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BMS212 - Bacteriology > Rickettsias & Chlamydias > Flashcards

Rickettsias & Chlamydias Flashcards

1
Q

Rickettsias (what they encompass)

-bacterial features

A

-Rickettsia & chlamydia
-Gram neg. bacteria
“between a virus and a bacteria”

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2
Q

How do Rickettsias differ from typical gram neg. bacteria?

A
  • stain poorly w/ gram stain (better w/ Giemsa stain)
  • replicate intracellular & w/ rare excpetions, not capable of free-living existence
  • Cultured only in viable cells (depend on host cell for energy requirements)
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3
Q

What Rickettsias produce disease in

-how easily destroyed

A
  • produce disease in vertebrates, many are zoonotic

- Most easily destroyed by heat and chemical dsinfectants (Q fever is specific exception)

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4
Q

Pathogenesis of Rickettsiales - 2 familes (Rickettsiaceae & Anaplasmataceae)

-what they have an affinity for

A
  • Family Rickettsiaceae have affinity for lymphoreticular endothelial or leucocytic cells
    • vascular damage such as serous effusion and haemorrhages (gives red rash)
  • Family Anaplasmataceae: have affinity for RBC and are associated w/ damage to RBC
    • result in anaemia and maybe haemoglobinuria
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5
Q

Natural reservoir of rickettsiales

A
  • Arthropod in which they multiply
    • usu w/out producing disease
  • vertebrates become infected through bites of infected insects (lice or fleas) or arachnids (ticks and mites)
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6
Q

Typhus and typhus like disease

-several species

A
  • e.g. Epidemic typhus (R. prowasekii)
  • endemic typus (murine typhus) (R. typhi)
  • Rocky mountain spotted fever - v. famous but not in australia (R. rickettsia)
  • Qld tick typhus (R. australis) (aka ‘spotted fever’)
  • scrub typhus (Orientia tsutsugamushi)
    • often disease ass. w/ lots of bush/vegetation
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7
Q

Scrubs typhus (Orientia tsutsugamushi)

A
  • called scrub typhus b.c. gnerally occurs after exposure to areas w/ secondary vegetation
  • Transmitted to humans through bite of trombiculid mites (chiggers)
    • found throughout mite’s body - highest no. occur in salivary glands
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8
Q

Mite Bites

  • what lesion called
  • features
A
  • Incubation period of scrub typhus = 10-12 days
  • flu-like symptoms initially, and swelling of lymph nodes (lymphadenopathy)
  • Lesion (ESCHAR) often seen at site of chigger
  • dull red rash may appear all over body
  • mortality 6-35%
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9
Q

Qld Tick typhus (R. australis)

A
  • Present in Australia and transmitted by tick in marsupial-tick cycle
    • such as Kangaroos
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10
Q

Murine typhus (R. typhi)

A

-Present in Australia
-Usually a milder disease and not fatal
Mice to fleas to man (aerosolisation inhalation infected flea faeces)

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11
Q

Epidemic typhus (T. prowazekii)

A
  • only infects humans
  • transmission cycle = man-louse-man
    • humans = reservoir
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12
Q

Rocky mountain spotted Fever (R. rickettsia)

A
  • Present in N. America, NOT australia
  • pathogen of man, but mild infection can occur in dogs
  • tick transmitted w/ reservoirs in rabbits, rodents, opossums and dogs
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13
Q

Q fever (Coxiella burneti)

  • Main reservoirs
  • ways it can be transmitted
A

-Domestic animals (mainly ruminants) = main reservoir
-can be found in wild animals (i.e. ticks in kangaroos)
*zoonotic
Transmitted by;
-milk
-pregnant sheep
-in abbatoirs
-dust in yards
-animal workers
-farmers

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14
Q

Clinical signs of Q-fever in man

A
  • An influenze-like disease w/ low mortality
  • Usu. abrupt fever; severe and intractable headache, pneumonitis but no rash
  • severe & chronic Q ever may result in complications such as myocarditis, pericarditis or endocaritis
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15
Q

Diagnosis of Q-fever

A

-Isolation of organims hazardous -> most common diagnosis is by detection of specific antibody in serum (first antibody = IgM; second antibody produced = IgG)

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16
Q

Q-Vax Vaccine

A

-Protective immunity lasts for many years in response to a single dose of vaccine

