S4M2 > Other Micro > Flashcards

Other Micro Flashcards

(59 cards)

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1
Q

Features of H.pylori, reservoir, transmission

A

Gram(-), Motile w/flagella, Microaerophilic, Cat(+), Ox(+)

Human reservoir, fecal-oral transmission

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2
Q

Virulence Factors of H. pylori!!!!!!!!

A

Urease (Urea -> NH3 + CO2)
Cytotoxin (VacA)
CagA (cell signaling in epithelial cells– affects actin, cytokines)

**A mutant lacking any ONE of these virulence factors will NOT be pathogenic!

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3
Q

Pathogenesis of H.pylori

A
  1. Attracted to hemin & urea– penetrate mucous layer lining gastric eptihelium
  2. H.pylori recruit & activate inflammatory cells & release urease, producing NH3, which neutralizes stomach acid
  3. H.pylori cytotoxin & NH3 destroy mucus-producing cells, exposing underlying CT to stomach acid –> ulcers
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4
Q

Consequences of H.pylori infection

A
  1. Atrophic gastritis (2*- occurs in months) -> gastroadenocarcenoma
  2. Hyperacidity -> duodenal ulceration
  3. Antigenic stimulation -> B-cell lymphoma
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5
Q

Marker for inflammation & cancer from H.pylori

A

CagA

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6
Q

Diagnosis & Treatment of H.pylori infection

A

Dx:
Bx + culture of gastric mucosa
Urease breath test– radioactive urea, test breath for radioactive CO2

Tx: PPI + Amoxicillin & Metronidazole
helps prevent recurrence

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7
Q

Candida albicans

A

Part of normal flora– overgrowth with abx or IC pts

Causes ORAL THRUSH or ESOPHAGITIS (in IC pts only)

See pseduohyphae & true hyphae in overgrowth; (yeast normally)

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8
Q

Clinical presentation of H.pylori

A

acquisition asymptomatic

pain, belching, vomiting
hypochlorhydria

Peptic ulcers: epigastric pain @ night or after meals- relieved by milk/antacids
(can cause bleeding or perforation)

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9
Q

Clinical presentation of viral diarrheas

A

Stool NOT BLOODY or MUCOID.
Usually fecal-oral
No anti-viral tx

Usually seen with Childhood diarrhea (rotavirus) or Outbreaks (Caliciviruses)

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10
Q

Rotavirus characteristics

A

dsRNA (segmented, naked)
DOUBLE-shelled

5 serotypes (usually type A for infx)

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11
Q

Rotavirus infection presentation

A

self-limiting, 48h incubation
Sudden onset of vomiting –> watery diarrhea @ 5 days –> abdominal cramps, low fever, dehydration

Infx restricted to ENTEROCYTES on small intestinal microvilli –> incr secretions + malabsorption

Vaccine available

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12
Q

Demographics of Rotavirus infx

A

Nov-march in temperate climates

Children <2y, elderly, institutionalized, healthcare personelle

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13
Q

Calicivirus:

A

+ssRNA (naked)
All ages, fecal-oral (airborn possible), mostly winter
<48h incubation, vomiting +/- watery diarrhea for 1-3 days.
NO vaccine

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14
Q

Helminths: groups, stages, characteristics

A

Tapeworm, fluke, roundworm

Egg -> larva -> adult (multi-cell, does not need microscope)

Do NOT multiply in humans
(Intermediate host– where eggs develop -> larvae)

Humans get infected by ingestion/penetration of eggs or larvae

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15
Q

Pinworm / Enterobius vermicularis

  • Susceptibility
  • life cycle
  • location
A
  • usually in young children but doesn’t discriminate
  • In GIT: ingest egg -> larva -> adult -> lay eggs
    • adults migrate at night thru anus, lay eggs outside, & die
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16
Q

Pinworm / enterobius

  • S/S
  • Dx
  • Tx
A
  • Mostly asymptomatic, but PERIANAL ITCH
  • mild dz– no invasion, no eosinophilia
  • eggs NOT in stool, only see adults @ night
  • Tx pt AND fam w/ anti-parasitic to control spread
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17
Q

Ascaris: lifecycle

A
  1. ingest eggs –> larvae
  2. hatch in intestine -> blood
  3. enter lung –> trachea –> swallowed
  4. larvae –> adult in intestine & eggs in feces (fecal-oral)
  5. Eggs mature in soil (faster in warmer temp)
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18
Q

