Gastrointestinal Infections Flashcards
Define acute diarrhea? Likely etiology?
0-14 days
Viral or bacterial
Define persistent diarrhea? Likely etiology?
14-29 days
Viral or bacterial in immunocompromised.
Define chronic diarrhea? Likely etiology?
30 days or more
Parasites, noninfectious etiology should be excluded
History to get in diarrhea patient [6]
- Travel
- Trips to pools, lakes, brackish or salt water
- Occupational history
- Abx use or healthcare exposure
- Animal contacts
- Prison or child care
Red flag symptoms of gastroenteritis [10]
- Persistent stook >1 week
- Fever
- Bloody diarrhea
- Severe abdominal pain
- Weight loss
- Dehydration
- Recent abx use or hospital stay
- Pregnancy
- Age over 65
- DM or HIV patient.
Who with diarrhea should get abx? [2]
- Immunosuppressed who are systemically unwell with fever or bloody diarrhea or abdominal pain
- Returning travelers with temp >38.5 and/or sepsis
Who absolutely should NOT get abx? [2]
E. coli 0157
Shiga toxin producing organisms
Duration of viral gastroenteritis based on etiology?
Noro: 2 days
Rota: 3-8 days
Diagnosis of viral gastroenteritis
Mostly clinical with N/V/diarrhea
EIA for noro, adeno, rota virus available
PCR for viruses is also available
PCR is more sensitive and specific than EIA
Treatment of viral gastroenteritis?
<65 a 1-2 day course of loperamide can be used
AVOID if bloody diarrhea or age >65 [risk of paralytic ileus]
What type of virus is norovirus?
RNA
Calicivaradea
Most common cause of gastroenteritis world wide?
Norovirus
Incubation period of norovirus?
24-48 hours
Lab abnormalities in norovirus?
WBC may be normal or elevated
Lymphopenia
Infection control and prevention principles for norovirus
- Private room
- Wash hands with soap and water
- Exclude people from work for 48-72 hours after resolution of symptoms
Most common causes of bacterial diarrhea in US? [7]
- Salmonella
- Camphy
- Shigella
- Shiga toxin producing E. coli
- Vibrio
- Yersinia
- Listeria
Name the pathogenic forms of E. coli [5]
- Enterotoxigenic [ETEC]
- Enteropathogenic [EPEC this is mostly in kids <6 mos]
- Enterohemorrhagic [EHEC AKA Shig toxin producing E. coli AKA STEC]
- Enteroinvasive [EIEC]
- Enteroaggregative [EAEC]
How does ETEC typically look?
Diarrhea in returning travelers with nausea but no vomiting.
Symptoms last ~5 days
What toxins does ETEC make? [2]
Heat-stable
Heat-labile
Presentation of EIEC?
Watery diarrhea that may progress to bloody
–> RARE.
Presentation of EAEC?
Persistent diarrhea in immune compromised
Two types of EHEC?
E. coli 0157:H7
E. coli O104:H4 [Shiga toxin producing]
Presentation of EHEC?
- Bloody diarrhea
- Abdominal tenderness
- No fever
EHEC complication
Pseudomembranous colitis
HUS 5-10 days after diarrhea
Intussusception
What type of culture should be done to diagnos EHEC?
MacConkey Sorbitol agar for O157:H7
Who gets HUS
Mostly those <10 years old
Abx use increases risk of HUS 25%
Gram stain of camphy?
Gram negative S or spiral shaped
Animal exposure related to camphy?
Poultry and birds
Who do you get camphy?
Eating undercooked meat Cross contamination of food from infected raw meat. Swimming or drinking contaminated water Person to person spread is rare. Sexual transmission in MSM rarely
Risk factors for camphy infection?
Decreased stomach acid [achkirhydria]
PPI use.
Camphy presenation
Incubation 3 days [mean 1-7]
Prodrome of fevers, rigors, dizziness prior to GI symptoms in 1/3
Watery or bloody diarrhea which is self limiting lasting 1 wk
N/V in 15-25%
Abrupt abd pain often periumbicical
Abd pain may mimic appendicitis and persist after diarrhea
Risk of campy bactermia
<1%
How long are patients after symptoms of camphy have resolved infectious?
Shed without symptoms for 38 days
Relapse in 5-10% with recurrent infections and bacteremia
Camphy complications [3]
Guillain-Barre
Reactive arthritis
Colitis
Tx or reactive artheitis? [2]
- Supportive
2. NSAIDs
GBS following camphy…
Occurs how often?
