Infectious Diarrhea Nicole Leone July 29th, 2013

Viral vs. Bacterial Age Presence of blood or mucus Exposures 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

Work Up Fecal Leukocytes Stool Culture Stool for Ova and Parasites 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

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

Salmonellosis Course Treatment < 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

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

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, Guillain Barre Syndrome

E.coli Enterotoxigenic E.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 Enteropathogenic E.coli (EPEC) Diarrheal illness most common in children < 6mo Diagnosis via PCR Enterohemorrhagic E.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)

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

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)

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 **Esp dangerous in patients with HIV

Giardiasis Diagnosis: stool microscopy 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 Diagnosis: stool microscopy Treatment: all symptomatic patients Metronidazole, Tinidazole, Nitazoxanide **giardia cysts survive readily in mountain streamsgiardiasis is important cause of diarrheal illness in hikers Giardia trophozoite

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

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

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%

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. Fam Hx 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.

Question #1 Of the following, the MOST likely cause of her illness is: A. Campylobacter jejuni infection B. Clostridium difficile infection C. Entamoeba histolytica infection D. Escherichia coli O157:H7 infection E. Shigella dysenteriae infection Symptoms of colitis: hematochezia, tenesmus Campylobacter found in GI tract of animals (domestic and wild poultry, dogs, cats), dogs have been implicated in transmission, in kennel environments C. diff: MCC of antibiotic associated colitis Entamoeba infection is rare cause of infectious colitis in US E.coli can be assoc w/ petting zoos, usually causes ENTERITIS Shigella, often found in child care centers and areas with crowded living conditions

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.

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 Chitterlings = pork intestines Diarrhea likely caused by Yersinia enterocolitica, diagnosis must be established by sending a stool culture to be processed on selective media (CIN agar) Routine stool culture detects Salmonella, Shigella, pathogenic E.coli Right answer; infant likely infected when hands of caregivers are contaminated and not washed prior to handling infant PCR is not commercially available Toxin assay is for C.diff; since 50% of healthy infants can be colonized with C.diff, stool toxin assay would not be helpful Bottle fed infant would be unlikely to have been exposed to a parasite