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GI Mike Rose > Bugs Week 4 > Flashcards

Bugs Week 4 Flashcards

1
Q

3 MC intestinal protozoans in U.S?

A
  1. Giardia
  2. ) Cryptosporidium
  3. ) Entamoeba
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2
Q

Giardia lamblia (intestinalis)

A

Sketchy: Giardia Jungle Ride

MC intestinal parasite in US

AKA beaver fever

Symptoms for 1-2 weeks or more. May seem to resolve and come back.

FOUL SMELLING diarrhea, flatulence, stools are greasy (float), malabsorbtion of fats, lipids, vitmains

Mechanism: Presence of parasite causes loss of surface area.

Trophozoite form - attachment, but not penetration

Cysts

Fecal matter = trophozoites and cysts = positive dx

Prevent w/ water filter

Rx: Metronidazole

MSM have increased risk

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3
Q

Cryptosporidium parvum

A

Sketchy: Tales from Crypts

Water parks = Crypto country. Often seen when sanitation system fails. Chlorination/UV treatment. Storms w/ drinking water (Milwaukee outbreak –> killed AIDS patients)

Sx: Diarrhea sx for 1-2 weeks to 1 month. May seem to resolve and then come back.

Mechanism: Absorption impaired and secretion enhanced

Opportunistic infection –> HIV –> chronic diarrhea/fluid loss –> can be fatal.

Ddx: WATERY, frequent non-bloody stools. Fever and nausea sometimes.

Small acid fast oocysts in feces.

Sporozoites in the gut.

Not immediately infectious. No direct fecal to oral.

Immunocomprimed Rx: Nitazoxanide (+metronidazole?) + HAART + Loperamide + Hydration

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4
Q

Cyclospora cayetanensis

A

Coccidia sublcass organism that can cause outbreaks of GI infections.

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5
Q

Entomoeba histolytica

A

Sketchy: Enter the Historical Dig

Causes amebiasis (amebic dysentery) and amebic liver abscesses.

More prevalent in tropical/subtropical climates

Only 10-20% of infected people become ill.

Male homosexuals are most at risk.

DDx: bloody mucus-ey loose stool. Relatively mild sx, but can invade the liver and form an abcess (single abscess in right lobe; RUQ pain, fever, and weigh loss)

Lab dx: Cysts in stool.

Histolytica = tissue lysis

Rx: Tissue antiparasitic (metronidazole) and luminal antiparasitic (i.e. iodoquine/paromomycin)

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6
Q

Amebic vs Bacillary Dysentery

A 
Amebic:
Onset - gradual
Fever - no 
Chills - no 
PUS- no
Prostration - less
Course - chronic
Bacillary 
Onset - sudden
Fever - yes
Chills - yes
PUS - Yes
Prostration - More
Course - acute
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7
Q

Enterobius vermicularis

A

Sketchy: Super Worms (Vermin lady)

Nematodes (Roundworms) Pinworm

Causes: Enterobiasis (AKA pinworm infectoion)

Staple sized worms

MC helminth infection in the US

Symptom: Perianal pruritis (may also present w/ insomnia, abdominal pain, anorexia, irritability. Rarely peritoneal granulomas and vulvovaginalis.

Acquired by ingestion of pinworm eggs (viable on surfaces for 2-3 weeks.

Retroinfection!

Dx: anal itching, confirm w/ appearance of worms 2-3hrs. after asleep. AM scotch tape test. Sample from under fingernails. No eggs in stool

Rx: Albendazole, Ivermectin, pyrantel pamoate, or levamisole

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8
Q

Nemacantor americanus

A

Sketchy: Super worms (America Dude)

Nematodes/Roundworms: AKA hookworm

Eggs in stool sample for dx

Life cycle: larvae in soil –> skin penetration –> circulatory –> lungs –> cough/swallow –> GI.

Can cause pruritic papular erythemetous rash at site of infection.

Major sx is IDA (1/4ml/day/worm)

Rx: Albendazole, Ivermectin, pyrantel pamoate, levamisole

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9
Q

Anclyostoma duodenale

A

Sketchy: Super worms (American Dude)

Nematodes/Roundworms: AKA hookworm

Life cycle: larvae in soil –> skin penetration –> circulatory –> lungs –> cough/swallow –> GI.

