have been associated with acute diarhoea

7 Worldwide, rotavirus is the commonest cause of severe dehydrating diarrhoea causing 0.6 million deaths annually, 90% of which occur in developing countries The incidence of specific pathogens varies between developed and developing countries In developed countries, about 40% of AD cases are due to rotavirus and only 10-20% are of bacterial origin while in developing countries, 50-60% are caused by bacteria while 15-25% are due to rotavirus

8 Other viral agents Enteric adenoviruses Astrovirus Human calciviruses (norovirus and sapovirus) Bacteria E. coli (EAEC, EPEC, EIEC) Shigella spp Staphylococcus spp Salmonella spp Yersinia enterocolitica Campylobacter jejuni Vibrio cholera Parasites Entamoeba histolitica Girdia lamblia Cryptosporidium Trichuris trichuria Strongyloides stercoralis

9 Major two forms of Acute diarrhea Acute watery diarrhea Rotavirus worldwide 40% of hospitalized children < 5 years Enterotoxigenic Escherichia coli (ETEC) in older children Vibrio cholerae in endemic areas Norovirus Invasive diarrhea Shigella flexneri, dysenteriae, boydii, sonnei Salmonella enterica Campylobacter spp, Enterohemorrhagic E. coli (EHEC), Enteroinvasive E. Coli (EIEC) Protozoan Entamoeba histolytica

10 What is the causative organism? Although accurate differentiation between bacterial, viral and parasitic gastroenteritis cannot be made except by stool analysis and stool culture, the cause can be suggested in most cases by considering the character of the stool and the associated findings especially fever. 1. Bacterial gastroenteritis: The possibility of bacterial gastroenteritis is considerable when the fever is above 38.5 C and the diarrhea is severe or bloody. Leucocytosis and elevated CRP level are common laboratory findings. 2. Viral gastroenteritis: Fever is usually below 38.5 C and the diarrhea is usually watery and not severe. The possibility is higher in the following situations (1) When there is preceding or associated viral respiratory infection, (2) When the diarrhea

11 3. Parasitic enteritis: Clinical manifestations depend on the causative agent. With Giardia lamblia infection, the diarrhea is usually watery, foul smelling, not severe and not associated with fever. The possibility becomes greater when diarrhea persists for more than 10 days (giardia is the most common cause of mild persistent watery diarrhea). With amoebiasis, diarrhea is commonly bloody but fever is absent (important differentiating point from bacterial gastroenteritis). Accurate diagnosis is made by stool analysis. Repeated stool analysis is important for the diagnosis of giardiasis because initial negative analysis does not exclude the possibility.

12 Complications of acute gastroenteritis 1. Dehydration 2. Shock:. 3. Acute renal failure: 4. Metabolic acidosis: 5. Hypokalemia: 6. Hypocalcemia:. 7. Convulsions: 8. Bleeding: 9. Persistent diarrhea: 10. Malnutrition: Kwashiorkor (with one attack) and marasmus (with repeated attacks).

13 Infection with Shiga toxin producing Escherichia coli (E. coli 0157: H7 )or Shigella dysenteriae may cause haemorrhagic colitis (with severe bloody diarrhoea), which may be complicated by haemolytic uraemic syndrome. This syndrome is endemic worldwide and characterised by acute onset of microangiopathic haemolytic anaemia, thrombocytopenia, acute renal impairment, and multisystem involvement

14 DD Other causes that can cause acute diahrea : 1. Dietetic diarrhea: It may follow recent change in the type of milk, concentrated formula or recent addition of new foods not suitable for the age of the infant. 2. Drug induced diarrhea: Most oral antibiotics especially ampicillin can cause acute diarrhea (antibiotic-associated diarrhea). 3. Parenteral diarrhea: It is a diarrhea that occurs secondary to infections outside the gastrointestinal tract as respiratory and urinary tract infection. 4.Spurious diarrhoea; for example, in chronic constipation with overflow incontinence

15 Investigations If the child is not dehydrated, nor the stools bloody, investigations are not generally necessary unless the child is hospitalized or has been exposed to others with proven bacterial gastroenteritis Samples also should be taken during outbreaks especially in childcare, school, hospital, or residential settings where there is a public health imperative to identify the pathogen and establish its source. Stool microscopy and culture is needed if there is blood and mucus in the diarrhoea.