Ascaris: epidemiology

A
  • Warm climates (1/3 of world infected)
  • Children in developing nations
  • In US: latino immigrants
  • Fecal-oral (veg contaminated)
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19
Q

Ascaris: disease

A
  • Mostly asymptomatic
  • More bugs/larger -> obstruction -> jaundice, pain, distention (due to blocked biliary/pancreatic ducts), and malnutrition
  • Exit thru anus– not painful but nasty
  • When moving in LUNG –> eosinophilia / dyspnea / pneumonitis / cough can occur.
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20
Q

Ascaris: Diagnosis

A

Thick sell, ruffled, wavy mammilated surface (looks like nipples lol)
Look for Ova & Parasite in stool

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21
Q

Hookworms:

  • types
  • life cycle
  • diagnosis
A

7-13mm- have biting plates
- Types: Ancyclostoma duodonae, necutor americanus (children walking barefoot)

  • eggs -> stool -> soil/water -> larvae (molt 2x) — 5-10 days later are infective:
    larvae -> skin -> lung -> swallow -> adult in GIT
  • Ova, stool with SMOOTH SHELL
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22
Q

Tenia Solium

  1. Definitive & intermediate hosts
  2. Location of cysts
  3. Infectious cycle
  4. Types
A
  1. definitive: human, intermediate: human, pig
  2. Cysts in muscle, brain
  3. Eggs in human poo -> other humans -> form larval cysts (only pigs can form larval cysts)
  4. Adult tapeworm = NO SX;
    Cysticercosis = brain inflammation
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23
Q

Cysticercosis: diagnosis

A

endemic in some countries

Larval cysts in several organs, but BRAIN & SC most severe.

Years later, causes focal seizures, mental impairment, meningitis, psych illness

Dx with Serology (no ADULT in intestine in Cysticercosis)

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24
Q

Schistosomiasis:

  • life cycle
  • epidemiology
Study These Flashcards
A

Swimming larvae -> skin -> lung, liver -> GIT -> poop -> larvae -> snails -> water

Humans bathing/swimming in fresh water w/proper snails
– increased risk with Dams

