infectious diarrhea

Question 1

Definition of diarrhea

Answer 1

acute: 14, chronic more than 14 days

Question 2

acute diarrhea clinical course

Answer 2

Usually self limitied, usually infectious, but even non-infectious cases will typically resolve

Average 3-7 BM per day
Volume <1 L/day
Most occur in winter months

Question 3

Infectious causes of acute diarrhea

Answer 3

Most gastroenteritis is viral, cultures only positive in 1.5-7 % of cases

Severe community acquired diarrhea; >4 fluid stools a day, > 3 days, 87% are bacterial

Question 4

Agents that commonly cause acute gastrointestinal illnesses

Answer 4

Bacteria- salmonella, shigella, campylobacter, e coli 0157h7, C diff

Viruses- Calcivised (norwalk-like and related), Rotavirus, adenovirus, astrovirus

Protozoa- giarda, cryptosporidium, entamoeba histolytica

Question 5

salmonella typhi

Answer 5

non-typhoid salmonella is much more common in US than typhoid type

Gram neg encapsulated bacilli
Poultry, eggs, and milk
Pet turtles
Risk factors-summer and fall, youngsters, IBD, immune deficiencies
colonic or dysenteric like illness although its a small bowel disease

Question 6

typhoid fever

Answer 6

gallbladder colonization associated with gall stones and a chronic carrier state– carrier state may cause falsely elevated frequency

Acute infection- anorexia, abdominal pain, bloating, nausea, vomiting, bloody diarrhea

Can develop bacteremia and fever

pts with SCD are susceptible to salmonella osteomyelitis

Question 7

salmonella

Answer 7

quickly adapts to low pH (stomach), microbiome protects against pathogenesis

Antibiotics–> may increase pathogenesis

Uptake into cell, survive in modified phagosome, and replicate

induce migration of neutrophils–> inflammatory response

Non-typhoid salmonella generally self limited except- high fevers, severe diarrhea, hospitalized pts

Question 8

campylobacter jejuni

Answer 8

leading cause of acute bacterial diarrhea world wide
33% of foodborne illnesses
undercooked poultry, unpasteurized milk or contaminated water
Ingestion of as a few as 500 C jejuni organisms
Incubation period of up to 8 days

Usually an influenza like prodrome, fever malaise, myalgias

Dysentery develops in 15-50% of pts

Self limited (ABx not always needed), watery or hemorrhagic, both small and large bowel symptoms

Question 9

Campylobacter presentations

Answer 9

can result in reactive arthritis or erythema nodosum
Guillain Barre syndrome
Peripheral–> central progressive paralysis caused by autoimmine- induced inflammation of peripheral nerves

Abdominal pain typically really bad with pseudo appendicitis, (yersinia can also do this)

Question 10

Giardia lamblia

Answer 10

flagellated protozoan, most common parasitic infection in humans, fecally contaminated water or food, endemic in unfiltered public and rural water supplies (well water, drinking from mountain streams),
acute or chronic diarrhea with upper abdominal bloating
Small bowel disease

Question 11

E coli

Answer 11

gram negative bacilli that colonize the healthy GIT, nost are non pathogenit but a small subset cause human disease

There are a variety of different types of E coli that are defined based on how they cause disease

Question 12

Enterohemorrhagic E COlui (EHEC)

Answer 12

E coli O157 H7
Undercooked beef or mishandling of ground beef, 4% oof foodborne illness,
39% of cultured pathogens in visibly BLOODY speciments

Associated with Hemolytic Uremic Syndrome (HUS), hemolysis, thrombocytopenia, and renal failure

Antibiotics may induce HUS

Question 13

Enterotoxigenic E coli (ETEC)

Answer 13

eTec= Travelers diarrhea

Fecal oral route
Express either LT or ST or both, heat labile (LT) toxin thats similar to cholera toxin, heat stable (ST) that increases intracellular cGMP with effect similar to the cAMP caused by LT

cAMP–> secretion of CL thru its channel, and prevent reabsorption of NaCl at villus tips –> Net Water secretion

Question 14

Enteroinvasice E coli (EIEC) and Enteroaggregative E colli (EAEC)

Answer 14

EIEC- resemble shigella in pathogenesis, invade the gut epithelial cells, produce a bloody diarrhea

EAEC- attach to enterocytes by adherence fimbrae, flagellan–> increases IL-8 –> intestinal inflammation
Although they produce a LT and Shiga-like toxins, histologic damage is minimal from these

Question 15

shigella

Answer 15

Gram negative bacilli that are unencapsulated, facultative anaerobes

Responsible for 10% of pediatric diarrheal disease (75% of diarrheal deaths)

Fecal oral route–highly contagious (as few as 10 organsims, acid resistant)
Daycare and institional setting can be transmitted person to person

Self limited 6 days of diarrhea, fever and abdominal pain, affects the left colon but ileum may be involved, Abx shortens symtptoms, Antidiarrheal are contraindicated, HUS, Seizures, reactive arthritis, Shiga like toxin

Question 16

vibrio cholerae

Answer 16

Gram neg bacteria, contaminated drinking water, seafood associated disease (animal reservoirs- shellfish and plankton)
Non invasive, remains within intestinal lumen

Enterotoxin, cholera toxin–> Increased cAMP–> opens CF TR–> releases chloride into the lumen–> draws water into the lumen

Watery diarrhea

Question 17

Norovirus

Answer 17

gastroenteritis out breaks world wid, contaminated food and water

schools cruise ships
Nausea, vomiting, watery diarrhea and abdomina pain
Self limited

Question 18

Rotavirus

Answer 18

childhood diarrhea and now theres a vaccine, hosptials and day cares

comiting and diarrhea

Question 19

cdiff treatment

Answer 19

clindamycin

Recent antibiotic adnd long duration og hospital stay immunosuppressed

fecal oral transmission of spores

Toxin a and b

Infants rearly get the disease,

Flagellar proteins and adhesion protien

toxic megacolon cause

Wear gloves and antibiotics, vancomycin and metronidazole