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Microbiology > Exam2Lec5ICBacteria > Flashcards

Exam2Lec5ICBacteria Flashcards

1
Q

How do intracellular pathogens get inside the cell?

A

Taken up by cell and create a endosome or phagosome
1. can escape endosome
2. prevent fusion with lysosomes so they cannot be broken down
3. fuse with lysosomes to form phagolysosome but survive in the phagolysosome

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2
Q

How do the intracellular bacteria get around?

A

ACTIN ROCKET

The bacteria hack the cytoskeleton and begin an actin tail assembly to be motile. Once motile with actin tail they can push to other cells

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3
Q

What are the facultative intracellular bacteria talked about in class?

A

Mycobacterium tuberculosis
Bartonella henselae

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4
Q

What are the general characteristics of the genus mycobacterium?

A

aerobic, gram + rods
Acid fast:
—- bind phenol-based dyes in presence of heat
—–retain dye when treated with acidified alcohol

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5
Q

How does acid fast work?

A

-bind phenol-based dyes in presence of heat
-retain dye when treated with acidified alcohol

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6
Q

why do we have to do an acid fast stain on Mycobacterium?

A

Complex cell wall lipids
-include mycolic acids–>waxy envelope so it is hard to penetrate

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7
Q

What is the growth speed of Genus mycobacterium?

A

VERY SLOW ~3 weeks to grow from small inoculate

Extra:
- Generation time:
—–15 - 20 min for E. coli
—– 60 min for C. diphtheriae
—— 300 min for M. tuberculosis

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8
Q

What is included in the complex cell wall lips of genus mycobacterium?

A

mycolic acids

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9
Q

The waxy layer or complex cell wall lipid of genus mycobacterium does what?

A

protects vs. phagolysosomal components, probably basis for survival in macrophages

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9
Q

What are the components of the mycobacterium cell envelope? List them

A

A = cell memebrane

B = peptidoglycan

C =arabinogalactan

D = lipoarabinomannan–> like LPS but not LPS

E = proteins

F = mycolic acids

G = surface glycolipid

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10
Q

Who has an increase susceptibility of TB?

A

Substance abusers, AIDS patients

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11
Q

What is the fatality rate in untreated TB?

A

50%

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12
Q

What is the transmission of tuberculosis?

A

Airborne droplets

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13
Q

Where do the TB pathogens usually reside in human body to cause infection first?

A

Macrophages in alveoli

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14
Q

what do TB x-rays look like?

A

patches of white lesions

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15
Q

Talk out the procession of tuberculosis

A
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16
Q

If you have little or no hypersensitivity, are you tuberculin negative or positive?

A

Negative

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17
Q

If you are tuberculin negative, what happens?

A

progressive systemic disease and death

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18
Q

If you have little to no hypersensitivity to TB, what happens?

A

progressive systemic disease and death

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19
Q

If your patient has a delayed type hypersensitivity and cell mediated immunity to TB, are they tuberculin negative or positive?

A

Positive

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20
Q

If a patient is tuberculin positive, what happens?

A

Disease is contained, bacteria live but fail to replicated

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21
Q

What T cells response to TB in tuberculin positive patients?

A

Th1

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22
Q

what occurs in 25% of cases in tuberculin positive cases five years later ?

A

Ghon complex–> lung damage

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23
Q

What is the end result when a patient is tuberculin positive?

A

91% no disease
6% clinical TB
2% Pulmonary
1% both
3% progressive systemic disease and death

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24
Q

Is M.tuberculosis a single or multiple body site infectious disease? Name it or them

A

MULTIPLE BODY SITES
- lungs, bones, joints, liver, spleen, GI tract, brain

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25
Q

Where is M.tuberculosis always?

A

always within cells of reticuloendothelial system–> macrophages

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25
Q

What is the main defense of the lung again M. Tuberculosis ? Explain

A

pulmonary alveolar macrophages (PAM)

Ability to mount rapid, effective activated macrophage response determines outcome

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26
Q

M. tuberculosis can survive/grow where? Activated or nonactivated PAM?

A

NON-activated PAM

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27
Q

What do T cells do to layer of macrophages with M. tuberculosis?