Can cause pruritic papular erythemetous rash at site of infection.

Major sx is IDA (1/4ml/day/worm)

Rx: Albendazole, Ivermectin, pyrantel pamoate, levamisole

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10
Q

Strongyloides stearcolis

A

Sketchy: Super worms (Strong guy)

Nematodes/Roundworms: AKA hookworm

Larva in stool sample for dx.

Life cycle: larvae in soil –> skin penetration –> circulatory –> lungs –> cough/swallow –> GI.

Sx: Stomach and GI complaints. Respiratory dry cough/throat irritation. Can cause pruritic papular erythemetous rash at site of infection. Recurrent raised red rash typically along thighs/buttocks.

Autoinfection, especially w/ immunosuppressed!

Rx: Ivermectin

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11
Q

Trichuris trichiura

A

Nematodes/Roundworms:whipworm

Trichuriasis

2.2 million cases/year in the US

Dx: eggs in feces = barrel shaped appearance

Finger clubbing is best indicator of infestation

Bloody diarrhea –> IDA

Heavy cases: frequent, painful stools w/ mucus, water and blood, tenesmus. Rectal prolapse.

Rx: Albendazole, Ivermectin, pyrantel pamoate, levamisole

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12
Q

Ascaris lumbricoides

A

Sketchy: Super Worms (Lumbering tree man)

Nematodes/Roundworms: Giant roundworm

Causes ascariasis

About half the population in tropical and subtropical areas are infected (about 1 billion affected per year)

If sx are experienced = abdominal discomfort. Severe = intestinal blockages –> dx w/ ultrasonography and radiology

Can cause cough (lung life cycle) –> Charcot Leyden crystals.

Dx: eggs w/ thick shells

Rx: Albendazole, Ivermectin, pyrantel pamoate, levamisole

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13
Q

Taenia

A

Sketchy: Cestode County Carnival (Tents)

Cestode/Tapeworm

Beef or pork tapeworm - obtained through improperly cooked meat.

Rare in US (livestock)

Dx: standard intestinal problems. Stool contains eggs and/or proglottids.

Cyticercosis possible if cysticeri migrate to muscle, brain, or other tissue.

Rx: Praziquantel or Albendazole

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14
Q

Diphyllobothrium

A

Sketchy: Cestode County Carnival (guy running to bathroom)

Cestode/Tapeworm

Fish tapeworm (huge!!!)

Life cycle: uncooked fish.

Sx: standard intestinal problems. Anemia due to B12 loss*.

Dx: Stool contains eggs and/or proglottids

Rx: Praziquantel or Albendazole

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15
Q

Echinococcus

A

Sketchy: Cestode County Carnival (Cocker spaniel)

Cestode/Tapeworm

Causes ecchinococcosis

Eggs in feces of dog –> oncosphere hatches –> slow growing cysts in organs (mainly liver).

Dx: Not GI illness, pain or discomfort in UQs or chest.

Risk: sheep farming + uncontrolled living w/ canines; trappers.

Rx: Praziquantel or Albendazole

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16
Q

Schistoma mansoni

A

Sketchy: San Franschisto Ocean Park (Man and his son)

Trematodes/Flukes

Schistosomiasis -2nd only to malaria for impact of parasitic disease

Two major forms: intestinal and urogenital (haematobium)

Definitive host = humans; intermediate = snail

Sx are caused by immune response to egg stage of schistoma.

Eggs are shed by adult worms causing inflammation in scarring. Years of damage–> liver, intestine, spleen, lungs, and bladder damage.

Repeatedly infected children can develop anemia, malnutrition, and learning difficulties.

Sx: within days = rash or itchy skin. 1-2 months = fever, chills, cough, and muscle aches; chronic = abdominal pain, enlarged liver, blood in urine/stool, and dysuria (risk of bladder cancer)

Rx: Praziquantel

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17
Q

Shistoma japonicum

A

Sketchy: San Franschisto Ocean Park (Japanese tourist)

Trematodes/Fluke

Schistosomiasis -2nd only to malaria for impact of parasitic disease

Two major forms: intestinal and urogenital (haematobium)

Definitive host = humans; intermediate = snail

Sx are caused by immune response to egg stage of schistoma.

Eggs are shed by adult worms causing inflammation in scarring. Years of damage–> liver, intestine, spleen, lungs, and bladder damage.

