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Micro/Immuno FINAL > Small G- Pathogens (chlamydiae, rickettsiae, ehrlichia) > Flashcards

Small G- Pathogens (chlamydiae, rickettsiae, ehrlichia) Flashcards

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1
Q

how small is chlamydiae?

A

.25 micrometers- .8 micrometers

just at limit of light microscopy
similar in size to some viruses

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2
Q

is chlamydia G+ or G-?

A

G-

LPS outer membrane and cytoplasmic membrane

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3
Q

does chlamydiae contain peptidoglycan?

A

no peptidoglycan (murein) in cell walls

  • genes are present
  • structure analogous to murein can be seen by EM
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4
Q

what type of pathogen is chlamydiae?

A
  • obligate intracellular pathogen (cannot grow outside of host): grow only inside cells or on live tissues
  • humans, animals, insects, protozoa
  • small genomes (1-1.2 megabases)

*“energy parasites”: depend on host for ATP, auxotrophic for some amino acids

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5
Q

does chlamydiae have a simple development cycle?

A

NO,

  1. for infection
  2. for replication (metabolically active)
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6
Q

what are the 4 species formally recognized in chlamydia classification?

A
  1. c. trachomatis (3 biovars: multiple strains in each)
  2. c. pneumoniae
  3. c. psittaci
  4. c. pecorum
  • 1 & 2 primarily found in human pathogens
  • 3 &4 primarily animal pathogens, but some capable of causing disease in humans
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7
Q

flip for some general facts on chlamydial infections

A
  • leading cause of preventable blindness in THE WORLD
  • the MOST common agents of sexually transmitted bacterial infections
  • speculation that every living adult has had pneumonia (“walking”) caused by c. pneumoniae
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8
Q

how is chlamydia spread?

A
  • droplet or direct contact infection
  • 4 F’s:
    • fingers
    • flies
    • fomites
    • fornication
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9
Q

where does chlamydia infect?

A

mucosal epithelial cells

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10
Q

is chlamydia infection localized or systemic?

A

localized

-eyes, lungs, genitalia

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11
Q

c. trachomatis infections are infections of the genital tract, what do they cause specifically in men and women?

A

men: prostitis, epididymitis
women: cervicitis, PID, premature births, pelvic pain, newborn eye/lung infections
both: urethritis, infertility, procitis, arthritis

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12
Q

is c. trachomatis usually asymptomatic in men or women?

A

WOMEN

chronic and repeat infections can cause sterility and or ectopic pregnancy

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13
Q

are c. trachomatis infections acute or chronic?

A

either!

there is a silent period- orgs location unknown

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14
Q

T/F: asymptomatic carriage results in most damage and scarring

A

TRUEIE

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15
Q

what two things can happen to infants during birth if the mother has chlamydia?

A

infection leading to:

  • conjunctivitis
  • pneumonia
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16
Q

how is chlamydiae internalized into a cell?

A
  • extracellular
    • elementary body (EB) transit form: not metabolically active
  • entry of EBs into epithelial cells: masquerade as nutrients, growth factors, hormones to bind to specific receptors
  • internalized by receptor-mediated endocytosis (endosomal vesicle that bacteria modifies for growth)
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17
Q

how do the EBs modify the endocytic vesicle?

A
  1. maintain pH above 6.2
  2. prevents vesicle from fusion with lysosomes

*vesicle is also modified with host components (glycolipids) for camouflage

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18
Q

what is a RB (reticulate body)?

A

metabolically active, in inclusion bodies get released from epithelial cells by exocytosis when reach a certain threshold

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19
Q

infectious EB change into larger intracellular active organisms (RB) which do what?

A
  • synthesize molecules using host metabolites and energy

- divide by binary fission

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20
Q

how to RB uptake nutrients?

A
  • tube-like structures (“drinking straws”) that allow them to feed on the eukaryotic host cell without leaving the inclusion vacuole
  • 18-23 hollow tubes that protrude from bacterial cell cytoplasm into host cell cytoplasm
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21
Q

what is trachoma?

