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MHD #3 > spirochetes > Flashcards

spirochetes Flashcards

1
Q

Treponema pallidum microscopy

A

dark field only

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2
Q

Leptospira interrogans microscopy

A

Leptospira interrogans

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3
Q

Borrelia recurrentis microscopy

A

light microscopy

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4
Q

Borrelia burgdorferi microscopy

A

light microscopy

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5
Q

Treponema pallidum vector & reservoir

A

none

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6
Q

Leptospira interrogans vector & reservoir

A

Rats, mice, wild rodents, dogs, swine, cattle

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7
Q

Borrelia recurrentis vector and resevoir

A

“V. louse,tick

R. Rodents”

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8
Q

Borrelia burgdorferi vector and resevoir

A

V. tick (Ixodes ticks)

R. mouse, deer

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9
Q

Treponema pallidum transmission

A

Intimate sexual contact infective primary or secondary lesion

Passes through placenta resulting in congenital infection

No sexual spread >4 years after acquiring infection

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10
Q

Treponema pallidum disease

A

Syphilis

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11
Q

Leptospira interrogans transmission

A

Contact or ingest infected animal urine- contaminated water

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12
Q

Leptospira interrogans disease

A

Leptospirosis

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13
Q

Borrelia recurrentis transmission

A

Ticks or lice

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14
Q

Borrelia recurrentis disease

A

Relapsing fever

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15
Q

Borrelia burgdorferi transmission

A

Ticks

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16
Q

Borrelia burgdorferi disease

A

Lyme borreliosis

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17
Q

Treponema pallidum: Cultural Characteristics

A

long generation time - 30 hours
very sensitive to drying and heat (cannot be spread on surfaces)
microaerophilic (survives 3-5% oxygen)
differentiated by clinical associations only

structure - has 3 axial fibrils

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18
Q

obliterative endarteritis

A

characteristic of a lesion from syphilis

severe proliferating endarteritis (inflammation of the intima or inner lining of an artery) that results in an occlusion of the lumen of the artery

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19
Q

Pathogenesis of Syphilis

A

Passes through intact mucosa or abraded skin

Multiplies locally and disseminates to lymph nodes and other organs

Symptoms or signs when number of organisms reaches critical mass

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20
Q

Primary Syphilis

A

• consists of an ulcerative lesion at site of inoculation with regional adenopathy (inguinal for a genital lesion)

  • Painless papule at site of inoculation which ulcerates – chancre
  • Ulcer has smooth margins and crusted base
  • Darkfield positive (organism can be collected from the chancre)
  • Firm local adenopathy
  • No systemic manifestations
  • Heals spontaneously (self-limiting)
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21
Q

Secondary syphilis

A

systemic flu-like illness which may develop 2-10 weeks after primary lesion heals

  • Papulosquamous rash – entire body including palms and soles (sandpaper- like)
  • Moist areas→papules coalesce – condylomata lata (warts on genital areas)
  • Other sites: hepatitis, aseptic meningitis, periostitis, nephritis (immune-complex type)
  • Fever and generalized lymphadenopathy
  • Heals spontaneously but may recur over four years
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22
Q

Untreated Syphilis

A

• 1/3 resolve the infection, i.e., cured

• Remaining 2/3
-  1/3 latent
 - 1/3 tertiary (late) syphilis
Neurosyphilis
Cardiovascular syphilis (prox. aorta)
Late benign gummatous syphilis
23
Q

Neurosyphilis

A

Asymptomatic – CSF infected without symptoms or signs

Meningovascular – Chronic meningitis → affects arteries and cranial nerves (base of brain – could lead to a stroke)

Paresis – Cortical degeneration with mental changes (cerebral cortex involvement)

Tabes dorsalis – Demyelination of posterior columns and dorsal roots
Loss of pain and temperature
Ataxia

24
Q

Congenital Syphilis

A 
Infection occurs in utero
Normal at birth→multisystem disease later
Rhinitis (purulent nasal discharge)
Rash
Bone and cartilage involvement (teeth)
Liver, spleen, lymph nodes, CNS
Prevent with treatment during pregnancy
Routine screening recommended
25
Q

Microscopic Diagnosis of Syphilis

A

Darkfield
Primary and secondary lesions


Direct Fluorescent Antibody Test
Immunofluorescence – monoclonal antibodies
Material from lesion or biopsy


PCR

(No cultures)

26
Q

Syphilis Serology – Nontreponemal Tests

A

Reaginic antibodies
IgM and IgG against cardiolipin (membrane protein)
NOT directed against T. pallidum

VDRL – Venereal Disease Research Laboratories
Done on CSF

RPR – Rapid Plasma Reagin
Serum

Quantitated and used to follow treatment
Revert to negative after treatment of early disease (higher positives in early disease)

False positive tests common

27
Q

Specific Treponemal Serology

A
  • FTA-Abs – Fluorescent Treponemal Antibody-Absorption Test
  • TPPA – PA = particle agglutination
  • EIA and CIA (Chemiluminescence immunoassay)

Decrease false positives when confirming RPR
Remain positive for life
Fewer than 25% revert to negative (AIDS)

(higher positives in late disease)

28
Q

FTA-Abs

A

Fluorescent Treponemal Antibody-Absorption Test

  • Absorbed with non-T. pallidum treponeme
  • Antigen is killed Reiter strain T. pallidum
29
Q

TPPA – PA = particle agglutination

A

Treponemal antigens adsorbed onto gelatin particle or RBC

MHA-TP–Microhemagglutination Treponema pallidum

30
Q

EIA and CIA

A

( Enzyme immunoassay (ELISA) ad Chemiluminescence immunoassay)
Cheap, automated, now in wide use for screening
* High false positive rate when used to screen low prevalence population

screening test

31
Q

treatment of T. pallidum

A

Long acting formulation used (long generation time)

    • Benzathine Penicillin G
  • Treatment differs according to stage (primary and secondary get a one time injection, late gets IV infusion)

Jarisch-Herxheimer Reaction
Fever, chills, headache, hypotension
Release of toxic products from killed spirochetes

Alternative - Tetracyclines (not possible with some forms, must desensitize pcn allergies)

32
Q

Borrelia

A

Borrelia are larger spirochetes that are visible in stained preparations. They have a mammalian reservoir with spread to humans by tick or louse vectors resulting in Relapsing Fever or Lyme Borreliosis

33
Q

which spirochete can be seen on a blood smear?