Repeatedly infected children can develop anemia, malnutrition, and learning difficulties.

Sx: within days = rash or itchy skin. 1-2 months = fever, chills, cough, and muscle aches; chronic = abdominal pain, enlarged liver, blood in urine/stool, and dysuria (risk of bladder cancer)

Dx: stool or urine sample for eggs. Serologic test.

Rx: praziquantel (second dose often necessary. Delay if acutely dx’d)

Steroids help in acute phase.

Prevent w/ sanitation and MDA.

Rx: Praziquantel

18
Q

Cercarial dermatitis

A

AKA swimmer’s itch

Birds pass eggs in feces –> molluscum –> humans exposed in swimming.

19
Q

Bifidobacteria

A

First colonizers of breast-fed infants

20
Q

Staph Aureus

A

Sketchy - Moses’s golden staff

Gram + Cocci
Catalase +
Coagulase +

Sx of food poisoning: N/V, stomach cramps, and diarrhea for 1-3 days.

Incubation = 1-7 hrs.

Rx: Self limiting (once toxin clears = no illness)

Toxin producing S. Aureus can be identified in stool/vomit.

Most conclusive test is linking of illness w/ a specific food containing preformed enterotoxin (only necessary in outbreaks)

Toxin can survive high temperatures (cooking doesn’t help).

S. Aureus can survive salt up to 15% and temps 15-45 degrees c. –> common foods = mayo/ham/custard

21
Q

Bacillus cereus

A

Sketchy - King Anthra’s Axe

Gram + Large (box-car shaped) Bacilli
Endospore forming
Facultative anaerobe
Mostly motile
B-hemolytic

Spores are commonly found in the soil and sometimes in plant foods grown close to ground.

REHEATED RICE (spores can survive rice cooking process!)

Two forms:
1.) Emetic - 1-6 hrs incubation. N/V. (Similar to SA food poisoning.) Mechanism = preformed enterotoxin that forms holes in membranes - cerulide.

2.)Diarrheal - 6-15 years incubation. Watery diarrhea and abdominal cramps (similar to C. perf infection). Mechanism = caused by large enterotoxin that cuases intestinal fluid secretion. Not preformed –> ingest large amounts of bacteria –> toxin produced in gut. Vulnerables may require abx.

Duration for both is only 24 hrs.

Dx: Often ignored/dismissed. B. cereus in food and vomitus or feces of same serotype. Only for outbreaks.

Some produce endotoxin!

22
Q

Clostridium botulinum

A

Sketchy - Robotulism

Gram + Bacilli
Spore forming
Obligate anaerobe
Motile

Botulism - ingesting toxin in food (home canned)
Wound botulism - generating toxin in wound (penetrating injury)
Infant botulism - ingesting spores (honey)

Rx: ventilator for respiratory failure. Antitoxin. Remove good if still in gut.

Toxin = neurotoxin that blocks SNARE proteins –> no release of Ach from motoric end plate –> descending muscle weakness and paralysis (diploplia, drooping eyelids, dry mouth, etc.)

Infants = lethargic, feed poorly, are constipated, weak cry.

23
Q

Clostridium perfringens

A

Sketchy - Private Ringen’s motorcyle accident

Gram + Bacilli
Spore Forming
Obligate anaerobe
Non-motile

3rd MCC of bacterial food borne illness.

Sx: Diarrhea and abdominal cramps. Last less than 24 hours. Usually no fever or vomiting. Illness not passed from person to person.

Incubation = 6-24 (8-12 is MC)

Positive dx = detection of toxin or high amounts of bacteria in feces.

Mechanism = toxin widens epithelial junctions in gut.

Occurs when foods are prepared in large quantities and kept warm for a long time. Gives spore in food a chance to start bacterial growth.

24
Q

Salmonella enterica

A

Sketchy - Salmon dinner

Gram - Bacillus
NON spore forming
H2S positive and lactose negative
Motile, flagellated

2nd MCC of bacterial food born illness

Salmonella Shigella (SS) agar (contains bile salts; indicator (lactose frementors = red) and ferric citrate (indication of H2S production –> black color)

Salmonellosis:
Sx: diarrhea (can be bloody), fever, and abdominal cramps. Usually last 4-7 days.

Reactive arthritis.

Incubation period: 12hr. to 3 day.

