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Medical Microbiology > Lecture 14 > Flashcards

Lecture 14 Flashcards

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USMLE® Step 1 flashcards Biology 101 flashcards
1
Q

What type of bacteria are Heliobacter pylori?

A

gram-

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2
Q

What are some characteristics of Heliobacter pylori?

A

helical-rod shape, motile 6-8 polar flagella

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3
Q

What year and by whom was Heliobacter pylori identified by?

A

1983 | Australian scientists

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4
Q

What were Heliobacter pylori previously known as and why?

A

Camplyobacter pylori because it was thought to resemble Camplyobacter species

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5
Q

What percentage of the world population do with Heliobacter pylori?

A

50%

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6
Q

What is the size of Heliobacter pylori compared to E.coli? (genome and physical size)

A

thin and long physically but smaller than E. coli | small genome

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7
Q

What is the reservoir for Heliobacter pylori?

A

human GI microbiota

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8
Q

Why is the stomach not a common environment for bacteria?

A

due to low pH (pH 2) = very acidic environment = very few survive

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9
Q

What bacteria learned in class causes cancer? (list all)

A

ONLY H. pylori

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10
Q

Which type of secretion system do Heliobacter pylori use?

A

type IV secretion system

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11
Q

Why was Heliobacter pylori a hot topic in research during the 90s?

A

H. pylori are common in the human population (in the GI microbiota) that is able to cause cancer

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12
Q

Are most people infected with Heliobacter pylori symptomatic or asymptomatic? Which condition may they also develop?

A

asymptomatic and may have chronic gastritis

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13
Q

What percentage of people infected with Heliobacter pylori will develop the disease but not cancer? What is a main tell-tale symptom?

A

10% – gastric or duodenal ulcer

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14
Q

What percentage of people infected with Heliobacter pylori will develop a cancer?

A

less than 1%

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15
Q

What are the 3 cancers that a Heliobacter pylori infection can manifest into?

A

adenocarcinoma, gastric cancer, gastric MALT lymphoma

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16
Q

What is atrophic gastritis?

A

well-established factor for adenocarcinoma

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17
Q

What do ulcers indicate?

A

an opening in the epithelium surrounding the stomach

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18
Q

How are ulcers created?

A

bacteria carries out a mechanism using urease to destroy epithelium cells of stomach lining

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19
Q

What are the common symptoms of gastric ulcers?

A

epigastric pain, burping, vomit, bleed, anorexia

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20
Q

What is epigastric pain?

A

pain due to empty stomach

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21
Q

How many new cases/yr in the US of gastric ulcers?

A

500K to 850K

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22
Q

What is the rate that a disease develops due to an infection from Heliobacter pylori?

A

slow, can take years

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23
Q

How long does it take for a patient infected with Heliobacter pylori to develop superficial/chronic gastritis?

A

several weeks to years

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24
Q

Where in the world is Heliobacter pylori most common/prevalent in? (3)

A

Africa, Asia, South America

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25
Q

What are the 2 modes of transmission of Heliobacter pylori?

A

oral-oral adn fecal-oral

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26
Q

What are the 5 virulence factors of Heliobacter pylori?

A

urease, adhesins, exotoxins CagA and VacA, flagella

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27
Q

What is urease and how does Heliobacter pylori use it?

A

enzyme breaks down urea into NH3 and CO2; does this in the stomach and makes stomach acid more neutral so it can survive

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28
Q

What is the VacA toxin?

A

transporter protein acting as a vacuolating cytotoxin

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29
Q

What does VacA toxin cause?

A

immune modulation, vacuolation, damage, apoptosis, permeability

30
Q

What is the CagA toxin?

A

Secreted by the type 4 secretion system; linked to initiation of carcinogenesis but not proven

31
Q

What does the CagA toxin cause?

A

disrupts cellular junctions and changes cellular polarity

32
Q

What is mucinase?

A

enzyme degrades mucous

33
Q

What are the invasive method(s) to diagnose for Heliobacter pylori infection?

A

mucosal gastric biopsy (taking tissue sample from stomach)

34
Q

What are the non-invasive methods to diagnose for Heliobacter pylori?

A

blood sample, stool, breath sample

35
Q

How effective and reliable are the diagnostic tests?

