GI infections (3)

Question 1

list the GI tract infections we are expected to know

Answer 1

1. C. difficile
2. gastroenteritis/travellers diarrhea
3. rotavirus
4. hepatic abscess
5. H. pylori related infections
6. esophagitis

Question 2

what is the #1 etiologic cause of antibiotic related diarrhea

Answer 2

C. difficile

96% of C. diff infections are antibiotic related

Question 3

how is C. difficile transmitted

Answer 3

fecal oral

Question 4

how can a C. difficile infection present

Answer 4

1. asymptomatic colonization
2. mild-moderate diarrhea
3. severe pseudomembranous colitis

Question 5

what is a pseudomembrane

Answer 5

a layer of exudate resembling a membrane, formed on the surface of the skin or a mucous membrane

Question 6

what is pseudomembranous colitis

Answer 6

C. difficile infection

Question 7

what antibiotics can cause C. difficile?

which are the most risky?

Answer 7

all antibiotics can cause C. difficile

most risky = CLINDAMYCIN and CIPROFLOXACIN
lincosamide and fluoroquinolone

Question 8

what are the toxins associated with C. diff, and what type of toxin are they

Answer 8

toxin A and toxin B

A = enterotoxin
B=cytotoxin (more potent)

Question 9

how does C. difficle cause disease

Answer 9

colonization of the colonic mucosa–> antibiotic therapy (disruption of normal intestinal flora)–>C. diff releases toxin A and toxin B–> mucosal injury and inflammation–> C. difficile colitis

Question 10

what is the J strain of C. diff

Answer 10

epidemic CLINDAMYCIN RESISTANT strain

Question 11

what is the NAP1/B1/027 strain of C. diff

Answer 11

emergent virulent strain

produces more toxins A and B, have higher recurrence, less clinical cure

FLUOROQUINOLONE resistance

Question 12

how long after Ab Tx does C. diff present

Answer 12

during Ab Tx or within 2 weeks

Question 13

what type of diarrhea does C. diff cause

Answer 13

watery

> 3 stools/day

Question 14

describe the clinical presentation of C. diff

Answer 14

watery diarrhea
elevated WBCs
60% have unexplained leukocytosis
low grade fever

Question 15

what is fulminant colitis

Answer 15

can arise as a result of C. diff infection

“toxic megacolon”

abdominal pain, distention, lactic acidosis, hypovolemia, high WBC, may NOT have diarrhea, pseudomembranes

URGENT SURGICAL EVAL

Question 16

Tx of C. diff (protocol)

Answer 16

1. Assess (vital signs, abdo exam, hydration; CBC, chemistry)
2. contact precautions
3. STOP: all possible antibiotics, proton pump inhibitors, all anti-diarrheal agents

Question 17

Tx of C. diff (meds)

Answer 17

1. mild-moderate disease–> METRONIDAZOLE
   reassess after 4-6 days and if not improved, add oral VANCOMYCIN
2. severe disease or recurrence–> oral VANCOMYCIN
   reassess in 4-6 days and if not better add METRONIDAZOLE

always: monitor patients closely, use ORAL vancomycin, contact GI, ID and surgery in severe disease

Question 18

what % of returning travellers get travellers diarrhea

Answer 18

30-70%

Question 19

is most travellers diarrhea viral or bacterial

Answer 19

bacterial

Question 20

what are the most common etiologic agents of travellers diarrhea

Answer 20

1. ETEC
2. Enteroaggregative E. coli (EAEC)
3. campylobacter jejuni
4. Salmonella spp
5. Shigella spp

Question 21

would you suspect intestinal helminths in a returning traveller with diarrhea?

Answer 21

not usually as most are asymptomatic and wouldn’t cause travellers diarrhea as much as a bacterial cause would

Question 22

what would you suspect as the etiologic agent in travellers diarrhea with the following presentations:

1. acute onset
2. gradual onset or chronic low grade diarrhea
3. bloody with fever
4. brief episode of vomiting and diarrhea resolving within 12 hours

Answer 22

1. bacterial or viral
2. protozoa (giardia or entamoeba histolytica)
3. (dysentery) shigella, campylobacter or salmonella
4. ingested toxin (food poisoning)

Question 23

though its usually not necessary to ID the pathogen in traveller’s diarrhea, when you need to, how do you do it?

Answer 23

1. stool culture for immunocompromised patients or in outbreaks, or with dysentery presentation–> can ID shigella, campylobacter, salmonella
   - CANT distinguish ETEC/EAEC from nonpathogenic E. coli and cant ID viral causes
2. stool microscopy (“ova and parasites”)
   - for giardia, cyclospora, entamoeba, microsporidia, cryptosporidia
   - order for symptoms lasting more than 10 days
3. direct fluorescent antibody (DFA)/ enzyme immunoassay for giardia and cryptosporidium

Question 24

would you or would you not use anti-motility agents with dysentery

Answer 24

NO

use anti motility agents only with Abs

Question 25

what is the leading cause of acute diarrhea in children

Answer 25

rotavirus responsible for 40% of hospital admissions worldwide

Question 26

what are the largest factors in diarrheal deaths?

