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S2B1: Infectious Disease > Gastrointestinal Infections VI > Flashcards

Gastrointestinal Infections VI Flashcards

1
Q

Characteristic of vibrio parahaemolyticus?

Describe how it manifests as noninflammatory bacterial gastroenterisis.

A
  • Vibrio parahaemolyticuscurved gram (-) rod
    • oxidase positive
    • halophile – requires salt to grow
  • Manifestations
    • 24 hr incubation
    • explosive diarrhea to cholera-like illness
    • headache
    • abdominal cramps
    • nausea
    • vomiting
    • low-grade fever
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2
Q

Common cause of Vibrio parahaemolyticus noninflammatory bacterial gastroenteritis?

Pathology?

Diagnosis?

Treatment?

Prevention?

A
  • Cause
    • eating raw shellfish
  • Pathology
    • thermostable Kanagawa hemolysin that induces chloride ion secretion
  • Diagnosis
    • clinical presentation
    • green colonies of TCBS agar
    • beta hemolytic on human RBC agar plates; not on sheep RBC agar plates
  • Treatment
    • oral replacement of fluids adn electrolytes
    • antibiotics
  • prevention
    • proper cooking of shellfish
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3
Q

Characteristic of vibrio cholerae?

Common causes and endemic areas?

A
  • Vibrio cholerae
    • slightly curved gram-negative rod
    • O1 and O139 serotypes (LPS) – severe disease
    • non-O1/O139 types milder disease
  • Endemic in
    • India, West Bengal, Bangladesh, South America, and Lousiana
    • ingested in contaminated water and food (shellfish and crabs)
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4
Q

Symptoms of vibrio cholerae caused noninflammatory bacterial gsatroenteritis?

Pathology of disease?

Diagnosis?

Treatment?

A
  • symptoms
    • abrupt onset of watery diarrhea
    • no fever
    • “rice water” stools
    • vomiting may occur
  • Pathology
    • large dose of cells needed
    • attache to microvilli
    • no invasion
    • produce cholera toxin
    • ADP robosylates GTP-binding protein
      • increase cAMP
        • inhibits NaCl absorption and stiumlates Cl- secretion
  • Diagnosis
    • clinical presentation
    • plating stool on TCBS agar (yellow on TCBS)
      • thiosulfate-citrate-bile-salts-sucrose agar
    • test for foxin in adrenal cell assay
  • Treatment
    • replace fluids and electrolytes
    • antibiotics reduce severity and length of disease
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5
Q
A
  1. vomiting
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6
Q

What are teh 3 major causes of parasitic gastroenteritis?

A
  • Giardiasis
  • Cyclosporiasis
  • Cryptosporidiosis
    • chronic problem in immunocompromised
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7
Q

What is the usual cause of Giardiasis?

Symtoms?

A
  • Usually ingest water containing Giadia cysts
    • become trophozoites in duodenum
  • Symptoms
    • many asymptomatic
    • watery diarrhea to malabsorption syndrome
    • incubation period 1-4 weeks
    • sudden onset of
      • foul-smelling watery diarrhea
      • cramps
      • flatulence
      • steatorrhea
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8
Q

Pathology of Giardiasis?

Diagnosis?

Treatment?

Prevention?

A
  • Pathology
    • adhere to microvilli
    • causes disaccharidase deficiency
    • results in osmotic diarrhea
    • bloating, flatulence, watery diarrhea
    • if continue – malabsorption and fatty diarrhea can result
  • Diagnosis
    • Hx of drinking contaminated water
    • clinical symptoms
    • confirmatory diagnosis – find organism in stool
  • Treatment
    • see pharmacology notes
  • Prevention
    • boil or filter all drinking water
    • chlorination doesn’t kill the cysts
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9
Q

Etiological cause of cyclosporiasis?

Cause?

Pathology?

A
  • Etiology: Cyclospora cayetanesis
  • common water contaminant
    • imported fresh fruits, vegetables & herbs
    • sporulated oocysts are infectious form of the parasite
  • Pathology
    • binds to epithelial cells in the small intestine
    • causes secretory diarrhea
    • mechanism unkown
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10
Q

Symptoms of Cyclosporiasis?

Diagnosis?

Treatment?

