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ENTERIC INFECTIONS

ENTERIC INFECTIONS

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ENTERIC INFECTIONS

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  1. ENTERIC INFECTIONS Amina Ahmed April 26, 2011

  2. Pathogens of Gastroenteritis

  3. Location, location, location…

  4. Etiology of Diarrhea in the ED Clin Infect Dis 2006; 43: 807-13

  5. Clin Infect Dis 2006; 43: 807-13

  6. Viral Gastroenteritis • Predominant cause of gastroenteritis in the US • Usually children < 5 y of age • Destruction of enterocytes in villous epithelium with resultant transudation of fluid • Most infections are asymptomatic • Symptomatic disease – loose, watery stools

  7. Viral Causes of Gastroenteritis

  8. Viral Gastroenteritis Clin Infect Dis 2006; 43: 807-13

  9. Rotavirus • Most common cause of severe enteritis in children • 20-50% of hospitalizations for gastroenteritis • Peak age of illness 3 to 35 months • Peaks activity in winter- spreads north and east • Natural infection • 40% protection against subsequent infection • 88% protection against severe diarrhea • Vaccine should protect against severe disease • *Know the epidemiology of rotavirus: mode of transmission, incubation period, age of onset, peak season.

  10. Rotavirus Gastroenteritis • Incubation 1 to 4 days • Transmission fecal-oral • Fever usually high (unlike other viral pathogens) • Diarrhea • Watery, nonbloody, foul-smelling • Up to 20 episodes per day • Vomiting is presenting symptom in 10% of illnesses *Recognize the clinical manifestations of rotavirus infection.

  11. Rotavirus detection in hospitalized children according to presenting symptoms and signs Pediatr Infect Dis J 2002;21:221-7

  12. Rotavirus : Diagnosis • Fecal examination • Gross blood and mucus usually absent • Fecal leukocytes absent • Occult blood may be present • Commercial assay (EIA) • Detection of antigen • Sensitivity 80-100% • Specificity 90-100% • *Know that the best test for the diagnosis of rotavirus infection is antigen testing, but that a specific diagnosis is not necessary for management.

  13. The Rise and Fall of RotaShield • Licensed 1998 • Efficacy 50-60% against rotavirus GE • Efficacy 80-90% against severe diarrhea • Intussussception • 21.7 fold increased risk after first dose • Clustering 3-14 days after first dose • Withdrawal of recommendations 1999 N Engl J Med 2001; 344: 564-72

  14. The New Rotavirus Vaccines

  15. Rotavirus Efficacy and Safety Trial (REST) • Randomized, placebo-controlled, double-blind trial • RotaTeq • 70,000 infants 6 – 12 weeks of age • Efficacy against RV gastroenteritis 74% • Efficacy against severe gastroenteritis 98% • Risk of intussusception similar for vaccine and placebo N Engl J Med 2006; 354: 23-33

  16. Recommendations for Rotavirus Vaccine • Routine vaccination at ages 2, 4, 6 months • First dose at 6-14 weeks of age • Maximum age - 14 weeks, 6 days • Subsequent doses at 4-10 week intervals • Final dose by 8 months • If Rotarix given at age 2 and 4 months, dose at 6 months not indicated • Limited safety data on first dose at > 14 weeks MMWR 2006; 55 (RR12): 1-13

  17. It’s in my blood… 8 month old with fever and diarrhea • Temperature 102 F • Seen in ED- WBC normal, blood culture obtained • Blood culture: Gram negative rods • Back to ED- still febrile, repeat blood culture • Second blood culture: Gram negative rods • Admitted

  18. Salmonella • S. enterica subsp. enterica serotypes (> 2000 serotypes) • S. enterica subsp. enterica serotypeTyphi (S. typhi) • S. enterica subsp. enterica serotypeTyphimirum • Incidence highest in children < 1 year of age • Transmission • Most infections are foodborne • Poultry, eggs • Fecal-oral spread • Direct animal contact (reptiles) *Know the mode of transmission of Salmonella species.

