Acute Gastroenteritis Past Paper 1446 PDF

Acute Gastroenteritis By: Dr. Hanan Sakr Sherbiny Associate Professor of Pediatrics University of Bisha 1446 ١  Our Objective in this lecture By the successful completion of this presentation, you are expected to: 1.D...

Acute Gastroenteritis By: Dr. Hanan Sakr Sherbiny Associate Professor of Pediatrics University of Bisha 1446 ١  Our Objective in this lecture By the successful completion of this presentation, you are expected to: 1.Define AGE and dehydration 2.List common causes of diarrhea 3.Describe features of different types of dehydrations 4.Suggest investigation needed for patient with AGE 5.Outline the different types of dehydration ٢  Definitions ▪The term gastroenteritis denotes inflammation of the gastrointestinal tract, most commonly the result of infections with bacterial, viral, or parasitic pathogens. Many of these infections are foodborne illnesses ▪Diarrhea: is usually defined as the passage of 3 or more abnormally loose or liquid stools per day. ▪Acute gastroenteritis (AGE) captures the bulk of infectious cases of diarrhea. The most common manifestations are diarrhea and vomiting, which can also be associated with systemic features such as abdominal pain and fever. ٣  Definitions ▪ Dysentery refers to a syndrome characterized by frequent small stools containing visible blood, often accompanied by fever, tenesmus, and abdominal pain. DD: from Bloody diarrhea (larger volume bloody stools with less systemic illness) because the etiologies may differ. ▪Prolonged (lasting 7-13 days) and persistent diarrhea (lasting 14 days or longer) are important because of their impact on growth and nutrition. ٤  Diarrheal Burden ▪ The global mortality due to diarrheal diseases has declined substantially (39%) during the past 2 decades, it remains unacceptably high. ▪ In 2015, diarrheal disease caused 8.6% of all childhood deaths, making it the 4th most common cause of child mortality worldwide. ▪ The decline in diarrheal mortality is due to: Preventive rotavirus vaccination improved case management of diarrhea: widespread home- and hospital-based oral rehydration solution (ORS) therapy and improved nutritional management of children with diarrhea. improved nutrition of infants and children. Recurrent, prolonged, or persistent, diarrheal illness can be associated with malnutrition, stunting, micronutrient deficiencies, and significant deficits in psychomotor and cognitive development. ٥  Causative Pathogens (viral) Rotavirus is the most common cause of AGE among children throughout the world. Norovirus (GII.4) has predominated globally during the past decade. Others: Adenovirus, 40 and 41 are most often associated with diarrhea, astroviruses are identified less often. ٦  Pathogens (Bacterial) ▪The major bacterial pathogens that cause AGE are nontyphoidal Salmonella (NTS), Shigella, Campylobacter , Escherichia coli, and Yersinia ▪Vibrio cholerae (O1 and O139) produce epidemic cholera and cause nearly all sporadic cases. ▪Clostridium difficile disease can be both nosocomial and community acquired in children. ▪Bacterial pathogens that cause foodborne illness due to their ability to produce emetic and/or enterotoxins include Bacillus cereus , Clostridium perfringens , and Staphylococcus aureus. ٧  Pathogen (Protozoal) ▪Giardia intestinalis, Cryptosporidium spp and Entamoeba histolytica are the most common parasites that cause diarrhea ▪ G. intestinalis (formerly G. lamblia and G. duodenalis ) is a flagellate protozoan that infects the small intestine and biliary tract. ٨  Seasonality Seasonality provides a clue to implicate specific pathogens, although patterns may differ in tropical and temperate climates. Rotavirus and norovirus peak in cool seasons, whereas enteric adenovirus infections occur throughout the year, with some increase in summer. Salmonella, Shigella, and Campylobacter Favor warm weather, whereas the tendency for Yersinia to tolerate cold manifests as a winter seasonality ٩ Host risk factors to AGN &associated morbidities Age predilection The incidence of rotavirus and NTS are highest in infancy. Endemic shigellosis peaks in 1-4 year Campylobacter and Cryptosporidium show a bimodal distribution with the greatest number of reported cases in infants and young children a secondary peak in adolescents and young adults. Pandemic V. cholerae and S. dysenteriae type 1 produce high attack rates