Infectious Diarrhea

1. Infectious Diarrhea Nicole Leone July 29th, 2013

2. Viral vs. Bacterial • Age • Bacterial and parasitic agents generally cause gastroenteritis in children at an older age (2-4 years) • Viral pathogens cause gastroenteritis in children < 2yo • Presence of blood or mucus • Presence of gross blood or mucus suggests bacterial or parasitic infection • Bloody diarrhea is rare with viral gastroenteritis • Occult blood does not count • Exposures • Bacterial or parasitic agents are usually associated with foreign travel, exposure to poultry or other farm animals, consumption of processed meat • Fecal WBCs • Presence of fecal leukocytes suggests bacterial/parasitic etiology • Indicates inflammation, does not distinguish infectious vs. non-infectious

3. Work Up • Fecal Leukocytes • Examining fecal smear stained with Wright stain • Stool Culture • Bacterial pathogen will be identified in 15-20% of cases • Not recommended for non-bloody diarrhea of brief duration in otherwise healthy children • Stool for Ova and Parasites • Indicated for children who have traveled to endemic area • Viral Antigen tests of stool • Helpful in distinguishing acute viral gastroenteritis from a bacterial process • Urine Culture • Infants and children with UTIs can have diarrhea • Abdominal Ultrasound • Useful to r/o intussusception, appendicitis

4. Salmonellosis • S.typhimurium and S.enteritidis are most common serotypes • S.enteritidis assoc. w/ foodborne disease (eggs) • Most common in children < 5yo, with highest incidence in 1st year • Younger patients have higher rates of associated bacteremia • Nausea, vomiting, fever, diarrhea, cramping • Occur within 8-72 hours of contaminated food ingestion • Higher dose of ingested bacteria correlates with increased severity of diarrhea • Bloody diarrhea is less common than with Shigella

5. Salmonellosis • Course • < 5% develop invasive disease (bacteremia) • Bacteremia can lead to endocarditis, osteomyelitis • Usually self-limited, fever resolves within 72h, diarrhea within 4-10 days • Treatment • Supportive • Antibiotics are indicated for children < 3mos, and those at high risk for invasive disease (malignancies, hemoglobinopathies, HIV, chronic GI disease) • Antibiotics: Ampicillin/Amoxicillin, Bactrim, Cefotaxime, Ceftriaxone • Antibiotics are NOT indicated for patients with uncomplicated (non-invasive) gastroenteritis caused by NON-TYPHOIDAL SALMONELLA

6. Shigellosis • Most common in children between 1-4yo • Present with high fever, abdominal cramps, watery diarrhea that becomes bloody and mucoid • Stool frequency is usually 8-10 per day • WBC can be normal or markedly elevated • Usually w/ high band count • Treatment • Antibiotics x 5 d eradicates organism from GI tract, reduces intensity and duration of illness, decreases spread • If acquired in US: Bactrim is 1st line • If acquired elsewhere: 3rd generation cephalosporin • Complications • Intestinal perforation, toxic megacolon, HUS, seizures, encephalopathy

7. Campylobacter • Enterocolitis caused by C.jejuni or C.coli • Diarrhea, fever, abdominal pain, vomiting • 50% with bloody stools • Febrile seizures may occur • Outbreaks common in children visiting dairy farms; organisms present in GI tracts of birds and animals • Neonatal infection • Acquired at time of birth ; Grossly bloody stools or fever may be only manifestation • Treatment • Most cases resolve spontaneously within 2 weeks • Azithromycin x 3-5 days eliminates the organism from the stool in 2-3d • Complications • Acute: Cholecystitis, Peritonitis, Rash, Septic pseudoaneurysm • Late: Reactive Arthritis, GuillainBarre Syndrome

8. E.coli • EnterotoxigenicE.coli (ETEC) “Traveler’s Diarrhea” • Watery diarrhea in children • One of the most common bacterial causes of dehydration in children < 2yo in developing countries • Often causes diarrhea in travelers to tropical regions • Treatment: supportive; antibiotics shortens disease duration to 1 day • EnteropathogenicE.coli (EPEC) • Diarrheal illness most common in children < 6mo • Diagnosis via PCR • EnterohemorrhagicE.coli (EHEC) • Shiga toxin producing • E.coli O157:H7 is associated with HUS • Responsible for outbreaks of bloody diarrhea • Early antibiotic administration is assoc. w/ increased risk of HUS (?enhanced toxin release as bacteria are killed)

9. Yersinia enterolitica • Associated with bloody stools in 25% of patients • Presentation: fever and diarrhea • Stool usually contains WBCs, blood and mucus • Causes acute ileitis—mimics appendicitis and Crohn’s disease • Main reservoir in US is swine, most infectious occur after ingestion of raw or improperly prepared food • Includes unpasteurized milk • Treatment • Most cases spontaneously resolve within 2 weeks • No known benefit of antibiotics except for reduced excretion • Bactrim, Cefotaxime, Aminoglycosides are recommended choices