25
Schistosomiasis: S/S
- Dermatitis (larva penetrates) - Hematuria (eggs in bladder) - Fibrosis & inflammation of liver -> portal HTN -> esophageal varices -> vomit blood Stool has ova w/ characteristic spine
26
Protozoal biology
- Unicellular, diploid, nuclear membrane - Most are larger than bacteria - NO cell wall (thus no gram stain) * *are able to form Double-Membraned Cysts to survive outside the body
27
Forms of protozoa
Trophozoites: metabolically active, replicate, motile, PATHOGENIC Cysts: dormant-- double membrane -> resistant to dessication & osmotic swelling; DON'T replicate-- survive & spread to new host
28
Giardia lamblia: cyst vs. trophozoite
Cyst: 4 Nuclei & infective Trophozoite: flagellated, 2 nuclei, motile, "heart shaped" :)
29
Giardia: demographics
- children 0-5y; backpackers from streams/lakes-- most from human cysts in H2O - MCC protozoal-induced diarrhea - Improper chlorination-- cysts don't die
30
Giardia: S/S
Diarrhea, cramps, bloating, flatulence, anorexia CHRONIC = >1week: weight loss, malabsorption (->steatorrhea), lactose intolerance NO fever, NO blood in stool
31
Giardia: pathogenesis
- Ingest cysts -> trophozoites - Use ventral disk to attach to SI mucosa - 1-2 week incubation (incr. in #) - -> disrupt brush borders (dissacharideases, lose absorptive surface--flat villi) ** NO INVASION. NO EXOTOXIN **
32
Giardia: diagnosis
- Stool: ova + parasite (fresh liquid stool may have trophozoites) - --Need 3 specimens (not always shedding) - ELISA + Ag detection w/Immuno is better
33
Giardia: immunity
- formed in infection - IgA is protective & helps recovery - Gain abs from breast feeding - Immunodeficiency -> predisposition to giardia
34
Cryptosporidium: reservoir, demographics
Cattle | AIDS pts, or immunocompetent but in developing nations
35
Cryptosporidium: pathogenesis, morphology
Path: 1. Ingest oocysts -> sporozoites 2. Invade surrounding cell membrane 3. asexual division (SOME for sexual gametocytes to become oocysts) Chlorine-resistant (pools) "Nipple" appearance on cells in intestinal bx
36
Cryptosporidium: epidemiology, clinical features
- 4% of diarrhea in US, 2% traveler's diarrhea - Higher incidence in developing nations - Watery diarrhea + steatorrhea - @ terminal ileum, prox colon (but disseminate in AIDS pts --> lung, pancreatitis, cholangitis) Incubation: 1week Lasts 5-10 days (14+ in dev. nations)
37
Cryptosporidium: diagnosis
Stool cysts - ACID FAST - auramine - immunofluorescence - ag detection
38
Microsporidium: Location, demographics, morphology
- Water (pig, dog, chicken, rabbit) - AIDS pts - Little vacuoles within cells
39
Microsporidium: life-cycle
Like fungi: Ingest spores - use polar tube to inject sporoplasm into host cell -> proliferate -> form spores that rupture cells to release more cells
40
Microsporidium: Clincal features, S/S
- Diarrhea (watery), ad pain, fever - some malabsorption - @ distal duodenum, prox jejunum - in AIDS pts-- disseminate to liver, brain, etc **spreads more than cryptosporidium
41
Isosporabelli: demographics, incubation, S/S
- AIDS pts ("AIDS Assoc Chronic Diarrhea) - 1 week incubation, lasts 2-3weeks - Watery diarrhea
42
Isosporabelli: Life cycle, Dx
1. Ingest oocyst -> sporozoites 2. Enter epithelial cells -> trophozoites 3. reproduce --> oocysts Dx: oocysts AUTOFLUORESCE in stool!
43
Enantomoeba Histolytica: Demographics, Incubation, S/S, Complications
- Rare in US (sanitation)-- in refugees, immigrants - 1 week incubation, 1-3 week duration - MCC diarrhea & dysentery (blood/mucus) in the WORLD - Cause deep ulcers in colon --> perforation - Liver/ Brain /Lung/ Subdiaphragm abscess - toxic megacolon
44
Enantomoeba histolytica: life cycle
1. Ingest cyst 2. Form trophozoite 3. Penetrate intestinal wall 4. Multiply in colon wall 5. Liver invasion via portal vein 6. Discarded in feces
45
Enantomoeba histolytica: morphology
Flask-shaped deep ulcers that bleed but rarely enter peritoneum Wheel & spoke appearance of trophozoites INGET RBCs Cyst has 4 nuclei
46
Enantomoeba histolytica: diagnosis
Stool smear: ova + parasite | Fresh stool will have trophozoites
47
If you have a patient with no symptoms but culture indicative of significant bacteremia, would you treat them with antibiotics?
NO if person is NOT pregnant | YES if person is pregnant or has a known obstruction (kidney stone)
48
If you have a male patient with Acute Hemorrhagic Cystitis... what is the cause?
VIRUS - - Adenovirus - - BK virus
49
Staph sprophyticus: - characteristics - demographics
Staph saprophyticus: - G(+), cat(+), coag(-), nitrite(-), novobiocin resistant. - causes lower UTIs in YOUNG SEXUALLY ACITVE FEMALES (Honeymoon Cystitis) or Postmenopausal women.
50
Which microorganism is associated with UTIs in BPH patients?
Enterococcus faecalis (G+ cocci in chains, Group D strep, cat -, Nitrite -)
51
Which microorganisms are Nitrate (+)?
- E.coli - Proteus - Klebsiella penumoniae
52
What are the virulence factors that help E.coli to be uropathogenic?
Type 1 pili, P. fimbriae
53
Lower UTI: types
- Cystitis - Urethritis - Prostatitis
54
Upper UTI: types
- Pyelonephritis - Intrarenal Abscess - Perinephric Abscess - Emphysematous Pyelonephritis
55
Cystitis: S/S
- Dysuria, frequency, urgency - Bladder fullness/pressure - NO abnormal vag discharge - Suprapubic discomfort/pain - Hematuria in 50%, bacteriuria, pyuria
56
Pyelonephritis: S/S
- Fever, chills, sweats - N/V - Flank pain or abd pain - Dehydration, Hypotension - Hematuria, bacteriuria, pyuria - May see WBC casst
57
Common causes of Upper UTI? (general)
- Untreated cystitis or other lower UTI infection | - Hematogenous spread from abscess or infection elsewhere
58
What can you determine if the Leukocyte Esterase test is negative?
Patient does NOT have infection
59
How do you determine "significant bacteremia"?
Quick & dirty: >1 organism per oil immersion field (in uncentrifuged urine) >1 = >10ˆ5 = >100'000 CFU/mL Long: uncetrifuged urine - count CFU CFU x 10ˆ3 = CFU/mL >100 colonies = >100'000 CFU/mL = significant
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