Gram-weird Flashcards

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1
Q

What organisms do not gram stain well?

A
"These Microbes May Lack Real Color"
Treponema
Mycobacteria
Mycoplasma
Legionella
Rickettsia
Chlamydia
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2
Q

Why don’t treponema gram stain well?

A

Too small to be visualized

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3
Q

Why don’t mycobacteria gram stain well?

A

High lipid content in walls – take up carbolfuschin better (acid-fast)

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4
Q

Why don’t mycoplasma gram stain well?

A

No cell wall.

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5
Q

Why don’t Legionella gram stain well?

A

Primarily intracellular - silver stain instead

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6
Q

Why don’t Rickettsia gram stain well?

A

Primarily intracellular

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7
Q

Why don’t Chlamydia gram stain well?

A

Primarily intracellular, lacks classic peptidoglycan because of low muramic acid

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8
Q

On what kind of culture does Legionella grow?

A

Charcoal yeast extract with iron and cysteine.

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9
Q

How can legionella be detected?

A

Urine antigen

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10
Q

Where is legionella found? How is it transmitted?

A

Ubiquitous in water environments - air conditioning systems/cooling towers. Transmitted via aerosol. No person to person.

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11
Q

What allows legionella to be a facultative intracellular parasite?

A
  1. Dot/Icm type IV secretion system inhibits macrophage phagosome-lysosome fusion.
  2. Cu-Zn superoxide dismutase and catalase-peroxidase protects bacteria from oxidative burst
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12
Q

What are the clinical manfestations of legionella?

A

Legionnaires Dz: Severe pneumonia, associated with fever, GI and CNS sx.
Pontiac fever: Mild flu-like syndrome, usually self-limiting w/in 1 week.

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13
Q

How is legionella treated?

A

Macrolide or quinolone.

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14
Q

What is the reservoir of Chlamydia?

A

Humans.

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15
Q

How is Chlamydia transmitted?

A

Direct personal contact.

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16
Q

What is the life cycle of Chlamyida?

A
  1. Elementary bodies, Enters cells via Endocytosis, is Enfectious.
  2. Reticulate body Replicates by fission, Reorganizes into elementary bodies.
    - larger and more osmotically fragile.
    * Chlamydia are OBLIGATE intracellular - steal ATP from host w/ translocator.
17
Q

How does chlamydia avoid phagosome-lysosome fusion?

A

Cell wall lacks muramic acid.

18
Q

What strains of Chlamydia cause atypical pneumonia?

A

C. pneumoniae and C. psittaci - aerosol tx.

19
Q

What’s special about C. psittaci’s reservoir?

A

Avian

20
Q

What does C. trachomatis cause?

A

Reactive arthritis (Reithers)
Non-gono urethritis
PID
Follicular conjunctivitis

21
Q

What do C. trachomatis serotypes, A, B and C cause?

A

Africa, Blindness (follicular conjunctivitis), Chronic Infection

22
Q

What do C. trachomatis serotypes L1, L2, and L3 cause?

A

Lymphogranuloma Venereum: small, painless ulcers on genitals –> swollen, painless inguinal lymph nodes that ulcerate (buboes). Treat w/ doxy.

23
Q

What do C. trachomatis serotypes D-K cause?

A

Everything else. Urethritis/PID/neonatal pneumonia w/ staccato cough w/ eosinophilia, neonatal conjunctivitis

24
Q

How is chlamydia treated?

A

Azithro (1x) or doxy.

25
Q

What is chlamydia diagnosed?

A

cytoplasmic inclusions seen on Giemsa or fluorescent antibody stained smear.

26
Q

How does gardnerella gram?

A

Gram variable. Pleomorphic.

27
Q

How does gardernella vaginalis present?

A

Bacterial vaginosis: gray vaginal discharge with fishy smell. Non-painful.

28
Q

What is BV associated with?

A

Sexual activity. Overgrowth of certain anaerobic bacteria in vagina.

29
Q

What are clue cells?

A

Vaginal epithelial cells covered with gardnerella bacteria, giving them a stippled appearance along outer margins.

30
Q

What is the treatment for BV?

A

metronidazole or clinda.

31
Q

How can the odor of BV be enhanced?

A

Whiff test - mixing discharge w/ 10% KOH