10. Clostridium difficile • Usually occurs after exposure to antibiotics • Especially ampicillin, clindamycin and cephalosporins • Varies from mild diarrhea to dysenteric syndrome • Diagnosis • Detection of C.difficile toxin by ELISA in stool • Stool culture does not differentiate toxin from non-toxin producing strains, and up to 50% of healthy infants can be colonized • Treatment • Antibiotics should be stopped or changed • If diarrhea persists or toxicity is present, PO flagyl or vancomycin is indicated for 7-10 days • IV flagyl can be considered in severely ill patient (No IV Vanco)

11. Cryptosporidium • Most common parasitic cause of acute foodborne diarrhea in US • Intracellular protozoan parasiteinterferes with intestinal absorption/secretionsecretory diarrhea • More common in children 1-9yo • Immunocompetent hosts: severely dehydrating, but self-limited diarrheal illness • Diarrhea, malaise, nausea, anorexia, crampy abdominal pain, fever • Fecal WBCs or blood rare • Immunocompromised hosts: life-threatening illness • Fecal-oral transmission (ingestion of oocysts), waterborne outbreaks • Diagnosis: microscopic examination of stool • Treatment • Supportive • Resolves without therapy in 10-14 days in normal hosts

12. Giardiasis • Diagnosis: stool microscopy • Treatment: all symptomatic patients • Metronidazole, Tinidazole, Nitazoxanide • Giardia lamblia is flagellated protozoan parasite • Seen in daycare center outbreaks, illness in international travelers • Children < 5yo have highest rates of infection • Transmitted via fecal-oral, water, food, sexual intercourse • Diarrhea sudden in onset, watery, foul smelling w/ steatorrhea • Assoc w/ abd cramps, malaise, weight loss • Symptoms can last up to 4 wks Giardia trophozoite

13. Rotavirus • Most commonly recognized viral pathogen of diarrheal disease in children • Makes up 30-70% of hospitalizations for AGE • Stools are watery or yellow without mucus or blood • Minimal to moderate fecal WBCs are seen in 30% • Higher incidence of vomiting and fever • Respiratory symptoms seen in 30-50% • Associated with more severe dehydration than other viral gastroenteritis • Detected in 25-30% of preschool age children who require hospitalization for diarrhea, vomiting and/or fever • Treatment • Supportive • Preventive: Rotavirus oral live vaccine at 2, 4, 6 mos

14. Adenovirus • Makes up 5-10% of hospitalizations for AGE • Serotypes 40 and 41 cause AGE; these strains DO NOT cause respiratory symptoms • Average age of illness is 1-2yrs • Incubation period 8-10d, symptoms last 5-12d • Diarrhea + vomiting and fever • No seasonality • Treatment • Supportive

15. Norovirus • Transmission mainly via fecal-oral route, but airborne transmission can occur • Outbreaks in daycare, schools • Illness varies from mild febrile illness with watery diarrhea to more severe with vomiting, headache and constitutional symptoms • Incubation period is 24-48hrs, abrupt onset of symptoms, course lasts < 48hrs • Most present with both vomiting and diarrhea • Stools are usually non-bloody, non-mucusy, lack fecal WBCs • Fever present in 50%

16. Question #1 • A previously healthy 17yo F presents to your office with 2 days of diarrhea associated with bleeding and tenesmus. She denies any history of abdominal pain, fevers, joint pains, constipation or weight loss. Growth and development are normal. She is in HS, lives at home with her parents and 1 male sibling and she volunteers 2 afternoons each week at an animal shelter. FamHx indicates that her mother has idiopathic ulcerative colitis and is being treated for a recent symptomatic flare. PE demonstrates a somewhat uncomfortable young woman with HR 80, BP 100/70. Abdomen is soft, non-distended without organomegaly, and there is moderate, direct tenderness in LLQ. Rectal exam demonstrates moderate tenderness and produces mucus streaked with gross blood.

17. Question #1 • Of the following, the MOST likely cause of her illness is: • A. Campylobacter jejuniinfection • B. Clostridium difficileinfection • C. Entamoebahistolyticainfection • D. Escherichia coli O157:H7 infection • E. Shigelladysenteriaeinfection

18. Question #2 • A 10 week old, bottle-fed infant presents to your office on January 5th with bloody diarrhea and fever. There are no known sick contacts, although the family recently had a gathering on NYE and served chitterlings. The infant is febrile but appears well, and results of the PE are unremarkable. She has a diarrheal stool with a small amount of mucus and blood in it while you are examining her. The peripheral WBC is 15 with 70% PMNs, 20% lymphs, 10% monos. Hgb is 11 and platelets are 260.

19. Question #2 • Of the following, the stool study MOST likely to establish the diagnosis is: • A. a culture on routine media • B. a culture on selective media • C. a polymerase chain reaction assay • D. a toxin assay • E. an ova and parasite assay