Prevention?

A
  • Symptom
    • normal immune system
      • asymptomatic to prolonged diarrhea lasting a month or more
      • other symptoms include; fever, fatigue, flatulence, and belching
      • self-limiting, wax & wane, or result in prolonged diarrhea
      • fatigue and malaise may persist after diarrhea has resolved
  • Diagnosis
    • look for variably staining acid-fast cysts in a stool smear
  • Treatment
    • see pharmacology notes
  • Prevention
    • in US avoid imported fresh fruits and vegetables
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11
Q

Common cause of Cryptosporidium?

Etiological cause?

Pathology?

A
  • Common water contaminant
    • Lives in fish, mammals and reptiles
    • small number of oocysts cause diarrhea
    • immunocompromised more likely to have symptoms & develop chronic diarrhea
  • Pathology
    • Afects ion transport
    • Inflammatory damage of microvilli leading to malabsorption
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12
Q

Symptoms of Cryptosporidium?

Diagnosis?

Treatment?

Prevention?

A
  • Symptoms
    • normal immune system
      • asymptomatic
      • self-limiting diarrhea (around 10 d duration)
    • immunocompromised
      • diarrheal disease can be severe
      • 50 or more stools per day
      • last months to years
  • Diagnosis
    • look for acid-fast cysts in stool smear
  • Treatment
    • see pharmacology nots
    • antidiarrheal drugs give temporary relief
  • Prevention
    • avoid contaminated water sourcs
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13
Q

What is the etiological agent responsible for producing antibiotic-associated pseudomembranous colitis?

Virulence factors?

Symptoms?

A
  • Clostridiodes difficile - resistant to many antibiotics
    • anaerobe
    • produces A and B toxin
  • Symptoms
    • asymptomatic to fulminatn colitis
      • depends on number of receptors for toxins on colon
    • watery diarrhea
    • crampy bilateral lower quadrant pain that decreases after bowel movement
    • low-grade fever
    • peripheral blood leukocytosis
  • 5-10 days post antibiotic
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14
Q

Symptoms of a C. diff infection?

A
  • Symptoms
    • pseudomembranous colitis – seen w/ colonoscopy
      • look for yellowish plaques
    • fulminant colitis
      • diarrhea, but can be constipated
      • diffuse severe abdominal pain
      • hypoactive bowel sounds
      • abdominal distension & guarding
      • marked peripheral blood leukocytosis
      • complications
        • perforation
        • toxic megacolon
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15
Q

Diagnosis C. diff infection?

Treatment?

Prevention?

A
  • Diagnosis
    • Hx antibiotic therapy
      • clindamycin & lincomycin
    • ELISA for toxin A & B
    • PCR for glutamate dehydrogenase screen of fecal sample
      • most sensitive
    • 50% of time stool ahve fecal leukocytes and are heme positive
    • endoscopy; yellow plaques
  • treatment
    • withdraw antibiotic
    • IV fluids/electryolyte
    • NO ANTIMOTILITY DRUGS - increase canges toxic megacolon & full-blown colitis
    • fecal transplantation
    • megacolon: bowel resection & ileostomy
  • Prevention
    • prevent spread to other patients and personnel
    • avoid prolonged us of broad-spectrum antibiotics
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16
Q

Gereal symptoms invasive gastroenteritis?

Common etiological causes?

A
  • Symptoms
    • fever
    • abdominal pain
    • pain while attampting to defecate (tenesmus)
  • Etiologies
    • Campylobacter
    • Shigella
    • Salmonella
    • EHEC
    • EIEC
    • Yersinia enterocolitica
    • Entamoeba histolytica
17
Q

Shape/characteristics fo Campyocater jejuni?

How is Campylobacteriosis often acquired?

Symptoms?

A
  • Characteristic
    • S shaped (sagull)– hard to grow
  • Acquired
    • non-chlorinated water
    • undercooked or raw meat, unpasteurized milk, nonchlorinated H2O
  • Symptoms
    • most cases mild
    • initial
      • periumbilical cramping
      • intense abdominal pain
      • malaise, myalgias, heaadache, vomiting
      • watery diarrhea most common
    • inflammatory bowel disease
      • malaise, fever, abdominal cramps, tenesumu, blood stool, fecal leukocytes, indistinguishable from shigell salmonella, E. coli
18
Q

Campylobacteriosis Pathogenesis?

