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Microbio Section 2 > All > Flashcards

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1
Q

What are the transmission methods of spirochetes?

A

Sexual - syphilis
Vector - Lyme Disease
Environmental - Leptospirosis

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2
Q

Describe spirochete’s virulence factors?

A

Mainly to evade the immune system

They are not very antigenic so we are not able to make vaccines

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3
Q

Argylll Robertson Pupil

A

Pupil won’t constrict with light, but will constrict when attempting to focus on a nearby object

This is a sign of neurosyphilis

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4
Q

Jarisch-Herxheimer reaction

A

Flu-like symptoms 24 hours after treatment with antibiotics

This can be used to identify infection with spirochetes

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5
Q

Stages of Syphilis

A
  1. Chancre
  2. variable rash with flu-like symptoms
  3. Latency or dangerous cardiac or CNS involvement –> Gummas
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6
Q

Which type of bacteria can cross into the blood/brain barrier?

A

Spirochetes

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7
Q

Treatment for spirochetes?

A

Treatment is very simple as long as it is diagnosed early.

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8
Q

Which bacteria causes syphillis and which causes Lyme disease

A
  1. Treponema Pallidum

2. Borrelia Burgorferi

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9
Q

Which type of bacteria can easily cross into the bloodstream?

A

Spirochetes

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10
Q

How long does it take for a tick to transmit lyme disease?

A

24 hours

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11
Q

If Lyme disease is suspected in a prevalent area, what treatment should be taken?

A

doxycycline prophylaxis

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12
Q

Lyme Disease Phases

A
  1. Skin infection - Bull’s eye rash
  2. Immune or neurological issues
  3. Chronic - more severe neurological issues, fibromyalgia
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13
Q

Treatment for Lyme Disease

A

Doxycycline or amoxycillin for a month - no more

Jarisch-herxheimer reaction may occur, which will confirm diagnosis

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14
Q

What type of cell do spirochetes mostly infect?

A

endothelium

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15
Q

What two physical features define Vibrios?

A
  1. Curved

2. Gram (-) rods

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16
Q

Most vibrio pathogens are?

A
  • Ocean-dwelling

- several are halophiles - lives in high salt concentrations

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17
Q

What are the transmission methods of vibrios?

A
  1. Mostly fecal-oral –>gastroenteritis
  2. infect wounds contaminated by seawater or ocean debris
  3. H. Pylori causes peptic ulcers
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18
Q

Why are vibrios able to infect the GI tract, and cause peptic ulcers?

A

-Special virulence factors

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19
Q

What is an o1 genetic marker and where are they found?

A
  • marker of colonization by lysogenetic bacteriophage, which carries virulence markers
  • They are found on V. Cholera
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20
Q

Describe the transmission of v. Cholerae

A
  • transmitted to humans by the fecal-oral route
  • usually killed by stomach acid
  • if it survives it secretes mucinase to attach to and colonize the intestine
  • after colonizing it secretes an enterotoxin
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21
Q

What is choleragen?

A
  • an A-B subunit enterotoxin
  • interferes with signal transduction to cause massive watery diarrhea
  • This results in dehydration and electrolyte imbalance
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22
Q

How does H.pylori survive in the stomach?

A

-It produces urease which converts urea to ammonia
-ammonia neutralizes stomach acid, which irritates the stomach lining and allows bacteria to reproduce
-irritation and induction of apoptosis by pathogen causes ulcers which predispose to cancer
-

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23
Q

Urea breath test

A
  • used to diagnose H. Pylori

- patients who swallow radio-labeled urea and are infected with H. Pyloria - they will exhale radiolabeled CO2

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24
Q

Treatment of H.Pylori

A

10-14 course of three antibiotics (trio) with peptobismol and proton pump inhibitors

reinfection can occur

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25
Q

Name four foodborne enterobacteria

A
  1. Shigella
  2. salmonella
  3. E. Coli
  4. yersinia
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26
Q

What are the two groups of enterobacteria opportunistic pathogens?

A
  1. Klebsiella / enterobacter/ serratia

2. Proteus/ providencia / morganella

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27
Q

List at least 3 defining characteristics of enterobacteria?