and mortality in all age groups ١٠ Additional risks factors for AGE include: Immunodeficiency measles lack of exclusive or predominant breastfeeding. Malnutrition and moderate to severe stunting increases the risk of diarrhea and its associated mortality, particularly when associated with micronutrient deficiency(Vitamin A and Zinc deficiency). ١١  Clinical Manifestations (Viral AGE ) ▪ ROTA virus AGE symptoms usually begin with vomiting followed by frequent passage of watery non-bloody stools, associated with fever in about half the cases , The diarrhea lacks fecal leukocytes, but stools from 20% of cases contain mucus. ▪ Recovery with complete resolution of symptoms generally occurs within 7 days ▪ Other viral agents elicit similar symptoms and cannot be distinguished from rotavirus based on clinical findings. ▪ Diarrheal illnesses caused by enteric adenovirus infections tend to be more prolonged than rotavirus (7 to 10 days), whereas astroviruses cause a shorter course (~5 days) usually without significant vomiting. ١٢  Clinical Manifestations (bacterial AGE ) Although there is considerable overlap, fever >40C, overt fecal blood, abdominal pain, no vomiting before diarrhea onset, and high stool frequency (>10 per day) are more common with bacterial pathogens The classical bacterial agents, NTS, Shigella, Campylobacter, and Yersinia, present with the following syndromes. Acute diarrhea: the most common presentation, may be accompanied by fever and vomiting.. Bloody diarrhea or frank dysentery is classically caused by Shigella. Watery diarrhea typically precedes dysentery Progression to dysentery indicates colitis and may occur within hours to days. Patients with severe infection may pass more than 20 dysenteric stools in 1 day. ١٣  Clinical Manifestations (Protozoal AGE) A protozoal etiology should be suspected when there is: Prolonged diarrheal illness characterized by episodes of explosive diarrhea with nausea, abdominal cramps, and abdominal bloating. The stools are usually watery but can be greasy and foul smelling due to concomitant malabsorption of fats, which is more likely to occur if the parasite load is high. Amebic dysentery is characterized by bloody or mucoid diarrhea, which may be profuse and lead to dehydration or electrolyte imbalances. ١٤  Dehydration Past classification: many guidelines divided patients into subgroups for mild (3– 5%), moderate (6–9%), and severe (≥10%) dehydration (body weight loss). Most guidelines now combine mild and moderate dehydration and simply use none, some, and severe dehydration. The individual signs that best predict dehydration: are prolonged capillary refill time >2 sec, abnormal skin turgor, hyperpnea (deep, rapid breathing suggesting acidosis), dry mucousmembranes, absent tears, and general appearance (including activity level and thirst). As the number of signs increases, so does the likelihood of dehydration. Tachycardia, altered level of consciousness, and cold extremities with or without hypotension suggest severe dehydration. ١٥  Complications Dehydration : The major complications from diarrhea from any cause are dehydration, electrolyte, or acid-base derangements, which can be life-threatening Malnutrition : Children who experience frequent episodes of acute diarrhea or prolonged or persistent episodes (seen especially in low resource settings) are at risk for poor growth and nutrition and complications such as secondary infections and micronutrient deficiencies (iron, zinc, vitamin A). Intussusception : Viral AGE illnesses are usually self-limited and resolve after several days. Rarely, intussusception is triggered by lymphoid hyperplasia associated with viral AGE. ١٦  Intestinal complications Extraintestinal complications: Persistent diarrhea Dehydration, metabolic Recurrent diarrhea (usually abnormalities, malnutrition, immunocompromised micronutrient deficiency persons) Toxic megacolon Bacteremia with systemic spread Intestinal perforation of bacterial pathogens, including Rectal prolapse endocarditis, osteomyelitis, meningitis, pneumonia, hepatitis, Post infectious peritonitis, complications Local spread (e.g., vulvovaginitis (immune mediated) and urinary tract infection, Reactive arthritis Mesenteric adenitis) Guillain-Barré syndrome Pseudoappendicitis Hemolytic uremic syndrome Glomerulonephritis, myocarditis, pericarditis Immunoglobulin A (IgA) nephropathy ١٧  Evaluation