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Clinical Microbiology (Exam 3) > Spirochetes > Flashcards

Spirochetes Flashcards

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1
Q

What are the general physical characteristics of spirochetes?

A
  • Long, slender, coiled gram negative rods with fibrils and an outer sheath.
  • Fibrils: flagella like organelles imparting motility.
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2
Q

Can treponema spp be grown in a lab?

A

no, it is too fastidious and needs the host to do things for it.

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3
Q

What does treponema pallidum cause?

A

syphillis

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4
Q

What does Treponema pallidum subsp. pertenue

cause and how does it spread?

A
  • causes yaws in children

- spread person to person by breaks in the skin.

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5
Q

What does Treponema pallidum subsp. endemicum

cause and how?

A
  • causes nonvenereal syphilis

- spread mouth to mouth via utensils

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6
Q

What is the third most common STD in the U.S.?

A

syphilis

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7
Q

Is there a cure for syphilis?

A

yes, penicillin

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8
Q

Can syphilis be found in creatures other than humans?

A

no

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9
Q

how many stages does syphilis have?

A

3, primary, secondary, and tertiary.

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10
Q

What does the primary stage of syphilis consist of?

A
  • chancre
  • skin lesion at site of bacterial penetration develops 10-90 days after the initial infection
  • bacteria proliferate and enter blood, lymphatics.
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11
Q

What does the secondary stage of syphilis consist of?

A
  • diffuse skin lesions over entire body,
  • flu like symptoms (2-10 wks following 1˚),
  • Patients often enter a latency period, disease becomes subclinical (asymptomatic).
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12
Q

What does the tertiary stage of syphilis consist of?

A

~1/3rd of untreated patients progress to the tertiary syphilis

  • all tissues could potentially be involved (10-25 yrs after the initial infection);
  • involvement of brain, neurosyphilis can cause dementia.
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13
Q

How is treponema pallidum identified?

A
  • Molecular (PCR)
  • Serodiagnosis (Reagin)
  • direct detection
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14
Q

Does yaws have a cure?

A

yes, a single dose of azithromycin

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15
Q

What is the pathogenesis of yaws?

A
  • Initially see skin lesion
  • progresses to disfigurement of nose/bones,
  • thickening and cracking of palms of hands, soles of the feet making walking difficult.
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16
Q

How many specia of borrelia burgdorferi sensu lato are there?

A

12 species

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17
Q

what species cause lyme disease?

A
  • B. burgdorferi sensu stricto

- Borrelia mayonii

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18
Q

How is borrelia identified?

A
  • Often can be seen in peripheral blood smears with the Wright’s stain before infection is clinically detected.
  • Cultivation is possible, numbers may be low
  • serology is preferred method
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19
Q

What is the treatment for borrelia?

A
  • doxycycline in adults
  • Doxycycline is contraindicated in children under 8-10 years of age, treatment is 14 day course of amoxicillin, No protocol for prophylaxis exists for children.
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20
Q

What are the stages of lyme disease?

A
  • Stage 1: Erythema chronicum migrans (bulls eye lesion), headaches, fatigue, chills 3-30 days after initial bite/feeding.
  • Stage 2: if left untreated, spirochetes have spread via blood, joint and muscle pain, cardiac arrhythmias, carditis, weeks following bite.
  • Stage 3: chronic arthritis (2-3 years after bite), possibly neurologic involvement
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21
Q

What are the two major species of leptospira?

A
  • Leptospira interrogans- cause of human leptospirosis.

- Leptospira biflexa-environmental strains

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22
Q

What disease is associated with leptospira?

A

Leptospirosis- a zoonotic disease, colonizes renal tubules of carrier animals (mammals, reptiles, fish, birds)

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23
Q

how is leptospirosis spread?

A

Humans contract via contact with urine or blood of infected animals through breaks in skin, mucous membranes, conjunctiva.

24
Q

What causes the most common STD in the U.S.?

A

C. trachomatis

25
Q

what does c. trachomatis cause?

A

Major cause of pelvic inflammatory disease and ectopic pregnancy.

26
Q

What is the pathogenesis of c. trachomatis?

A
  • Humans are the natural habitat.
  • Trachoma-ocular eye infection causing blindness
  • Lymphogranuloma venereum (LGV)
  • Genital infections- urethritis, cervicitis, proctitis, epididymitis
27
Q

What is the treatment for c. trachomatis?

A

azithromycin or doxycycline.

28
Q

What are the important species of chlamydia?

A
  • c. trichomatis
  • c. psittaci
  • c. pneuoniae
29
Q

What are the general characteristics of chlamydia spp?

A
  • Obligate intracellular bacteria, previously considered viruses.
  • Cannot be grown on cell-free media.
  • Life cycle is similar to parasites by have a intracellular form termed a reticulate body and an extracellular, inert (lacking or weak), form the elementary body. The EB cannot survive for long outside of a host cell.
30
Q

What causes rocky mountain spotted fever and how is it identified?