Diagnosis?

Treatment?

A
  • Pathogenesis
    • Shiga toxin
  • Diagnosis
    • seagull shaped bacterial w/ darting motility in watery, bloody leukocyte-filled stool
    • Campy-BAP or Skirrow media
  • treatment
    • most self-lmiting
    • oral rehydration; correct electrolyte imbalances
    • Use antibiotic is patient has
      • fever
      • increasing bloody diarrhea
      • symptoms longer than a week
19
Q

Characteristics of Shigella?

How is Shigellosis most often acquried?

A
  • Characeristics
    • Group D- S. sonnei (most common in US)
    • Group B- S. flexneri
    • nonmotile, doe NOT ferment lactose, gram (-) rod
    • resistant to stomach acid
  • Acquired
    • fecal oral
    • contaminated water sources
    • daycare, nursing homes, prisions
      • food, fingers, feces, flies
20
Q

Symptoms of Shigellosis?

Pathogenesis?

Diagnosis?

Treatment?

A
  • Symptoms
    • incubation 36-72 hrs
    • fever, abdominal cramping and pain
    • watery diarrhea
    • after 2 days diarrhea, then dysentery adn tenesmus
    • may initiate septicemia by E. coli
    • rarely gets into bloodstream
  • Pathogenesis
    • Shiga toxin
  • Diagnosis
    • clinical symptoms- presumptive diagnosis
    • definitive Dx- isolate organism from stools
    • grow on S-S agar
    • fecal leukocytes will be present
  • Treatment
    • usually self-limiting
    • to shorten course adn limit person-to-person spread, treat with antibiotics
    • dont give antidiarrheal compounds
    • replace fluids & electrolytes
  • Prevention
    • wash your hands
21
Q

Characteristics of Salmonella?

How is Salmonellosis most often acquired?

What are the etiological agents responsible for enteric fever?

A
  • Charcteristics
    • motile, nonlactose fermenting rods
  • Acquired
    • from food, animals
    • person-to-person from chronic carriers
  • Enteric fever
    • S. Typhi
    • S. Paratyphi A
    • S. Schottmuelleri
    • S. Hirschfeldii
22
Q

Symptoms caused from Salmonella enteritis?

Symptoms caused from Salmonella septicemia?

Symptoms caused from Salmonella enteric fever

A
  • Enteritis
    • ingest food
    • 6-48 hr later: nausea, abdominal cramps, vomiting, nonbloody diarrhea (rarely causes bloody diarrhea). fever, headache myalgia
    • lasts 2d-1 week
    • usually self-limiting
  • Septicemia
    • S. enterica most likely to cause
    • high risk in pediatric, geriatric, and immunocompromised populations
    • just like any other gram-negative sepsis
  • Enteric fever
    • pass through lining of intestine
    • engulfed by macrophages
    • taken to liver, spleen, and bone marrow (replicate)
      • 10-14 days later gradually rising fever
      • lasts week of two
      • then diarrhea
      • can have skin lesions “rose spots”
      • colonization gallbladder = carrier state
23
Q

Diagnosis Salmonellosis?

Treatment?

Prevention?

A
  • Diagnosis
    • less inflammation compared to shigellosis
    • fewere leukocytes in stool
    • use S-S agar to isolate organisms
  • Treatment
    • fluid replacement; NO antidiarrheals
    • enteritis- self-limiting
    • patients more likely to develop bacteremias shoudl be treated with antibiotics
    • enteric fever- antibiotic therapy immediately
  • Prevention
    • travelrs vaccination- for typhoid fever
      • oral live attenuated
      • Vi capsular polysaccharide vaccine- IM
24
Q

Difference in the capabilities of EHEC and EIEC?

A
  • EHEC
    • allow them to invated in cells & produce shiga toxin
      • causes HC and can damage kidneys –> HUS
      • most common cause of HC and HUS is E. coli O157:H7
        • O = LPS
        • H = flagella
  • EIEC
    • can invade, but do NOT produce shigatoxin
25
Q

Symptoms of EHEC?

Symptoms EIEC?