of AGE The initial evaluation of all patients with AGE, the physician should focus on: Dangerous signs: patient's hydration status and electrolyte balance, evidence of sepsis or invasive bacterial infection, which could complicate bacterial AGE Etiologic agent: Once the patient is stabilized, the history and physical examination can focus on detecting risk factors and exposures, as well as the clinical features that may suggest specific etiologic agents Important elements of the medical history include: ▪ the duration of diarrhea , vomiting (onset, amount and frequency), and the amount and type of solid and liquid oral intake ▪ description of stools (frequency, amount, presence of blood or mucus), ▪ fever (duration, magnitude), ١٨  Clinical signs of dehydration should be evaluated ▪ urine output (number of wet diapers per day and time since the last urination), whether eyes appear sunken, whether the child is active, whether the child drinks vigorously, ▪The date and value of the most recent weight measurement: A documented weight loss can be used to calculate the fluid deficit. The past medical history should identify comorbidities that might increase the risk or severity of AGE. ١٩  Degree of Dehydration ▪ A variety of scales are available to grade the severity of dehydration in young children, but no single, standard, validated method exists. ▪ Note that signs of dehydration may be masked when a child is hypernatremic. ▪ The World Health Organization defines: Some dehydration as the presence of two or more of the following signs: restlessness/irritability, sunken eyes, drinks eagerly, thirsty, and skin pinch goes back slowly. Severe dehydration is defined as two or more of the following signs: lethargy/unconsciousness, sunken eyes, unable to drink/drinks poorly, and skin pinch goes back very slowly (>2 sec). ٢٠ ٢١ Classification into; no, some, or severe dehydration  Classical Classification Of Dehydration ٢٢  Physical findings ▪ Certain physical signs are best assessed before approaching the child directly, so he/ she remains calm, including General appearance (activity, response to stimulation) and, Respiratory patterns. ▪ Skin turgor is assessed by pinching a small skin fold on the lateral abdominal wall at the level of the umbilicus. If the fold does not promptly return to normal after release, the recoil time is quantified as delayed slightly or ≥2 sec. Excess subcutaneous tissue and hypernatremia may produce a false negative test and malnutrition can prolong the recoil time. ▪ To measure capillary refill time, the palmar surface of the child's distal fingertip is pressed until blanching occurs, with the child's arm at heart level. The time elapsed until restoration of normal color after release usually exceeds 2 sec in the presence of dehydration. ▪ Mucous membrane moisture level, presence of tears, and extremity temperature should be assessed. ٢٣  Laboratory Diagnosis Most cases of AGE do not require diagnostic laboratory testing ▪ Stool Analysis: could be examined for mucus, blood, neutrophils or fecal lactoferrin, a neutrophil product. The finding of more than 5 leukocytes per high- power field or a positive lactoferrin assay in an infant not breastfeeding suggests an infection with a classical bacterial enteropathogen ▪ Stool cultures for detection of bacterial agents are costly, so requests should be restricted to patients with: ▪ clinical features predictive of bacterial AGE, ▪ have moderate or severe disease, ▪ immunocompromised, ▪ have a highly suggestive epidemiologic history. ٢٤ ▪ All bloody stools should also be inoculated into media specific for detection of E. coli 0157:H7 or directly tested for the presence of Shiga-like toxin (or both). ▪ Laboratory diagnosis of viral AGE: may be helpful when an outbreak is suspected (PCR) ▪ Evaluation for intestinal protozoa that cause diarrhea is usually indicated inpatients who recently traveled to an endemic area, have contact with untreated water, and manifest suggestive symptoms. ▪ The most commonly used method: ▪ Direct microscopy of stool for cysts and trophozoites, ▪ Analyzing 3 specimens from separate days is optimal, ▪ Enzyme immunoassays are available for Cryptosporidium, Giardia, and Entamoeba that are more sensitive and specific than direct microscopy and provide a useful diagnostic tool ▪ ٢٥  Molecular methods (NAAT) are also available. Several culture- independent