16 Rotavirus can be detected by stool immunoassay. If extra - gastrointestinal infection is suspected, confirmation may be required from blood and urine cultures or X - ray. Investigations to be considered are shown in this table.

17 Measurement of Urea&Creatinine and Electrolytes can be considered in : Severe dehydration or shock Children on IV fluid Children with severe malnutrition Suspected cases of hypernatreamic dehydration

18 How is dehydration assessed? It is important to assess hydration in gastroenteritis as hydration status determines the immediate management of this condition. The infant or child with profuse watery diarrhoea and frequent vomiting is most at risk. Clinical signs are usually not present until a child has lost at least 5% of his or her body weight. Documented recent weight lost is a good indicator of the degree of dehydration, but this information is rarely available. The best clinical indicators of more than 5% dehydration are prolonged capillary refill, abnormal skin turgor, and absent tears

19 AAP guideline classifies patients as mild (3-5%), moderate (6-9%) and severe (>10%) dehydration

20 Management

21 Prevention of dehydration is the cornerstone of gastroenteritis treatment in children Encourage the child s preferred, usual, and age appropriate diet to prevent or limit dehydration, also early refeeding reduces the duration of diarrhoea. if breastfeeding, continue; if formula feeding, do not dilute or switch formulas As soon as the dehydration is corrected, a regular diet should resume

22 Restrictive regimens like The BRAT diet are not recommended (bananas, rice, applesauce, and toast) is too restrictive, Published guidelines recommend early reintroduction of milk and solids including complex carbohydrates, lean meats, yogurt, and vegetables If the child is vomiting, offer frequent (every 10 to 60 minutes) small feedings for the child with some dehydration, treat with commercial oral rehydration solution (ORS) for a period of 4 to 6 hours or until an adequate degree of rehydration is achieved. Early oral rehydration therapy using an oral rehydration solution (ORS), before the child becomes more severely dehydrated, is important and can be done at home

23 Clear liquids, such as water, sodas, chicken broth, and apple juice, should not replace an ORS because they are hyperosmolar and do not adequately replace potassium, bicarbonate, and sodium. These fluids, especially water and apple juice, can cause hyponatremia. An adult ORS also should not be used.

24 ORS Lancet- "potentially the most important medical advance this century World Health Organization estimates that 90% of diarrheal deaths worldwide could be prevented with appropriate treatment with ORS

25 ORS-principle Na+ absorption is impaired in the diarrhoeal state. if the Na+ is not absorbed water cannot be absorbed. Excess Na+ in the lumen of the intestine causes increased secretion of water and the diarrhoea worsens. Glucose - absorbed through the intestinal wall - unaffected by the diarrhoeal disease state - sodium is carried in conjunction through by a co-transport coupling mechanism. This occurs in a 1:1 ratio, one molecule of glucose cotransporting one sodium ion (Na+).

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27 Reduced osmolarity ORS 41% less need for IV fluids Less stool output Less vomiting

28 The key to success with ORT is frequent small amounts of an approved Oral Rehydration Solution (ORS), given over a 4-6 hour time period. ORT will be initiated within the hospitals and clinics. However, the patient may be discharged prior to the completion of total rehydration. The entire guideline follows: Calculate total volume deficit: Mild dehydration (<5%): 50 ml/kg + 10 ml/kg additional volume for each diarrhea stool Moderate dehydration (5-10%): 100 ml/kg + 10 ml/kg additional volume for each diarrhea stool

29 First hour of therapy: Administer 5 ml of ORS every two minutes for an hour If the patient vomits*, suspend ORT for 15 minutes and resume first hour of therapy. After first hour of therapy: Allow patient to rest for 15 minutes Second hour of therapy: Increase ORS amount to 6-10 ml (amount is determined by the size of the child) of ORS every two minutes for an hour**

30 If patient tolerates total volume instruct parent to introduce normal diet for age when patient is considered rehydrated. If patient does not tolerate normal diet, continue ORS for another four to eight hours, and advance to normal diet as soon as possible. * If vomiting persists, three or more times during first two hours of ORS attempt, consider insertion of small nasogastric tube or IV hydration.