A

Serology is Gold standard, detection of R. rickettsii antigen.

31
Q

What are the general characteristics of rickettsia spp.?

A
  • Obligate intracellular bacteria
  • Small, pleomorphic gram negative bacilli
  • Humans are accidental hosts, animal reservoirs.
  • Ticks, lice and fleas serve as vectors for spread of the bacteria.
32
Q

What does a rickettsia culture require?

A

embryonated eggs

33
Q

What species are part of the rickettsia spotted fever group?

A
  • R. conorii (Israeli spotted fever) Europe, Middle east

- R. rickettsii (Rocky mountain spotted fever) U.S.

34
Q

What species are part of the rickettsia typhus group?

A
  • R. prowazekii ( epidemic typhus)

- R. typhi (murine ((endemic)) typhus: fever, headache, rash, doxycycline is curative

35
Q

Which bacteria are obligate intracellular bacteria?

A
  • Ehrlichia
  • Anaplasma
  • Rickettsia
  • Chlamydia
36
Q

what does ehrlichia cause and how is it treated?

A
  • fever, headache, chills, vomiting, confusion, joint pain

- 7-10 day course of doxycycline

37
Q

how is ehrlichia transmitted?

A
  • E. chaffeensis is transmitted by the Lone Star Tick (Amblyomma americanum). Believed to be different than STARI
  • Tick needs to be attached to human skin for 24 hours to transmit the bacteria.
  • Dogs, cats may serve as reservoirs (Merck Manual).
38
Q

Which bacterial species are cell wall deficient?

A
  • mycoplasma
  • ureaplasma
  • Smallest of known free-living bacteria (0.3 to 0.8 microns)
  • Can be normal flora of the mouth, upper respiratory and genitourinary tract.
  • fastidious
39
Q

what is the pathogenesis of mycoplasma pneumo?

A

Mycoplasma pneumoniae causes walking pneumonia, primary atypical pneumonia.

40
Q

what is the pathogenesis of mycoplasma hominis?

A

Mycoplasma hominis –systemic infections in neonates, urogenital infections in adults.
-Colonies have a ‘fried egg’ appearance on agar.

41
Q

what is the pathogenesis of ureaplasma urealyticum?

A

Ureaplasma urealyticum has been isolated from tissues of stillborn infants, controversy as to if it causes chorioamnionitis.

42
Q

what media is used for mycoplasma and ureaplasma?

A
  • sp4 media

- Incubate at 35 degrees C, 5-10% CO2 for up to 30 days.

43
Q

how are ureaplasma and mycoplasma identified?

A
  • Molecular methods (off of specimens) quick turn around time!
  • Serodiagnosis
44
Q

how are mycoplasma and ureaplasma infections treated?

A

Treatment: resistance to beta-lactams (penicillin) which inhibit cell wall synthesis; tetracycline is effective.

45
Q

What species are considered aerobic actinomyces?

A

Nocardia, Streptomyces, Rhodococcus

46
Q

Which two aerobic actinomyces species are acid fast and why?

A
  • nocardia andrhodococcus

- Both species cells walls have high contents of mycolic acids.

47
Q

can the aerobic actinomyces be identified to the species level?

A

Speciation is beyond many routine clinical labs at this time, may need to send to reference labs for speciation.

48
Q

What are the general characteristics of streptomyces?

A

Gram positive, branching filaments with no mycolic acids, and are non-acid fast.
Branching is extensive with chains and spores.

49
Q

what does streptomyces cause?

A

Cause chronic granulomatous lesions of the skin called mycetomas- infection of subcutis with draining sinus tracts following traumatic inoculation often of the lower limb with white to yellow granules.

50
Q

Where do nocardia generally live?

A

Inhabit soil and water, decompose plant material.

51
Q

How are nocardia transmitted?

A

Transmission via inhalation or inoculation (cuts etc).

52
Q

What are the general characteristics of nocardia?

A

Gram positive (variable), catalase +, branching, filamentous bacteria capable of fragmenting in rods and cocci microscopically.

  • Can grow on Sheep, chocolate but require 48 -72 hours for growth
  • Produces orange, glabrous colonies on Middlebrook’s agar and has a musty basement odor.
53
Q

What nocardia spp is responsible for most infection and what does it cause?

A

-Nocardia asteroides is responsible for most human infection greater than 80% of any species of the genera.
-Facultative intracellular pathogen of human cells
Can cause skin infections (actinomycetoma) to pulmonary infections.

54
Q

What are the general characteristics of rhodococcus?

A
  • Gram positive, catalase +, branching, filamentous bacteria capable of fragmenting in rods and cocci.
  • Some are facultative intracellular bacteria that reside within macrophages.
55
Q

what do rhodococcus infections cause in humans?

A

Infections stem from pulmonary, skin (actinomycetoma) to osteomyelitis.

Clinical Microbiology (Exam 3) (4 decks)

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