GI tract infections

Question 1

C. difficile colitis

-epidemiology (risk factors, transmission)

Answer 1

Risk Factors: recent antibiotic use, recent hospitalization, long-term care facilities, older age, proton pump inhibitors
Transmission: fecal-oral

Question 2

C. difficile colitis

-pathophysiology

Answer 2

Ab kill normal flora, C. diff overgrows, releases toxin A and B, mucosal injury and inflammation.
Pseudomembranes are formed

Question 3

Ab most likely to lead to C. diff colitis

Answer 3

Clindamycin
Fluoroquinolones

But ALL can lead to it.

Question 4

C. difficile colitis

-clinical presentation

Answer 4

• usually within 2 weeks of Ab therapy
• watery diarrhea
• elevated WBCs
• low grade fever
• in severe cases, fulminant colitis

Question 5

C. difficile management

Answer 5

• Mild/moderate: metronidazole
• Severe: vancomycin (PO)

If neither gets better in 4-6 days, add the other.

Question 6

Traveller’s diarrhea

-likely etiology for acute onset, gradual onset/chronic, dysentery, one brief episode

Answer 6

Acute onset:
80-90% Bacteria
-ETEC and EAEC most common
10-20% Viral

Gradual onset/Chronic
-Giardia or Entameoba histolytica

Dysentery
-Salmonella, campylobacter, shigella

Brief episode
-preformed toxin food poisoning

Question 7

Stool samples cansnd cannots

Answer 7

Can: shigella, campylobacter, salmonella, O&P
Cannot: distinguish ETEC/EAEC from normal E. coli, identify viral causes

Question 8

Management of travellers diarrhea

Answer 8

1) identify the pathogen if symptoms are severe and persist >72hr
2) Rehydration fluid
3) Ab only for severe symptoms: fluoroquinolones, azithromycin
3) Don’t use anti-motility agents unless you are using an Ab

Question 9

Rotavirus

-epidemiology (infectivity, demographics)

Answer 9

• highly infectious (lots of virions passed, only need a few to infect)
• 6-24 months weaning, developing world because they don’t use vaccine

Question 10

Rotavirus

-pathophysiology

Answer 10

• The virus infects and replicates in cells at the tip of villi in the small intestine.
• These cells die/are damaged
• Reduced absorptive capacity
• Intensely dehydrating

Question 11

Rotavirus

-management

Answer 11

• Oral rehydration solution
• Zinc
• In some countries can give the ROTARIX vaccine to prevent the episode in the first place, but if you get it you have immunity usually

Question 12

Hepatic abscess

-etiology

Answer 12

Amoebic liver abscess

• travel or from endemic area
• negative blood cultures
• anchovy paste aspirate

Bacterial liver abscess

• developed world
• biliary tract obstruction
• polymicrobial
• purulent aspirate
• postive blood cultures

Question 13

Management of hepatic abscesses

Answer 13

Amoebic

• don’t have to drain usually
• Metronidazole

Bacterial

• always drain
• Ab that cover G(-) bacilii, enterococci and anaerobes

Question 14

Helicobacter pylori

-pathophysiology

Answer 14

• swims through mucus of stomch
• can neutralize stomach acid (urease)
• adheres to epithelial cells
• causes inflammation –> gastric or duodenal ulcer
• USUALLY ASYMPTOMATIC until ulcer or gastric cancer

Question 15

Gastric ulcers

-etiology

Answer 15

70-80% H. pylori

Question 16

Duodenal ulcers

-etiology

Answer 16

-90% H. pylori

Question 17

Helicobacter pylori

-epidemiology (transmission, how common, demographics)

Answer 17

Transmission: fecal-oral
Most common bacterial infection in humans
More prevalent in older high socioeconomic status people

Question 18

Helicobacter pylori

-Diagnosis of infection

Answer 18

Can be done for anyone with symptoms of gastric ulcers, cancer etc..

• Urease breath test
• serology
• stool antigen
• endoscopy+biopsy

*which one you choose depends on clinical situation and the pre-test probability

Question 19

Management of helicobacter pylori infection

Answer 19

HP-Pac

-Lansprazole, clarithromycin, amoxicillin

Question 20

Oropharyngeal candidiasis

• Risk factors
• treatment

Answer 20

Risk: HIV+, infant, corticosteroid (e.g. asthma inhalers), post-antibiotic

Treatment:
Evaluate for HIV if >12mo
Nystatin swish and swallow 
\+/-
Clotrimazole troches
\+/-
Fluconazole

Question 21

Esophageal candidiasis

• risk factors
• treatment

Answer 21

Risk: already have oral thrush, HIV+, cancer, transplant

Treatment:
-systemic anti-fungals (fluconazole)

Question 22

Hepatitis A,b,c risk factors

Answer 22

Hep A

• raw oysters
• contaminated food/water

Hep B, C

• sexual
• IVDU

Question 23

Hep C treatment

Answer 23

pegylated interferon/ribivarin

Question 24

Define: 
diarrhea
gastroenteritis
enteritis
colitis
enterocolitis
dysentery 
enteric fever

Answer 24

Diarrhea: abnormal liquid/unformed stool or at increased frequency.

Gastroenteritis: inflammation of stomach and sm intestines

Colitis: inflammation of the colon

Dysentry: pus+ blood in the stool with fever, low volume stools +/- cramping +/- vomiting

Enteric fever: diarrhea with blood stream invasion (=typhoid fever…don’t need blood in the stool)