A

T-cells forms around damaged tissue, this walls off lesion with thick fibrin coat
—-granuloma, specifically called tubercle
—-Calcification ==> lesions in chest X-rays

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28
Q

What causes lesions in chest X-ray ?

A

Calcification

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29
Q

Granuloma can also be called what?

A

tubercle

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29
Q

Granuloma can also be called what?

A

tubercle

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30
Q

what is the response in healthy adult exposed to low numbers of M.tuberculosis?

A

TH1 response and activated macrophages appear early enough to stop infection

—>no appreciable damage to lung
—>skin test positive, but no symptomatic TB
—>viable bacteria may remain with potential for future reactivation TB – this applies regardless of presence of primary disease

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31
Q

What are the symptoms of M.tuberculosis ?

A

—fever, coughing, bloody sputum
—Weight loss, loss of energy
—Progressive lung damage
—Bacteria may escape lungs ==> systemic disease

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32
Q

How do we diagnosis TB? even the not so effective ones

A

Stain of sputum —> acid fast bacteria
—> problem: not specific for TB

Culture
—-> problem: 1-2 months to grow

TB skintest: key to rapid easy surveillance

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33
Q

How does the TB skin test work?

A

ID injection of tuberculin–> purified protein derivative (PPD) which stimulates pre-primed CD4 -helper cells at injection site that leads to secretion of cytokines and delayed hypersensitivity reaction

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34
Q

how long do you have to wait after TB exposure?

A

about 4 weeks

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35
Q

What is the percentage of people that were positive skin test develop active TB?

A

3-5%

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35
Q

What is the percentage of people that were positive skin test develop active TB?

A

3-5%

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36
Q

What would cause a positive TB test if not exposed?

A

BCG vaccine

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37
Q

PPD skin test is considered what reaction?

A

delayed hypersensitivity

38
Q

How does the PPD skin test work? more immunology explanation

A

-PPD injected and interacts with tissue macrophages or dendritic cells

-PPD is processed and the APC produce factors that attract lymphocytes

  • The processed PPD is moved to cell surface and presented to PPD specific T cells at the injection sit

-Interaction of PPD T cell and PPD on APC cell surfaces causes chemotactic factors and gamma interferons

-Monocytes begain to migrate to injection site from the blood in 24-48 hours. This induration is the result of this late inflammatory reaction

  • The IFN gamma activates the monocytes/macrophages to enhanced killing of M. tuberculosis
39
Q

What activates the monocytes/macrophages to enhance killing of M.tuberculosis ?

A

IFN gamma

40
Q

What is traditional therapy for TB?

A

combinations used (INH-rifampin)
streptomycin, isonicotinic acid hydrazide (isoniazid, INH) rifampin, ethionamide, pyrazinamide, ethambutol, PAS

41
Q

When used medications singly instead of combo, what happens?

A

RESISTANCE

More specific: streptomycin, INH, ethionamide, and rifampin

42
Q

What is treatment combo success rate for TB?

A

90%, even in AID patients!

43
Q

What are the exceptions of the 90% treatment success rate?

A

MDR TB- multi drug resistant TB
XDR TB-extensively drug resistant TB
CDR TB-completely resistant to TB

44
Q

What is the prevention for TB

A

Bacille calmette-guerin (BCG)

45
Q

Bacille calmette-guerin (BCG) was made how?

A

M. bovis subcultured every 3 weeks for 13 years – became avirulent for calves

46
Q

What country did not use BCG?

A

USA

47
Q

How is BCG given? old and new

A

initially orally but now intradermally

48
Q

What are the limits of BCG?

