Gastrointestinal Infections VI Flashcards by Katherine E Nordstrom

Characteristic of vibrio parahaemolyticus?

Describe how it manifests as noninflammatory bacterial gastroenterisis.

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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Common cause of Vibrio parahaemolyticus noninflammatory bacterial gastroenteritis?

Pathology?

Diagnosis?

Treatment?

Prevention?

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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Characteristic of vibrio cholerae?

Common causes and endemic areas?

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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Symptoms of vibrio cholerae caused noninflammatory bacterial gsatroenteritis?

Pathology of disease?

Diagnosis?

Treatment?

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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vomiting

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What are teh 3 major causes of parasitic gastroenteritis?

Giardiasis
Cyclosporiasis
Cryptosporidiosis
- chronic problem in immunocompromised

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What is the usual cause of Giardiasis?

Symtoms?

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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Pathology of Giardiasis?

Diagnosis?

Treatment?

Prevention?

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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Etiological cause of cyclosporiasis?

Cause?

Pathology?

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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Symptoms of Cyclosporiasis?

Diagnosis?

Treatment?

Prevention?

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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Common cause of Cryptosporidium?

Etiological cause?

Pathology?

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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Symptoms of Cryptosporidium?

Diagnosis?

Treatment?

Prevention?

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

Virulence factors?

Symptoms?

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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Symptoms of a C. diff infection?

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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Diagnosis C. diff infection?

Treatment?

Prevention?

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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Gereal symptoms invasive gastroenteritis?

Common etiological causes?

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

Shape/characteristics fo Campyocater jejuni?

How is Campylobacteriosis often acquired?

Symptoms?

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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

Campylobacteriosis Pathogenesis?

Diagnosis?

Treatment?

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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

Characteristics of Shigella?

How is Shigellosis most often acquried?

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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

Symptoms of Shigellosis?

Pathogenesis?

Diagnosis?

Treatment?

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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

Characteristics of Salmonella?

How is Salmonellosis most often acquired?

What are the etiological agents responsible for enteric fever?

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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

Symptoms caused from Salmonella enteritis?

Symptoms caused from Salmonella septicemia?

Symptoms caused from Salmonella enteric fever

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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

Diagnosis Salmonellosis?

Treatment?

Prevention?

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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

Difference in the capabilities of EHEC and EIEC?

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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

Symptoms of EHEC? Symptoms EIEC? Diagnosis?

* 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

Treatment EHEC and EIEC? Prevention?

* 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

Characteristics of Yersinia enterocolicica?

* 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

Manifestations of Yersinia enterocolitica? Epidemiology?

* 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

Diagnosis of Yersinia enterocolitica? Treatment and prevention?

* 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

How is entamoeba histolytica often acquired? How can you differentiate it from other amebiasis?

* 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

Symptoms of Entamoeba histolytica infection? Pathology?

* 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

Diagnosis, treatment and prevention of Entamoeba histolytica infection?

* 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

Gastrointestinal Infections VI Flashcards

(32 cards)