Spirochetes Flashcards
(55 cards)
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.
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.
3
Q
What does treponema pallidum cause?
A
syphillis
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.
5
Q
What does Treponema pallidum subsp. endemicum
cause and how?
A
- causes nonvenereal syphilis
- spread mouth to mouth via utensils
6
Q
What is the third most common STD in the U.S.?
A
syphilis
7
Q
Is there a cure for syphilis?
A
yes, penicillin
8
Q
Can syphilis be found in creatures other than humans?
A
no
9
Q
how many stages does syphilis have?
A
3, primary, secondary, and tertiary.
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.
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).
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.
13
Q
How is treponema pallidum identified?
A
- Molecular (PCR)
- Serodiagnosis (Reagin)
- direct detection
14
Q
Does yaws have a cure?
A
yes, a single dose of azithromycin
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.
16
Q
How many specia of borrelia burgdorferi sensu lato are there?
A
12 species
17
Q
what species cause lyme disease?
A
- B. burgdorferi sensu stricto
- Borrelia mayonii
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
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.
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
21
Q
What are the two major species of leptospira?
A
- Leptospira interrogans- cause of human leptospirosis.
- Leptospira biflexa-environmental strains
22
Q
What disease is associated with leptospira?
A
Leptospirosis- a zoonotic disease, colonizes renal tubules of carrier animals (mammals, reptiles, fish, birds)
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
what does c. trachomatis cause?
Major cause of pelvic inflammatory disease and ectopic pregnancy.
26
What is the pathogenesis of c. trachomatis?
- Humans are the natural habitat.
- Trachoma-ocular eye infection causing blindness
- Lymphogranuloma venereum (LGV)
- Genital infections- urethritis, cervicitis, proctitis, epididymitis
27
What is the treatment for c. trachomatis?
azithromycin or doxycycline.
28
What are the important species of chlamydia?
- c. trichomatis
- c. psittaci
- c. pneuoniae
29
What are the general characteristics of chlamydia spp?
- 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
What causes rocky mountain spotted fever and how is it identified?
Serology is Gold standard, detection of R. rickettsii antigen.
31
What are the general characteristics of rickettsia spp.?
- 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
What does a rickettsia culture require?
embryonated eggs
33
What species are part of the rickettsia spotted fever group?
- R. conorii (Israeli spotted fever) Europe, Middle east
| - R. rickettsii (Rocky mountain spotted fever) U.S.
34
What species are part of the rickettsia typhus group?
- R. prowazekii ( epidemic typhus)
| - R. typhi (murine ((endemic)) typhus: fever, headache, rash, doxycycline is curative
35
Which bacteria are obligate intracellular bacteria?
- Ehrlichia
- Anaplasma
- Rickettsia
- Chlamydia
36
what does ehrlichia cause and how is it treated?
- fever, headache, chills, vomiting, confusion, joint pain
| - 7-10 day course of doxycycline
37
how is ehrlichia transmitted?
- 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
Which bacterial species are cell wall deficient?
- 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
what is the pathogenesis of mycoplasma pneumo?
Mycoplasma pneumoniae causes walking pneumonia, primary atypical pneumonia.
40
what is the pathogenesis of mycoplasma hominis?
Mycoplasma hominis –systemic infections in neonates, urogenital infections in adults.
-Colonies have a ‘fried egg’ appearance on agar.
41
what is the pathogenesis of ureaplasma urealyticum?
Ureaplasma urealyticum has been isolated from tissues of stillborn infants, controversy as to if it causes chorioamnionitis.
42
what media is used for mycoplasma and ureaplasma?
- sp4 media
| - Incubate at 35 degrees C, 5-10% CO2 for up to 30 days.
43
how are ureaplasma and mycoplasma identified?
- Molecular methods (off of specimens) quick turn around time!
- Serodiagnosis
44
how are mycoplasma and ureaplasma infections treated?
Treatment: resistance to beta-lactams (penicillin) which inhibit cell wall synthesis; tetracycline is effective.
45
What species are considered aerobic actinomyces?
Nocardia, Streptomyces, Rhodococcus
46
Which two aerobic actinomyces species are acid fast and why?
- nocardia andrhodococcus
| - Both species cells walls have high contents of mycolic acids.
47
can the aerobic actinomyces be identified to the species level?
Speciation is beyond many routine clinical labs at this time, may need to send to reference labs for speciation.
48
What are the general characteristics of streptomyces?
Gram positive, branching filaments with no mycolic acids, and are non-acid fast.
Branching is extensive with chains and spores.
49
what does streptomyces cause?
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
Where do nocardia generally live?
Inhabit soil and water, decompose plant material.
51
How are nocardia transmitted?
Transmission via inhalation or inoculation (cuts etc).
52
What are the general characteristics of nocardia?
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
What nocardia spp is responsible for most infection and what does it cause?
-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
What are the general characteristics of rhodococcus?
- Gram positive, catalase +, branching, filamentous bacteria capable of fragmenting in rods and cocci.
- Some are facultative intracellular bacteria that reside within macrophages.
55
what do rhodococcus infections cause in humans?
Infections stem from pulmonary, skin (actinomycetoma) to osteomyelitis.