rapid multiplex molecular panels for detection of viral, bacterial, and protozoal gastrointestinal pathogens directly from stool samples are FDA approved. Advantages: including reduced sample volume requirements, broad coverage without the need to select specific tests, enhanced ability to detect coinfections, increased sensitivity, and rapid turnaround.. ٢٦ ▪ Most episodes of diarrheal dehydration are isonatremic and do not warrant serum electrolyte measurements. Electrolyte measurements are most useful in: children with severe dehydration, when intravenous fluids are administered, when there is a history of frequent watery stools, yet the skin pinch feels doughy without delayed recoil, which suggests hypernatremia, or when inappropriate rehydration fluids have been administered at home. ▪ Blood culture should be obtained if there is concern for systemic bacterial infection. ▪ Others CBC, blood film, sweat chloride test ٢٧  Treatment The broad principles of management of AGE in children include: Rehydration and maintenance ORS plus replacement of continued losses in diarrheal stools and vomitus after rehydration, Continued breastfeeding, and refeeding with an age appropriate, unrestricted diet as soon as dehydration is corrected. Zinc supplementation is recommended for children in developing countries. ٢٨  Hydration ▪ Children, especially infants, are more susceptible than adults to dehydration because: Greater basal fluid and electrolyte requirements per kilogram They are dependent on others to meet these demands. ▪ Dehydration must be evaluated rapidly and corrected in 4-6 hr according to the degree of dehydration and estimated daily requirements ▪ When there is emesis, small volumes of ORS can be given initially by a dropper, teaspoon, or syringe, beginning with as little as 5 mL at a time. The volume is increased as tolerated. ▪ The low-osmolality World Health Organization (WHO) ORS containing 75 mEq of sodium, 64 mEq of chloride, 20 mEq of potassium, and 75 mmol of glucose per liter, with total osmolarity of 245 mOsm/L, is now the global standard of care and more effective than home fluids. ▪ Oral rehydration can also be given by a nasogastric tube if needed; this is not the usual route. ٢٩  Some Dehydration Rehydration: ORS, 50-100 mL/kg over 3-4 hr. Continue breast feeding. Maintenance: After 4 hr, give food every 3-4 hr for children who normally receive solid foods. Replacement of concurrent loss Infants and children: 10 kg bodyweight: 100-200 mL ORS for each diarrheal stool or vomiting episode; up to ~1 L/day Replace losses as above as long as diarrhea or vomiting continues ٣٠ ٣١  Severe Dehydration Rehydration: Severe dehydration Malnourished infants, frequent boluses of 10 mL/kg body weight due to reduced capacity to increase cardiac output with larger volume resuscitation. Infants (10 mL/kg/hr). ٣٤  For all types of Dehydration After rehydration is complete, maintenance fluids should be resumed along with an age appropriate normal diet offered every 3-4 hr. Children previously receiving a lactose-containing formula can tolerate the same product in most instances. Diluted formula does not appear to confer any benefit. Breastfed infants should continue nursing throughout the illness. Low-osmolarity ORS can be given to all age groups, with any cause of diarrhea. It is safe in the presence of hypernatremia, as well as hyponatremia (except when edema is present). Some commercially available formulations that can be used as ORS include Pedialyte Popular beverages that should not be used for rehydration include apple juice, Gatorade, and commercial soft drinks ٣٥  Enteral Feeding and Diet Selection Continued breastfeeding and refeeding with an age-appropriate, unrestricted diet as soon as dehydration is improving or resolved aids in recovery from the episode. Foods with complex carbohydrates (rice, wheat, potatoes, bread, and cereals), fresh fruits, lean meats, yogurt, and vegetables should be reintroduced while ORS is given to replace ongoing losses from emesis or stools and for maintenance. Fatty foods or foods high in simple sugars (juices, carbonated sodas) should be avoided. The usual energy density of any diet used for the therapy of diarrhea should be around 1 kcal/g, aiming to provide an energy intake of a minimum of 100 kcal/kg/day and a protein intake of 2-3 g/ kg/day. If the normal diet includes infant formula, it should