Dx: stool culture

Rx: supportive unless spreads beyond gut.

Resevoirs: eggs, raw milk, veggies

25
Q

Campylobacter jejuni

A

Sketchy - Camping Guy and Bears

Gram - Bacilli
Microaerophilic
Motile
Cold sensitive

MCC of bacterial food borne illness

Zoonosis from animals/animal products (chicken).

Karmali agar is selective medium (charcoal-based w/ vanco, cefoperzone, and cyclohexamide). Sensitive organism.

Sx:Diarrhea and cramping, abdominal pain, and fever. Can last a week. Can be bloody diarrhea. Can have vomiting.

Mechanism = inflammatory response to cell invasion.

Incubation period: 2-5 days.

Positive dx: stool culture

Possible complication = Guillain-Barre; Reactive arthritis

26
Q

Listeria monocytogenes

A

Sketchy - Santa’s list

Gram + Bacilli
Non-fastidious*
Flagellated, motile
Non spore forming
Oxidase -

B-hemolytic (under colonies)

Rare illness, a leading cause of death by food born illness.

Listeriosis = mild GI infection for most. Most vulnerable are older adults, pregnant women, newborns, and opportunistic.

Meningitis and sepsis in vulnerable populations.

Dx: Bacterium in normally sterile site (not stool!)

Mechanism for invasion: immune cells spread listeria to other organs; trojan horse; liver is a major target.

Common sources: Sprouts, deli meats and hot dogs, smoked seafood, soft cheeses, raw milk

27
Q

Vibrio parahemolytica

A

Sketchy - Colonel Cholera sets up Base cAMP

Gram negative
Vibrio (curved rod)
Facultative anaerobes
Flagellated, motile
Oxidase +

Water loving

Kovacs oxidase reagent turns purple.

Sx: Fairly mild bloody diarrhea, stomach cramps, fever, nausea and/or vomiting. Sx last less than a week.

Immunocompromised it can spread to the blood –> deadly infections.

Mechanism = enterotoxins: hemolysins TDH and or TRH. Form pores in RBCs but also in epithelial cells

Dx: vibrio isolated

Resevoirs = shell fish.

28
Q

Shigella spp.

A

Sketchy: She Gorilla’s Circus

Gram negative bacillus
Facultative anaerobe
Nonmotile
Non spore forming
Mainly lactose negative H2S negative

Very closel related E. coli.

Invasive

Shigella sonnei: most shigella caused GI illness
Shigella flexnori: causes bacillary dysentery (and reactive arthritis)
Shigella dysenteriae: Rarest but most severe dysentery.

Transmission: fecal-oral

Many access through M cells thorugh type III secretion system.

Actin rockets to move around

Antibiotics in severe cases.

Can cause HUS.

29
Q

Shigella sonnei

A

Most shigella caused GI illness

Sx: Diarrhea (often bloody), fever, stomach cramps, sx start 1-2 days following exposure. Usually resolve in 5-7 days.

30
Q

Shigella Dysentery

A

Frequent, small bowel movements w/ blood and mucus. Accompanied by rectal pain and spasms (tenesmus)

MC bacillary form is Shigella flexnori
Most severe bacillary dysentery = Shigella dysenteriae
Amebic dysentery = Entomoeba histolytica

Invasive plus has a phage-born toxin
Shiga toxin, also casued verotoxin (A-B) toxin that acts on vascular endothelial cells.

31
Q

Ecoli ETEC

A

Sketchy - E cola’s fountain soda (traveling water truck)

Gram negative bacillus
Facultative anaerobe
Motile
Non spore forming
Mainly lactose positive

Traveler’s diarrhea, diarrhea in children

SX: profuse watery diarrhea and abdominal cramping. Fever, chills. N/V, anorexia. Typically lasts 3-4 days, less than 10

Incubation period: 1-3 days

Rx: not abx

Track outbreaks w/ commercial PCR and antibody based kits.

Typical reservoir = under-cooked beef or unclean veggies

32
Q

E coli STEC (EHEC)

A

Sketchy - E cola’s fountain soda (kid on red stool)

Gram negative bacillus
Facultative anaerobe
Motile
Non spore forming
Mainly lactose positive

Shiga toxin w/ outbreaks in US O157:H7. Toxin is an AB5 toxin.