Answer 26

unsafe water inadequate sanitation poor hygiene

Question 27

where do most diarrhea deaths occur

Answer 27

Africa | South Asia

Question 28

how many rotavirus particles are required for infection

Answer 28

10

Question 29

what is the most common age affected by rotavirus

Answer 29

6-24 months babies are protected by IgA in breastmilk

Question 30

how do you diagnose rotavirus

Answer 30

ELISA or latex agglutination or PCR

Question 31

how do you treat rotavirus

Answer 31

ORS Zinc continued breastfeeding

Question 32

how do you prevent rotavirus

Answer 32

ROTARIX vaccine 2 doses at 2 and 4 months

Question 33

do hepatic abscesses usually present with bowel symptoms

Answer 33

no, often present without

Question 34

what is the most likely organism causing amoebic liver abscess

Answer 34

entamoeba histolytica | or E. dispar

Question 35

how do you distinguish between E. histolytica and E. dispar as the cause of an ALA?

Answer 35

their cysts are indistinguishable on microscopy E. histolytica can have ingested RBCs whereas E. dispar doesn't E. histolytica have invasive disease (liver, intestine, lung, brain) whereas E. dispar is asymptomatic colonization

Question 36

which is more common in the developed world, ALA or bacterial liver abscess

Answer 36

bacterial

Question 37

what is the source of ALA infection? bacterial liver abscess?

Answer 37

ALA = 100% hematogenous bacterial = biliary (60%), hematogenous (20%) and other like trauma, iatrogenic, extension

Question 38

what is the aspirate like in ALA? in bacterial?

Answer 38

ALA = brown, no odor, "anchovy paste" quality bacterial = purulent, green/yellow, foul odor

Question 39

what organisms cause bacterial liver abscesses

Answer 39

1. E. coli 2. Klebsiella 3. Strep 4. enterococcus 5. bacteroides often polymicrobial

Question 40

what are serology results for ALA? bacterial liver abscecss?

Answer 40

``` ALA = + bacterial = - ```

Question 41

Tx for ALA

Answer 41

1. METRONIDAZOLE | 2. paramomycin/iodoquinol

Question 42

Tx for bacterial liver abscess

Answer 42

empiric coverage for enteric GNRs, enterococcus, anaerobes

Question 43

what is the most common cause of gastritis

Answer 43

H. pylori related infections

Question 44

what is the most common chronic bacterial infection in humans

Answer 44

H. pylori related infections

Question 45

what causes 90% of duodenal ulcers

Answer 45

H. pylori

Question 46

how is H. pylori transmitted

Answer 46

fecal-oral and oral-oral

Question 47

what bacteria increases the risk of gastric cancer

Answer 47

H. pylori

Question 48

pathophysiology of H. pylori infections

Answer 48

bacterial UREASE hydrolyzes urea --> NH4 NH4 neutralizes stomach acid SPIRAL shaped, flagella, and MUCOLYTIC enzymes of H. pylori allow it to "swim" through mucous to epithelium ADHESINS bind to epithelial receptors

Question 49

who do you test for H. pylori

Answer 49

anyone with: gastric cancer active PUD of Hx of PUD anyone with symptoms of dyspepsia

Question 50

what tests do you use for H. pylori

Answer 50

1. urease breath test (really sensitive and specific) 2. serology (ELISA, IgG) 3. stool antigen (less accurate) 4. endoscopy and biopsy (for urease, histology and culture)--> do in older patients with "danger signs"

Question 51

Tx of H. pylori

Answer 51

HP-Pac--> Lansoprazole + clarithromycin + amoxicillin (14 days) 20% of pts fail first Tx

Question 52

what is the primary HIV opportunistic infection when CD4 cell count falls below 200

Answer 52

thrush

Question 53

how do you treat oropharyngeal candidiasis

Answer 53

NYSTATIN rinse clotrimazole troches ARVs if HIV+ fluconazole

Question 54

what is esophageal candidiasis

Answer 54

esophagitis usually with thrush HIV or other immunosuppresion = comorbid

Question 55

Tx of esophageal candidiasis

Answer 55

always SYSTEMIC antifungals empiric Tx same in immunocompromised as competent FLUCONAZOLE echinocandins amphotericin B

Question 56

what are GI infections usually caused by?

Answer 56

usually due to ingestion of a pathogen or toxin that either localizes to the gut or disseminates beyond can also be caused by disruption of normal gut flora, gut architecture or host immune system

Question 57

what causes most travellers diarrhea

Answer 57

ETEC or EAEC usually doesnt require diagnostic tests or antibiotics

Question 58

is liver abscess serious?

Answer 58

YES it is a serious condition that requires prompt hospitalization, CT scan, empiric Ab therapy to cover ENTERIC GRAM - RODS, ENTEROCOCCUS and ANAEROBES

Question 59

most common cause of bacterial liver abscess

Answer 59

biliary tract obstruction or infection

Question 60

how does most entamoeba present?

Answer 60

usually asymptomatically

Question 61

how does E. histolytica usually present

Answer 61

can be locally invasive and disseminate (i.e ALA)

Question 62

who requires an evaluation for immunosuppresion on presentation with thrush

Answer 62

patients older than 12 months old