not be diluted, or changed to a lactose-free preparation unless lactose malabsorption is evident. Withdrawal of milk and replacement with specialized lactose-free formulations are unnecessary. ٣٦  Zinc Supplementation Zinc supplementation in children with diarrhea in developing countries leads to: reduced duration and severity of diarrhea could potentially prevent a large proportion of cases from recurring. can significantly reduce all-cause mortality by 46% and hospital admission by 23%. Administration of zinc in community settings leads to increased use of ORS and reduction in the inappropriate use of antimicrobials. ▪ All children older than 6 mo of age with acute diarrhea in at-risk areas should receive oral zinc (20 mg/day) in some form for 10-14 days during and continued after diarrhea. ▪ The role of zinc in well nourished, zinc replete populations in developed countries is less certain. ٣٧  Additional Therapies The use of probiotic non-pathogenic bacteria for prevention and therapy of diarrhea has been successful in some settings, although the evidence does not support a recommendation for their use in all settings. Ondansetron (oral mucosal absorption preparation) reduces the incidence of emesis, thus permitting more effective oral rehydration and is well-established in emergency management of AGE in high-resource settings, reducing intravenous fluid requirements and hospitalization. Antimotility agents (loperamide) are contraindicated in children with dysentery and probably have no role in the management of acute watery diarrhea in otherwise healthy children. Similarly, antiemetic agents, such as the phenothiazines, are of little value and are associated with potentially serious side effects (lethargy, dystonia, malignant hyperpyrexia). ٣٨  Antibiotic Therapy ▪ Judicious antibiotic therapy for suspected or proven bacterial infections can reduce the duration and severity of illness and prevent complications ▪ Several factors justify limited use. First, most episodes of AGE are self-limited among otherwise healthy children. Second, the increasing prevalence of antibiotic resistance has prompted restricted use of these drugs. Third, antibiotics may worsen outcome, because some studies have shown that antibiotic therapy of STEC infection increases the risk of HUS and prolongs excretion of NTS without improving clinical outcome. ▪ Therefore antibiotics are used primarily to treat severe infections, prevent complications in high-risk hosts, or to limit the spread of infection. ▪ Microbiologic (culture) confirmation of the etiology and susceptibility testing should be sought prior to treatment if possible. ٣٩  Preventive strategies Promotion of Exclusive Breastfeeding and Vitamin A Exclusive breastfeeding protects young infants from diarrheal disease through the promotion of passive immunity and through reduction in the intake of potentially contaminated food and water. Vitamin A supplementation reduces all-cause childhood mortality by 25% and diarrhea-specific mortality by 30%. ٤٠  Preventive strategies (vaccines) ▪ Rotavirus vaccine: Three live oral rotavirus vaccines are licensed: the 3-dose pentavalent G1, G2, G3, G4, P human-bovine vaccine (RotaTeq), the 2-dose monovalent human G1P vaccine (ROTARIX), and the 3-dose monovalent human-bovine 116E G6P vaccine (Rotavax). (rot-Teq, rotarex, Rotavax) ▪ Vaccine (live virus) associated rotavirus infection has been reported in children with severe combined immunodeficiency disease, but the vaccine has been shown to be safe in HIV-infected populations. ▪ Cholera: Two licensed, efficacious 2-dose oral inactivated cholera vaccines (Dukoral for children 2 yr and older and ShanChol for children 1 yr or older) ▪ Typhoid fever vaccine are available: a polysaccharide vaccine delivered intramuscularly that can be administered to children older than 2 yr (Vivotif) and an oral, live attenuated vaccine that can be administered to children over 6 yr of age (Typhim Vi). ٤١  Improved Water and Sanitary Facilities and Promotion of Personal and Domestic Hygiene Much of the reduction in diarrhea prevalence in the developed world is the result of improvement in standards of hygiene, sanitation, and water supply. An estimated 88% of all diarrheal deaths worldwide can be attributed to unsafe water, inadequate sanitation, and poor hygiene. ٤٢  References Nelson textbook of pediatrics, 21 edition, chapter 366 ٤٣ ٤٤