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IDMM > GI infections (3) > Flashcards

GI infections (3) Flashcards

1
Q

list the GI tract infections we are expected to know

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

what is the #1 etiologic cause of antibiotic related diarrhea

A

C. difficile

96% of C. diff infections are antibiotic related

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3
Q

how is C. difficile transmitted

A

fecal oral

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4
Q

how can a C. difficile infection present

A
  1. asymptomatic colonization
  2. mild-moderate diarrhea
  3. severe pseudomembranous colitis
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5
Q

what is a pseudomembrane

A

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

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6
Q

what is pseudomembranous colitis

A

C. difficile infection

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7
Q

what antibiotics can cause C. difficile?

which are the most risky?

A

all antibiotics can cause C. difficile

most risky = CLINDAMYCIN and CIPROFLOXACIN
lincosamide and fluoroquinolone

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8
Q

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

A

toxin A and toxin B

A = enterotoxin
B=cytotoxin (more potent)

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9
Q

how does C. difficle cause disease

A

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

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10
Q

what is the J strain of C. diff

A

epidemic CLINDAMYCIN RESISTANT strain

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11
Q

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

A

emergent virulent strain

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

FLUOROQUINOLONE resistance

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12
Q

how long after Ab Tx does C. diff present

A

during Ab Tx or within 2 weeks

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13
Q

what type of diarrhea does C. diff cause

A

watery

> 3 stools/day

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14
Q

describe the clinical presentation of C. diff

A

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

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15
Q

what is fulminant colitis

A

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

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16
Q

Tx of C. diff (protocol)

A
  1. Assess (vital signs, abdo exam, hydration; CBC, chemistry)
  2. contact precautions
  3. STOP: all possible antibiotics, proton pump inhibitors, all anti-diarrheal agents
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17
Q

Tx of C. diff (meds)

A
  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

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18
Q

what % of returning travellers get travellers diarrhea

A

30-70%

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19
Q

is most travellers diarrhea viral or bacterial

A

bacterial

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20
Q

what are the most common etiologic agents of travellers diarrhea

A
  1. ETEC
  2. Enteroaggregative E. coli (EAEC)
  3. campylobacter jejuni
  4. Salmonella spp
  5. Shigella spp
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21
Q

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

A

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

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22
Q

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
A
  1. bacterial or viral
  2. protozoa (giardia or entamoeba histolytica)
  3. (dysentery) shigella, campylobacter or salmonella
  4. ingested toxin (food poisoning)
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23
Q

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

A
  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
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24
Q

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

A

NO

use anti motility agents only with Abs

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25
Q

what is the leading cause of acute diarrhea in children

A

rotavirus

responsible for 40% of hospital admissions worldwide

26
Q

what are the largest factors in diarrheal deaths?

A

unsafe water
inadequate sanitation
poor hygiene

27
Q

where do most diarrhea deaths occur

A

Africa

South Asia

28
Q

how many rotavirus particles are required for infection

A

10

29
Q

what is the most common age affected by rotavirus

A

6-24 months

babies are protected by IgA in breastmilk

30
Q

how do you diagnose rotavirus

A

ELISA or latex agglutination or PCR

31
Q

how do you treat rotavirus

A

ORS
Zinc
continued breastfeeding

32
Q

how do you prevent rotavirus

A

ROTARIX vaccine

2 doses at 2 and 4 months

33
Q

do hepatic abscesses usually present with bowel symptoms

A

no, often present without

34
Q

what is the most likely organism causing amoebic liver abscess

A

entamoeba histolytica

or E. dispar

35
Q

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

A

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

36
Q

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

A

bacterial

37
Q

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

A

ALA = 100% hematogenous

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

38
Q

what is the aspirate like in ALA? in bacterial?

A

ALA = brown, no odor, “anchovy paste” quality

bacterial = purulent, green/yellow, foul odor

39
Q

what organisms cause bacterial liver abscesses

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

often polymicrobial

40
Q

what are serology results for ALA? bacterial liver abscecss?

A 
ALA = +
bacterial = -
41
Q

Tx for ALA

A
  1. METRONIDAZOLE

2. paramomycin/iodoquinol

42
Q

Tx for bacterial liver abscess

A

empiric coverage for enteric GNRs, enterococcus, anaerobes

43
Q

what is the most common cause of gastritis

A

H. pylori related infections

44
Q

what is the most common chronic bacterial infection in humans

A

H. pylori related infections

45
Q

what causes 90% of duodenal ulcers

A

H. pylori

46
Q

how is H. pylori transmitted

A

fecal-oral and oral-oral

47
Q

what bacteria increases the risk of gastric cancer

A

H. pylori

48
Q

pathophysiology of H. pylori infections

A

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

49
Q

who do you test for H. pylori

A

anyone with:
gastric cancer
active PUD
of Hx of PUD

anyone with symptoms of dyspepsia

50
Q

what tests do you use for H. pylori

A
  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”
51
Q

Tx of H. pylori

A

HP-Pac–> Lansoprazole + clarithromycin + amoxicillin (14 days)

20% of pts fail first Tx

52
Q

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

A

thrush

53
Q

how do you treat oropharyngeal candidiasis

A

NYSTATIN rinse

clotrimazole troches
ARVs if HIV+
fluconazole

54
Q

what is esophageal candidiasis

A

esophagitis
usually with thrush
HIV or other immunosuppresion = comorbid

55
Q

Tx of esophageal candidiasis

A

always SYSTEMIC antifungals

empiric Tx same in immunocompromised as competent

FLUCONAZOLE

echinocandins
amphotericin B

56
Q

what are GI infections usually caused by?

A

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

57
Q

what causes most travellers diarrhea

A

ETEC or EAEC

usually doesnt require diagnostic tests or antibiotics

58
Q

is liver abscess serious?

A

YES

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

59
Q

most common cause of bacterial liver abscess

A

biliary tract obstruction or infection

60
Q

how does most entamoeba present?

A

usually asymptomatically

61
Q

how does E. histolytica usually present

A

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

62
Q

who requires an evaluation for immunosuppresion on presentation with thrush

A

patients older than 12 months old

IDMM (29 decks)

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