A

Initial deaths in children from contaminated vaccine

Different strains/vaccines–> 40 manufacturers

Adverse reactions–> localized to fatal disseminated BCG infection

Clinical trials show varied efficacy

COMPROMISES THE TB SKIN TEST

49
Q

What are general details of Bartonella henelae (Bh)

A

Fastidious slow growing bacterium

Facultative intracellular

Gram (-) rod

Two forms in culture:
— Autoadherent, forms clumps (rough)
—-Non-adherent, single bacteria (smooth)

50
Q

What is the morphology of Bh?

A

Gram negative rod

51
Q

what are the forms in culture of Bh?

A

— Autoadherent, forms clumps (rough)
—-Non-adherent, single bacteria (smooth)

52
Q

what are the forms in culture of Bh?

A

— Autoadherent, forms clumps (rough)
—-Non-adherent, single bacteria (smooth)

53
Q

What are the two diseases caused by Bh?

A

Cat-scratch disease
Bacillary angiomatosis

54
Q

What is cat scratch disease and what is bacteria caused by it?

A

Bh

Lymphadenopathy—> immunocompetent individuals

55
Q

Cat scratch disease is found in what types of individuals ?

A

Immunocompetent

56
Q

What is bacillary angiomatosis and what bacteria causes this?

A

Bh

Lesion of the skin or internal organs associated with systemic infection and characterized by proliferation of the vascular endothelium

In immunocompromised people

57
Q

What type of individuals get bacillary angiomatosis

A

immunocompromised

58
Q

what is the reservoir host for Bh?

A

feline

59
Q

What is the vector for Bh?

A

Cat-flea

60
Q

What are the virulence factors of Bh?

A

BadA-adhesin

Type IV secretion system (VirB)

Beps- effector proteins

60
Q

What are the virulence factors of Bh?

A

BadA-adhesin

Type IV secretion system (VirB)

Beps- effector proteins

61
Q

How does Bh cause angiogenesis?

A

Interaction with macrophages to produce proangiogenic factors (VEGF)—> BadA

Interaction with endothelial cells to inhibit apoptosis and to promote proliferation and table (capillary) formation (IL-8) and chemotaxis of macrophages (MCP-1)—>VirB and Beps

62
Q

What is the type of secretion system in Bh?

A

type IV–> VirB

63
Q

How do you diagnosis Bh?

A

Serology
PCR

64
Q

How do you treat Bh?

A

Azithromycin or doxycycline for systemic infection

65
Q

What is the prevention of Bh?

A

No vaccine

Limit exposure to cats for immunocompromised

66
Q

What are the obligate intracellular bacteria ?

A

Rickettsia rickettsii –> RMSF

Ehrlichia chaffeensis–> ehrlichiosis

Chlamydia trachomatis

67
Q

What does rickettsiae include?

A

Rickettsia, Coxiella, Ehrlichia, Anaplasma

68
Q

What is the morphology of rickettsiae ?

A

Gram negative pleomorphic(all of bacteria make different size and shapes) rods

69
Q

What is the vector of rickettsiae?

A

arthropod—> ticks

70
Q

What is the reservoir for rickettsiae?

A

animal

71
Q

What are the skin manifestation of bacterial zoonoses?

A

macule: small flat area with discoloration

papule: small, solid, raised skin lesion
erythema: redness or inflammation

petechiae: flush red or purple spots caused by minute hemorrhages

Nodule: small firm rounded mass or lesion

72
Q

Rock mountain spotted fever is caused by what?

A

Rickettsia rickettsii

73
Q

What is the reservoir or Rock mountain spotted fever ?

A

rodents, dogs, ticks

74
Q

what is the vector of Rock mountain spotted fever

A

ticks

75
Q

What is the presentation of Rock mountain spotted fever ?

A

Triad of fever, tick bite and rash (centripetal, maculopapular with petechiae)

Other symptoms: headache, confusion myalgia, vascular collapse (DIC, heart failure), renal failure

76
Q

What is the diagnosis of Rock mountain spotted fever ?