Diagnosis?

A
  • EHEC
    • severe crampy abdominal pain, watery diarhea followed by bloody diarrhea
      • (hemorrhagic colitis; HC)
    • Usually no fever
    • HUS triad- acute renal failure, thrombocytopenia, microangiopathic hemolytic anemia (schistocyte)
    • HC precedes HUS usually
  • EIEC
    • watery diarrhea that can on occasion result in dysenteric stools
    • not much if any fever
  • Diagnosis
    • EHEC and EIEC
      • isolate and idnetify the organism
      • grow EHEC O157:H7 on sorbitol-MacCOnkey plates–can’t ferment sorbitol
26
Q

Treatment EHEC and EIEC?

Prevention?

A
  • Treatment
    • EHEC
      • avoid antimotility drugs adn antibiotics
        • antibiotics release more toxina nd increas change of HUS
    • EIEC- normally self lmiting
      • avoid antimotility drugs
      • can use antibiotis in severe cases
  • Prevention
    • EHEC
      • thoroughly cook hamburgers, drinkk pasteurized fruit juices
    • EIEC
      • drink from safe water sources
27
Q

Characteristics of Yersinia enterocolicica?

A
  • Characteristics
    • gram (-) rod
    • does not ferment lactose; urease positive
    • motile at 25 but NOT at 37
    • can grow at 4 degrees, but optimum is 25-28 degrees
    • bull’s eye appearance on CIN agan
28
Q

Manifestations of Yersinia enterocolitica?

Epidemiology?

A
  • Diarrhea
    • subacute onset
    • occasionally bloody stols; abodominal pain (right lower quadrant), fever, nausea, and comiting; pharyngitis
    • longe duration 12-22 days
  • Septicemia
    • can develop into septic shock
    • infants, impaired immunity, iron-overload
  • Pseudoappendicitis
    • colonies in ileum and appendix
    • right lower abdominal pain, fever, vomiting, leukocytosis
    • Post infectious sequaelae
      • erythema nodosum and reactive arthritis (northern european with HLA-B27)
  • Epidemiology
    • humans and mmmals
    • ingest- contaminated food/water
    • contaminated blood transfusions
29
Q

Diagnosis of Yersinia enterocolitica?

Treatment and prevention?

A
  • Diagnosis
    • culture samples (stool, blood) on CIN medium incubate at room temperature for several days
    • Bull’s eye appearance of colonies
    • lactose negative; urease positive, motile at 25 but NOT at 37
  • Treatment
    • supportive care and antibiotics
    • avoid antimotility drugs
  • Prevention
    • prevent contamination of food/wate by pets and otehr animals
    • fully cook food and drink pasteurized milk and milk products
30
Q

How is entamoeba histolytica often acquired?

How can you differentiate it from other amebiasis?

A
  • Acquired
    • ingest cysts from contaminate dfood and water
  • Pathogenesis
    • trophozoites live in proximal colon
    • will ingest RBC (uniqe)
    • can invate the liver, lungs, brain and bloodstream
31
Q

Symptoms of Entamoeba histolytica infection?

Pathology?

A
  • symptoms
    • incubation 1-5 days
    • diarrhea, abdominl cramps, vomiting, tenesumu
    • stools can be watry of dysenteric (watery wiht mucous adn blood)
    • amebic abscess- abrupt onset of high fever, right upper quadrant pain, anorexia, nausea, vomiting
  • Pathology
    • colonic ulcers, granulomas diffuse hepatitis, hepatic abscess, and rectal ulcerations
    • in colon the trophozoites produce ulcers
    • Flask-shaped ulcers
    • In liver
      • necrosis of endothelium and penetrate periportal sinusoid to the loules
      • Aspirations- “Anchovy paste” appearance may form very large abscesses
32
Q

Diagnosis, treatment and prevention of Entamoeba histolytica infection?

A
  • Diagnosis
    • see parasite in feces
    • leukocytosis in peripheral blood smea
    • chest radiograph, CT or MRI for extra-intestinal infections
  • Treatment
    • antiparasitic drugs
      • mild to moderate disease
      • drain liver abscess if larger than 12 cm
  • Prevention
    • drink safe water

S2B1: Infectious Disease (6 decks)

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