17
Q

Bartonella

  • features
  • B. quintana (AKA?)
  • B. henselae (AKA?)
  • features
A
  • Small gram negative
  • replicates intracelluarly in endothelial cells and erythrocytes (mammalian reservoir hosts)

B. quintana: “trench fever”
-transmitted by body louse

B. henselae: carried by cats
“cat scratch fever”
-fever + lymphadenopathy (swollen lymph nodes)
-ticks/fleas involved in transmission

18
Q

Order: Chlamydia

A
  • 2 genera & 6 species of major significance as pathogens in man & domestic/wild animals
  • e.g.C. tracomatis, C. pneumoniae, C. psittaci, C. felis, C. abortus, C. pecorum
19
Q

Developmental cycle of Chlamydia

A
  • Elementary body attaches to surface of cell
  • endocytosis of EB occurs
  • EB reorganises into reticulate body (which is much bigger)
  • RB replicates by binary fission
  • RBs reorganised to EB
  • Inclusion granule has both RBs and EBs
  • in c. pneumoniae and C. trachomatis = reverse endocytosis
  • in C. psittaci: lysis of cells and inclusions
20
Q

Chlamydial diseases

A
  • tend to run chronic courses
  • can persist in infected individuals or animals for prolonged periods
  • of low pathogenicity except when animals stressed
  • trachoma in man due to C. trachomatis (increases in severity as well as in prevalence when personal hygiene and public sanitation are poor)
21
Q

C. trachomatis

A

-only infects humans (other species have multiple hosts)
2 syndromes;
1. Trachoma
2. Urogenital infection

22
Q

C. trachomatis

-Urinogential tract infections

A
  • sexually transmitted
  • half of infected women and quarter of men may have no symptoms
  • early symptoms include abnormal genital discharge or pain during urination, frequent urination, burning groin
  • men may also develop epididymitis (pain or swelling in scrotal area)
23
Q

C. pneumoniae

-In humans & Koalas

A
  • primarily pathogen in man, but has been isolated from koalas
    • is widespread in koalas, but not significant cause of disease
    • occ. respiratory disease manifest by coughing, sneezing, serous nasal discharge
  • Humans: a common respiratory pathogen in ppl causing mild respiratory signs
24
Q

C. psittaci

A
  • wild and domesticated birds (most domesticated mammales and wild animals)
  • low pathogenicity w/ clinical disease ass w/ stress
  • zoonotic
  • transmission through direct contact or susceptible animals w/ infected animals or fomites
  • inhalation of aerosols containing dried faecal or nasal excretement is also possible
25
Q

C. abortus

A
  • most common infectious cause of abortion in sheep
  • also cause of reproductive failure in cattle, horses and pigs
  • zoonotic and can cause severe, life-threatening disease in pregnant women
  • infection in pregnant women can result in spontaneous abortion or stillbirths
    • typically preceeded by several days of acute influenza like illness (maybe also renal failure, hepatic dysfunction, disseminated intravascular coagulation and possibly death
26
Q

C. felis

A
  • feline chlamydiosis
  • pneumonia and conjuctivitis in cats
  • highly debilitating and contagious
  • sneezing or nasal discharge may develop
  • clinical signs 5-10 days after infection
  • transmission = direct cat-cat contact
  • vaccines commercially available
  • can be zoonotic
27
Q

C. pecurm in koalas

A
  • ocular disease
  • urinogenital tract infection
  • urinary incompetence “wet bottom syndrome”
  • sexual contact, mother to young and possibly by fighting males (transmission)
  • thought koalas acquired infection initially from cattle/sheep
  • spreads through urine
28
Q

Rickettsiales vs. chlamydiales

  • Mode of replication
  • Dependence on host cell
  • Biological vectors
  • what they are susceptible to
  • cross reaction
A

MOR - Rick = fission w/ cross-wall formation, daughter cells w/ infectivity of parent cell
-generation time = 18hrs
-Chlamydiales: defined developmental cycle
-generation time = 30 hrs
Dependence - Rick = Limited dependence on host cell
-chlamyd = extreme dependence on host
Bio vectors = Rick = transmitted by arthrodopods (are natural host)
-chlamyd = arthropods not involved in transmission

  • both are susceptibility to tetracyclines
  • no cross-reaction w/ chlamydia

BMS212 - Bacteriology (15 decks)

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