A

Clinical triad

The importance of patient’s history
- possible tick bite
-outdoor activity
-travel to endemic areas

Lab: direct IFA or PCR, retrospective serology

77
Q

What is the laboratory diagnosis of Rock mountain spotted fever ?

A

direct IFA or PCR

Retrospective serology

78
Q

What is the treatment of Rock mountain spotted fever ?

A

Tetracyclines

79
Q

What is the prevention of Rock mountain spotted fever ?

A

tick removal, DEET

80
Q

What is similar to RMSF? what is the difference?

A

Ehrlichiosis but no rash

81
Q

What is the reservoir of Ehrlichiosis ?

A

Deer–> deer mice

82
Q

What is the vector of Ehrlichiosis ?

A

Amblyomma species (specific species of tick)

83
Q

What is the diagnosis of Ehrlichiosis?

A

serology or blood smears stains with Giemsa

84
Q

What is the treatment of Enrlichiosis

A

Tetracyclines

85
Q

What are considered energy parasites?

A

Chlamydia

86
Q

What is the morphology of chlamydia?

A

small pleomorphic, gram negative

87
Q

What is unique about chlamydia ?

A

No peptidoglycan so no beta lactam antibiotics

88
Q

What will not work on Chlamydia and why?

A

beta lactam antibiotics because chlamydia does not have peptidoglycan

89
Q

Chlamydia has how many forms of life cycle? what are they?

A

Two

  • Extracellular form: elementary body
    -replicative form: reticular body
90
Q

Explain the lifecycle of Chlamydia ?

A
91
Q

What are the infections caused by Chlamydia trachoatis?

A

-Respiratory tract

  • ocular —> conjunctivitis and trachoma

-genital tract—> nongonococcal urethritis, PID and lymphogranuloma venereum

92
Q

What are the ocular infections caused by Chlamydia?

A

Conjunctivitis

Trachoma (Symptoms begin with mild itching and irritation of the eyes and eyelids. They may progress to blurred vision, eye pain, and even blindness)

93
Q

What are the genital infections of Chlamydia?

A

nongonococcal urethritis

PID

lymphogranuloma venereum (know this this because it’s unique)

94
Q

Each of the following statements concerning Mycobacterium tuberculosis is correct EXCEPT:

(A) After being stained with carbolfuchsin, M. tuberculosis resists decolorization with acid alcohol.
(B) Mycobacterium tuberculosis has a large amount of mycolic acid in its cell wall.
(C) Mycobacterium tuberculosis appears as a red rod in Gram- stained specimens.
(D) Mycobacterium tuberculosis appears as a red rod in acid-fast–
stained specimens.

A

c

95
Q

Each of the following statements concerning chlamydiae is correct EXCEPT:

(A) Chlamydiae are strict intracellular parasites because they cannot synthesize sufficient adenosine triphosphate (ATP).
(B) Chlamydiae possess both DNA and RNA and are bounded by a cell wall.
(C) Chlamydia trachomatis has multiple serotypes that can cause different diseases.
(D) Most chlamydiae are transmitted by arthropods.

A

d

96
Q

Each of the following statements concerning Rocky Mountain spotted fever is correct EXCEPT:

(A) The causative organism forms β-hemolytic colonies on blood agar.
(B) Headache, fever, and rash are characteristic features of the disease.
(C) The disease occurs primarily east of the Mississippi.
(D) The disease is caused by a Rickettsia.

A

a

97
Q

Each of the following statements concerning Mycobacterium tuberculosis is correct EXCEPT:

(A) Some strains of M. tuberculosis isolated from patients exhibit multiple drug resistance (i.e., they are resistant to both isoniazid and rifampin).
(B) Mycobacterium tuberculosis contains a small amount of lipid in its cell wall and therefore stains poorly with the Gram stain.
(C) Mycobacterium tuberculosis grows slowly, often requiring 3 to 6 weeks before colonies appear.
(D) The antigen in the tuberculin skin test is a protein extracted from the organism.

A

b

Microbiology (18 decks)

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