When does it occur?
Why does it occur?
Occurs in 3-40% of those infected
Occurs 1-2 weeks after infection
Due to formation of GM1 ganglioside antibody present in peripheral nerve myelin
How does miller fisher GBS look?
Ataxia, eye muscle weakness, areflexia but usually no limb weakness
How does post camphy colitis look
Effects ileum and jejunum
May go on to effect cecum and colon
May be part of pathogenesis of IBD
Diagnosis of GBS or reactive arthritis due to camphy?
- Stool cultures will be negative
- Use serology, ELISA, or compliment fixation
Who with camphy diarrhea should get abx? [5]
- Immunosuppressed
- Elderly
- Pregnant
- Sever disease [fever + bloody diarrhea, symptoms >1 wk]
- Relapsing symptoms
Treatment if abx is infected for camphy diarrhea? [2]
Azitho
Cipro Alt
3 days in normal host
1-2 weeks in severe disease or immunocompromised
Treatment for camphy bacteremia
Carbapenem + aminoglycoside
What are the two non-typhoidal salmonella?
- Enteritidis
2. Typhimurium
What type of disease does non-typhoidal salmonella cause?
Inflammatory diarrhea
When does non-typhoidal salmonella peak?
Summer and fall
What types of exposure places one at risk for non-typhoidal salmonella?
- Poultry
- Eggs [Transovarial transmission from infected hens to intact egg shells].
- Fresh Produce
- Contaminated infant milk formula
Presentation of non-typhoidal salmonella
Incubation of 8-72 hours
Fever, diarrhea, abdominal pain, nausea, vomiting
Fever for 48-72 hours
Diarrhea for 4-7 days
How often does non-typhoidal salmonella develop bactermia?
<5%
Complications of non-typhoidal salmonella bactermia? [4]
- Mycotic aneurysms
- Abscesses
- Osteomyelitis
- Endocarditis
Diagnosis of non-typhoidal salmonella
- Stool culture
2. Blood culture if persistent fever.
Treatment of non-typhoidal salmonella
Avoid abx in most due to risk of prolonged carriage
Supportive
Who with non-typhoidal salmonella should get abx? [7]
- Immunocompromised
- HIV patients
- Age >50 due to increased risk of endovascular infection
- Stools >9-10 days
- Persistent fever
- Hospital admission
- Cardiac or other valvular disease
Abx selection for non-typhoidal salmonella [4]
- Azithro [preferred]
- Cipro/Levo [only 0.4% resistance in USA]
- 3rd gen cephalosporins [2.4% resistance for ceftriaxone]
- Bactrim [alt]
Length of treatment for non-typhoidal salmonella [3]
3-7 for severe non-bactermic disease
3-14 if at risk for endovascular or joint complications
2-6 weeks if HIV
Which type of non-typhoidal salmonella is cleared quickly and has lower risk of carriage?
Typhimurium
Define chronic carriage with non-typhoidal salmonella
Continued shedding for over 1 year with repeated positive cultures.
Who tends to become chronic non-typhoidal salmonella carriers?
- Women
- Older adults
- Young children
- Biliary tract abnormalities such as gallstones
Treatment of non-typhoidal salmonella chronic carriage
Quinolones for 4-6 weeks
Amoxicillin for 6 weeks
Bactrim for 12 weeks
May need cholecystectomy
Follow up cultures 6 months after completed therapy
Etiology of enteric fever aka typhoid fever
- Salmonella enterica serotype Typhi
2. Salmonella enterica serotype Paratyphi A, B, and C
Where does enteric/typhoid fever occur?
Asia and Africa most commonly.
Who gets enteric/typhoid fever [2]
- Children
- Adults
–> Elderly is less common.
Who becomes a chronic carrier in enteric/typhoid fever [2]
- Women
2. Those with gallstones
What is chronic carriage in enteric/typhoid fever?
Sheds in stool and urine for >12 months following infection in 1-6% of patients.
Risk factors for shedding salmonella in the urine? [3]
- BPH
- Renal Stones
- Concurrent schistosoma infection
Presentation of enteric/typhoid fever
Week 1: Fever >40 C with chills and rigors. Faget’s sign. Diarrhea OR constipation.
Week 2: Abd pain with rose spots transiently
Week 3: Abd perforation secondary to necrosis and lymphatic hyperplasia of Peyer’s patches. Hepatosplenomegaly, GI bleeding, septic shock, AMS.
Alternatively infection may resolve in a few weeks to months without abx.