  19. Just when you thought that MICHAEL JORDAN had won it all, here comes Dr. STANFORD SHULMAN with a new honor: a strain of salmonella. Shulman, chief of infectious diseases at Children's Memorial Hospital in Chicago, discovered the unique strain and decided to name it Salmonella mjordan. Shulman insisted that it was appropriate to honor the greatest basketball player in history with an organism that causes diarrhea, severe headaches, abdominal pain and other discomfort. Jordan's agent, DAVID FALK, accepted the honor reluctantly, and suggested future organisms needing names look elsewhere.

  20. Salmonella : Clinical Syndromes • Non-Typhi Serotypes • Asymptomatic carriage • Enteritis • Bacteremia • Metastatic focal infections • Osteomyelitis, meningitis • S. enterica serovar Typhi • Typhoid fever • *Recognize the clinical manifestations of non-typhoidal Salmonella infection.

  21. Salmonella Enteritis • Incubation 6-72 h (24 h) • Fever (70%) • Nausea / vomiting • Crampy abdominal pain • Watery diarrhea or dysentery • Symptoms last < 1 week • Fecal excretion lasts weeks to months • *Recognize the clinical manifestations of non-typhoidal Salmonella gastroenteritis.

  22. Salmonella Bacteremia • True incidence unknown • 1-5% overall • ? Higher incidence in young infants (< 1 year) • Populations at increased risk • Immunocompromised • Hemolytic anemia • *Identify patients at high risk of invasive Salmonella infection (eg, young infants, patients with immunocompromise or hemoglobinopathy).

  23. Salmonella : Antimicrobial Therapy • Not indicated for uncomplicated enteritis • No effect on clinical course • Indicated for those at risk for complications • Young infants (< 3 months) • Hemolytic anemias • Immunocompromised • Indicated for extraintestinal infections • Bacteremia, osteomyelitis, meningitis • *Know that otherwise healthy patients with uncomplicated Salmonella gastroenteritis should not receive antimicrobial therapy.

  24. Salmonella : Antimicrobial Therapy • Gastroenteritis • Ampicillin, amoxicillin • Resistance increasing • TMP-SMX • Resistance increasing • Cefixime ? Fluoroquinolones? • Bacteremia / extraintestinal infections • Cefotaxime, ceftriaxone • Aminoglycosides have no clinical effect • *Plan the treatment of an invasive Salmonella infection

  25. Febrile Seizure? 2 year old admitted with febrile seizure • Temperature 104 F • Generalized seizure • Diarrhea for 1 day • Exam normal in postictal period • WBC 6,000 (15% bands) • CSF not obtained

  26. Shigella • Bacillary dysentery • Four serogroups • S. dysenteriae • Uncommon in the United States • S. flexneri • S. boydii • S. sonnei

  27. Shigella : Epidemiology • Peak incidence ages 1 to 4 years • Highly contagious • 10-100 organisms • Transmission fecal-oral • Person-to-person • Contaminated food or water *Know the mode of transmission of Shigella species.

  28. Shigella : Clinical Presentation • Incubation period 12 to 48 h • Signs and symptoms • Fever • Watery diarrhea, then hemorrhagic colitis • Abdominal cramps, nausea/vomiting • Tenesmus • Symptoms resolve in 1 week • Fecal excretion 1-30 days • *Know the major clinical manifestations of Shigella species: fever; seizures; diarrhea; blood, mucous, and neutrophils in stool.

  29. Shigella : Extraintestinal Disease • Bacteremia/septicemia uncommon in US • Neurologic manifestations • Seizures • Lethargy, confusion • Postinfectious • Reactive arthritis

  30. Shigella : Seizures • Occur in 5-20% of cases • Predominantly in < 5 y of age • Generalized in > 80% • CSF, EEG normal • Etiology unclear- unlikely due to Shiga toxin Am J Dis Child 1987; 141: 208-210; Pediatrics 1999; 103: e18

  31. Shigella : Treatment • Antibiotic therapy • Shortens duration of symptoms • Reduces duration of excretion • Treatment options • Ampicillin-resistance high- use only if susceptible • TMP-SMX- resistance increasing • Cefixime • Ceftriaxone *Plan the treatment of Shigella infection.