A

c. trachomatis strains that cause:
- inflamm of conjunctiva, can cause blindness, scarring cornea

-spread by direct contact with eye, nose,and throat secretions from affected individuals, or contact with objects such as towels and/or washcloths

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22
Q

what is lymphogranuloma venerum?

A
  • STD
  • systemic, invasive infection apparent in the lymph nodes that drain the genital tract
  • predominately in developing countries:
  • rare in US (200-400 cases)
  • more common in africa, asia, india, s. america
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23
Q

T/F: chlamydophila pneumoniae perhaps is the least prevalent chamydial pathogen in the human population

A

FALSE its the most

50% of people up to the age of 20 have been infected, 80% of older adults

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24
Q

what kind of body response is elicited in chlamydophila pneumoniae infections?

A
  • usually asymptomatic or acute respiratory response

- chronic resp. infections have been associated with asthma, CF, lung cancer

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25
what type of condition is closely associated with chlamydophila pneumoniae infections?
ATHEROSCLEROTIC HEART LESIONS 40-100% of people with the previous have this infection -usually not problematic unless you have some other disease with it
26
how are chlamydial infections treated?
- metabolic active RB forms are targets of antimicrobials - four membrane layer to penetrate 1. host cell plasma mem 2. inclusion membrane 3. chlamydial outer membrane 4. chlamydial cytoplasmic mem - orgs grow slow so antibiotics must be maintained for long time
27
are EBs susceptible to antibiotic treatement
no because they are not metabolically active
28
rickettsiae is in what shape?
small G- rods that don't stain well
29
what type of pathogen are rickettsiae?
obligate intracellular bacteria
30
how are rickettsiae transmitted?
zoonoses: infections transmitted from animals to humans
31
are rickettsiae energy parasites like chlamydiae?
NO they can synthesize some of their own ATP and are capable of INDEPENDENT METABOLISM but they prefer to use host's
32
do rickettsiae have flagella or endospores?
nopers
33
how are rickettsiae cultured?
- in animals - in embryonated eggs - in cell cultures in the lab
34
describe rickettsiae transmission? what is the common vector?
- rocky mountain wood tick and american dog tick - once infected, a tick can carry the pathogen for life - adult ticks feed on large mammals, including humans, larval and nymph forms feast on small rodents - most tick species require blood meal before developing into next life stage - during feeding as larva or nymph, ticks may become infected with the R. rickettsii bacteria - bacteria pass on the infection to humans as adult ticks, during blood meal - bacteria spread via bloodstream
35
how do rickettsiae attach for spread and multiplication?
- attach to VASCULAR ENDOTHELIAL CELLS (small blood vessels): induce endocytosis - once inside, presumably lyse the phagosome (PHOSPHOLIPASE) and enter the cytosol - engulfed through receptor mediated endocytosis - mode of exit from cell VARIES
36
where does rickettsiae replicate?
cytosol
37
how does R. prowazekii exit the cell?
lysis
38
how does R. rickettsii exit the cell?
- gets extruded from the cell through local projections (filopodia) - actin in the host cell associates with R. rickettsii and the actin helps to "push" the bacteria thru the filopodia
39
how does R. tsutsugamushi exit the cell?
- exits by budding thru the cell membrane - remains enveloped in the host cell membrane as it infects other cells - binds to neighboring cells=merging of membranes
40
T/F: the degree of injury to the host is proportional to the number of intracellular bacteria
TRUE
41
how are hemorrhagic spots created in infections with rickettsiae?
from lysis of cells resulting in the leakage of blood (rash)
42
can rickettsiae travel to the heart and brain?
for sure
43
T/F: 10% of patients will clear the infection even before antimicrobial treatment
75%%%%%
44
what are the 3 typhus group fevers caused by?
