Chlamydia

Question 1

General characteristics

Answer 1

• obligate intracellular pathogen
• have LPS, but no or a very small amount of peptidoglycan –> not susceptible to peptidoglycan inhibiting drugs (ex: penicillin)!!
• are not transmitted by arthropods
• parasitize epithelial cells

Question 2

Elementary body

Answer 2

Metabolically inactive, infectious, adapted for extracellular survival

• 0.3-0.4 um spore-like
• waits to be phagocytized and infect new host cell

Question 3

Reticulate body

Answer 3

Metabolically active, not infectious, adapted for intracellular growth

Question 4

C. abortus

Answer 4

Abortion in small ruminants, mainly sheep

- enzootic abortion of ewes and goats

Question 5

C. felis

Answer 5

Chronic conjunctivitis (chlamydial conjunctivitis), rhinitis, bronchopneumonia
- in stray and domestic cats

Question 6

C. pneumoniae

Answer 6

Respiratory pathogen in people

Question 7

C. psittaci

Answer 7

Avian chlamydiosis (psittacosis)
- in birds or poultry fowl

Question 8

C. suis

Answer 8

Involved in multiple infection sites of the body

- swine

Question 9

C. pecorum

Answer 9

Sporadic bovine encephalomyelitis

- neurologic signs and polyserositis

Question 10

C. trachomatis

Answer 10

Diseases in people

- trachoma, urogenital infection, lymphogranuloma venereum

Question 11

Why is the respiratory system involved?

Answer 11

Aerosol transmission is one of the main infected routes

Question 12

Avian chlamydiosis

Answer 12

Accompanied by conjunctivitis, serositis, fibrinopericarditis, hepatomegaly, anemia

• transmission by fecal-oral route or inhalation
• respiratory discharge contains elementary bodies resistant to drying = remain inactive for months when protected by organic debris
• EB attach to epithelial cells = differentiation to RB that divide and multiply by binary fission = numerous infectious EB

Question 13

Dogs infected with ________

Answer 13

C. psittaci

- bronchopneumonia, fever, dry cough, keratoconjunctivitis

Question 14

Cats infected with _______

Answer 14

C. felis

- rhinitis, conjunctivitis, bronchopneumonia

Question 15

What are the 3 main difficulties in treatment?

Answer 15

• minimal symptomology
• latency of infection
• susceptibility of compromised host to reinfection

Question 16

What are the drugs of choice?

Answer 16

Tretracyclines or fluoroquinolones

Question 17

Prophylactic immunization

Answer 17

Elicits sterilizing immunity and virtually 100% protection from disease
- does not apply to chlamydiae!!

Question 18

C. abortus live vaccines

Answer 18

Prevents abortion in small ruminants

- might be involved in enzootic abortion

Question 19

C. psittaci infection

Answer 19

Lethal intracellular bacteria!
- causes avian chlamydiosis, human psittacosis, seminal vesiculitis, pneumonia in neonates, conjunctivitis, synovial tissue arthritis

Question 20

Diagnosis of avian chlamydiosis

Answer 20

Requires isolation and identification of C. psittaci in chick embryo or cell cultures (BGM, L929, Vero)

Question 21

Avian chlamydiosis treatment

Answer 21

Is a reportable disease!

• no effective vaccine for use in birds
• tetracyclines are antibiotics of choice

Question 22

Feline chlamydiosis

Answer 22

C. felis

• conjunctivitis
• aka: feline pneumonitis (but rarely causes pneumonia)
• untreated = infection will clear spontaneously, may recur every 10-14 days

Question 23

C. abortus in ruminants

Answer 23

Recognized as one of the most important causes of abortion in sheep

• abortion in other species is more sporadic and less common
• aborting ewes should be kept separate until uterine discharges dry up
• pregnant animals can be segregated during lambing and calving seasons

Question 24

C. abortus control

Answer 24

Isolating all affected ewes and lambs, treating in contact ewes with long-acting oxytetracycline or oral tetracycline

Question 25

Epitheliocystis

Answer 25

Disease of the gills of fish

- considered to be chlamydia or chlamydia like organism