A
  1. gram negative
  2. nonsporulating
  3. straight rods
  4. facultative aerobes
  5. catalase +
  6. Oxidase -
  7. Glucose fermenters
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28
Q

What is special about enterobacteria?

A

They are promiscuous to incorporating foreign DNA and acquiring virulence factors:

This is a problem for risk of extreme antibiotic resistance for the entire group

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29
Q

Enterobacteria Antimicrobial sensitivity testing

A
  1. Smear an agar plate with liquid culture of the patient isolate
  2. place disks of various antibiotics on plate before overnight incubation
  3. If successful plating-> lawns of bacteria are interrupted by zones of clearing
  4. measure zones and compare to a table
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30
Q

Enterobacteria gut virulence factors

A 
Gut virulence acquired factors:
        1. Pili for adhesion
        2. Type 3 secretion systems
                 adhesion
                 subversion of gut macrophage
                 enterotoxin
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31
Q

Foodborne Enterobacteria pathogenesis

A

allow themselves to be sampled by M cells in peyers patches, where they alter local macrophages for bacterial survival and spread to the exterior surface of the gut (T3SS)

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32
Q

Which bacteria further use macrophages as trojan horses for passage into lymph nodes?

A
  1. Local - Y. enterocolita - false appendicitis

2. System wide - S . Typhi - Typhoid fever

33
Q

Hemolytic Uremic Syndrome (HUS) is caused by which two bacteria?

A
  • Shigella and EHEC
34
Q

What causes HUS? What age group does it primarily affect?

A
  • Release of shiga toxin into the bloodstream

- Pediatric patients

35
Q

Reactive arthritis is caused by which five types of bacteria?

A
  • Shigella
  • Salmonella
  • Yersinia
  • Campylobacter
  • Chlamydia
36
Q

What is the transmission method of foodborne enterobacteria?

A

-Fecal oral

37
Q

Who is especially susceptive to Reactive arthritis?

A

-Patients positive for HLA-B27

38
Q

What are the symptoms of reactive arthritis?

A
  • Conjunctivitis, urethritis, arthritis

- Can’t see, can’t pee, can’t climb a tree

39
Q

What type of pathogens are ICU bugs?

A

Opportunistic enterobacteria infections of noncomosial origin (from hospitals)

40
Q

What are obligate anaerobes?

A
  • They derive their ATP from fermentation pathways

- Most lack enzymes necessary to grow in the presence of oxygen -superoxide dismutase and oxidase

41
Q

What is fermentation?

A

An energy-inefficient process that produces organic acids, alcohols, or even solvents as waste products

42
Q

Anaerobic pathogens are either (2)

A
  1. normal flora that escape their proper compartment –> form an abscess at new site
  2. Soil organisms that enter the body either through wounds or through consumption of vacuum-packed food
43
Q

Culturing of anaerobes -3 steps

A
  1. Liquid media can be treated with reducing agents and tightly stoppered in a FULLY-filled container
  2. agar plates must be incubated in anaerobic culture jar
  3. Very sensitive anaerobes - glovebox
44
Q

How to identify unknown anaerobes (3)

A
  1. Gram stain
  2. Biochemical tests
  3. Gas chromatographic analysis of their fermentation products
45
Q

Gram + anaerobes (2)

A
  1. clostridia
  2. actinomyces
    (All anaerobes except GNAB)
46
Q

Anaerobes of normal flora (3)

A
  1. GNAB
  2. Actinomyces
  3. C. Difficile
47
Q

Anaerobes from the soil

A

The other clostridia (C. Tetani, C. botulinum, C. perfringens)
These form spores which can enter through wounds or vacuum packed food

48
Q

Anaerobic virulence

A

Exotoxin expression

49
Q

Tetanus and botulism produce

A

neurotoxins

50
Q

Anaerobic bacteria with tissue-degrading enzymes produce:

A

Gas gangrene and abscesses

51
Q

Treatment of anaerobic infections

A
  • concludes with antibiotics
  • abscess treatment - surgical care - draining and debriding
  • Toxigenic - antitoxin
52
Q

GNAB

A

Gram Negative Anerobic bacilli

-Bacteroides and Prevotella , also includes Fusobacter

53
Q

Why is TB such a successful pathogen?