SX: profuse watery diarrhea and abdominal cramping. Can progress to bloody diarrhea. Fever, chills. N/V, anorexia. Typically lasts 3-4 days, less than 10

Hemorrhagic colitis and/or HUS. Children more vulnerable.

Incubation period: 1-3 days

Rx: not abx

Track outbreaks w/ commercial PCR and antibody based kits.

Typical reservoir = under cooked beef or unclean veggies

33
Q

Vibrio cholerae

A

Sketchy - Colonel Cholera’s Base cAMP.

Gram negative
Vibrio (curved rod)
Facultative anaerobes
Flagellated, motile
Oxidase +

Kovacs oxidase reagent turns purple.

Water is primary resevoir. Fecal oral transmission.

Typically only serogroups O1 and O139 produce cholera toxin –> acitvates AC –> increase cAMP –> chloride in lumen –> water follows.

Acute illness: Rice water stools w/ severe dehydration.

Dx: by isolating causative organism from stools.

Rx: ORS/IV fluids.

34
Q

Salmonella Typhi

A

Sketchy - Salmon dinner

Gram - Bacillus
NON spore forming
H2S positive and lactose negative
Motile, flagellated

Infections are 50x less common than nontyphoidable salmonellosis in US

Typhoid fever not typhus (rickettsial infection)

Fecal oral transmission

Vaccine available.

Life threatening illness in GI tract –> bloodstream.

Sx: high fevers (103-104), weakness and headache. Stomach pains, anorexia, diarrhea OR constipation. Sometimes a rash of flat, rose colored spots

Antibiotic treatment is recommended!

35
Q

Low inoculum organisms

A

Shigella, Giardia, Entamoeba, Norovirus, cryptosporidosis and STEC (EHEC) E coli.

Medium is not grossly infected

Secondary cases common. Can be spread in day-care centers, families.

Example: toddler contacts cryptosporidosis in wading poool

36
Q

High inoculum organisms

A

Vibrio cholera, C. perfingens.

Medium is highly contaminated

Secondary cases are rare

I.e. traveler gets cholera from seafood carried to US from Ecuador on luggage

37
Q

Clostridium difficile

A

Sketchy - Field trip to the Chocolate Factory

Gram + (variable) bacilli
Spore forming
Obligate anaerobe
Motile

Exotoxins cause cell death, shallow ulcers, pseudomembranes. Early lesions are superficial. May enventually invade. Pseudomembranous colitis.

Can cause diarrhea (MC), pseudomembranous colitis, fulminant colitis (danger for perforation).

Infection induces enterocyte apoptosis.

Dx: w/ toxin detection

Rx: Metronidazole, oral vancomycin (and fidaxamicin); bowel resection or fecal transplant.

Severe disease

38
Q

Rotavirus

A 
RNA virus
Icosahedral nucleocapsid
Nonenveloped
DS segmented Genome (III)
Reovirdae (Repetovirus)

Spread fecal-oral

Cytolytic and toxin-like action on intestinal epithelium causes loss of electrolytes

Most serious in individuals under 2 (not before 6 months –> IgA in breast milk). Asymptomatic over 5 years old.

Large amounts of virus are released during diarrheal phase. Maximal at 2-5 days after the beginning of diarrhea.

Outbreaks MC at day care centers, preschools, and among hospitalized infants. –> higher cases in winter.

ELISA, RTPCR, or electron microscopy

Double capsid structure (removed by stomach –> ISVP is infectious

Group A most common (determined by VP6)

NSP4 stimulates release and cell lysis

2 vaccines: Rotarix (single strain) and Rotateq (5 strains)

39
Q

Norwalk Virus

A

MCC of foodborne disease outbreaks in the US.

SS + RNA virus (Class IV)
Icosahedral Nucleocapsid
Nonenveloped
Calcivirae

Fecal-oral transmission

Outbreaks of gastroenteritis.

Disease resolves after 48 hrs. w/o serious consequences

Can mutate quickly (drift)

40
Q

Adenovirus (serotypes 40-42)

A

DS DNA Virus Linear (class I)
Icosahedral nucleocapsid
Nonenveloped
Adenoviridae

ELISA or PCR

Careful handwashing, chlorination of swimming pools, supportive care.

Live oral vaccine for types 4 and 7 given to Military

GI Mike Rose (6 decks)

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