A

B. recurrentis - on a Wright’s stained blood smear

34
Q

Borrelia cultures

A

B. recurrentis – blood, serum or tissue-containing media
B. burgdorferi – Barbour, Stoenner, Kelly broth

not commonly done - usually rely on serologic tests

35
Q

Relapsing Fever

A

B. recurrentis and related organisms escape immune recognition by altering their antigenic structure during infection

Gene switch from silent to expression locus (like N. gonorrhoeae) on plasmid

Relapses caused by emergence and multiplication of antigenic variants

36
Q

Epidemiology – Relapsing Fever

A

Epidemic – Louse-borne relapsing fever in times of catastrophe such as war or famine - caused by B. recurrentis

Endemic – Tick-borne relapsing fever in
mountain regions of Western US. caused by other borrelia. associated with living in places with lots of rodents

37
Q

Relapsing Fever: Clinical Manifestations

A 
Fever
Chills
Muscle pain
Headache
Relapses – antigenic variation
Resolves 3-5 days, remits after 7-9 days
Each relapse is less severe
38
Q

Diagnosis Relapsing Fever

A 
Laboratory Diagnosis
Blood smear
Culture – rarely performed
Serology
Cross reactions with other spirochetes
39
Q

Treatment of relapsing fever

A

Tetracycline, Erythromycin

Jarisch-Herxheimer reactions common

40
Q

Epidemiology of Lyme Boreliosis

A

Zoonosis in which deer and white-footed mouse are primary reservoirs
- Spread by tick – Ixodes ricinus complex

Two year tick life cycle
All stages feed on humans
Nymphs in spring and summer major source

41
Q

Pathogenesis: Lyme Borreliosis

A

Tick bite → multiply locally
Enter lymph or blood → disseminate to many sites

Antibody is associated with near disappearance of spirochetes
Suggests immune pathogenesis in late stage disease

42
Q

Erythema migrans

A

Expanding erythematous lesion at site of tick bite - bulls-eye pattern

  • Organisms cultured from biopsy
  • Accompanied by flu-like illness
43
Q

Early Disseminated Lyme Disease

A

Days to weeks after primary infection
Fatigue, headache, fever, malaise
Multiple skin lesions

Neurologic: Meningitis, radiculitis, facial nerve paralysis(most common) , other neuropathies

Cardiac: Heart block (more common), myocarditis

Arthritis: develops in 60% untreated – weeks to years later

44
Q

Late Stage Lyme Disease

A

Arthritis
Recurrent episodes of pain and swelling of large joints especially knees

Encephalopathy
Fatigue, memory loss, cognitive defects
Controversial

Skin: acrodermatitis chronica atrophicans

45
Q

Laboratory Diagnosis of Lyme Borreliosis

A 
Culture is usually not available
Serology
ELISA or IFA
Both IgM and IgG responses measured
Confirm with western blot

DNA detection by PCR
Skin biopsy – 65%-75%
Synovial fluid – 50%-85%
CSF – 25%

46
Q

Therapy and Prevention of Lyme Borreliosis

A

Antimicrobial therapy
Early – Doxycycline, amoxicillin, cefuroxime orally
Late – Oral as above or
Penicillin G or ceftriaxone parenterally

Prevention with repellants
Tick checks
Vaccine
Recombinant OspA Vaccine removed from market

47
Q

Leptospira interrogans - Structural and Cultural Characteristics

A

Thin spirochete – 6-20 μm x 0.1μm
218 serovars
Specific syndromes associated with serotypes are not distinctive
Leptospires can be cultivated in liquid media

48
Q

Epidemiology – Leptospirosis

A

Zoonosis with many animal hosts
Rats, mice, wild rodents, dogs, swine, cattle
Transmission

Ingestion of or direct contact with food or water contaminated with infected animal urine

49
Q

Pathogenesis – Leptospirosis

A

After infection, spirochetes invade bloodstream and affect endothelial cell integrity causing vasculitis in many organs
Immune complexes found in kidney
Organisms excreted in urine

50
Q

Leptospirosis first stage

A

(Bacteremia)

Fever, headache, myalgias, conjunctival suffusion, abdominal pain

51
Q

Leptospirosis second stage

A

(Immune)

Aseptic meningitis or generalized illness with myalgias, headache, uveitis and rash

52
Q

Leptospirosis severe stages

A

stages blend
Prominent hepatitis, kidney involvement, hemorrhage
Mortality 5-10%

53
Q

Leptospirosis: Diagnosis

A

Culture blood and CSF (early), urine (late)

Serology – Microscopic agglutination test (MAT) after first week (difficult)

ELISA and IHA tests less standardized (but easier)

PCR very sensitive in research laboratories

54
Q

Leptospirosis: treatment

A

Penicillin or doxycycline

MHD #3 (11 decks)

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