Pathology of the GI Tract- SI and Colon (6)

Question 1

infectious enterocolitis presents with a broad range of symptoms including what?

Answer 1

diarrhea, abdominal pain, urgency, perianal discomfort, incontinence, and hemorrhage

Question 2

what should the diagnostic tests for infectious enterocolitis be driven by?

Answer 2

clinical history

Question 3

few or no leukocytes and many erythrocytes in fecal test suggests what?

Answer 3

amebiasis

Question 4

what are the characteristics of vibrio cholerae?

Answer 4

they are comma-shaped, gram negative bacteria

Question 5

what is cholera?

Answer 5

a disease that has been endemic in the Ganges Valley of India and Bangladesh throughout history

Question 6

how are the stools described in cases of cholera?

Answer 6

rice water stools with a fishy odor

Question 7

what is the most common bacterial enteric pathogen in developed countries and is an important cause of traveler’s diarrhea?

Answer 7

C. jejuni

Question 8

what causes campylobacter enterocolitis?

Answer 8

c. jejuni

Question 9

how does one typically get c. jejuni?

Answer 9

improperly cooked chicken, unpasteurized milk, or contaminated water

Question 10

how does campylobacter enterocolitis present?

Answer 10

watery or bloody diarrhea; enteric fever; reactive arthritis , guillain-barre, and erythema nodosum

Question 11

what is bloody diarrhea generally associated with?

Answer 11

bacterial invasion and is caused by only a minority of campylobacter strains

Question 12

what is enteric fever?

Answer 12

systemic infection that is associated with abdominal pain and fever- non-specific

Question 13

when does enteric fever occur?

Answer 13

when bacteria proliferate within the lamina propria and mesenteric lymph nodes

Question 14

what patients are at more of a risk of getting reactive arthritis when infected with campylobacter infection?

Answer 14

patients with HLA-B27 genotype

Question 15

what is guillain-barre syndrome?

Answer 15

acute inflammatory demyelinating polyneuropathy; an ascending process

Question 16

what is erythema nodosum?

Answer 16

a type of skin inflammation that is located in a part of the fatty layer of the skin

Question 17

how does erythema nodosum typically present?

Answer 17

reddish, painful, tender lumps most commonly located in the front of the legs below the knees

Question 18

what are the characteristics of shigella?

Answer 18

they are gram-negative unencapsulated, nonmotile, facultative anaerobes that belong to the Enterobacteriaceae family and are closely related to enteroinvasive E. coli

Question 19

what is the most common causes of bloody diarrhea worldwide?

Answer 19

shigella

Question 20

who is at risk for getting infected with shigella?

Answer 20

in the US and europe- children in daycare centers, migrant workers, travelers to low resource countries, and individuals in nursing homes

Question 21

who is at risk of death associated with shigella?

Answer 21

deaths are generally limited to children younger than 5 years of age

Question 22

where is shigella endemic?

Answer 22

in countries with poor sanitation

Question 23

in what part of the GI tract does shigella most commonly infect?

Answer 23

shigella infections are most prominent in the left colon, but the ileum may also be involved, perhaps reflecting the abundance of M cells in the dome epithelium overlying Peyer patches

Question 24

what is the histology like in cases of shigella?

Answer 24

because of the tropism for M cells, aphthous ulcers similar to those seen in Crohn disease may occur

Question 25

what does the mucosa look like in cases of shigella?

Answer 25

it is hemorrhagic and ulcerated, and pseudomembranes may be present

Question 26

after an incubation period of up to 1 week, what does shigella cause?

Answer 26

self-limited disease characterized by 7-10 days of diarrhea, fever, and abdominal pain (enteric fever)

Question 27

how does shigella infection present in children?

Answer 27

duration of symptoms is usually shorter in children, but severity is often much greater

Question 28

in adults, what is an uncommon subacute presentation of shigella?

Answer 28

weeks of waxing and waning diarrhea that can mimic new-onset ulcerative colitis

Question 29

what does confirmation of shigella require?

Answer 29

stool culture

Question 30

how should you treat shigella infections?

Answer 30

antibiotics but NOT antidiarrheal medications

Question 31

what are the complications associated with shigellosis?

Answer 31

extra-intestinal manifestations (reactive arthropathy); shiga toxin can cause hemolytic-uremic syndrome; toxic megacolon

Question 32

discuss the likelihood of becoming infected with salmonella?

Answer 32

very few viable salmonella are necessary to cause infection; the absence of gastric acid, in individuals with atrophic gastritis or those on acid-suppressive therapy, further reduces the required inoculum

Question 33

what population of people is salmonella most common?

Answer 33

young children or older adults, with peak incidence in the summer and fall

Question 34

what is essential for the diagnosis of salmonella?

Answer 34

stool cultures

Question 35

what are the two types of salmonella infection?

Answer 35

typhoidal and non-typhoidal

Question 36

what does typhoidal salmonella infection cause?

Answer 36

typhoid fever and paratyphoid fever

Question 37

what does non-typhoidal salmonella cause?

Answer 37

gastroenteritis and food poisoning

Question 38

infection by salmonella paratyphi is more common among what group of people?

Answer 38

travelers

Question 39

what areas are strongly associated with salmonella typhoidal?

Answer 39

travel to india, mexico, philippines, pakistan, el salvador, and haiti

Question 40

who is the reservoir for salmonella typhi and paratyphi?

Answer 40

humans

Question 41

gallbladder colonization with S. typhi or S. paratyphi may be associated with what?

Answer 41

gallstones and a chronic carrier state

Question 42

how does acute infection with salmonella typhi present?