A

very high = 95% effeciency

36
Q

What are 4 tests to diagnose for Heliobacter pylori?

A

serological (antigens), PCR, culture, urease test

37
Q

Can we eradicate Heliobacter pylori from human bodies?

A

No because the pathogen will come back via transmission AND can cause unnecessary antibiotic resistance = create a superbug

38
Q

What is the treatment involved for Heliobacter pylori infections?

A

combination of multiple antibiotics

39
Q

What kind of bacteria are spirochetes?

A

different from gram+/– ; has outermembrane and periplasm; fastidious grows at 35ºC = slow growers

40
Q

What is unique about spirochetes?

A

periplasmic flagella

41
Q

What disease does Borrelia cause?

A

Lyme disease (zoonotic)

42
Q

What are three species of Borrelia discussed?

A

B. burgdorferi | B. garinii | B. afzelli

43
Q

What is periplasmic flagella?

A

flagella that is loacted in the periplasm

44
Q

What does the genome of B. burgdorferi consist of?

A

small linear chormosome (<1 Mbp) and 22 linear/circular plasmids

45
Q

Wht are spirochete-causing diseases difficult to treat?

A

complex infections with multiple stages

46
Q

What is the leading vector-borne bacterial disease of humans in the world?

A

Lyme disease

47
Q

When was Lyme disease first described? And where?

A

1975, Lyme Conneticut

48
Q

As Lyme disease is a multisystem illness, what organ systems does it affect?

A

skin, nervous system, heart, joints

49
Q

What vector does Borrelia reside in for transmission?

A

deer tick

50
Q

What are the target mammalian hosts of Borrelia?

A

white-footed mouse, rates, squirrels, humans, etc.

51
Q

What is another common bacterial disease that causes multi-stage disease affecting multisystems?

A

syphillus

52
Q

Where in the US is Lyme disease most common?

A

North east USA

53
Q

Where in the world is Lyme disease most common?

A

northern parts of the world

54
Q

What explains for the location of Lyme disease prevalence nationwide and worldwide?

A

Borellia vector likes northern temperate and cold climates not tropical

55
Q

How many cases in the US per year does Lyme disease happen?

A

30K

56
Q

How many stages does Lyme disease have?

A

3

57
Q

How many days does it take to begin seeing the early symptoms (stage 1) of Lyme disease?

A

3-30 days`

58
Q

What are common early symptoms of Lyme disease?

A

swollen lymph nodes, muscle/joint aches, fever, chills, fatigue, EM rash (occasionally)

59
Q

What is Erythema migrans?

A

expanding inflammatory skin rash, “bull’s eye” appearance at site of tick bite, rarely itchy/painful

60
Q

What percent of people with Lyme disease develop an erythema migrans rash?

A

70-80%

61
Q

What are the late signs/symptoms of Lyme disease?

A

heart problems, neurological issues, arthritis, short-term memory loss

62
Q

How much you remove a tick properly?

A

Grab by head

63
Q

What are 2 prevention methods developed/used?

A

behavioral = right clothing and awareness of nature | vaccine (OspA) but discontinued

64
Q

What seasons pose the highest risk of infected tick bites happening?

A

late spring, beginning summer, can still get infected in fall too

65
Q

What is stage 1 of the pathogenesis of Lyme disease?

A

localized infection with mild-flue-like symptoms

66
Q

What is stage 2 of the pathogenesis of Lyme disease?

A

disseminated infection, transient blood-borne phase, colonization diverse tissues

67
Q

What is stage 3 of the pathogenesis of Lyme disease?

A

late stage infection: arthritid, Lyme encephalopathy

68
Q

What are the 2 virulence factors of Borrelia?

A

outermembrane proteins (OspA, OspC) (protective antigens) , peptidoglycan as an endotoxin

69
Q

Where (in which animal) are the virulence factors of Borrelia mostly expressed?

A

inside the vector (tick), not human host

70
Q

What are the 4 diagnostic tests used to detect for infection due to Borrelia?

A

clinical diagnosis, culture from infected sites, PCR-based assay, serological assays (late stages)

71
Q

What is the treatent against Lyme disease?

A

Doxy, Amoxy, Cephalo (3rd gen)

Medical Microbiology (20 decks)

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