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Y1 - Microbio Exam 2 > 18_Chlamydia, Rickettsia, Ehrlichia > Flashcards

18_Chlamydia, Rickettsia, Ehrlichia Flashcards

1
Q

what do the following have in common?

  • chlamydia
  • rickettsia
  • ehrlichia
  • anaplasma
  • bartonella
A
  • most of these organisms are obligate intracellular pathogens (except Bartonella)
  • cannot be grown in the lab except in tissue culture, or in other eukaryotic cells such as embryonated hens’ eggs (except Bartonella & Coxiella CAN be cultured)
  • many produce rashes and many have arthropod vectors
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2
Q

chlamydia trachomatis:

4 major clinical symptoms

A
  1. genital infection: nongonoccocal urethritis
    • Serovars D-K
  2. inclusion conjunctivitis in infants (Serovars, D-K)
  3. Trachoma: chronic follicular conjunctivitis leading to blindness
    • Serivars A, B, Ba, C
  4. lymphogranulumoa nevereum: STD-swelling in inguinal lymph nodes leading to bubos; serovars L1, L2, L3 (uncommon in US)

*Chlamydia infections ONLY have a human reservoir

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3
Q

Chlamydia trachomatis:

genital infections (serovars D-K)

A
  • this organism causes urethritis, characterized in male by a thin urethral discharge, and sometimes dysuria
    • *the absence of purulent discharge distinguishes Chlamydia from gonococcal infxn in men
  • women may have dysuria and a discharge or be asymptomatic
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4
Q

what is often co-infected w/ chlamydia trachomatis?

A
  • *Co-infection w/ Neisseria gonorrhoeae is common; sometimes called “nongonococcal urethritis” or “post-gonococcal urethritis”
  • male: epididymitis over 50% can be asymptomatic
  • female: cervicitis, salpingitis, pelvic inflammatory disease (PID), ectopic pregnancy, sterility
    • 2/3 of females are asymptomatic
    • 2016 US > 1,598,354 cases reported to CDC; most common notifiable disease in the US
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5
Q

Serovars can cause genital infections, and can cause what else?

A
  • extragenital infxns: rectal and pharyngeal infections in men/women
  • highest rates: men who have sex with men
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6
Q

In what 2 ways do infants manifest the Chlamydia trachomatis?

A

Infants may acquire the organism when passing thru the vaginal tract of an infected mother; transmission rate is over a 1/3. Infants manifest by:

  1. Inclusion conjunctivitis: watery progressing to mucopurulent discharge 5-12 days after birth
  2. Interstitial pneumonia: 6 wks- 6 months
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7
Q

What is the leading cause of blindness in the world?

Causing 41 million infected, 10 million bind

A

Chlamydia trachomatis causes trachoma;

  • a bacterial infection of the eye causing follicular conjunctivitis
  • cobblestone inflammation
  • late trachoma
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8
Q

Chlamydia trachomatis: Trachoma

  1. serovars
  2. mechanism
  3. transmission
A
  1. serovars: A, B, Ba, C
  2. mechanism:
    • scarring on the inside of the eyelid, which becomes rough –> corneal scarring and damage
    • blindness due to chronic infxn and reinfxn in endemic areas
  3. transmission
    • transmitted person-to-person by fingers, fomites (towels & wash cloths), and flies
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9
Q

Chlamydial microbiology:

  1. type of pathogens
  2. structure & staining
  3. morphological forms
  4. actions
A
  1. type of pathogens: all organisms are obligate intracellular pathogens
  2. structure & staining:
    • gram negative: no peptidoglycan
    • small 0.3-1 micrometer
  3. morphological forms
    • elementary body: infectious form
    • reticulate body: intracellular replicative form; replication is in an “inclusion”, which is a membrane bound vacuole
  4. actions:
    • no phagolysosomal fusion: organisms stay in the vesicle
    • infect columnar or transitional epithelial cells
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10
Q

chlamydia life cycle:

elementary body and reticulate body

A
  • Elementary body
    • size about 0.3 micrometers
    • rigid cell wall
    • RNA:DNA content #1:1
    • Isolated organisms infectious
    • adapted for extracellular survival
  • Reticulate body
    • size 0.5-1 micrometer
    • fragile cell wall
    • RNA:DNA content #3:1
    • Isolated organisms not infectious
    • adapted for intracellular survival
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11
Q

which is the phase of the Chlamydia lifecycle is:

  • adapted for extracellular survival
  • adapted for intracellular survival
A
  • Extracellular survival: Elementary body
    • smaller, rigid cell wall
  • Intracellular survival: Reticulate body
    • larger, fragile cell wall
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12
Q

Chlamydia trachomatis:

diagnosis and treatment

A
  • Diagnosis: nucleic acid amplification (NAATs) for genital serovars, both for genital and extragenital infxns
    • samples
      • women: vaginal swab, or cervical
      • male: clean catch urine or urethral swab
    • specimens do not have to have living organisms
    • Chlamydia are obligate intracellular pathogens and cannot be cultured on bacteriologic media
  • Treatment: Azithromycin or Doxycycline or topical tetracycline
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13
Q

Chlamydophila (Chlamydia) pneumoniae infections:

  • transmission
  • symptoms
A
  • transmission: human to human
  • sxs:
    • pneumonia (walking pneumoniae or atypical pneumoniae)
    • bronchitis
    • sinusitis, laryngitis, pharyngitis less common
    • atherosclerosis, asthma, alzheimer’s disease, lung cancer, COPD, multiple sclerosis
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14
Q

Chlamydophila (Chlamydia) pneumoniae

diagnosis and treatment

A
  • These organisms are obligate intracellular pathogens; they have elementary bodies and reticulate bodies like other Chlamydia
  • Diagnosis
    • cell culture of oropharyngeal swabs
    • 4x rise in IgG antibody detected by indirect immunofluorescence against formalin fixed in elementary bodies of reagent strains grown in tissue culture
  • Treatment: macrolides: (Azithromycin or tetracycline in adults)
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15
Q

Rickettsia can cause what types of fevers?

how many organisms cause spotted fevers?

A
  • Spotted fevers
  • Typhus fevers

18 diff’t species can cause just spotted fevers; most countries have their own endemic organisms

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16
Q

Rickettsia rickettsii:

  1. transmission
  2. incubation period
  3. sxs
  4. rash
A
  1. transmission:
    • rodent reservoirs (mice, voles, squirrels, chipmunks)
    • transmitted by ticks; infected tick bite transmits disease
  2. incubation period of 5-14 days
  3. sxs: fever, headache, maculopapular rash, myalgia, confusion
    • rash: rash starts on extremities: wrists and ankles and spreads to the trunk;
    • appearance of rash on palms and soles is diagnostic;
    • only syphilis also has a rash on palms and soles
17
Q

Which tick causes the Rocky Mountain Spotted Fever?

A

Rocky Mountain Wood Tick;

aka Dermacentor andersoni

18
Q

Rickettsia rickettsii:

  1. structure
  2. type of pathogen
  3. sxs
  4. 2nd week of disease?
A
  1. structure:
    • small coccobacilli (0.3-0.5 um)
    • stains poorly w/ gram stain,
    • structurally similar to Gram negative bacteria
  2. type of pathogen: obligate intracellular pathogen; infects vascular endothelium. Escapes endocytic vacuole and replicates in the cytoplasm
  3. sxs: vascular vessel damage, rash
  4. 2nd week of disease can get shock syndrome and disseminated intravascular coagulation
19
Q

Rickettsia rickettsii:

  1. diagnosis
  2. treatment
A
  • Diagnosis
    • hx of tick on patient; –> highest incidence April to September
    • direct fluorescence of skin lesion biopsy
    • growth in embryonated hens’ eggs
    • does not stain w/ standard stains so cannot be seen on smears of blood or tissue
  • Treatment
    • doxycycline in first week
    • prior to Abx era: 28% mortality; w/ Abx tx: 1% mortality
20
Q

Rickettsia prowazekii:

  1. reservoir
  2. mechanism
  3. sxs
  4. diagnosis
  5. treatment
A
  1. reservoir: body louse reservoir
  2. mechanism:
    • infected louse bites human and defecates infected feces
    • human scratches adn rickettsia enters the body
  3. sxs: fever, headache, rash, myalgia begin 1-2 wks after bite
  4. diagnosis: serology by indirect fluorescence
  5. treatment: doxycycline
21
Q

Hx of Rickettsia prowazekii

A

an ancient scourge;

Napoleon’s defeat in Russia has been attributed to the weather; but RT-PCR evidence from body segments of lice in graves of soldiers;

extracts of dental pulp of skeletons, shows that lice and soldiers were infected w/ R. prowazekii

22
Q

Where do R. rickettsi and R. prowasekii replicate?