Answer 42

anorexia, abdominal pain, bloating, nausea, vomiting, and bloody diarrhea; followed by a short asymptomatic phase that gives way to bacteremia and fever with flu-like symptoms; abdominal tenderness may mimic appendicitis

Question 43

what does systemic dissemination of salmonella typhi cause?

Answer 43

extraintestinal complications including encephalopathy, meningitis, seizures, endocarditis, myocarditis, PNA, and cholecystitis

Question 44

who are the at risk groups for salmonella typhi?

Answer 44

cancer, immunosuppression, EtOH, cardiovascular, sickle cell, hemolytic anemia patients

Question 45

what skin manifestation is associated with salmonella typhi infection?

Answer 45

erythematous maculopapular rash (rose spots)

Question 46

what are 3 species of yersinia?

Answer 46

enterocolitica, pseudotuberculosis, pestis

Question 47

how is iron associated with yersinia?

Answer 47

iron enhances virulence and stimulates systemic dissemination- this explains why individuals with increased non-heme iron, such as those with certain chronic forms of anemia or hemochromatosis, are at greater risk for sepsis and death

Question 48

What part of the GI tract does yersinia typically involve?

Answer 48

right side: ileum, appendix, and right colon

Question 49

where do the yersinia organisms proliferate?

Answer 49

extracellularly in lymphoid tissue, resulting in regional lymph node and peyer patch hyperplasia as well as bowel wall thickening

Question 50

what happens to the mucosa in yersenia infections?

Answer 50

the mucosa overlying lymphoid tissue may become hemorrhagic and aphthous erosions and ulcers may appear along with neutrophil infiltrates and granulomas

Question 51

what is yersinia sometimes confused with?

Answer 51

crohn disease

Question 52

what are the post yersinia infection complications?

Answer 52

reactive arthritis with urethritis and conjunctivitis, myocarditis, erythema nodosum, and kidney disease

Question 53

what are the characteristics of escherichia coli?

Answer 53

they are gram-negative bacilli that colonize the healthy GI tract; most are nonpathogenic, but a subset cause human disease

Question 54

what is ETEC?

Answer 54

enterotoxigenic- principal cause of traveler's diarrhea

Question 55

what is EHEC?

Answer 55

enterohemorrhagic- E. coli O157:H7 and nonOH157:H7

Question 56

what is pseudomembranous colitis?

Answer 56

disruption of the normal colonic microbiota by antibiotics allows overgrowth of Clostridioides difficile

Question 57

who is at risk for pseudomembranous colitis?

Answer 57

in addition to antibiotic treatment, risk factors include advanced age, hospitalization, and immunosuppression

Question 58

what are pseudomembranes made up of?

Answer 58

an adherent layer of inflammatory cells and debris

Question 59

what is specifically characteristic or indicative of pseudomembranous colitis?

Answer 59

pathognomonic histopathology

Question 60

what is the presentation of pseudomembranous colitis?

Answer 60

fever, leukocytosis, abdominal pain, cramps, watery diarrhea, and dehydration

Question 61

what is a potentially fatal complication associated with pseudomembranous colitis?

Answer 61

toxic megacolon

Question 62

how is the diagnosis of pseudomembranous colitis typically made?

Answer 62

by detection of C. difficile toxin, rather than by culture, and supported by the characteristic histopathology

Question 63

what are generally effective therapies for pseudomembranous colitis?

Answer 63

metronidazole and vancomycin

Question 64

what is whipple disease?

Answer 64

a rare, multivisceral chronic disease, first described as intestinal lipodystrophy

Question 65

what population of people is whipple disease most common?

Answer 65

in caucasian men, particularly farmers and others with occupational exposure to soil or animals

Question 66

what is the clinical presentation of whipple disease?

Answer 66

triad of diarrhea, weight loss, and arthralgia

Question 67

what are the extraintestinal symptoms associated with whipple disease that typically precede malabsorption?

Answer 67

arthritis, arthralgia, fever, lymphadenopathy, and neurologic, cardiac, or pulmonary disease

Question 68

what is the morphologic hallmark of whipple disease?

Answer 68

a dense accumulation of distended, foamy, macrophages in the small intestinal lamina propria

Question 69

what do the macrophages seen in whipple disease contain?

Answer 69

periodic acid-Schiff (PAS)- positive, diastase-resistant granules that represent partially digested bacteria within lysosomes

Question 70

a similar infiltrate of foamy macrophages is present in intestinal mycobacterial infections, and the organisms are PAS-positive in both whipple disease and mycobacterial infections. How can you tell them apart?

Answer 70

the acid-fast stain can be helpful, since mycobacteria stain positively, while T. whippelii does not

Question 71

approximately half of all gastroenteritis outbreaks worldwide are thought to be due to what?

Answer 71

norovirus

Question 72

what is responsible for most sporadic cases of norovirus?

Answer 72

fecal-oral transmission

Question 73

where do norovirus infections spread easily?

Answer 73

within schools, hospitals, nursing homes, and other large groups in close quarters, such as on cruise ships

Question 74

who is especially at risk for significant infections of norovirus?

Answer 74

immunocompromised patients

Question 75

what is rotavirus?

Answer 75

an encapsulated virus with a segmented, double-stranded RNA genome

Question 76

who is the most vulnerable for rotavirus?

Answer 76

children between 6 and 24 months

Question 77

where are rotavirus outbreaks common?

Answer 77

in hospitals and daycare centers

Question 78

what is the effect of rotavirus?

Answer 78

the loss of absorptive function and net secretion of water and electrolytes is compounded by an osmotic diarrhea cause by the incomplete absorption of nutrients