A

It has been a major human disease for 5000 years and has consummately adapted to infect humans

54
Q

Eradication of which type of bacteria seemed possible until AIDS?

A

M. Tuberculosis

55
Q

Why is TB a public health nightmare?

A

MDR and XDR strains

56
Q

Name 3 characteristics of mycobacteria

A
  1. gram stain poorly
  2. acid fast
  3. very slow growing
57
Q

Acid Fast staining procedure

A
  1. carbolfuschin stain
  2. Acid/alcohol decolorization
  3. Methylene blue counterstain

acid-fast +s hold carbolfuschin during decolorization –Mycobacterium - pink cords

58
Q

Transmission of M. Tuberculosis

A
  • Almost always to lung by inhalation
  • to lymph nodes, kidney, bones
  • CNS by hematogenous spread
  • GI by swallowing infected sputum
59
Q

Immunocompetent response to TB

A
  • Strong CMI
  • Can hold infection latent for decades
  • immunosenescence or suppression reactivates
60
Q

Which bacteria is capable of hematogenous spread by intracellular infection of naive macrophages?

A

-TB

61
Q

Describe the CMI response to TB

A

-CD8 cells kill infected macrophages and establish caseating granulomas in which the infection is contained

62
Q

Why cytokine response is important to the granulomatous response to TB? and how is this proven?

A
  • TNF alpha

- remicade - anti TNFalpha causes susceptibility to reactivation

63
Q

What are the symptoms of classic TB?

A

Pulmonary: Cough, weight loss - consumption, fever, night sweats, hemoptysis - blood in sputum, chest pain

64
Q

If you suspect someone has TB what should you do?

A

-check sputum and x-ray

65
Q

What are some extrapulmonary manifestations of TB?

A
  • scrofula- neck
  • GU tract
  • Meningitis or abscess – CNS
  • Skeletal - long bone or vertebral
  • Miliary
  • GI - very rare for now
66
Q

In a pediatric patient with TB what should you assume and do?

A
  • must have been recently acquired - trace source!

- watch for miliary and meningitis

67
Q

How do you determine exposure to TB? what else should you do?

A
  • TST and or IGRA - 2 weeks

- perform antibiotic resistance testing as soon as cultures grow - another 3 weeks

68
Q

Treatment of TB

A
  • directly observed therapy with 4+ drugs featuring isoniazid
  • isolate patient for first two weeks
69
Q

Vaccine for TB

A
  • BCG
  • live attenuated M bovis
  • used abroad but not cost affective here
  • important because it can create weak-moderate false positive TST
70
Q

What are the most helpful factors for reducing incidence of TB?

A

-Good diet and housing

71
Q

Latent cases of which disease are NOT contagious?

A

TB

72
Q

Atypical mycobacteria

A

-environmentally-acquired infections that cause neither TB or leprosy

73
Q

Atypical mycobacteria infection in an:

  1. immunocompetent adult
  2. child
  3. immunosuppressed
A
  1. cutaneous
  2. scrofula
  3. systemic symptoms particularly from m kanasii or MAI/C
74
Q

Which infections are especially difficult to treat once established?

A

Atypical mycobacteria - require multiple antibiotics

75
Q

Is M. Leprae able to be cultured?

A

No! It is the slowest growing human pathogen and prefers 30-37 degrees

76
Q

Describe the transmission of M. Leprae?

A
  • extremely long incubation period
  • doesn’t transmit easily
  • only 5-10% of humans susceptible
77
Q

What are the two forms of Hansen’s disease, what is the immune response to them, and what is their PPD status?

A
  1. Tuberculoid - paucibacillary
    - -vigorous CMI - contains infection and damages nerves
    - -PPD+
  2. Lepromatous -multibacillary
    - -Weak MI - extensive cutaneous symptoms
    - -PPD-
78
Q

What does lepromin PPD test ?

A

Immunocompetence NOT exposure

79
Q

How would you treat an infection with M. Leprae?

A

Two years of dapsone + rifampin

Microbio Section 2 (1 decks)

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