31 What is the role of drugs? Drugs are rarely needed. Antiemetic agents are not recommended for routine use,although new generation antiemetics (such as the serotonin antagonist ondansetron) do not have extrapyramidal effects and reduce the duration and frequency of vomiting, they also increase diarrhoea. Antimotility agents (such as loperamide) decrease the duration of diarrhoea, but they have potential severe adverse effects Vitamin A does not influence the course of acute gastroenteritis

32 Zinc zinc is lost during diarrhoea Zinc deficiency is associated with impaired electrolyte and water absorption, decreased brush border enzyme activity and impaired cellular and humoral immunity Treatment with zinc reduces the duration and severity of AD and also reduces the frequency of further episodes during the subsequent 2-3 months WHO recommends that children from developing countries with diarrhoea be given zinc for days 10mg daily for children <6 months 20 mg daily for children >6 months

33 Probiotics(Sherwood Gorbach and Barry Goldin,1985) High-dose ( CFU) Lactobacillus GG helpful Basu, J Clin Gastroenterol 43:208, 2009 Lactobacillus GG (6x10 6 CFU) not effective Basu, J Paediatr Child Health 43:837, 2007 Probiotic Bifilac useful Narayanappa, Indian J Pediatr 75:709, 2008 So Continue studying formulations, populations

34 antibiotics Even though bacterial pathogens are the commonest cause of AD in developing countries, there should be cautious and rational use of antibiotics to discourage development of microbial resistance, avoid side effects and reduce cost Antibiotics should be used for(is there is need to mention names of ab) Severe invasive bacterial diarrhoea eg Shigellosis Cholera GirdiasisImmunocompromised children Antibiotics are contraindicated in: E. coli 0157: H7 because they increase the risk of Haemolytic Uraemic syndrome (HUS) Uncomplicated salmonella enteritis because they prolong bacteria shedding

35 Is a lactose-free diet necessary? The vast majority of patients with AGE do not develop clinically important lactose intolerance. In selected patients with documented, persistent lactose intolerance, lactose-free formulas are recommended

36 When to discharge the patient It is recommended that for children receiving care in a hospital setting, prompt discharge be considered when the following levels of recovery are reached: sufficient rehydration achieved as indicated by weight gain and/or clinical status; IV or NG fluids not required; oral intake equals or exceeds losses; adequate family teaching has occurred; and medical follow up is available via telephone or office visit

37 How to prevent This involves intervention at two levels: Primary prevention (to reduce disease transmission) Rotavirus and measles vaccines Handwashing with soap Providing adequate and safe drinking water Environmental sanitation Secondary prevention (to reduce disease severity) Promote breastfeeding Vitamin A supplementation Treatment of episodes of AD with zinc

38 Post-gastroenteritis syndrome Infrequently, following an episode of gastroenteritis, the introduction of a normal diet results in a return of watery diarrhoea. Temporary lactose intolerance may have developed. In such circumstances, a return to an oral rehydration solution for 24 h, followed by a further introduction of a normal diet, is usually successful. In very severe cases, a period of parenteral nutrition is required to enable the injured small intestinal mucosa to recover sufficiently to absorb luminal nutrients.

39 Conclusion Prescribe ORS for all ages. Continue Breast feeding and diet. Explain danger signals. 20 mg/10 mg of elemental zinc probiotics: doubtable value Judicious use of antibiotics for dysentery and systemic infections No anti-motility agents Anti-emitic drugs : not for routine use