1. R. prowazekii 2. R. typhi 3. Orientia (formeraly rickettsia) tsutsugamushi
45
describe the fever from R. prowazekii
typhus fever purplish rash, RECRUDESCENT typhus (reactivation of the dormant agent seen in US), transmitted by human lice
46
describe the fever from R. typhi
more prevalent and wide spread, MURINE TYPHUS, transmitted by rats and rat fleas
47
describe the fever from orientia tsutsugamushi
SCRUB TYPHUS, variety of antigenic types, NO RASH
48
what type of pathogen is Ehrlichia?
obligate intracellular bacteria
49
how is Ehrlichia transmitted?
by lone star tick
50
what immune cells does Ehrlichia infect?
- monocytes and macrophages | - human granulocytic ehrlichiosis (HGE) and human monocytic ehrlichiosis (HME)
51
what symptoms arise from infection with Ehrlichia?
fever, malaise, headache and myalgia
52
how does Ehrlichia develop first?
develops first as reticulate cells (RC) and then as dense-core cells (DC)
53
how are rickettsioses diagnosed?
- problematic: * during 1st visit, pts don't typically have fever or rash, and may not be aware of tick bite * require eukaryotic cell cultures or innoculation of animals * handling is notoriously hazardous - clinical diagnostic tests * antibody titers * fluorescent antibody assay * complement fixation * latex agglutination
54
what is mycoplasma?
-smallest organisms capable of growth on cell-free media
55
what does mycoplasma require?
sterol (cholesterol) because bacteria don't have a cell wall
56
what characteristic appearance does mycoplasma have?
fried egg appearance
57
does mycoplasma grow in small or large colonies and at a fast or slow rate?
small and slow
58
what does mycoplasma lack?
cell wall (no murein) so not sensitive to penicilin
59
where is mycoplasma found?
humans, other mammals, and birds
60
what are the 4 mycoplasma species that cause disease?
1. m. pneumoniae: prototype mycoplasma, primary atypical pneumonia 2. m. genitalium 3. m. hominis 4. ureaplasma urealyticum * *2-4 are genitourinary tract infections
61
T/F: some mycoplasmas are part of the normal human oral flora
TRUEEE
62
what is the only reservoir of m. pneuominae?
humans | -unlike pneumococci, prolonged asymptomatic colonization is uncommon
63
are m. pneumoniae infections contagious?
mild and moderately contagious spread through close-contact group passed by respiratory droplets
64
describe "walking pneumonia."
primary atypical pneumonia not cleared by penicillin, presents differently because just affecting respiratory epithelium
65
what epithelium does m. pneumoniae adhere to?
respiratory epithelium: terminal adhesion structures, tip-mediated attachment organelle
66
what are the main cells of the inflammatory response to mycoplasmas?
lymphocytes
67
what is unusual about the spread of mycoplasmas?
- largely limited to the respiratory mucosa that lines the airways - doesn't get into the lung alveoli - bronchopneumonia
68
do mycoplasmas cause a lot of tissue destruction?
- no highly destructive of tissues, but ciliary function of bronchioles is impaired * tissue toxic substances may include H2O2 * inflamm mediators
69
what other damage can mycoplasmas cause?
- hemolytic anemia * IgM=cold hemagglutinins * at lower temps, these antibodies cause RBCs to stick together & partial lysis, @ mucosal surfaces * detectable in 50% of cases * clinically significant hemolysis is rare - encephalitis: spread to brain - erythma multiforme (rash): systemic
70
which of the genital mycoplasmas is the newest emerging human pathogen, what can it cause, and where is it isolated from?
m. genitalium: - urethritis, cervicitis, endometritis, PID - isolated from synovial and resp fluids - a lot like m. pneumoniae
71
which two genital mycoplasmas are frequently associated with disease in newborns?
- m. hominis and u. urealyticum - commonly found in resp and genitourinary tracts - present in most of the sexually active population
72
how are m. hominis and u. urealyticum isolated in newborns and do they always cause disease?
spinal fluid and they only cause disease in susceptible individuals

Micro/Immuno FINAL (16 decks)

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