A

these replicate in cytoplasm

23
Q

Ehrlichia & Anaplasma:

similarities and differences

A

Both are both tickborne diseases

  • Ehrlichia chaffeensis: human monocytic Ehrlichiosis
    • Lone star ticks
  • Anaplasma phagocytophilium: human granulocytic anaplasmosis (formerly human granulocyte ehrlichiosis)
    • Ixodes ticks

~10% of people bitten by ticks are co-infected w/ lyme disease

24
Q

Which type of tick causes Anaplasmosis & Lyme disease?

What about Ehrlichiosis?

A
  • Blacklegged tick (Ixodes scapularis) –> Anaplasmosis
  • Lone star tick (Amblyomma americanum) –> Ehrlichiosis
25
Q

How do HME and HGA present histologically?

(Human monocytic ehrlichiosis - HME)

(Human granulocytic anaplasmosis - HGA)

A

Inclusions or morulae

26
Q

Ehrlichiosis and Anaplasmosis:

  1. symptoms
  2. diagnosis
  3. therapy
A
  1. sxs: fever, severe headache, myalgias, chills, fatigue
    • sxs occur 1-2 weeks following tick bite
  2. diagnosis: PCR and/or 4x rise in IgG antibody in acute and convalescent serum as detected by indirect fluorescence
  3. therapy: doxycycline
27
Q

Life cycles of Ixodes ticks

A
  • Primary route:
    • 1st blood metal –> Infected nymph –> infected human
  • Secondary route:
    • 2nd blood metal –> Infected adult –> infected human
28
Q

Mechanism of action: Ehrlichia Infection

A
  • Ehrlichia replicate in the phagosome of monocytes which results in “Incusion Bodies” or morulae visible in the light microscope
  • Ehrlichia in morula then exit the host cell following rupture of the morula –> can then spread the infection
29
Q

Bartonella henselae (cat scratch disease):

  1. sxs
  2. transmission
  3. how was etiologic agent discovered?
  4. type of pathogen
A
  1. sxs: febrile lymphadenitis (enlarged lymph nodes), rash, conjunctivitis, fever, rarely encephalitis, usually self-limiting (many are asymptomatic)
  2. transmission: cat fleas may transmit b/w cats: cats transmit to humans, possibly via fleas. No human-human transmission
  3. how was etiologic agent discovered?
    • discovered in 1983 w/ silver stain
  4. type of pathogen: not an obligate intracellular pathogen; will grow on laboratory medium, but difficult to culture
    • PCR was best for diagnosis
30
Q

Which bacteria can cause bacillary angiomatosis?

Define bacillary angiomatosis.

Patients and symptoms.

A
  • Bartonella henselae and Bartonella quintana
  • Bacillary angiomatosis: a disease characterized by unique vascular lesions caused by infection with small, gram-negative organisms
  • Affects AIDS patients; proliferation of small blood vessels of skin and viscera
31
Q

Compare chlamydia trachomatis, and pneumoniae?

A
  • C. trachomatis: human to human
    • multi. serogroups each causing diff’t diseases; urogenital, incl. conjunctivitis, trachoma
  • C. pneumoniae: human to human
32
Q

Compare Rickettsia rickettsii and prowazekii

A

Rickettsia rickettsii:

  • caused by tick vector –> Rocky Mt. Spotted Fever

Rickettsia prowazekii:

  • caused by louse vector –> Epidemic Typhus
33
Q

Compare Ehrlichia chaffeensis and Anaplasma phagocytophilia

A
  • Ehrlichia chaffeensis:
    • human monocytic Ehrlichiosis: tick vector
  • Anaplasma phagocytophilia:
    • human granulocytic anaplasmosis
    • tick vector same as lyme disease
34
Q

Compare Bartonella henselae and quintana

A

Bartonella: can be cultured on media but fragile and fastidious. Not an obligate intracellular pathogen

  • henselae: cat scratch fever
    • fleas transmit between cats –>
    • cats can transmit to humans, so it is a zoonosis
  • quintana: trench fever and bacillary angiomatosis
    • body louse transmits
35
Q

Chlamydia trachomatis: lymphogranuloma venereum

  • sxs in males
  • sxs in females
A

A sexually transmitted disease:

  • Males: initial small painless ulcer or papule that heals; MSM get proctitis
    • progression to infxn of the inguinal lymph nodes which enlarge, becoming bubos
    • MSM may not get inguinal sxs; generalized sxs may occur
    • late sxs: urethral and rectal strictures, perirectal abscesses, and fissures
  • Females: ulcers may go unnoticed; inguinal sxs do not alwasy occur
    • Get cervicitis and salpingitis

Y1 - Microbio Exam 2 (18 decks)

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