  32. The Stomach Flu • 12 year old boy admitted with fever, headache, myalgias, abdominal pain, and diarrhea • Fever resolved but abdominal pain persisted • Abdominal CT • Edema in bowel wall

  33. Campylobacter jejuni • Most common cause of bacterial enteritis • Approximately 2 million infections per year • Highest incidence in < 5 y and 15-29 y • Transmission • Contaminated food • Undercooked poultry • Direct contact with infected pets • Person-to-person *Know the epidemiology of Campylobacter infections.

  34. C. jejuni : Clinical Presentation • Enteritis • Immunoreactive complications • Guillain-Barré • Reactive arthritis • Extraintestinal infection (rare with C. jejuni) • Bacteremia • Perinatal infection

  35. C. jejuni Enteritis • Incubation 24-72 h • Prodrome of abdominal pain, myalgia, HA • Gastroenteritis • Fever • Loose stools or watery diarrhea or dysentery • Abdominal cramps • Vomiting frequent • Resolution in 1-2 weeks *Recognize the clinical manifestations of Campylobacter infection.

  36. C. jejuni : Guillain-Barré • 20-40% GBS cases due to C. jejuni • 1/2,000-5,000 infections followed by GBS • Interval between diarrhea and onset of neurologic symptoms is 10 days (6-21 d) • Mechanism unclear

  37. C. jejuni : Treatment • Most episodes self-limited • No clinical benefit if treated late in disease • Early treatment may shorten course of disease • Antibiotics decrease duration of excretion • Antibiotics indicated for • Severe or prolonged illness • Immunocompromised host, bacteremia • Treatment- erythromycin (5 days) • Resistant to penicillins, cephalosporins, TMP-SMX *Plan the treatment of Campylobacter infections.

  38. Happy Holidays! 5 month old seen in ED twice for respiratory symptoms and diarrhea • Cough, wheezing the week PTA • Diarrhea without blood; “foul” • Diarrhea persistent during hospitalization • WBC 23,000 with normal differential • Stool with 10-20 WBC, 0 RBC

  39. Yersinia enterocolitica • Common in cooler climates (Northern Europe) • Peak season fall, winter • Most common in children < 5 years of age • Transmission • Contaminated foods • Raw milk, chitterlings • Direct contact with animals • Reservoirs include rodents, pigs, sheep

  40. ‘Tis the Season Pediatr Infect Dis 2000; 19: 954-8

  41. Yersinia : Clinical Manifestations • Enterocolitis • Mesenteric adenitis (pseudoappendicitis) • Bacteremia/septicemia • Infants < 3 months of age • Immunocompromised host • Iron overload • *Recognize the clinical manifestations of Yersinia enterocolitica infection.

  42. Clinical Manifestations of 57 Children with Y. enterocolitica Gastroenteritis Symptoms / Signs Number (%) Mean Duration (d) Diarrhea 56 (98) 14 Fever 39 (68) 3.9 Abdominal pain 31 (64) 7.7 Vomiting 22 (38) 2.4 J Pediatr 1980; 96: 26-31

  43. Yersinia : Treatment • Antibiotics of questionable benefit for enteritis • No impact on clinical or bacteriologic course • Antibiotics indicated • Immunocompromised with enteritis • Bacteremia • Treatment options • Enteritis: TMP-SMX • Bacteremia: AG or 3o Cephalosporin • Resistant to 2o cephalosporins, penicillins • *Know indications for the treatment of Yersinia enterocolitica infection: drug(s) of choice, alternative drugs.

  44. Petting Zoo Two Words…

  45. E. coli : Enteric Infections

  46. E. coli O157 : Epidemiology • E. coli O157:H7 most common EHEC in NA • Highest attack rate in children < 5 y • Transmission • Contaminated beef (reservoir is cattle) • Food contaminated by feces of animals • Person-to-person

  47. E. coli O157: Pathogenesis • Attaches to luminal enterocytes in ileum and colon • Shiga-like toxins (SLT I, II) released • Disruption of protein synthesis • Gut-blood barrier compromised • SLT’s circulate systemically