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diagnostic microbiology > Exam 3 review sheet > Flashcards

Exam 3 review sheet Flashcards

1
Q

Gram positive cocci (anaerobe)

A

Peptostreptococcus

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2
Q

Gram negative bacilli (anaerobe)

A

Bacteriodes
Fusobacterium

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3
Q

Gram positive rods (anaerobes)

A

Clostridium
Propionibacteria

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4
Q

Aerobes vs. Anaerboes

A

AEROBES - Uses O₂ as a terminal electron acceptor; have the enzymes Superoxide Dismutase for breaking down harmful Superoxides to H₂O₂, and Catalase, for converting toxic H₂O₂ into water.

ANAEROBES - Obtain energy from fermentation or respiration using SO₄ or NO₃ as terminal electron acceptors

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5
Q

Obligate Anaerobes vs. Microaerophilic Anaerobes

A

Obligate Anaerobes usually do not have the enzymes Superoxide Dismutase and Catalase, and therefore cannot tolerate being around any amount of O₂.

Microaerophilic Anaerobes can withstand some O₂ but grow better in Anaerobic conditions

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6
Q

Facultative Anaerobes

A

Can grow in both types of environments; typically do better in O₂ environments but possess Fermentation machinery as well.

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7
Q

Where are anaerobes normal flora

A

upper respiratory tract
mouth
GI tract
genital
skin

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8
Q

Anaerobes are frequently involved in what type of infections?

A

polymicrobic infection
**(involving more than one bacterial species)
Often involving both aerobes and anaerobes

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9
Q

Exogenous infections

A

From an outside source
**Ex: food-borne botulism
**Tetanus

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10
Q

Endogenous infection

A

*Arise from sources within the body when they move from areas of normal flora into other sites
*Most infections are endogenous, from organisms inside the body
*Examples: surgery, disease, trauma

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11
Q

Anaerobic media Containing a reducing agents

A

Sodium thioglycollate
Cystine
**They absorb oxygen

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12
Q

Thioglycolate

A

*Enriched broth with hemin and vitamin K
*Supports growth of most anaerobes
**Grows at bottom of tube
**Used as backup in case plated media fails to grow

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13
Q

Anaerobic media is usually supplemented with what?

A

Supplemented with hemin, blood, and vitamin K and sodium bicarbonate (source of CO2) for fastidious organisms

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14
Q

Anaerobic-selective media

A

Anaerobic PEA
Anaerobic KV

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15
Q

Ways to generate anaerobic atmosphere

A

Gas-generating system within a closed jar or bag
Preferred to collect by needle aspiration instead of swab
*to prevent exposure to O2

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16
Q

Specimens that should not be cultured for anaerobes

A

Throat or nasopharyngeal swabs
Gingival swabs
Sputum or Bronchial washes
Gastric contents, feces, rectal swab

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17
Q

Characteristics of Anaerobic Infections

A

Foul-Smelling Discharge
Gas in the Tissues (they produce CO₂ and H₂; i.e. Gas Gangrene)
Abscess Formation - Sets up microenvironment conducive for growth
Infection is in close proximity to a Mucosal Surface

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18
Q

Give a basic morphology of Spirochetes

A

Long, thin, motile & helical bacteria
NOT seen on Gram stain

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19
Q

Treponema pallidum is associated with what disease?

A

venereal Syphilis

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20
Q

T pallidum subsp endemicum is associated with what disease?

A

Endemic syphilis aka Bejel

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21
Q

T.pallidum subsp pertenue is associated with what disease?

A

Yaws

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22
Q

Borrelia burgdorferi is associated with what disease?

A

Lyme disease

23
Q

Borrelia recurrentis is associated with what disease?

A

Relapsing fever

24
Q

Leptospira interrogans is associated with what disease?

A

Leptospirosis

25
Q

Important categories of Spirochetes are?

A

Treponema
Borrelia
Leptospira

26
Q

Spirochetes have corkscrew-like motility due to the possession of?

A

Endoflagella

27
Q

Endoflagella consists of

A

axial filaments

28
Q

Spirochetes are best visualized via?

A

Darkfield microscopy
Fluorescent microscopy

29
Q

How is syphilis spread?

A

sexual intercourse or transplacentally

30
Q

What is primary syphilis?

A

Development of chancre at the site of inoculation
approximately 3 weeks after exposure
The chancre usually heals spontaneously after 4
to 6 weeks

31
Q

What is secondary syphilis?

A

Sets in 1-3 months after primary lesion heals
Widespread rash of the skin and mucosa membranes (hands and soles of feet)
lesions are filled with treponemas and considered infectious
“The Great Imitator”

32
Q

What is tertiary syphilis?

A

responsible for a majority of the morbidity and mortality associated with the disease
Occurs 5-30 years after primary syphilis
destruction of tissue caused by a response to the presence of treponemal antigens

33
Q

What are “nontreponemal” tests?

A

Test for antibodies developed against lipids released from damaged cells during early stage of disease. Screens for syphilis but may be false positive

34
Q

What are “treponemal” tests?

A

Test for Ab to treponemal antigens, highly specific

35
Q

What disease does Borrelia burgdorferi cause?

A

Lyme disease

36
Q

How is lyme disease spread?

A

via bites of Ixodes ticks

37
Q

Lyme disease stage 1

A

Erythema Migrans (looks like target)
Flu-like
lasts 1 month

38
Q

What is stage 2 lyme disease?

A

Facial palsy
cardiac
migratory pain
fatigue syndrome

39
Q

What is stage 3 lyme disease?

A

acute or chronic arthritis
CNS involvement

40
Q

How do you dx lyme disease?

A

early: clinical grounds
late: serological-ELISA + Western blot

41
Q

Which species of Leptospira causes disease?

A

Leptospira interrogans

42
Q

Direct transmission of L. interrogans occurs with infected

A

urine

43
Q

Indirect transmission of L. interrogans occurs with infected

A

water

44
Q

What is the gold standard in diagnosing leptospirosis?

A

Urine culture

45
Q

Where is leptospirosis most prevalent?

A

Rural areas

46
Q

Leptospirosis is a

A

zoonotic disease

47
Q

What cell culture lines are most often used for recovering Chlamydia trachomatis?

A

-McCoy Cells

48
Q

Chlamydia infections are most often implicated in

A

urethritis, conjunctivitis, STDs

49
Q

Describe the features of Mycobacteria

A
  • Aerobic
  • Non-motile, Non-spore forming
  • Straight or slightly curved rods
  • Distinctive cell wall - has high mycolic acid level
  • Fastidious
  • Slow growers
50
Q

Describe the Mycobacteria characteristics

A
  • ‘waxy’ cell wall (lipid-rich)
  • Resistance to drying + hydrophobic
  • Resistance to antibiotics and disinfectants
  • Resistance to acids and alkalis * ‘acid and alcohol fast’
  • Impermeable to standard stains
  • Survives in macrophages
51
Q

What stains are used for mycobacterium

A
  • Ziehl-Neelsen / Kinyoun= carbolfuchsin
  • Auramine-rhodamine = fluorescent
52
Q

What is the Runyon classification based on?

A

based on the rate of growth, production of yellow pigment and whether this pigment was produced in the dark or only after exposure to light.

53
Q

Runyon classification groups

A

Group 1- photochromogens
Group 2- Scotochromogens
Group 3- Nonphotochromogens
Group 4- Fast growers

54
Q

How is mycobacterium diagnosed

A

Microscopy
Culture (what are the different types of media?)
Molecular = PCR, NAAT, probes (main concepts of tests)
Done in BSL3 facility

diagnostic microbiology (11 decks)

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